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LoopVectorizer: Fix a bug in the code that updates the loop exiting block.

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LCSSA PHIs may have undef values. The vectorizer updates values that are used by outside users such as PHIs.
The bug happened because undefs are not loop values. This patch handles these PHIs.

PR14725



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171251 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem 2012-12-30 07:47:00 +00:00
parent a6542923b8
commit db2367512e
2 changed files with 42 additions and 0 deletions
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13
lib/Transforms/Vectorize/LoopVectorize.cpp
View File

@ -909,6 +909,19 @@ InnerLoopVectorizer::vectorizeLoop(LoopVectorizationLegality *Legal) {
(RdxPhi)->setIncomingValue(SelfEdgeBlockIdx, Scalar0);
(RdxPhi)->setIncomingValue(IncomingEdgeBlockIdx, RdxDesc.LoopExitInstr);
}// end of for each redux variable.
// The Loop exit block may have single value PHI nodes where the incoming
// value is 'undef'. While vectorizing we only handled real values that
// were defined inside the loop. Here we handle the 'undef case'.
// See PR14725.
for (BasicBlock::iterator LEI = LoopExitBlock->begin(),
LEE = LoopExitBlock->end(); LEI != LEE; ++LEI) {
PHINode *LCSSAPhi = dyn_cast<PHINode>(LEI);
if (!LCSSAPhi) continue;
if (LCSSAPhi->getNumIncomingValues() == 1)
LCSSAPhi->addIncoming(UndefValue::get(LCSSAPhi->getType()),
LoopMiddleBlock);
}
}
Value *InnerLoopVectorizer::createEdgeMask(BasicBlock *Src, BasicBlock *Dst) {

29
test/Transforms/LoopVectorize/lcssa-crash.ll Normal file
View File

@ -0,0 +1,29 @@
; RUN: opt < %s -loop-vectorize -force-vector-width=4
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
%type1 = type { %type2 }
%type2 = type { [0 x i8*], i8**, i32, i32, i32 }
define void @test() nounwind uwtable align 2 {
br label %for.body.lr.ph.i.i.i
for.body.lr.ph.i.i.i:
br label %for.body.i.i.i
for.body.i.i.i:
%indvars.iv = phi i64 [ %indvars.iv.next, %for.inc.i.i.i ], [ 0, %for.body.lr.ph.i.i.i ]
br label %for.inc.i.i.i
for.inc.i.i.i:
%indvars.iv.next = add i64 %indvars.iv, 1
%lftr.wideiv = trunc i64 %indvars.iv.next to i32
%exitcond = icmp ne i32 %lftr.wideiv, undef
br i1 %exitcond, label %for.body.i.i.i, label %for.end.i.i.i
for.end.i.i.i:
%lcssa = phi %type1* [ undef, %for.inc.i.i.i ]
unreachable
}