[LV] Identify more induction PHIs by coercing expressions to AddRecExprs
Summary:
Some PHIs can have expressions that are not AddRecExprs due to the presence
of sext/zext instructions. In order to prevent the Loop Vectorizer from
bailing out when encountering these PHIs, we now coerce the SCEV
expressions to AddRecExprs using SCEV predicates (when possible).
We only do this when the alternative would be to not vectorize.
Reviewers: mzolotukhin, anemet
Subscribers: mssimpso, sanjoy, mzolotukhin, llvm-commits
Differential Revision: http://reviews.llvm.org/D17153
llvm-svn: 268633
diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 2d1f10f..c6b0f7b 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -698,16 +698,43 @@
llvm_unreachable("invalid enum");
}
-bool InductionDescriptor::isInductionPHI(PHINode *Phi, ScalarEvolution *SE,
- InductionDescriptor &D) {
+bool InductionDescriptor::isInductionPHI(PHINode *Phi,
+ PredicatedScalarEvolution &PSE,
+ InductionDescriptor &D,
+ bool Assume) {
+ Type *PhiTy = Phi->getType();
+ // We only handle integer and pointer inductions variables.
+ if (!PhiTy->isIntegerTy() && !PhiTy->isPointerTy())
+ return false;
+
+ const SCEV *PhiScev = PSE.getSCEV(Phi);
+ const auto *AR = dyn_cast<SCEVAddRecExpr>(PhiScev);
+
+ // We need this expression to be an AddRecExpr.
+ if (Assume && !AR)
+ AR = PSE.getAsAddRec(Phi);
+
+ if (!AR) {
+ DEBUG(dbgs() << "LV: PHI is not a poly recurrence.\n");
+ return false;
+ }
+
+ return isInductionPHI(Phi, PSE.getSE(), D, AR);
+}
+
+bool InductionDescriptor::isInductionPHI(PHINode *Phi,
+ ScalarEvolution *SE,
+ InductionDescriptor &D,
+ const SCEV *Expr) {
Type *PhiTy = Phi->getType();
// We only handle integer and pointer inductions variables.
if (!PhiTy->isIntegerTy() && !PhiTy->isPointerTy())
return false;
// Check that the PHI is consecutive.
- const SCEV *PhiScev = SE->getSCEV(Phi);
+ const SCEV *PhiScev = Expr ? Expr : SE->getSCEV(Phi);
const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(PhiScev);
+
if (!AR) {
DEBUG(dbgs() << "LV: PHI is not a poly recurrence.\n");
return false;