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If ADD, SUB, or MUL have an overflow bit that's used, don't do transformation on

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them. The DAG combiner expects that nodes that are transformed have one value
result.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60857 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling
2008-12-10 22:36:00 +00:00
parent e5ad88e97f
commit 2476e5d345
2 changed files with 51 additions and 4 deletions
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15
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -967,6 +967,11 @@ SDValue DAGCombiner::visitADD(SDNode *N) {
if (FoldedVOp.getNode()) return FoldedVOp; if (FoldedVOp.getNode()) return FoldedVOp;
} }
if (N->getNumValues() != 1)
// FIXME: DAG combiner cannot handle multiple return values on arithmetic
// operators.
return SDValue();
// fold (add x, undef) -> undef // fold (add x, undef) -> undef
if (N0.getOpcode() == ISD::UNDEF) if (N0.getOpcode() == ISD::UNDEF)
return N0; return N0;
@ -1162,6 +1167,11 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
if (FoldedVOp.getNode()) return FoldedVOp; if (FoldedVOp.getNode()) return FoldedVOp;
} }
if (N->getNumValues() != 1)
// FIXME: DAG combiner cannot handle multiple return values on arithmetic
// operators.
return SDValue();
// fold (sub x, x) -> 0 // fold (sub x, x) -> 0
if (N0 == N1) if (N0 == N1)
return DAG.getConstant(0, N->getValueType(0)); return DAG.getConstant(0, N->getValueType(0));
@ -1220,6 +1230,11 @@ SDValue DAGCombiner::visitMUL(SDNode *N) {
if (FoldedVOp.getNode()) return FoldedVOp; if (FoldedVOp.getNode()) return FoldedVOp;
} }
if (N->getNumValues() != 1)
// FIXME: DAG combiner cannot handle multiple return values on arithmetic
// operators.
return SDValue();
// fold (mul x, undef) -> 0 // fold (mul x, undef) -> 0
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF) if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT); return DAG.getConstant(0, VT);

40
test/CodeGen/X86/add-with-overflow.ll
View File

@ -1,7 +1,7 @@
; RUN: llvm-as < %s | llc -march=x86 | grep {jo} | count 1 ; RUN: llvm-as < %s | llc -march=x86 | grep {jo} | count 2
; RUN: llvm-as < %s | llc -march=x86 | grep {jc} | count 1 ; RUN: llvm-as < %s | llc -march=x86 | grep {jc} | count 2
; RUN: llvm-as < %s | llc -march=x86 -fast | grep {jo} | count 1 ; RUN: llvm-as < %s | llc -march=x86 -fast | grep {jo} | count 2
; RUN: llvm-as < %s | llc -march=x86 -fast | grep {jc} | count 1 ; RUN: llvm-as < %s | llc -march=x86 -fast | grep {jc} | count 2
@ok = internal constant [4 x i8] c"%d\0A\00" @ok = internal constant [4 x i8] c"%d\0A\00"
@no = internal constant [4 x i8] c"no\0A\00" @no = internal constant [4 x i8] c"no\0A\00"
@ -38,6 +38,38 @@ carry:
ret i1 false ret i1 false
} }
define i1 @func3() nounwind {
entry:
%t = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 0, i32 0)
%sum = extractvalue {i32, i1} %t, 0
%obit = extractvalue {i32, i1} %t, 1
br i1 %obit, label %carry, label %normal
normal:
%t1 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @ok, i32 0, i32 0), i32 %sum ) nounwind
ret i1 true
carry:
%t2 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @no, i32 0, i32 0) ) nounwind
ret i1 false
}
define i1 @func4() nounwind {
entry:
%t = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 0, i32 0)
%sum = extractvalue {i32, i1} %t, 0
%obit = extractvalue {i32, i1} %t, 1
br i1 %obit, label %carry, label %normal
normal:
%t1 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @ok, i32 0, i32 0), i32 %sum ) nounwind
ret i1 true
carry:
%t2 = tail call i32 (i8*, ...)* @printf( i8* getelementptr ([4 x i8]* @no, i32 0, i32 0) ) nounwind
ret i1 false
}
declare i32 @printf(i8*, ...) nounwind declare i32 @printf(i8*, ...) nounwind
declare {i32, i1} @llvm.sadd.with.overflow.i32(i32, i32) declare {i32, i1} @llvm.sadd.with.overflow.i32(i32, i32)
declare {i32, i1} @llvm.uadd.with.overflow.i32(i32, i32) declare {i32, i1} @llvm.uadd.with.overflow.i32(i32, i32)