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The change for PR9190 wasn't quite right. We need to avoid making the

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transformation if we can't legally create a build vector of the correct
type. Check that we can make the transformation first, and add a TODO to
refactor this code with similar cases.

Fixes: PR9223 and rdar://9000350


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125631 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eric Christopher 2011-02-16 01:10:03 +00:00
parent f621e3b6d6
commit 169e1552e7
2 changed files with 53 additions and 2 deletions
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14
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -1532,8 +1532,18 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
}
// fold (sub x, x) -> 0
if (N0 == N1)
return DAG.getConstant(0, N->getValueType(0), LegalTypes);
// FIXME: Refactor this and xor and other similar operations together.
if (N0 == N1) {
if (!VT.isVector()) {
return DAG.getConstant(0, VT);
} else if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)){
// Produce a vector of zeros.
SDValue El = DAG.getConstant(0, VT.getVectorElementType());
std::vector<SDValue> Ops(VT.getVectorNumElements(), El);
return DAG.getNode(ISD::BUILD_VECTOR, N->getDebugLoc(), VT,
&Ops[0], Ops.size());
}
}
// fold (sub c1, c2) -> c1-c2
if (N0C && N1C)
return DAG.FoldConstantArithmetic(ISD::SUB, VT, N0C, N1C);

41
test/CodeGen/X86/legalize-sub-zero-2.ll Normal file
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@ -0,0 +1,41 @@
; RUN: llc < %s -mtriple=i386-apple-darwin
define fastcc void @foo(i32 %type) nounwind optsize {
entry:
switch i32 %type, label %bb26 [
i32 33634, label %bb11
i32 5121, label %bb27
]
bb11: ; preds = %entry
br label %bb27
bb26: ; preds = %entry
unreachable
bb27: ; preds = %bb11, %entry
%srcpb.0 = phi i32 [ 1, %bb11 ], [ 0, %entry ]
br i1 undef, label %bb348, label %bb30.lr.ph
bb30.lr.ph: ; preds = %bb27
%.sum743 = shl i32 %srcpb.0, 1
%0 = mul i32 %srcpb.0, -2
%.sum745 = add i32 %.sum743, %0
br i1 undef, label %bb70, label %bb71
bb70: ; preds = %bb30.lr.ph
unreachable
bb71: ; preds = %bb30.lr.ph
br i1 undef, label %bb92, label %bb80
bb80: ; preds = %bb71
unreachable
bb92: ; preds = %bb71
%1 = getelementptr inbounds i8* undef, i32 %.sum745
unreachable
bb348: ; preds = %bb27
ret void
}