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When TCO is turned on, it is possible to end up with aliasing FrameIndex's. Therefore,

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CombinerAA cannot assume that different FrameIndex's never alias, but can instead use
MachineFrameInfo to get the actual offsets of these slots and check for actual aliasing.

This fixes CodeGen/X86/2010-02-19-TailCallRetAddrBug.ll and CodeGen/X86/tailcallstack64.ll
when CombinerAA is enabled, modulo a different register allocation sequence.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@114348 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2010-09-20 20:39:59 +00:00
parent 1dc335a79f
commit 4a9f150926
2 changed files with 17 additions and 6 deletions
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15
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -7030,8 +7030,19 @@ bool DAGCombiner::isAlias(SDValue Ptr1, int64_t Size1,
if (Base1 == Base2 || (GV1 && (GV1 == GV2)) || (CV1 && (CV1 == CV2)))
return !((Offset1 + Size1) <= Offset2 || (Offset2 + Size2) <= Offset1);
// If we know what the bases are, and they aren't identical, then we know they
// cannot alias.
// It is possible for different frame indices to alias each other, mostly
// when tail call optimization reuses return address slots for arguments.
// To catch this case, look up the actual index of frame indices to compute
// the real alias relationship.
if (isFrameIndex1 && isFrameIndex2) {
MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
Offset1 += MFI->getObjectOffset(cast<FrameIndexSDNode>(Base1)->getIndex());
Offset2 += MFI->getObjectOffset(cast<FrameIndexSDNode>(Base2)->getIndex());
return !((Offset1 + Size1) <= Offset2 || (Offset2 + Size2) <= Offset1);
}
// Otherwise, if we know what the bases are, and they aren't identical, then
// we know they cannot alias.
if ((isFrameIndex1 || CV1 || GV1) && (isFrameIndex2 || CV2 || GV2))
return false;

8
test/CodeGen/X86/2010-09-17-SideEffectsInChain.ll
View File

@ -19,8 +19,8 @@ entry:
}
; CHECK: movq ___stack_chk_guard@GOTPCREL(%rip), %rax
; CHECK: movb (%rsp), %dl
; CHECK-NEXT: movb 30(%rsp), %sil
; CHECK: movb %dl, (%rsp)
; CHECK-NEXT: movb %sil, 30(%rsp)
; CHECK: movb 30(%rsp), %dl
; CHECK: movb (%rsp), %sil
; CHECK: movb %sil, (%rsp)
; CHECK: movb %dl, 30(%rsp)
; CHECK: callq ___stack_chk_fail