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[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

llvm-svn: 334271
This commit is contained in:
Roman Shirokiy 2018-06-08 08:21:20 +00:00
parent 07996a54ba
commit 9ba0aa2da0
2 changed files with 25 additions and 2 deletions
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3
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -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;
}
}
}

24
llvm/test/Transforms/LoopVectorize/pr36983.ll Normal file
View File

@ -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
}