Generalize icmp matching in IndVars' eliminateTrunc
We were only matching RHS being a loop invariant value, not the inverse. Since there's nothing which appears to canonicalize loop invariant values to RHS, this means we missed cases.
Differential Revision: https://reviews.llvm.org/D63112
llvm-svn: 363108
diff --git a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
index 9a4ebd3..f1048d9 100644
--- a/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyIndVar.cpp
@@ -521,20 +521,19 @@
if (isa<Instruction>(U) &&
!DT->isReachableFromEntry(cast<Instruction>(U)->getParent()))
continue;
- if (ICmpInst *ICI = dyn_cast<ICmpInst>(U)) {
- if (ICI->getOperand(0) == TI && L->isLoopInvariant(ICI->getOperand(1))) {
- assert(L->contains(ICI->getParent()) && "LCSSA form broken?");
- // If we cannot get rid of trunc, bail.
- if (ICI->isSigned() && !DoesSExtCollapse)
- return false;
- if (ICI->isUnsigned() && !DoesZExtCollapse)
- return false;
- // For equality, either signed or unsigned works.
- ICmpUsers.push_back(ICI);
- } else
- return false;
- } else
+ ICmpInst *ICI = dyn_cast<ICmpInst>(U);
+ if (!ICI) return false;
+ assert(L->contains(ICI->getParent()) && "LCSSA form broken?");
+ if (!(ICI->getOperand(0) == TI && L->isLoopInvariant(ICI->getOperand(1))) &&
+ !(ICI->getOperand(1) == TI && L->isLoopInvariant(ICI->getOperand(0))))
return false;
+ // If we cannot get rid of trunc, bail.
+ if (ICI->isSigned() && !DoesSExtCollapse)
+ return false;
+ if (ICI->isUnsigned() && !DoesZExtCollapse)
+ return false;
+ // For equality, either signed or unsigned works.
+ ICmpUsers.push_back(ICI);
}
auto CanUseZExt = [&](ICmpInst *ICI) {
@@ -557,7 +556,8 @@
};
// Replace all comparisons against trunc with comparisons against IV.
for (auto *ICI : ICmpUsers) {
- auto *Op1 = ICI->getOperand(1);
+ bool IsSwapped = L->isLoopInvariant(ICI->getOperand(0));
+ auto *Op1 = IsSwapped ? ICI->getOperand(0) : ICI->getOperand(1);
Instruction *Ext = nullptr;
// For signed/unsigned predicate, replace the old comparison with comparison
// of immediate IV against sext/zext of the invariant argument. If we can
@@ -566,6 +566,7 @@
// TODO: If we see a signed comparison which can be turned into unsigned,
// we can do it here for canonicalization purposes.
ICmpInst::Predicate Pred = ICI->getPredicate();
+ if (IsSwapped) Pred = ICmpInst::getSwappedPredicate(Pred);
if (CanUseZExt(ICI)) {
assert(DoesZExtCollapse && "Unprofitable zext?");
Ext = new ZExtInst(Op1, IVTy, "zext", ICI);