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InstCombine: Ensure select condition types are identical before merging

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Selection conditions may be vectors or scalars.  Make sure InstCombine
doesn't indiscriminately assume that a select which is value dependent
on another select have identical select condition types.

This fixes PR22773.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231156 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
David Majnemer 2015-03-03 22:40:36 +00:00
parent 92dabb5710
commit 8db493c4e1
2 changed files with 42 additions and 28 deletions
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60
lib/Transforms/InstCombine/InstCombineSelect.cpp
View File

@ -1203,37 +1203,41 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
return NV;
if (SelectInst *TrueSI = dyn_cast<SelectInst>(TrueVal)) {
// select(C, select(C, a, b), c) -> select(C, a, c)
if (TrueSI->getCondition() == CondVal) {
if (SI.getTrueValue() == TrueSI->getTrueValue())
return nullptr;
SI.setOperand(1, TrueSI->getTrueValue());
return &SI;
}
// select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
// We choose this as normal form to enable folding on the And and shortening
// paths for the values (this helps GetUnderlyingObjects() for example).
if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
Value *And = Builder->CreateAnd(CondVal, TrueSI->getCondition());
SI.setOperand(0, And);
SI.setOperand(1, TrueSI->getTrueValue());
return &SI;
if (TrueSI->getCondition()->getType() == CondVal->getType()) {
// select(C, select(C, a, b), c) -> select(C, a, c)
if (TrueSI->getCondition() == CondVal) {
if (SI.getTrueValue() == TrueSI->getTrueValue())
return nullptr;
SI.setOperand(1, TrueSI->getTrueValue());
return &SI;
}
// select(C0, select(C1, a, b), b) -> select(C0&C1, a, b)
// We choose this as normal form to enable folding on the And and shortening
// paths for the values (this helps GetUnderlyingObjects() for example).
if (TrueSI->getFalseValue() == FalseVal && TrueSI->hasOneUse()) {
Value *And = Builder->CreateAnd(CondVal, TrueSI->getCondition());
SI.setOperand(0, And);
SI.setOperand(1, TrueSI->getTrueValue());
return &SI;
}
}
}
if (SelectInst *FalseSI = dyn_cast<SelectInst>(FalseVal)) {
// select(C, a, select(C, b, c)) -> select(C, a, c)
if (FalseSI->getCondition() == CondVal) {
if (SI.getFalseValue() == FalseSI->getFalseValue())
return nullptr;
SI.setOperand(2, FalseSI->getFalseValue());
return &SI;
}
// select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
Value *Or = Builder->CreateOr(CondVal, FalseSI->getCondition());
SI.setOperand(0, Or);
SI.setOperand(2, FalseSI->getFalseValue());
return &SI;
if (FalseSI->getCondition()->getType() == CondVal->getType()) {
// select(C, a, select(C, b, c)) -> select(C, a, c)
if (FalseSI->getCondition() == CondVal) {
if (SI.getFalseValue() == FalseSI->getFalseValue())
return nullptr;
SI.setOperand(2, FalseSI->getFalseValue());
return &SI;
}
// select(C0, a, select(C1, a, b)) -> select(C0|C1, a, b)
if (FalseSI->getTrueValue() == TrueVal && FalseSI->hasOneUse()) {
Value *Or = Builder->CreateOr(CondVal, FalseSI->getCondition());
SI.setOperand(0, Or);
SI.setOperand(2, FalseSI->getFalseValue());
return &SI;
}
}
}

10
test/Transforms/InstCombine/select-select.ll
View File

@ -21,4 +21,14 @@ define float @foo2(float %a) #0 {
ret float %f
}
; CHECK-LABEL: @foo3
define <2 x i32> @foo3(<2 x i1> %vec_bool, i1 %bool, <2 x i32> %V) {
; CHECK: %[[sel0:.*]] = select <2 x i1> %vec_bool, <2 x i32> zeroinitializer, <2 x i32> %V
; CHECK: %[[sel1:.*]] = select i1 %bool, <2 x i32> %[[sel0]], <2 x i32> %V
; CHECK: ret <2 x i32> %[[sel1]]
%sel0 = select <2 x i1> %vec_bool, <2 x i32> zeroinitializer, <2 x i32> %V
%sel1 = select i1 %bool, <2 x i32> %sel0, <2 x i32> %V
ret <2 x i32> %sel1
}
attributes #0 = { nounwind readnone ssp uwtable }