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Fix ScalarEvolutionExpander when creating a PHI in a block with duplicate predecessors

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It seems that when I fixed this, almost exactly a year ago, I did not quite do
it correctly. When we have duplicate block predecessors, we can indeed not have
different incoming values for the same block, but we *must* have duplicate
entries. So, instead of skipping the duplicates, we explicitly add the
duplicate incoming values.

Fixes PR20442.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214423 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel 2014-07-31 19:13:38 +00:00
parent 94f7c7aeaa
commit 50c05c91f9
2 changed files with 84 additions and 1 deletions
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6
lib/Analysis/ScalarEvolutionExpander.cpp
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@ -1443,8 +1443,12 @@ Value *SCEVExpander::visitAddRecExpr(const SCEVAddRecExpr *S) {
Constant *One = ConstantInt::get(Ty, 1);
for (pred_iterator HPI = HPB; HPI != HPE; ++HPI) {
BasicBlock *HP = *HPI;
if (!PredSeen.insert(HP))
if (!PredSeen.insert(HP)) {
// There must be an incoming value for each predecessor, even the
// duplicates!
CanonicalIV->addIncoming(CanonicalIV->getIncomingValueForBlock(HP), HP);
continue;
}
if (L->contains(HP)) {
// Insert a unit add instruction right before the terminator

79
test/CodeGen/PowerPC/pr20442.ll Normal file
View File

@ -0,0 +1,79 @@
; RUN: llc -mcpu=pwr7 < %s | FileCheck %s
target datalayout = "E-m:e-p:32:32-i64:64-n32"
target triple = "powerpc-unknown-linux-gnu"
; This code would cause code generation like this after PPCCTRLoops ran:
; %indvar = phi i32 [ 0, %for.body ], [ %indvar.next, %if.then6 ]
; %j.1.ph13 = phi i32 [ %j.110, %if.then6 ], [ 0, %for.body ], [ 0, %for.body ]
; %c.0.ph12 = phi i32 [ %dec, %if.then6 ], [ %2, %for.body ], [ %2, %for.body ]
; which would fail verification because the created induction variable does not
; have as many predecessor entries as the other PHIs.
; CHECK-LABEL: @fn1
; CHECK: mtctr
%struct.anon = type { i32 }
%struct.anon.0 = type { i32 }
@b = common global %struct.anon* null, align 4
@a = common global %struct.anon.0* null, align 4
; Function Attrs: nounwind readonly uwtable
define i32 @fn1() #0 {
entry:
%0 = load %struct.anon** @b, align 4
%1 = ptrtoint %struct.anon* %0 to i32
%cmp = icmp sgt %struct.anon* %0, null
%2 = load %struct.anon.0** @a, align 4
br i1 %cmp, label %for.bodythread-pre-split, label %if.end8
for.bodythread-pre-split: ; preds = %entry
%aclass = getelementptr inbounds %struct.anon.0* %2, i32 0, i32 0
%.pr = load i32* %aclass, align 4
br label %for.body
for.body: ; preds = %for.bodythread-pre-split, %for.body
switch i32 %.pr, label %for.body [
i32 0, label %while.body.lr.ph.preheader
i32 2, label %while.body.lr.ph.preheader
]
while.body.lr.ph.preheader: ; preds = %for.body, %for.body
br label %while.body.lr.ph
while.body.lr.ph: ; preds = %while.body.lr.ph.preheader, %if.then6
%j.1.ph13 = phi i32 [ %j.110.lcssa, %if.then6 ], [ 0, %while.body.lr.ph.preheader ]
%c.0.ph12 = phi i32 [ %dec, %if.then6 ], [ %1, %while.body.lr.ph.preheader ]
br label %while.body
while.cond: ; preds = %while.body
%cmp2 = icmp slt i32 %inc7, %c.0.ph12
br i1 %cmp2, label %while.body, label %if.end8.loopexit
while.body: ; preds = %while.body.lr.ph, %while.cond
%j.110 = phi i32 [ %j.1.ph13, %while.body.lr.ph ], [ %inc7, %while.cond ]
%aclass_index = getelementptr inbounds %struct.anon* %0, i32 %j.110, i32 0
%3 = load i32* %aclass_index, align 4
%aclass5 = getelementptr inbounds %struct.anon.0* %2, i32 %3, i32 0
%4 = load i32* %aclass5, align 4
%tobool = icmp eq i32 %4, 0
%inc7 = add nsw i32 %j.110, 1
br i1 %tobool, label %while.cond, label %if.then6
if.then6: ; preds = %while.body
%j.110.lcssa = phi i32 [ %j.110, %while.body ]
%dec = add nsw i32 %c.0.ph12, -1
%cmp29 = icmp slt i32 %j.110.lcssa, %dec
br i1 %cmp29, label %while.body.lr.ph, label %if.end8.loopexit17
if.end8.loopexit: ; preds = %while.cond
br label %if.end8
if.end8.loopexit17: ; preds = %if.then6
br label %if.end8
if.end8: ; preds = %if.end8.loopexit17, %if.end8.loopexit, %entry
ret i32 undef
}
attributes #0 = { nounwind readonly uwtable }