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When moving a block for table jumps, make sure the prior block terminator

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is analyzable so it can be updated. If it's not, be safe and don't move the
block.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89022 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Grosbach 2009-11-17 01:21:04 +00:00
parent 2cbe71cdf0
commit a0a95a3c1c
1 changed files with 9 additions and 7 deletions
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16
lib/Target/ARM/ARMConstantIslandPass.cpp
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@ -1749,21 +1749,23 @@ AdjustJTTargetBlockForward(MachineBasicBlock *BB, MachineBasicBlock *JTBB)
// heuristic. FIXME: We can definitely improve it.
MachineBasicBlock *TBB = 0, *FBB = 0;
SmallVector<MachineOperand, 4> Cond;
SmallVector<MachineOperand, 4> CondPrior;
MachineFunction::iterator BBi = BB;
MachineFunction::iterator OldPrior = prior(BBi);
// If the block terminator isn't analyzable, don't try to move the block
if (TII->AnalyzeBranch(*BB, TBB, FBB, Cond))
return NULL;
bool B = TII->AnalyzeBranch(*BB, TBB, FBB, Cond);
// If the block ends in an unconditional branch, move it. Be paranoid
// If the block ends in an unconditional branch, move it. The prior block
// has to have an analyzable terminator for us to move this one. Be paranoid
// and make sure we're not trying to move the entry block of the function.
if (Cond.empty() && BB != MF.begin()) {
MachineFunction::iterator BBi = BB;
MachineFunction::iterator OldPrior = prior(BBi);
if (!B && Cond.empty() && BB != MF.begin() &&
!TII->AnalyzeBranch(*OldPrior, TBB, FBB, CondPrior)) {
BB->moveAfter(JTBB);
OldPrior->updateTerminator();
BB->updateTerminator();
// Update numbering to account for the block being moved.
MF.RenumberBlocks(OldPrior);
MF.RenumberBlocks();
++NumJTMoved;
return NULL;
}