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LoopSimplify bug fix. Handle indirect loop back edges. 

Do not call SplitBlockPredecessors on a loop preheader when one of the
predecessors is an indirectbr. Otherwise, you will hit this assert:
!isa<IndirectBrInst>(Preds[i]->getTerminator()) && "Cannot split an edge from an IndirectBrInst"

llvm-svn: 153134
This commit is contained in:
Andrew Trick 2012-03-20 21:24:52 +00:00
parent bb01cbb312
commit f7711010e1
2 changed files with 49 additions and 5 deletions
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13
llvm/lib/Transforms/Utils/LoopSimplify.cpp
View File

@ -538,8 +538,7 @@ void LoopSimplify::PlaceSplitBlockCarefully(BasicBlock *NewBB,
///
Loop *LoopSimplify::SeparateNestedLoop(Loop *L, LPPassManager &LPM,
BasicBlock *Preheader) {
// Don't try to separate loops without a preheader (this excludes
// loop headers which are targeted by an indirectbr).
// Don't try to separate loops without a preheader.
if (!Preheader)
return 0;
@ -554,11 +553,15 @@ Loop *LoopSimplify::SeparateNestedLoop(Loop *L, LPPassManager &LPM,
// handles the case when a PHI node has multiple instances of itself as
// arguments.
SmallVector<BasicBlock*, 8> OuterLoopPreds;
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
if (PN->getIncomingValue(i) != PN ||
!L->contains(PN->getIncomingBlock(i)))
!L->contains(PN->getIncomingBlock(i))) {
// We can't split indirectbr edges.
if (isa<IndirectBrInst>(PN->getIncomingBlock(i)->getTerminator()))
return 0;
OuterLoopPreds.push_back(PN->getIncomingBlock(i));
}
}
DEBUG(dbgs() << "LoopSimplify: Splitting out a new outer loop\n");
// If ScalarEvolution is around and knows anything about values in

41
llvm/test/Transforms/LoopSimplify/2012-03-20-indirectbr.ll Normal file
View File

@ -0,0 +1,41 @@
; RUN: opt < %s -loop-simplify -S | FileCheck %s
; Make sure the preheader exists.
; CHECK: sw.bb103:
; CHECK: indirectbr {{.*}}label %while.cond112
; CHECK: while.cond112:
; But the tail is not split.
; CHECK: for.body:
; CHECK: indirectbr {{.*}}label %while.cond112
define fastcc void @build_regex_nfa() nounwind uwtable ssp {
entry:
indirectbr i8* blockaddress(@build_regex_nfa, %while.cond), [label %while.cond]
while.cond: ; preds = %if.then439, %entry
indirectbr i8* blockaddress(@build_regex_nfa, %sw.bb103), [label %do.body785, label %sw.bb103]
sw.bb103: ; preds = %while.body
indirectbr i8* blockaddress(@build_regex_nfa, %while.cond112), [label %while.cond112]
while.cond112: ; preds = %for.body, %for.cond.preheader, %sw.bb103
%pc.0 = phi i8 [ -1, %sw.bb103 ], [ 0, %for.body ], [ %pc.0, %for.cond.preheader ]
indirectbr i8* blockaddress(@build_regex_nfa, %Lsetdone), [label %sw.bb118, label %Lsetdone]
sw.bb118: ; preds = %while.cond112
indirectbr i8* blockaddress(@build_regex_nfa, %for.cond.preheader), [label %Lerror.loopexit, label %for.cond.preheader]
for.cond.preheader: ; preds = %sw.bb118
indirectbr i8* blockaddress(@build_regex_nfa, %for.body), [label %while.cond112, label %for.body]
for.body: ; preds = %for.body, %for.cond.preheader
indirectbr i8* blockaddress(@build_regex_nfa, %for.body), [label %while.cond112, label %for.body]
Lsetdone: ; preds = %while.cond112
unreachable
do.body785: ; preds = %while.cond, %while.body
ret void
Lerror.loopexit: ; preds = %sw.bb118
unreachable
}