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[LoopVersioning] Relax an assert for LCSSA PHIs 

When you have multiple LCSSA (single-operand) PHIs that are converted
into two-operand PHIs due to versioning, only assert that the PHI
currently being converted has a single operand.  I.e. we don't want to
check PHIs that were converted earlier in the loop.

Fixes PR27023.

Thanks to Karl-Johan Karlsson for the minimized testcase!

llvm-svn: 264081
This commit is contained in:
Adam Nemet 2016-03-22 18:38:15 +00:00
parent e409e688a3
commit 8b47e0d0ea
2 changed files with 39 additions and 3 deletions
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7
llvm/lib/Transforms/Utils/LoopVersioning.cpp
View File

@ -133,10 +133,11 @@ void LoopVersioning::addPHINodes(
// First see if we have a single-operand PHI with the value defined by the
// original loop.
for (auto I = PHIBlock->begin(); (PN = dyn_cast<PHINode>(I)); ++I) {
assert(PN->getNumOperands() == 1 &&
"Exit block should only have on predecessor");
if (PN->getIncomingValue(0) == Inst)
if (PN->getIncomingValue(0) == Inst) {
assert(PN->getNumOperands() == 1 &&
"Exit block should only have on predecessor");
break;
}
}
// If not create it.
if (!PN) {

35
llvm/test/Transforms/LoopVersioning/lcssa.ll Normal file
View File

@ -0,0 +1,35 @@
; RUN: opt -basicaa -loop-versioning -S < %s | FileCheck %s
target triple = "x86_64-unknown-linux-gnu"
define void @fill(i8** %ls1.20, i8** %ls2.21, i8* %cse3.22) {
; CHECK: bb1.lver.check:
; CHECK: br i1 %memcheck.conflict, label %bb1.ph.lver.orig, label %bb1.ph
bb1.ph:
%ls1.20.promoted = load i8*, i8** %ls1.20
%ls2.21.promoted = load i8*, i8** %ls2.21
br label %bb1
bb1:
%_tmp302 = phi i8* [ %ls2.21.promoted, %bb1.ph ], [ %_tmp30, %bb1 ]
%_tmp281 = phi i8* [ %ls1.20.promoted, %bb1.ph ], [ %_tmp28, %bb1 ]
%_tmp14 = getelementptr i8, i8* %_tmp281, i16 -1
%_tmp15 = load i8, i8* %_tmp14
%add = add i8 %_tmp15, 1
store i8 %add, i8* %_tmp281
store i8 %add, i8* %_tmp302
%_tmp28 = getelementptr i8, i8* %_tmp281, i16 1
%_tmp30 = getelementptr i8, i8* %_tmp302, i16 1
br i1 false, label %bb1, label %bb3.loopexit
bb3.loopexit:
%_tmp30.lcssa = phi i8* [ %_tmp30, %bb1 ]
%_tmp15.lcssa = phi i8 [ %_tmp15, %bb1 ]
%_tmp28.lcssa = phi i8* [ %_tmp28, %bb1 ]
store i8* %_tmp28.lcssa, i8** %ls1.20
store i8 %_tmp15.lcssa, i8* %cse3.22
store i8* %_tmp30.lcssa, i8** %ls2.21
br label %bb3
bb3:
ret void
}