[LV] Fix PR36983. For a given recurrence, fix all phis in exit block

There could be more than one PHIs in exit block using same loop recurrence.
Don't assume there is only one and fix each user.

Differential Revision: https://reviews.llvm.org/D47788

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334271 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index 3b4c544..bbace44 100644 (file)
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3530,12 +3530,11 @@ void InnerLoopVectorizer::fixFirstOrderRecurrence(PHINode *Phi) {
   // Finally, fix users of the recurrence outside the loop. The users will need
   // either the last value of the scalar recurrence or the last value of the
   // vector recurrence we extracted in the middle block. Since the loop is in
-  // LCSSA form, we just need to find the phi node for the original scalar
+  // LCSSA form, we just need to find all the phi nodes for the original scalar
   // recurrence in the exit block, and then add an edge for the middle block.
   for (PHINode &LCSSAPhi : LoopExitBlock->phis()) {
     if (LCSSAPhi.getIncomingValue(0) == Phi) {
       LCSSAPhi.addIncoming(ExtractForPhiUsedOutsideLoop, LoopMiddleBlock);
-      break;
     }
   }
 }

diff --git a/test/Transforms/LoopVectorize/pr36983.ll b/test/Transforms/LoopVectorize/pr36983.ll
new file mode 100644 (file)
index 0000000..71b1719
--- /dev/null
+++ b/test/Transforms/LoopVectorize/pr36983.ll
@@ -0,0 +1,24 @@
+; RUN: opt < %s -loop-vectorize -S | FileCheck %s
+
+; There could be more than one LCSSA PHIs in loop exit block.
+
+; CHECK-LABEL: bb1.bb3_crit_edge:
+; CHECK: %_tmp133.lcssa1 = phi i16 [ %scalar.recur, %bb2 ], [ %vector.recur.extract.for.phi, %middle.block ]
+; CHECK: %_tmp133.lcssa = phi i16 [ %scalar.recur, %bb2 ], [ %vector.recur.extract.for.phi, %middle.block ]
+
+define void @f1() {
+bb2.lr.ph:
+  br label %bb2
+
+bb2:                                              ; preds = %bb2, %bb2.lr.ph
+  %_tmp132 = phi i16 [ 0, %bb2.lr.ph ], [ %_tmp10, %bb2 ]
+  %_tmp133 = phi i16 [ undef, %bb2.lr.ph ], [ %_tmp10, %bb2 ]
+  %_tmp10 = sub nsw i16 %_tmp132, 1
+  %_tmp15 = icmp ne i16 %_tmp10, 0
+  br i1 %_tmp15, label %bb2, label %bb1.bb3_crit_edge
+
+bb1.bb3_crit_edge:                                ; preds = %bb2
+  %_tmp133.lcssa1 = phi i16 [ %_tmp133, %bb2 ]
+  %_tmp133.lcssa = phi i16 [ %_tmp133, %bb2 ]
+  ret void
+}