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authorHans Wennborg <hans@hanshq.net>2018-02-19 14:16:41 +0000
committerHans Wennborg <hans@hanshq.net>2018-02-19 14:16:41 +0000
commit359e6a40497597a9b79191d3d31bd47761eb08a9 (patch)
tree02dc018919c590b4d6e325c52dafecb12213163d /lib
parentc3ab0c1f90b9c67761e5f12ee79ee08390bb6f6e (diff)
Merging r325148:
------------------------------------------------------------------------ r325148 | ctopper | 2018-02-14 19:08:33 +0100 (Wed, 14 Feb 2018) | 7 lines [InstCombine] Don't fold select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W)) if the binop is rem or div. The select may have been preventing a division by zero or INT_MIN/-1 so removing it might not be safe. Fixes PR36362. Differential Revision: https://reviews.llvm.org/D43276 ------------------------------------------------------------------------ git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@325501 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r--lib/Transforms/InstCombine/InstCombineSelect.cpp19
1 files changed, 17 insertions, 2 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 6f26f7f5cd1..c790de3505f 100644
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1643,11 +1643,25 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
}
}
+ auto canMergeSelectThroughBinop = [](BinaryOperator *BO) {
+ // The select might be preventing a division by 0.
+ switch (BO->getOpcode()) {
+ default:
+ return true;
+ case Instruction::SRem:
+ case Instruction::URem:
+ case Instruction::SDiv:
+ case Instruction::UDiv:
+ return false;
+ }
+ };
+
// Try to simplify a binop sandwiched between 2 selects with the same
// condition.
// select(C, binop(select(C, X, Y), W), Z) -> select(C, binop(X, W), Z)
BinaryOperator *TrueBO;
- if (match(TrueVal, m_OneUse(m_BinOp(TrueBO)))) {
+ if (match(TrueVal, m_OneUse(m_BinOp(TrueBO))) &&
+ canMergeSelectThroughBinop(TrueBO)) {
if (auto *TrueBOSI = dyn_cast<SelectInst>(TrueBO->getOperand(0))) {
if (TrueBOSI->getCondition() == CondVal) {
TrueBO->setOperand(0, TrueBOSI->getTrueValue());
@@ -1666,7 +1680,8 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
// select(C, Z, binop(select(C, X, Y), W)) -> select(C, Z, binop(Y, W))
BinaryOperator *FalseBO;
- if (match(FalseVal, m_OneUse(m_BinOp(FalseBO)))) {
+ if (match(FalseVal, m_OneUse(m_BinOp(FalseBO))) &&
+ canMergeSelectThroughBinop(FalseBO)) {
if (auto *FalseBOSI = dyn_cast<SelectInst>(FalseBO->getOperand(0))) {
if (FalseBOSI->getCondition() == CondVal) {
FalseBO->setOperand(0, FalseBOSI->getFalseValue());