Merging r322473:

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r322473 | a.elovikov | 2018-01-15 02:56:07 -0800 (Mon, 15 Jan 2018) | 23 lines

[LV] Don't call recordVectorLoopValueForInductionCast for newly-created IV from a trunc.

Summary:
This method is supposed to be called for IVs that have casts in their use-def
chains that are completely ignored after vectorization under PSE. However, for
truncates of such IVs the same InductionDescriptor is used during
creation/widening of both original IV based on PHINode and new IV based on
TruncInst.

This leads to unintended second call to recordVectorLoopValueForInductionCast
with a VectorLoopVal set to the newly created IV for a trunc and causes an
assert due to attempt to store new information for already existing entry in the
map. This is wrong and should not be done.

Fixes PR35773.

Reviewers: dorit, Ayal, mssimpso

Reviewed By: dorit

Subscribers: RKSimon, dim, dcaballe, hsaito, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D41913
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@322673 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 6ef54385c45..64f206ea92e 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -2630,9 +2630,12 @@ void InnerLoopVectorizer::createVectorIntOrFpInductionPHI(
   Instruction *LastInduction = VecInd;
   for (unsigned Part = 0; Part < UF; ++Part) {
     VectorLoopValueMap.setVectorValue(EntryVal, Part, LastInduction);
-    recordVectorLoopValueForInductionCast(II, LastInduction, Part);
+
     if (isa<TruncInst>(EntryVal))
       addMetadata(LastInduction, EntryVal);
+    else
+      recordVectorLoopValueForInductionCast(II, LastInduction, Part);
+
     LastInduction = cast<Instruction>(addFastMathFlag(
         Builder.CreateBinOp(AddOp, LastInduction, SplatVF, "step.add")));
   }
@@ -2754,15 +2757,17 @@ void InnerLoopVectorizer::widenIntOrFpInduction(PHINode *IV, TruncInst *Trunc) {
 
   // If we haven't yet vectorized the induction variable, splat the scalar
   // induction variable, and build the necessary step vectors.
+  // TODO: Don't do it unless the vectorized IV is really required.
   if (!VectorizedIV) {
     Value *Broadcasted = getBroadcastInstrs(ScalarIV);
     for (unsigned Part = 0; Part < UF; ++Part) {
       Value *EntryPart =
           getStepVector(Broadcasted, VF * Part, Step, ID.getInductionOpcode());
       VectorLoopValueMap.setVectorValue(EntryVal, Part, EntryPart);
-      recordVectorLoopValueForInductionCast(ID, EntryPart, Part);
       if (Trunc)
         addMetadata(EntryPart, Trunc);
+      else
+        recordVectorLoopValueForInductionCast(ID, EntryPart, Part);
     }
   }