maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[DAGCombiner] Allow divide by constant optimization on opaque constants. 

Summary:
I believe this restores the behavior we had before r339147.

Fixes PR38622.

Reviewers: RKSimon, chandlerc, spatel

Reviewed By: chandlerc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D50936

llvm-svn: 340120
This commit is contained in:
Craig Topper 2018-08-18 05:52:42 +00:00
parent 526a31a5a4
commit cc5dbbf759
2 changed files with 80 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -3224,7 +3224,7 @@ SDValue DAGCombiner::visitSDIVLike(SDValue N0, SDValue N1, SDNode *N) {
// alternate sequence. Targets may check function attributes for size/speed
// trade-offs.
AttributeList Attr = DAG.getMachineFunction().getFunction().getAttributes();
if (isConstantOrConstantVector(N1, /*NoOpaques*/ true) &&
if (isConstantOrConstantVector(N1) &&
!TLI.isIntDivCheap(N->getValueType(0), Attr))
if (SDValue Op = BuildSDIV(N))
return Op;
@ -3316,7 +3316,7 @@ SDValue DAGCombiner::visitUDIVLike(SDValue N0, SDValue N1, SDNode *N) {
// fold (udiv x, c) -> alternate
AttributeList Attr = DAG.getMachineFunction().getFunction().getAttributes();
if (isConstantOrConstantVector(N1, /*NoOpaques*/ true) &&
if (isConstantOrConstantVector(N1) &&
!TLI.isIntDivCheap(N->getValueType(0), Attr))
if (SDValue Op = BuildUDIV(N))
return Op;

78
llvm/test/CodeGen/X86/divide-by-constant.ll
View File

@ -330,3 +330,81 @@ entry:
%div = udiv i64 %rem, 7
ret i64 %div
}
define { i64, i32 } @PR38622(i64) {
; X32-LABEL: PR38622:
; X32: # %bb.0:
; X32-NEXT: pushl %ebp
; X32-NEXT: .cfi_def_cfa_offset 8
; X32-NEXT: pushl %ebx
; X32-NEXT: .cfi_def_cfa_offset 12
; X32-NEXT: pushl %edi
; X32-NEXT: .cfi_def_cfa_offset 16
; X32-NEXT: pushl %esi
; X32-NEXT: .cfi_def_cfa_offset 20
; X32-NEXT: subl $12, %esp
; X32-NEXT: .cfi_def_cfa_offset 32
; X32-NEXT: .cfi_offset %esi, -20
; X32-NEXT: .cfi_offset %edi, -16
; X32-NEXT: .cfi_offset %ebx, -12
; X32-NEXT: .cfi_offset %ebp, -8
; X32-NEXT: movl {{[0-9]+}}(%esp), %ebx
; X32-NEXT: movl {{[0-9]+}}(%esp), %ebp
; X32-NEXT: pushl $0
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: pushl $-294967296 # imm = 0xEE6B2800
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: pushl %ebp
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: pushl %ebx
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: calll __udivdi3
; X32-NEXT: addl $16, %esp
; X32-NEXT: .cfi_adjust_cfa_offset -16
; X32-NEXT: movl %eax, %esi
; X32-NEXT: movl %edx, %edi
; X32-NEXT: pushl $0
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: pushl $-294967296 # imm = 0xEE6B2800
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: pushl %ebp
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: pushl %ebx
; X32-NEXT: .cfi_adjust_cfa_offset 4
; X32-NEXT: calll __umoddi3
; X32-NEXT: addl $16, %esp
; X32-NEXT: .cfi_adjust_cfa_offset -16
; X32-NEXT: movl %eax, %ecx
; X32-NEXT: movl %esi, %eax
; X32-NEXT: movl %edi, %edx
; X32-NEXT: addl $12, %esp
; X32-NEXT: .cfi_def_cfa_offset 20
; X32-NEXT: popl %esi
; X32-NEXT: .cfi_def_cfa_offset 16
; X32-NEXT: popl %edi
; X32-NEXT: .cfi_def_cfa_offset 12
; X32-NEXT: popl %ebx
; X32-NEXT: .cfi_def_cfa_offset 8
; X32-NEXT: popl %ebp
; X32-NEXT: .cfi_def_cfa_offset 4
; X32-NEXT: retl
;
; X64-LABEL: PR38622:
; X64: # %bb.0:
; X64-NEXT: movq %rdi, %rax
; X64-NEXT: shrq $11, %rax
; X64-NEXT: movabsq $4835703278458517, %rcx # imm = 0x112E0BE826D695
; X64-NEXT: mulq %rcx
; X64-NEXT: shrq $9, %rdx
; X64-NEXT: imull $-294967296, %edx, %eax # imm = 0xEE6B2800
; X64-NEXT: subl %eax, %edi
; X64-NEXT: movq %rdx, %rax
; X64-NEXT: movl %edi, %edx
; X64-NEXT: retq
%2 = udiv i64 %0, 4000000000
%3 = urem i64 %0, 4000000000
%4 = trunc i64 %3 to i32
%5 = insertvalue { i64, i32 } undef, i64 %2, 0
%6 = insertvalue { i64, i32 } %5, i32 %4, 1
ret { i64, i32 } %6
}