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ARM AnalyzeBranch should conservatively return true when it sees a predicated

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indirect branch at the end of the BB. Otherwise if-converter, branch folding
pass may incorrectly update its successor info if it consider BB as fallthrough
to the next BB.

rdar://13782395


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181161 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng
2013-05-05 18:06:32 +00:00
parent 9a28cc14a9
commit 0553e1efcd
1 changed files with 9 additions and 3 deletions
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12
lib/Target/ARM/ARMBaseInstrInfo.cpp
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@@ -283,14 +283,20 @@ ARMBaseInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
return false; return false;
--I; --I;
} }
if (!isUnpredicatedTerminator(I))
return false;
// Get the last instruction in the block. // Get the last instruction in the block.
MachineInstr *LastInst = I; MachineInstr *LastInst = I;
unsigned LastOpc = LastInst->getOpcode();
// Check if it's an indirect branch first, this should return 'unanalyzable'
// even if it's predicated.
if (isIndirectBranchOpcode(LastOpc))
return true;
if (!isUnpredicatedTerminator(I))
return false;
// If there is only one terminator instruction, process it. // If there is only one terminator instruction, process it.
unsigned LastOpc = LastInst->getOpcode();
if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) { if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
if (isUncondBranchOpcode(LastOpc)) { if (isUncondBranchOpcode(LastOpc)) {
TBB = LastInst->getOperand(0).getMBB(); TBB = LastInst->getOperand(0).getMBB();