llvm-project/llvm/test/CodeGen/X86/pr32345.ll

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; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -fast-isel-sink-local-values -O0 -mtriple=x86_64-unknown-linux-gnu -o - %s | FileCheck %s -check-prefix=X640
; RUN: llc -fast-isel-sink-local-values -O0 -mtriple=i686-unknown -o - %s | FileCheck %s -check-prefix=6860
; RUN: llc -fast-isel-sink-local-values -mtriple=x86_64-unknown-linux-gnu -o - %s | FileCheck %s -check-prefix=X64
; RUN: llc -fast-isel-sink-local-values -mtriple=i686-unknown -o - %s | FileCheck %s -check-prefix=686
@var_22 = external global i16, align 2
@var_27 = external global i16, align 2
define void @foo() {
; X640-LABEL: foo:
; X640: # %bb.0: # %bb
[FastISel] Sink local value materializations to first use Summary: Local values are constants, global addresses, and stack addresses that can't be folded into the instruction that uses them. For example, when storing the address of a global variable into memory, we need to materialize that address into a register. FastISel doesn't want to materialize any given local value more than once, so it generates all local value materialization code at EmitStartPt, which always dominates the current insertion point. This allows it to maintain a map of local value registers, and it knows that the local value area will always dominate the current insertion point. The downside is that local value instructions are always emitted without a source location. This is done to prevent jumpy line tables, but it means that the local value area will be considered part of the previous statement. Consider this C code: call1(); // line 1 ++global; // line 2 ++global; // line 3 call2(&global, &local); // line 4 Today we end up with assembly and line tables like this: .loc 1 1 callq call1 leaq global(%rip), %rdi leaq local(%rsp), %rsi .loc 1 2 addq $1, global(%rip) .loc 1 3 addq $1, global(%rip) .loc 1 4 callq call2 The LEA instructions in the local value area have no source location and are treated as being on line 1. Stepping through the code in a debugger and correlating it with the assembly won't make much sense, because these materializations are only required for line 4. This is actually problematic for the VS debugger "set next statement" feature, which effectively assumes that there are no registers live across statement boundaries. By sinking the local value code into the statement and fixing up the source location, we can make that feature work. This was filed as https://bugs.llvm.org/show_bug.cgi?id=35975 and https://crbug.com/793819. This change is obviously not enough to make this feature work reliably in all cases, but I felt that it was worth doing anyway because it usually generates smaller, more comprehensible -O0 code. I measured a 0.12% regression in code generation time with LLC on the sqlite3 amalgamation, so I think this is worth doing. There are some special cases worth calling out in the commit message: 1. local values materialized for phis 2. local values used by no-op casts 3. dead local value code Local values can be materialized for phis, and this does not show up as a vreg use in MachineRegisterInfo. In this case, if there are no other uses, this patch sinks the value to the first terminator, EH label, or the end of the BB if nothing else exists. Local values may also be used by no-op casts, which adds the register to the RegFixups table. Without reversing the RegFixups map direction, we don't have enough information to sink these instructions. Lastly, if the local value register has no other uses, we can delete it. This comes up when fastisel tries two instruction selection approaches and the first materializes the value but fails and the second succeeds without using the local value. Reviewers: aprantl, dblaikie, qcolombet, MatzeB, vsk, echristo Subscribers: dotdash, chandlerc, hans, sdardis, amccarth, javed.absar, zturner, llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D43093 llvm-svn: 327581
2018-03-15 05:54:21 +08:00
; X640-NEXT: movzwl var_22, %eax
; X640-NEXT: movzwl var_27, %ecx
[FastISel] Sink local value materializations to first use Summary: Local values are constants, global addresses, and stack addresses that can't be folded into the instruction that uses them. For example, when storing the address of a global variable into memory, we need to materialize that address into a register. FastISel doesn't want to materialize any given local value more than once, so it generates all local value materialization code at EmitStartPt, which always dominates the current insertion point. This allows it to maintain a map of local value registers, and it knows that the local value area will always dominate the current insertion point. The downside is that local value instructions are always emitted without a source location. This is done to prevent jumpy line tables, but it means that the local value area will be considered part of the previous statement. Consider this C code: call1(); // line 1 ++global; // line 2 ++global; // line 3 call2(&global, &local); // line 4 Today we end up with assembly and line tables like this: .loc 1 1 callq call1 leaq global(%rip), %rdi leaq local(%rsp), %rsi .loc 1 2 addq $1, global(%rip) .loc 1 3 addq $1, global(%rip) .loc 1 4 callq call2 The LEA instructions in the local value area have no source location and are treated as being on line 1. Stepping through the code in a debugger and correlating it with the assembly won't make much sense, because these materializations are only required for line 4. This is actually problematic for the VS debugger "set next statement" feature, which effectively assumes that there are no registers live across statement boundaries. By sinking the local value code into the statement and fixing up the source location, we can make that feature work. This was filed as https://bugs.llvm.org/show_bug.cgi?id=35975 and https://crbug.com/793819. This change is obviously not enough to make this feature work reliably in all cases, but I felt that it was worth doing anyway because it usually generates smaller, more comprehensible -O0 code. I measured a 0.12% regression in code generation time with LLC on the sqlite3 amalgamation, so I think this is worth doing. There are some special cases worth calling out in the commit message: 1. local values materialized for phis 2. local values used by no-op casts 3. dead local value code Local values can be materialized for phis, and this does not show up as a vreg use in MachineRegisterInfo. In this case, if there are no other uses, this patch sinks the value to the first terminator, EH label, or the end of the BB if nothing else exists. Local values may also be used by no-op casts, which adds the register to the RegFixups table. Without reversing the RegFixups map direction, we don't have enough information to sink these instructions. Lastly, if the local value register has no other uses, we can delete it. This comes up when fastisel tries two instruction selection approaches and the first materializes the value but fails and the second succeeds without using the local value. Reviewers: aprantl, dblaikie, qcolombet, MatzeB, vsk, echristo Subscribers: dotdash, chandlerc, hans, sdardis, amccarth, javed.absar, zturner, llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D43093 llvm-svn: 327581
2018-03-15 05:54:21 +08:00
; X640-NEXT: xorl %ecx, %eax
; X640-NEXT: movzwl var_27, %ecx
; X640-NEXT: xorl %ecx, %eax
; X640-NEXT: movslq %eax, %rdx
; X640-NEXT: movq %rdx, -{{[0-9]+}}(%rsp)
; X640-NEXT: movzwl var_22, %eax
; X640-NEXT: movzwl var_27, %ecx
; X640-NEXT: xorl %ecx, %eax
; X640-NEXT: movzwl var_27, %ecx
; X640-NEXT: xorl %ecx, %eax
; X640-NEXT: movslq %eax, %rdx
; X640-NEXT: movzwl var_27, %eax
; X640-NEXT: subl $16610, %eax # imm = 0x40E2
; X640-NEXT: movl %eax, %eax
; X640-NEXT: movl %eax, %ecx
; X640-NEXT: # kill: def $cl killed $rcx
[FastISel] Sink local value materializations to first use Summary: Local values are constants, global addresses, and stack addresses that can't be folded into the instruction that uses them. For example, when storing the address of a global variable into memory, we need to materialize that address into a register. FastISel doesn't want to materialize any given local value more than once, so it generates all local value materialization code at EmitStartPt, which always dominates the current insertion point. This allows it to maintain a map of local value registers, and it knows that the local value area will always dominate the current insertion point. The downside is that local value instructions are always emitted without a source location. This is done to prevent jumpy line tables, but it means that the local value area will be considered part of the previous statement. Consider this C code: call1(); // line 1 ++global; // line 2 ++global; // line 3 call2(&global, &local); // line 4 Today we end up with assembly and line tables like this: .loc 1 1 callq call1 leaq global(%rip), %rdi leaq local(%rsp), %rsi .loc 1 2 addq $1, global(%rip) .loc 1 3 addq $1, global(%rip) .loc 1 4 callq call2 The LEA instructions in the local value area have no source location and are treated as being on line 1. Stepping through the code in a debugger and correlating it with the assembly won't make much sense, because these materializations are only required for line 4. This is actually problematic for the VS debugger "set next statement" feature, which effectively assumes that there are no registers live across statement boundaries. By sinking the local value code into the statement and fixing up the source location, we can make that feature work. This was filed as https://bugs.llvm.org/show_bug.cgi?id=35975 and https://crbug.com/793819. This change is obviously not enough to make this feature work reliably in all cases, but I felt that it was worth doing anyway because it usually generates smaller, more comprehensible -O0 code. I measured a 0.12% regression in code generation time with LLC on the sqlite3 amalgamation, so I think this is worth doing. There are some special cases worth calling out in the commit message: 1. local values materialized for phis 2. local values used by no-op casts 3. dead local value code Local values can be materialized for phis, and this does not show up as a vreg use in MachineRegisterInfo. In this case, if there are no other uses, this patch sinks the value to the first terminator, EH label, or the end of the BB if nothing else exists. Local values may also be used by no-op casts, which adds the register to the RegFixups table. Without reversing the RegFixups map direction, we don't have enough information to sink these instructions. Lastly, if the local value register has no other uses, we can delete it. This comes up when fastisel tries two instruction selection approaches and the first materializes the value but fails and the second succeeds without using the local value. Reviewers: aprantl, dblaikie, qcolombet, MatzeB, vsk, echristo Subscribers: dotdash, chandlerc, hans, sdardis, amccarth, javed.absar, zturner, llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D43093 llvm-svn: 327581
2018-03-15 05:54:21 +08:00
; X640-NEXT: sarq %cl, %rdx
; X640-NEXT: # kill: def $dl killed $dl killed $rdx
; X640-NEXT: # implicit-def: $rsi
; X640-NEXT: movb %dl, (%rsi)
; X640-NEXT: retq
;
; 6860-LABEL: foo:
; 6860: # %bb.0: # %bb
; 6860-NEXT: pushl %ebp
; 6860-NEXT: .cfi_def_cfa_offset 8
; 6860-NEXT: .cfi_offset %ebp, -8
; 6860-NEXT: movl %esp, %ebp
; 6860-NEXT: .cfi_def_cfa_register %ebp
; 6860-NEXT: pushl %ebx
; 6860-NEXT: pushl %edi
; 6860-NEXT: pushl %esi
; 6860-NEXT: andl $-8, %esp
; 6860-NEXT: subl $32, %esp
; 6860-NEXT: .cfi_offset %esi, -20
; 6860-NEXT: .cfi_offset %edi, -16
; 6860-NEXT: .cfi_offset %ebx, -12
[FastISel] Sink local value materializations to first use Summary: Local values are constants, global addresses, and stack addresses that can't be folded into the instruction that uses them. For example, when storing the address of a global variable into memory, we need to materialize that address into a register. FastISel doesn't want to materialize any given local value more than once, so it generates all local value materialization code at EmitStartPt, which always dominates the current insertion point. This allows it to maintain a map of local value registers, and it knows that the local value area will always dominate the current insertion point. The downside is that local value instructions are always emitted without a source location. This is done to prevent jumpy line tables, but it means that the local value area will be considered part of the previous statement. Consider this C code: call1(); // line 1 ++global; // line 2 ++global; // line 3 call2(&global, &local); // line 4 Today we end up with assembly and line tables like this: .loc 1 1 callq call1 leaq global(%rip), %rdi leaq local(%rsp), %rsi .loc 1 2 addq $1, global(%rip) .loc 1 3 addq $1, global(%rip) .loc 1 4 callq call2 The LEA instructions in the local value area have no source location and are treated as being on line 1. Stepping through the code in a debugger and correlating it with the assembly won't make much sense, because these materializations are only required for line 4. This is actually problematic for the VS debugger "set next statement" feature, which effectively assumes that there are no registers live across statement boundaries. By sinking the local value code into the statement and fixing up the source location, we can make that feature work. This was filed as https://bugs.llvm.org/show_bug.cgi?id=35975 and https://crbug.com/793819. This change is obviously not enough to make this feature work reliably in all cases, but I felt that it was worth doing anyway because it usually generates smaller, more comprehensible -O0 code. I measured a 0.12% regression in code generation time with LLC on the sqlite3 amalgamation, so I think this is worth doing. There are some special cases worth calling out in the commit message: 1. local values materialized for phis 2. local values used by no-op casts 3. dead local value code Local values can be materialized for phis, and this does not show up as a vreg use in MachineRegisterInfo. In this case, if there are no other uses, this patch sinks the value to the first terminator, EH label, or the end of the BB if nothing else exists. Local values may also be used by no-op casts, which adds the register to the RegFixups table. Without reversing the RegFixups map direction, we don't have enough information to sink these instructions. Lastly, if the local value register has no other uses, we can delete it. This comes up when fastisel tries two instruction selection approaches and the first materializes the value but fails and the second succeeds without using the local value. Reviewers: aprantl, dblaikie, qcolombet, MatzeB, vsk, echristo Subscribers: dotdash, chandlerc, hans, sdardis, amccarth, javed.absar, zturner, llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D43093 llvm-svn: 327581
2018-03-15 05:54:21 +08:00
; 6860-NEXT: movw var_22, %ax
; 6860-NEXT: movzwl var_27, %ecx
; 6860-NEXT: movw %cx, %dx
; 6860-NEXT: xorw %dx, %ax
; 6860-NEXT: # implicit-def: $esi
; 6860-NEXT: movw %ax, %si
; 6860-NEXT: xorl %ecx, %esi
; 6860-NEXT: # kill: def $si killed $si killed $esi
; 6860-NEXT: movzwl %si, %ecx
[FastISel] Sink local value materializations to first use Summary: Local values are constants, global addresses, and stack addresses that can't be folded into the instruction that uses them. For example, when storing the address of a global variable into memory, we need to materialize that address into a register. FastISel doesn't want to materialize any given local value more than once, so it generates all local value materialization code at EmitStartPt, which always dominates the current insertion point. This allows it to maintain a map of local value registers, and it knows that the local value area will always dominate the current insertion point. The downside is that local value instructions are always emitted without a source location. This is done to prevent jumpy line tables, but it means that the local value area will be considered part of the previous statement. Consider this C code: call1(); // line 1 ++global; // line 2 ++global; // line 3 call2(&global, &local); // line 4 Today we end up with assembly and line tables like this: .loc 1 1 callq call1 leaq global(%rip), %rdi leaq local(%rsp), %rsi .loc 1 2 addq $1, global(%rip) .loc 1 3 addq $1, global(%rip) .loc 1 4 callq call2 The LEA instructions in the local value area have no source location and are treated as being on line 1. Stepping through the code in a debugger and correlating it with the assembly won't make much sense, because these materializations are only required for line 4. This is actually problematic for the VS debugger "set next statement" feature, which effectively assumes that there are no registers live across statement boundaries. By sinking the local value code into the statement and fixing up the source location, we can make that feature work. This was filed as https://bugs.llvm.org/show_bug.cgi?id=35975 and https://crbug.com/793819. This change is obviously not enough to make this feature work reliably in all cases, but I felt that it was worth doing anyway because it usually generates smaller, more comprehensible -O0 code. I measured a 0.12% regression in code generation time with LLC on the sqlite3 amalgamation, so I think this is worth doing. There are some special cases worth calling out in the commit message: 1. local values materialized for phis 2. local values used by no-op casts 3. dead local value code Local values can be materialized for phis, and this does not show up as a vreg use in MachineRegisterInfo. In this case, if there are no other uses, this patch sinks the value to the first terminator, EH label, or the end of the BB if nothing else exists. Local values may also be used by no-op casts, which adds the register to the RegFixups table. Without reversing the RegFixups map direction, we don't have enough information to sink these instructions. Lastly, if the local value register has no other uses, we can delete it. This comes up when fastisel tries two instruction selection approaches and the first materializes the value but fails and the second succeeds without using the local value. Reviewers: aprantl, dblaikie, qcolombet, MatzeB, vsk, echristo Subscribers: dotdash, chandlerc, hans, sdardis, amccarth, javed.absar, zturner, llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D43093 llvm-svn: 327581
2018-03-15 05:54:21 +08:00
; 6860-NEXT: movl %ecx, {{[0-9]+}}(%esp)
; 6860-NEXT: movl $0, {{[0-9]+}}(%esp)
[FastISel] Sink local value materializations to first use Summary: Local values are constants, global addresses, and stack addresses that can't be folded into the instruction that uses them. For example, when storing the address of a global variable into memory, we need to materialize that address into a register. FastISel doesn't want to materialize any given local value more than once, so it generates all local value materialization code at EmitStartPt, which always dominates the current insertion point. This allows it to maintain a map of local value registers, and it knows that the local value area will always dominate the current insertion point. The downside is that local value instructions are always emitted without a source location. This is done to prevent jumpy line tables, but it means that the local value area will be considered part of the previous statement. Consider this C code: call1(); // line 1 ++global; // line 2 ++global; // line 3 call2(&global, &local); // line 4 Today we end up with assembly and line tables like this: .loc 1 1 callq call1 leaq global(%rip), %rdi leaq local(%rsp), %rsi .loc 1 2 addq $1, global(%rip) .loc 1 3 addq $1, global(%rip) .loc 1 4 callq call2 The LEA instructions in the local value area have no source location and are treated as being on line 1. Stepping through the code in a debugger and correlating it with the assembly won't make much sense, because these materializations are only required for line 4. This is actually problematic for the VS debugger "set next statement" feature, which effectively assumes that there are no registers live across statement boundaries. By sinking the local value code into the statement and fixing up the source location, we can make that feature work. This was filed as https://bugs.llvm.org/show_bug.cgi?id=35975 and https://crbug.com/793819. This change is obviously not enough to make this feature work reliably in all cases, but I felt that it was worth doing anyway because it usually generates smaller, more comprehensible -O0 code. I measured a 0.12% regression in code generation time with LLC on the sqlite3 amalgamation, so I think this is worth doing. There are some special cases worth calling out in the commit message: 1. local values materialized for phis 2. local values used by no-op casts 3. dead local value code Local values can be materialized for phis, and this does not show up as a vreg use in MachineRegisterInfo. In this case, if there are no other uses, this patch sinks the value to the first terminator, EH label, or the end of the BB if nothing else exists. Local values may also be used by no-op casts, which adds the register to the RegFixups table. Without reversing the RegFixups map direction, we don't have enough information to sink these instructions. Lastly, if the local value register has no other uses, we can delete it. This comes up when fastisel tries two instruction selection approaches and the first materializes the value but fails and the second succeeds without using the local value. Reviewers: aprantl, dblaikie, qcolombet, MatzeB, vsk, echristo Subscribers: dotdash, chandlerc, hans, sdardis, amccarth, javed.absar, zturner, llvm-commits, hiraditya Differential Revision: https://reviews.llvm.org/D43093 llvm-svn: 327581
2018-03-15 05:54:21 +08:00
; 6860-NEXT: movw var_22, %ax
; 6860-NEXT: movzwl var_27, %ecx
; 6860-NEXT: movw %cx, %dx
; 6860-NEXT: xorw %dx, %ax
; 6860-NEXT: # implicit-def: $edi
; 6860-NEXT: movw %ax, %di
; 6860-NEXT: xorl %ecx, %edi
; 6860-NEXT: # kill: def $di killed $di killed $edi
; 6860-NEXT: movzwl %di, %ebx
; 6860-NEXT: # kill: def $cl killed $cl killed $ecx
; 6860-NEXT: addb $30, %cl
; 6860-NEXT: xorl %eax, %eax
; 6860-NEXT: movb %cl, {{[-0-9]+}}(%e{{[sb]}}p) # 1-byte Spill
; 6860-NEXT: shrdl %cl, %eax, %ebx
; 6860-NEXT: movb {{[-0-9]+}}(%e{{[sb]}}p), %cl # 1-byte Reload
; 6860-NEXT: testb $32, %cl
; 6860-NEXT: movl %ebx, {{[-0-9]+}}(%e{{[sb]}}p) # 4-byte Spill
; 6860-NEXT: movl %eax, {{[-0-9]+}}(%e{{[sb]}}p) # 4-byte Spill
; 6860-NEXT: jne .LBB0_2
; 6860-NEXT: # %bb.1: # %bb
; 6860-NEXT: movl {{[-0-9]+}}(%e{{[sb]}}p), %eax # 4-byte Reload
; 6860-NEXT: movl %eax, {{[-0-9]+}}(%e{{[sb]}}p) # 4-byte Spill
; 6860-NEXT: .LBB0_2: # %bb
; 6860-NEXT: movl {{[-0-9]+}}(%e{{[sb]}}p), %eax # 4-byte Reload
; 6860-NEXT: # kill: def $al killed $al killed $eax
; 6860-NEXT: # implicit-def: $ecx
; 6860-NEXT: movb %al, (%ecx)
; 6860-NEXT: leal -12(%ebp), %esp
; 6860-NEXT: popl %esi
; 6860-NEXT: popl %edi
; 6860-NEXT: popl %ebx
; 6860-NEXT: popl %ebp
Correct dwarf unwind information in function epilogue This patch aims to provide correct dwarf unwind information in function epilogue for X86. It consists of two parts. The first part inserts CFI instructions that set appropriate cfa offset and cfa register in emitEpilogue() in X86FrameLowering. This part is X86 specific. The second part is platform independent and ensures that: * CFI instructions do not affect code generation (they are not counted as instructions when tail duplicating or tail merging) * Unwind information remains correct when a function is modified by different passes. This is done in a late pass by analyzing information about cfa offset and cfa register in BBs and inserting additional CFI directives where necessary. Added CFIInstrInserter pass: * analyzes each basic block to determine cfa offset and register are valid at its entry and exit * verifies that outgoing cfa offset and register of predecessor blocks match incoming values of their successors * inserts additional CFI directives at basic block beginning to correct the rule for calculating CFA Having CFI instructions in function epilogue can cause incorrect CFA calculation rule for some basic blocks. This can happen if, due to basic block reordering, or the existence of multiple epilogue blocks, some of the blocks have wrong cfa offset and register values set by the epilogue block above them. CFIInstrInserter is currently run only on X86, but can be used by any target that implements support for adding CFI instructions in epilogue. Patch by Violeta Vukobrat. Differential Revision: https://reviews.llvm.org/D42848 llvm-svn: 330706
2018-04-24 18:32:08 +08:00
; 6860-NEXT: .cfi_def_cfa %esp, 4
; 6860-NEXT: retl
;
; X64-LABEL: foo:
; X64: # %bb.0: # %bb
; X64-NEXT: movzwl {{.*}}(%rip), %ecx
; X64-NEXT: movzwl {{.*}}(%rip), %eax
; X64-NEXT: xorw %cx, %ax
; X64-NEXT: xorl %ecx, %eax
; X64-NEXT: movzwl %ax, %eax
; X64-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
; X64-NEXT: addb $30, %cl
; X64-NEXT: # kill: def $cl killed $cl killed $ecx
; X64-NEXT: shrq %cl, %rax
; X64-NEXT: movb %al, (%rax)
; X64-NEXT: retq
;
; 686-LABEL: foo:
; 686: # %bb.0: # %bb
; 686-NEXT: pushl %ebp
; 686-NEXT: .cfi_def_cfa_offset 8
; 686-NEXT: .cfi_offset %ebp, -8
; 686-NEXT: movl %esp, %ebp
; 686-NEXT: .cfi_def_cfa_register %ebp
; 686-NEXT: andl $-8, %esp
; 686-NEXT: subl $8, %esp
; 686-NEXT: movzwl var_27, %ecx
; 686-NEXT: movzwl var_22, %eax
; 686-NEXT: xorw %cx, %ax
; 686-NEXT: xorl %ecx, %eax
; 686-NEXT: movzwl %ax, %eax
; 686-NEXT: movl %eax, (%esp)
; 686-NEXT: movl $0, {{[0-9]+}}(%esp)
; 686-NEXT: addb $30, %cl
; 686-NEXT: xorl %edx, %edx
; 686-NEXT: shrdl %cl, %edx, %eax
; 686-NEXT: testb $32, %cl
; 686-NEXT: jne .LBB0_2
; 686-NEXT: # %bb.1: # %bb
; 686-NEXT: movl %eax, %edx
; 686-NEXT: .LBB0_2: # %bb
; 686-NEXT: movb %dl, (%eax)
; 686-NEXT: movl %ebp, %esp
; 686-NEXT: popl %ebp
Correct dwarf unwind information in function epilogue This patch aims to provide correct dwarf unwind information in function epilogue for X86. It consists of two parts. The first part inserts CFI instructions that set appropriate cfa offset and cfa register in emitEpilogue() in X86FrameLowering. This part is X86 specific. The second part is platform independent and ensures that: * CFI instructions do not affect code generation (they are not counted as instructions when tail duplicating or tail merging) * Unwind information remains correct when a function is modified by different passes. This is done in a late pass by analyzing information about cfa offset and cfa register in BBs and inserting additional CFI directives where necessary. Added CFIInstrInserter pass: * analyzes each basic block to determine cfa offset and register are valid at its entry and exit * verifies that outgoing cfa offset and register of predecessor blocks match incoming values of their successors * inserts additional CFI directives at basic block beginning to correct the rule for calculating CFA Having CFI instructions in function epilogue can cause incorrect CFA calculation rule for some basic blocks. This can happen if, due to basic block reordering, or the existence of multiple epilogue blocks, some of the blocks have wrong cfa offset and register values set by the epilogue block above them. CFIInstrInserter is currently run only on X86, but can be used by any target that implements support for adding CFI instructions in epilogue. Patch by Violeta Vukobrat. Differential Revision: https://reviews.llvm.org/D42848 llvm-svn: 330706
2018-04-24 18:32:08 +08:00
; 686-NEXT: .cfi_def_cfa %esp, 4
; 686-NEXT: retl
bb:
%tmp = alloca i64, align 8
%tmp1 = load i16, i16* @var_22, align 2
%tmp2 = zext i16 %tmp1 to i32
%tmp3 = load i16, i16* @var_27, align 2
%tmp4 = zext i16 %tmp3 to i32
%tmp5 = xor i32 %tmp2, %tmp4
%tmp6 = load i16, i16* @var_27, align 2
%tmp7 = zext i16 %tmp6 to i32
%tmp8 = xor i32 %tmp5, %tmp7
%tmp9 = sext i32 %tmp8 to i64
store i64 %tmp9, i64* %tmp, align 8
%tmp10 = load i16, i16* @var_22, align 2
%tmp11 = zext i16 %tmp10 to i32
%tmp12 = load i16, i16* @var_27, align 2
%tmp13 = zext i16 %tmp12 to i32
%tmp14 = xor i32 %tmp11, %tmp13
%tmp15 = load i16, i16* @var_27, align 2
%tmp16 = zext i16 %tmp15 to i32
%tmp17 = xor i32 %tmp14, %tmp16
%tmp18 = sext i32 %tmp17 to i64
%tmp19 = load i16, i16* @var_27, align 2
%tmp20 = zext i16 %tmp19 to i32
%tmp21 = sub nsw i32 %tmp20, 16610
%tmp22 = zext i32 %tmp21 to i64
%tmp23 = ashr i64 %tmp18, %tmp22
%tmp24 = trunc i64 %tmp23 to i8
store i8 %tmp24, i8* undef, align 1
ret void
}