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Fix a corner case hit by redundant phi elimination running after LSR.

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Fixes PR11761: bad IR w/ redundant Phi elim


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148177 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2012-01-14 03:17:23 +00:00
parent da22344804
commit dd1f22f25d
2 changed files with 61 additions and 1 deletions
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12
lib/Analysis/ScalarEvolutionExpander.cpp
View File

@ -1541,6 +1541,13 @@ SCEVExpander::getOrInsertCanonicalInductionVariable(const Loop *L,
/// general code-insertion helper.
bool SCEVExpander::hoistStep(Instruction *IncV, Instruction *InsertPos,
const DominatorTree *DT) {
// Phi nodes are strangely positional but don't follow normal rules for
// instruction dominance. Handle them immediately.
if (isa<PHINode>(InsertPos))
return isa<PHINode>(IncV);
else if (isa<PHINode>(IncV))
return false;
if (DT->dominates(IncV, InsertPos))
return true;
@ -1648,7 +1655,10 @@ unsigned SCEVExpander::replaceCongruentIVs(Loop *L, const DominatorTree *DT,
<< *IsomorphicInc << '\n');
Value *NewInc = OrigInc;
if (OrigInc->getType() != IsomorphicInc->getType()) {
IRBuilder<> Builder(OrigInc->getNextNode());
Instruction *IP = isa<PHINode>(OrigInc)
? (Instruction*)L->getHeader()->getFirstInsertionPt()
: OrigInc->getNextNode();
IRBuilder<> Builder(IP);
Builder.SetCurrentDebugLocation(IsomorphicInc->getDebugLoc());
NewInc = Builder.
CreateTruncOrBitCast(OrigInc, IsomorphicInc->getType(), IVName);

50
test/Transforms/LoopStrengthReduce/X86/2012-01-13-phielim.ll Normal file
View File

@ -0,0 +1,50 @@
; RUN: llc < %s -O3 -march=x86-64 -mcpu=core2 | FileCheck %s
declare i1 @check() nounwind
declare i1 @foo(i8*, i8*, i8*) nounwind
; Check that redundant phi elimination ran
; CHECK: @test
; CHECK: %while.body.i
; CHECK: movs
; CHECK-NOT: movs
; CHECK: %for.end.i
define i32 @test(i8* %base) nounwind uwtable ssp {
entry:
br label %while.body.lr.ph.i
while.body.lr.ph.i: ; preds = %cond.true.i
br label %while.body.i
while.body.i: ; preds = %cond.true29.i, %while.body.lr.ph.i
%indvars.iv7.i = phi i64 [ 16, %while.body.lr.ph.i ], [ %indvars.iv.next8.i, %cond.true29.i ]
%i.05.i = phi i64 [ 0, %while.body.lr.ph.i ], [ %indvars.iv7.i, %cond.true29.i ]
%sext.i = shl i64 %i.05.i, 32
%idx.ext.i = ashr exact i64 %sext.i, 32
%add.ptr.sum.i = add i64 %idx.ext.i, 16
br label %for.body.i
for.body.i: ; preds = %for.body.i, %while.body.i
%indvars.iv.i = phi i64 [ 0, %while.body.i ], [ %indvars.iv.next.i, %for.body.i ]
%add.ptr.sum = add i64 %add.ptr.sum.i, %indvars.iv.i
%arrayidx22.i = getelementptr inbounds i8* %base, i64 %add.ptr.sum
%0 = load i8* %arrayidx22.i, align 1
%indvars.iv.next.i = add i64 %indvars.iv.i, 1
%cmp = call i1 @check() nounwind
br i1 %cmp, label %for.end.i, label %for.body.i
for.end.i: ; preds = %for.body.i
%add.ptr.i144 = getelementptr inbounds i8* %base, i64 %add.ptr.sum.i
%cmp2 = tail call i1 @foo(i8* %add.ptr.i144, i8* %add.ptr.i144, i8* undef) nounwind
br i1 %cmp2, label %cond.true29.i, label %cond.false35.i
cond.true29.i: ; preds = %for.end.i
%indvars.iv.next8.i = add i64 %indvars.iv7.i, 16
br i1 false, label %exit, label %while.body.i
cond.false35.i: ; preds = %for.end.i
unreachable
exit: ; preds = %cond.true29.i, %cond.true.i
ret i32 0
}