[InstCombine] Make folding (X >s -1) ? C1 : C2 --> ((X >>s 31) & (C2 - C1)) + C1 support splat vectors
This also uses decomposeBitTestICmp to decode the compare.
Differential Revision: https://reviews.llvm.org/D36781
llvm-svn: 311044
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 4de2902..b5fa2dc 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "InstCombineInternal.h"
+#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/ValueTracking.h"
@@ -694,27 +695,31 @@
// FIXME: Type and constness constraints could be lifted, but we have to
// watch code size carefully. We should consider xor instead of
// sub/add when we decide to do that.
- if (IntegerType *Ty = dyn_cast<IntegerType>(CmpLHS->getType())) {
- if (TrueVal->getType() == Ty) {
- if (ConstantInt *Cmp = dyn_cast<ConstantInt>(CmpRHS)) {
- ConstantInt *C1 = nullptr, *C2 = nullptr;
- if (Pred == ICmpInst::ICMP_SGT && Cmp->isMinusOne()) {
- C1 = dyn_cast<ConstantInt>(TrueVal);
- C2 = dyn_cast<ConstantInt>(FalseVal);
- } else if (Pred == ICmpInst::ICMP_SLT && Cmp->isZero()) {
- C1 = dyn_cast<ConstantInt>(FalseVal);
- C2 = dyn_cast<ConstantInt>(TrueVal);
- }
- if (C1 && C2) {
+ if (CmpLHS->getType()->isIntOrIntVectorTy() &&
+ CmpLHS->getType() == TrueVal->getType()) {
+ const APInt *C1, *C2;
+ if (match(TrueVal, m_APInt(C1)) && match(FalseVal, m_APInt(C2))) {
+ ICmpInst::Predicate Pred = ICI->getPredicate();
+ Value *X;
+ APInt Mask;
+ if (decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) {
+ if (Mask.isSignMask()) {
+ assert(X == CmpLHS && "Expected to use the compare input directly");
+ assert(ICmpInst::isEquality(Pred) && "Expected equality predicate");
+
+ if (Pred == ICmpInst::ICMP_NE)
+ std::swap(C1, C2);
+
// This shift results in either -1 or 0.
- Value *AShr = Builder.CreateAShr(CmpLHS, Ty->getBitWidth() - 1);
+ Value *AShr = Builder.CreateAShr(X, Mask.getBitWidth() - 1);
// Check if we can express the operation with a single or.
- if (C2->isMinusOne())
- return replaceInstUsesWith(SI, Builder.CreateOr(AShr, C1));
+ if (C2->isAllOnesValue())
+ return replaceInstUsesWith(SI, Builder.CreateOr(AShr, *C1));
- Value *And = Builder.CreateAnd(AShr, C2->getValue() - C1->getValue());
- return replaceInstUsesWith(SI, Builder.CreateAdd(And, C1));
+ Value *And = Builder.CreateAnd(AShr, *C2 - *C1);
+ return replaceInstUsesWith(SI, Builder.CreateAdd(And,
+ ConstantInt::get(And->getType(), *C1)));
}
}
}