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[DAGCombiner] Fix invalid alias analysis. 

Summary:
When we know for sure whether two addresses do or do not alias, we
should immediately return from DAGCombiner::isAlias().

I think this comes from a bad copy/paste, Sorry for not catching that during the
code review.

Fixes PR41855.

Reviewers: niravd, gchatelet, EricWF

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61846

llvm-svn: 360566
This commit is contained in:
Clement Courbet 2019-05-13 09:07:37 +00:00
parent 381ba9aedc
commit 9afc4764dd
2 changed files with 19 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -6128,7 +6128,7 @@ static unsigned BigEndianByteAt(unsigned BW, unsigned i) {
}
// Check if the bytes offsets we are looking at match with either big or
// little endian value loaded. Return true for big endian, false for little
// little endian value loaded. Return true for big endian, false for little
// endian, and None if match failed.
static Optional<bool> isBigEndian(const SmallVector<int64_t, 4> &ByteOffsets,
int64_t FirstOffset) {
@ -19800,8 +19800,7 @@ bool DAGCombiner::isAlias(SDNode *Op0, SDNode *Op1) const {
bool IsAlias;
if (BaseIndexOffset::computeAliasing(Op0, MUC0.NumBytes, Op1, MUC1.NumBytes,
DAG, IsAlias) &&
!IsAlias)
DAG, IsAlias))
return IsAlias;
// The following all rely on MMO0 and MMO1 being valid. Fail conservatively if

32
llvm/test/CodeGen/X86/lifetime-alias.ll
View File

@ -40,26 +40,28 @@ define dso_local i8 @main() local_unnamed_addr #0 personality i8* bitcast (i32 (
; CHECK-NEXT: movl $1701999988, -{{[0-9]+}}(%rsp) # imm = 0x65727574
; CHECK-NEXT: movb $0, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movaps %xmm0, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movabsq $1513209474796486656, %rax # imm = 0x1500000000000000
; CHECK-NEXT: movq $0, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movb $21, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movabsq $7308613581744070988, %rax # imm = 0x656D69547473614C
; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movups {{.*}}(%rip), %xmm1
; CHECK-NEXT: movaps %xmm1, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movabsq $7308613581744070988, %rcx # imm = 0x656D69547473614C
; CHECK-NEXT: movq %rcx, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movabsq $792633534417207296, %rcx # imm = 0xB00000000000000
; CHECK-NEXT: movq %rcx, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movq -{{[0-9]+}}(%rsp), %rcx
; CHECK-NEXT: movq %rcx, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movzwl -{{[0-9]+}}(%rsp), %ecx
; CHECK-NEXT: movw %cx, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %cl
; CHECK-NEXT: movb %cl, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %cl
; CHECK-NEXT: movb %cl, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movl -{{[0-9]+}}(%rsp), %ecx
; CHECK-NEXT: movl %ecx, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movb $0, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movabsq $792633534417207296, %rax # imm = 0xB00000000000000
; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movq -{{[0-9]+}}(%rsp), %rax
; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movzwl -{{[0-9]+}}(%rsp), %eax
; CHECK-NEXT: movw %ax, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %al
; CHECK-NEXT: movb %al, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movb -{{[0-9]+}}(%rsp), %al
; CHECK-NEXT: movb %al, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movl -{{[0-9]+}}(%rsp), %eax
; CHECK-NEXT: movl %eax, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movaps %xmm0, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movq $0, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movq -{{[0-9]+}}(%rsp), %rax
; CHECK-NEXT: movq %rax, -{{[0-9]+}}(%rsp)
; CHECK-NEXT: movaps -{{[0-9]+}}(%rsp), %xmm1
; CHECK-NEXT: movups %xmm1, -{{[0-9]+}}(%rsp)