llvm-project/llvm/test/CodeGen/X86/peephole-recurrence.mir

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Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
# RUN: llc -mtriple=x86_64-- -run-pass=peephole-opt -o - %s | FileCheck %s
--- |
define i32 @foo(i32 %a) {
bb0:
br label %bb1
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb1: ; preds = %bb7, %bb0
%vreg0 = phi i32 [ 0, %bb0 ], [ %vreg3, %bb7 ]
%cond0 = icmp eq i32 %a, 0
br i1 %cond0, label %bb4, label %bb3
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb3: ; preds = %bb1
br label %bb4
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb4: ; preds = %bb1, %bb3
%vreg5 = phi i32 [ 2, %bb3 ], [ 1, %bb1 ]
%cond1 = icmp eq i32 %vreg5, 0
br i1 %cond1, label %bb7, label %bb6
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb6: ; preds = %bb4
br label %bb7
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb7: ; preds = %bb4, %bb6
%vreg1 = phi i32 [ 2, %bb6 ], [ 1, %bb4 ]
%vreg2 = add i32 %vreg5, %vreg0
%vreg3 = add i32 %vreg1, %vreg2
%cond2 = icmp slt i32 %vreg3, 10
br i1 %cond2, label %bb1, label %bb8
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb8: ; preds = %bb7
ret i32 0
}
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
define i32 @bar(i32 %a, i32* %p) {
bb0:
br label %bb1
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb1: ; preds = %bb7, %bb0
%vreg0 = phi i32 [ 0, %bb0 ], [ %vreg3, %bb7 ]
%cond0 = icmp eq i32 %a, 0
br i1 %cond0, label %bb4, label %bb3
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb3: ; preds = %bb1
br label %bb4
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb4: ; preds = %bb1, %bb3
%vreg5 = phi i32 [ 2, %bb3 ], [ 1, %bb1 ]
%cond1 = icmp eq i32 %vreg5, 0
br i1 %cond1, label %bb7, label %bb6
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb6: ; preds = %bb4
br label %bb7
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb7: ; preds = %bb4, %bb6
%vreg1 = phi i32 [ 2, %bb6 ], [ 1, %bb4 ]
%vreg2 = add i32 %vreg5, %vreg0
store i32 %vreg0, i32* %p
%vreg3 = add i32 %vreg1, %vreg2
%cond2 = icmp slt i32 %vreg3, 10
br i1 %cond2, label %bb1, label %bb8
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb8: ; preds = %bb7
ret i32 0
}
...
---
# There is a recurrence formulated around %0, %10, and %3. Check that operands
# are commuted for ADD instructions in bb.5.bb7 so that the values involved in
# the recurrence are tied. This will remove redundant copy instruction.
name: foo
tracksRegLiveness: true
registers:
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
- { id: 0, class: gr32, preferred-register: '' }
- { id: 1, class: gr32, preferred-register: '' }
- { id: 2, class: gr32, preferred-register: '' }
- { id: 3, class: gr32, preferred-register: '' }
- { id: 4, class: gr32, preferred-register: '' }
- { id: 5, class: gr32, preferred-register: '' }
- { id: 6, class: gr32, preferred-register: '' }
- { id: 7, class: gr32, preferred-register: '' }
- { id: 8, class: gr32, preferred-register: '' }
- { id: 9, class: gr32, preferred-register: '' }
- { id: 10, class: gr32, preferred-register: '' }
- { id: 11, class: gr32, preferred-register: '' }
- { id: 12, class: gr32, preferred-register: '' }
liveins:
- { reg: '$edi', virtual-reg: '%4' }
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
body: |
bb.0.bb0:
successors: %bb.1(0x80000000)
liveins: $edi
%4 = COPY $edi
%5 = MOV32r0 implicit-def dead $eflags
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.1.bb1:
successors: %bb.3(0x30000000), %bb.2(0x50000000)
; CHECK: %0:gr32 = PHI %5, %bb.0, %3, %bb.5
%0 = PHI %5, %bb.0, %3, %bb.5
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
%6 = MOV32ri 1
TEST32rr %4, %4, implicit-def $eflags
JE_1 %bb.3, implicit $eflags
JMP_1 %bb.2
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.2.bb3:
successors: %bb.3(0x80000000)
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
%7 = MOV32ri 2
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.3.bb4:
successors: %bb.5(0x30000000), %bb.4(0x50000000)
%1 = PHI %6, %bb.1, %7, %bb.2
TEST32rr %1, %1, implicit-def $eflags
JE_1 %bb.5, implicit $eflags
JMP_1 %bb.4
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.4.bb6:
successors: %bb.5(0x80000000)
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
%9 = MOV32ri 2
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.5.bb7:
successors: %bb.1(0x7c000000), %bb.6(0x04000000)
%2 = PHI %6, %bb.3, %9, %bb.4
%10 = ADD32rr %1, %0, implicit-def dead $eflags
; CHECK: %10:gr32 = ADD32rr
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
; CHECK-SAME: %0,
; CHECK-SAME: %1,
%3 = ADD32rr %2, killed %10, implicit-def dead $eflags
; CHECK: %3:gr32 = ADD32rr
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
; CHECK-SAME: %10,
; CHECK-SAME: %2,
%11 = SUB32ri8 %3, 10, implicit-def $eflags
JL_1 %bb.1, implicit $eflags
JMP_1 %bb.6
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.6.bb8:
%12 = MOV32r0 implicit-def dead $eflags
$eax = COPY %12
RET 0, $eax
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
...
---
# Here a recurrence is formulated around %0, %11, and %3, but operands should
# not be commuted because %0 has a use outside of recurrence. This is to
# prevent the case of commuting operands ties the values with overlapping live
# ranges.
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
name: bar
tracksRegLiveness: true
registers:
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
- { id: 0, class: gr32, preferred-register: '' }
- { id: 1, class: gr32, preferred-register: '' }
- { id: 2, class: gr32, preferred-register: '' }
- { id: 3, class: gr32, preferred-register: '' }
- { id: 4, class: gr32, preferred-register: '' }
- { id: 5, class: gr64, preferred-register: '' }
- { id: 6, class: gr32, preferred-register: '' }
- { id: 7, class: gr32, preferred-register: '' }
- { id: 8, class: gr32, preferred-register: '' }
- { id: 9, class: gr32, preferred-register: '' }
- { id: 10, class: gr32, preferred-register: '' }
- { id: 11, class: gr32, preferred-register: '' }
- { id: 12, class: gr32, preferred-register: '' }
- { id: 13, class: gr32, preferred-register: '' }
liveins:
- { reg: '$edi', virtual-reg: '%4' }
- { reg: '$rsi', virtual-reg: '%5' }
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
body: |
bb.0.bb0:
successors: %bb.1(0x80000000)
liveins: $edi, $rsi
%5 = COPY $rsi
%4 = COPY $edi
%6 = MOV32r0 implicit-def dead $eflags
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.1.bb1:
successors: %bb.3(0x30000000), %bb.2(0x50000000)
%0 = PHI %6, %bb.0, %3, %bb.5
; CHECK: %0:gr32 = PHI %6, %bb.0, %3, %bb.5
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
%7 = MOV32ri 1
TEST32rr %4, %4, implicit-def $eflags
JE_1 %bb.3, implicit $eflags
JMP_1 %bb.2
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.2.bb3:
successors: %bb.3(0x80000000)
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
%8 = MOV32ri 2
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.3.bb4:
successors: %bb.5(0x30000000), %bb.4(0x50000000)
%1 = PHI %7, %bb.1, %8, %bb.2
TEST32rr %1, %1, implicit-def $eflags
JE_1 %bb.5, implicit $eflags
JMP_1 %bb.4
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.4.bb6:
successors: %bb.5(0x80000000)
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
%10 = MOV32ri 2
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.5.bb7:
successors: %bb.1(0x7c000000), %bb.6(0x04000000)
%2 = PHI %7, %bb.3, %10, %bb.4
%11 = ADD32rr %1, %0, implicit-def dead $eflags
; CHECK: %11:gr32 = ADD32rr
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
; CHECK-SAME: %1,
; CHECK-SAME: %0,
MOV32mr %5, 1, $noreg, 0, $noreg, %0 :: (store 4 into %ir.p)
%3 = ADD32rr %2, killed %11, implicit-def dead $eflags
; CHECK: %3:gr32 = ADD32rr
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
; CHECK-SAME: %2,
; CHECK-SAME: %11,
%12 = SUB32ri8 %3, 10, implicit-def $eflags
JL_1 %bb.1, implicit $eflags
JMP_1 %bb.6
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
bb.6.bb8:
%13 = MOV32r0 implicit-def dead $eflags
$eax = COPY %13
RET 0, $eax
Remove redundant copy in recurrences Summary: If there is a chain of instructions formulating a recurrence, commuting operands can help removing a redundant copy. In the following example code, ``` BB#1: ; Loop Header %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: ; Loop Latch %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def,tied1> = ADD32rr %vreg1<kill,tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1,%vreg0 %vreg3<def,tied1> = ADD32rr %vreg2<kill,tied0>, %vreg10<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2,%vreg10 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> ``` Existing two-address generation pass generates following code: ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg1<kill>; GR32:%vreg10,%vreg1 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg0<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg0 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` This is suboptimal because the assembly code generated has a redundant copy at the end of #BB6 to feed %vreg13 to BB#1: ``` .LBB0_6: addl %esi, %edi addl %ebx, %edi cmpl $10, %edi movl %edi, %esi jl .LBB0_1 ``` This redundant copy can be elimiated by making instructions in the recurrence chain to compute the value "into" the register that actually holds the feedback value. In this example, this can be achieved by commuting %vreg0 and %vreg1 to compute %vreg10. With that change, code after two-address generation becomes ``` BB#1: %vreg0<def> = COPY %vreg13<kill>; GR32:%vreg0,%vreg13 ... BB#6: derived from LLVM BB %bb7 Predecessors according to CFG: BB#5 BB#4 %vreg2<def> = COPY %vreg15<kill>; GR32:%vreg2,%vreg15 %vreg10<def> = COPY %vreg0<kill>; GR32:%vreg10,%vreg0 %vreg10<def,tied1> = ADD32rr %vreg10<tied0>, %vreg1<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg10,%vreg1 %vreg3<def> = COPY %vreg10<kill>; GR32:%vreg3,%vreg10 %vreg3<def,tied1> = ADD32rr %vreg3<tied0>, %vreg2<kill>, %EFLAGS<imp-def,dead>; GR32:%vreg3,%vreg2 CMP32ri8 %vreg3, 10, %EFLAGS<imp-def>; GR32:%vreg3 %vreg13<def> = COPY %vreg3<kill>; GR32:%vreg13,%vreg3 JL_1 <BB#1>, %EFLAGS<imp-use,kill> JMP_1 <BB#7> ``` and the final assembly does not have redundant copy: ``` .LBB0_6: addl %edi, %eax addl %ebx, %eax cmpl $10, %eax jl .LBB0_1 ``` Reviewers: qcolombet, MatzeB, wmi Reviewed By: wmi Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D31821 llvm-svn: 306758
2017-06-30 07:11:24 +08:00
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