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Teach if-converter to avoid removing BBs whose addresses are takne. rdar://13782395

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181160 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2013-05-05 18:03:49 +00:00
parent acc47c738d
commit 9a28cc14a9
1 changed files with 19 additions and 2 deletions
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21
lib/CodeGen/IfConversion.cpp
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@ -1039,6 +1039,10 @@ bool IfConverter::IfConvertSimple(BBInfo &BBI, IfcvtKind Kind) {
return false;
}
if (CvtBBI->BB->hasAddressTaken())
// Conservatively abort if-conversion if BB's address is taken.
return false;
if (Kind == ICSimpleFalse)
if (TII->ReverseBranchCondition(Cond))
llvm_unreachable("Unable to reverse branch condition!");
@ -1116,6 +1120,10 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
return false;
}
if (CvtBBI->BB->hasAddressTaken())
// Conservatively abort if-conversion if BB's address is taken.
return false;
if (Kind == ICTriangleFalse || Kind == ICTriangleFRev)
if (TII->ReverseBranchCondition(Cond))
llvm_unreachable("Unable to reverse branch condition!");
@ -1184,7 +1192,8 @@ bool IfConverter::IfConvertTriangle(BBInfo &BBI, IfcvtKind Kind) {
// block. By not merging them, we make it possible to iteratively
// ifcvt the blocks.
if (!HasEarlyExit &&
NextBBI->BB->pred_size() == 1 && !NextBBI->HasFallThrough) {
NextBBI->BB->pred_size() == 1 && !NextBBI->HasFallThrough &&
!NextBBI->BB->hasAddressTaken()) {
MergeBlocks(BBI, *NextBBI);
FalseBBDead = true;
} else {
@ -1234,6 +1243,10 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
return false;
}
if (TrueBBI.BB->hasAddressTaken() || FalseBBI.BB->hasAddressTaken())
// Conservatively abort if-conversion if either BB has its address taken.
return false;
// Put the predicated instructions from the 'true' block before the
// instructions from the 'false' block, unless the true block would clobber
// the predicate, in which case, do the opposite.
@ -1382,7 +1395,8 @@ bool IfConverter::IfConvertDiamond(BBInfo &BBI, IfcvtKind Kind,
// tail, add a unconditional branch to it.
if (TailBB) {
BBInfo &TailBBI = BBAnalysis[TailBB->getNumber()];
bool CanMergeTail = !TailBBI.HasFallThrough;
bool CanMergeTail = !TailBBI.HasFallThrough &&
!TailBBI.BB->hasAddressTaken();
// There may still be a fall-through edge from BBI1 or BBI2 to TailBB;
// check if there are any other predecessors besides those.
unsigned NumPreds = TailBB->pred_size();
@ -1551,6 +1565,9 @@ void IfConverter::CopyAndPredicateBlock(BBInfo &ToBBI, BBInfo &FromBBI,
/// i.e., when FromBBI's branch is being moved, add those successor edges to
/// ToBBI.
void IfConverter::MergeBlocks(BBInfo &ToBBI, BBInfo &FromBBI, bool AddEdges) {
assert(!FromBBI.BB->hasAddressTaken() &&
"Removing a BB whose address is taken!");
ToBBI.BB->splice(ToBBI.BB->end(),
FromBBI.BB, FromBBI.BB->begin(), FromBBI.BB->end());