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[InstCombine] fix shuffle-of-binops bug 

With non-commutative binops, we could be using the same
variable value as operand 0 in 1 binop and operand 1 in 
the other, so we have to check for that possibility and
bail out.

llvm-svn: 335312
This commit is contained in:
Sanjay Patel 2018-06-21 23:56:59 +00:00
parent 23408c25f3
commit 4784e1506e
2 changed files with 11 additions and 4 deletions
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10
llvm/lib/Transforms/InstCombine/InstCombineVectorOps.cpp
View File

@ -1166,6 +1166,13 @@ static Instruction *foldSelectShuffles(ShuffleVectorInst &Shuf) {
if (isa<Constant>(X))
return nullptr;
// Constant operands must be on the same side of each binop. We can't fold:
// shuffle (sdiv X, C0), (sdiv C1, X).
bool B00IsConst = isa<Constant>(B0->getOperand(0));
bool B10IsConst = isa<Constant>(B1->getOperand(0));
if (B00IsConst != B10IsConst)
return nullptr;
// Remove a binop and the shuffle by rearranging the constant:
// shuffle (op X, C0), (op X, C1), M --> op X, C'
// shuffle (op C0, X), (op C1, X), M --> op C', X
@ -1178,8 +1185,7 @@ static Instruction *foldSelectShuffles(ShuffleVectorInst &Shuf) {
NewC = getSafeVectorConstantForIntDivRem(NewC);
BinaryOperator::BinaryOps Opc = B0->getOpcode();
bool Op0IsConst = isa<Constant>(B0->getOperand(0));
Instruction *NewBO = Op0IsConst ? BinaryOperator::Create(Opc, NewC, X) :
Instruction *NewBO = B00IsConst ? BinaryOperator::Create(Opc, NewC, X) :
BinaryOperator::Create(Opc, X, NewC);
// Flags are intersected from the 2 source binops.

5
llvm/test/Transforms/InstCombine/shuffle_select.ll
View File

@ -224,12 +224,13 @@ define <4 x double> @fdiv(<4 x double> %v0) {
ret <4 x double> %t3
}
; FIXME:
; The variable operand must be either the first operand or second operand in both binops.
define <4 x double> @frem(<4 x double> %v0) {
; CHECK-LABEL: @frem(
; CHECK-NEXT: [[T3:%.*]] = frem <4 x double> <double 1.000000e+00, double 2.000000e+00, double 7.000000e+00, double 8.000000e+00>, [[V0:%.*]]
; CHECK-NEXT: [[T1:%.*]] = frem <4 x double> <double 1.000000e+00, double 2.000000e+00, double 3.000000e+00, double 4.000000e+00>, [[V0:%.*]]
; CHECK-NEXT: [[T2:%.*]] = frem <4 x double> [[V0]], <double 5.000000e+00, double 6.000000e+00, double 7.000000e+00, double 8.000000e+00>
; CHECK-NEXT: [[T3:%.*]] = shufflevector <4 x double> [[T1]], <4 x double> [[T2]], <4 x i32> <i32 0, i32 1, i32 6, i32 7>
; CHECK-NEXT: ret <4 x double> [[T3]]
;
%t1 = frem <4 x double> <double 1.0, double 2.0, double 3.0, double 4.0>, %v0