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Fix a DAG combine bug visitBRCOND() is transforming br(xor(x, y)) to br(x != y).

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It cahced XOR's operands before calling visitXOR() but failed to update the
operands when visitXOR changed the XOR node.

rdar://12968664


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171999 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2013-01-09 20:56:40 +00:00
parent f48acd5ecd
commit 78ec0255d9
2 changed files with 59 additions and 12 deletions
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30
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -6735,18 +6735,24 @@ SDValue DAGCombiner::visitBRCOND(SDNode *N) {
if (Op0.getOpcode() == Op1.getOpcode()) {
// Avoid missing important xor optimizations.
SDValue Tmp = visitXOR(TheXor);
if (Tmp.getNode() && Tmp.getNode() != TheXor) {
DEBUG(dbgs() << "\nReplacing.8 ";
TheXor->dump(&DAG);
dbgs() << "\nWith: ";
Tmp.getNode()->dump(&DAG);
dbgs() << '\n');
WorkListRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(N1, Tmp);
removeFromWorkList(TheXor);
DAG.DeleteNode(TheXor);
return DAG.getNode(ISD::BRCOND, N->getDebugLoc(),
MVT::Other, Chain, Tmp, N2);
if (Tmp.getNode()) {
if (Tmp.getNode() != TheXor) {
DEBUG(dbgs() << "\nReplacing.8 ";
TheXor->dump(&DAG);
dbgs() << "\nWith: ";
Tmp.getNode()->dump(&DAG);
dbgs() << '\n');
WorkListRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(N1, Tmp);
removeFromWorkList(TheXor);
DAG.DeleteNode(TheXor);
return DAG.getNode(ISD::BRCOND, N->getDebugLoc(),
MVT::Other, Chain, Tmp, N2);
}
// visitXOR has changed XOR's operands.
Op0 = TheXor->getOperand(0);
Op1 = TheXor->getOperand(1);
}
}

41
test/CodeGen/X86/2013-01-09-DAGCombineBug.ll Normal file
View File

@ -0,0 +1,41 @@
; RUN: llc -mtriple=x86_64-apple-macosx10.5.0 < %s
; rdar://12968664
define void @t() nounwind uwtable ssp {
br label %4
; <label>:1 ; preds = %4, %2
ret void
; <label>:2 ; preds = %6, %5, %3, %2
switch i32 undef, label %2 [
i32 1090573978, label %1
i32 1090573938, label %3
i32 1090573957, label %5
]
; <label>:3 ; preds = %4, %2
br i1 undef, label %2, label %4
; <label>:4 ; preds = %6, %5, %3, %0
switch i32 undef, label %11 [
i32 1090573938, label %3
i32 1090573957, label %5
i32 1090573978, label %1
i32 165205179, label %6
]
; <label>:5 ; preds = %4, %2
br i1 undef, label %2, label %4
; <label>:6 ; preds = %4
%7 = icmp eq i32 undef, 590901838
%8 = or i1 false, %7
%9 = or i1 true, %8
%10 = xor i1 %8, %9
br i1 %10, label %4, label %2
; <label>:11 ; preds = %11, %4
br label %11
}