[PATCH] D47216: [LV] Fix to pr37515, FP primary induction crashes LV

[Hideki Saito via Phabricator via llvm-commits]

hsaito created this revision.
hsaito added reviewers: Ayal, mkuper, spatel, rengolin.
Herald added a subscriber: llvm-commits.

LV never had an ability to convert FP primary induction to INT primary induction, but it has been lacking an appropriate safety check.
Whether it's legal to convert FP primary induction to INT primary induction and if so under what conditions are debatable, but bailing
out when it's not proven safe (and currently never proven to be safe as far as LV's existing code is concerned) is a valid thing to do.

The bug may be introduced (or exposed depending on how you see it) by FP induction support ( approx. 2yrs ago?).


Repository:
  rL LLVM

https://reviews.llvm.org/D47216

Files:
  lib/Transforms/Vectorize/LoopVectorizationLegality.cpp


Index: lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
+++ lib/Transforms/Vectorize/LoopVectorizationLegality.cpp
@@ -726,7 +726,7 @@
 
   if (!PrimaryInduction) {
     LLVM_DEBUG(dbgs() << "LV: Did not find one integer induction var.\n");
-    if (Inductions.empty()) {
+    if (Inductions.empty() || !WidestIndTy) {
       ORE->emit(createMissedAnalysis("NoInductionVariable")
                 << "loop induction variable could not be identified");
       return false;


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