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Speculatively revert 98104; could be what's causing crashes

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98108 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dale Johannesen 2010-03-10 00:11:34 +00:00
parent 90e4af7b9d
commit 7dda453410
1 changed files with 3 additions and 56 deletions
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59
lib/CodeGen/BranchFolding.cpp
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@ -347,29 +347,15 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
--I1; --I2;
// Skip debugging pseudos; necessary to avoid changing the code.
while (I1->isDebugValue()) {
if (I1==MBB1->begin()) {
while (I2->isDebugValue()) {
if (I2==MBB2->begin())
// I1==DBG at begin; I2==DBG at begin
return TailLen;
--I2;
}
++I2;
// I1==DBG at begin; I2==non-DBG, or first of DBGs not at begin
if (I1==MBB1->begin())
return TailLen;
}
--I1;
}
// I1==first (untested) non-DBG preceding known match
while (I2->isDebugValue()) {
if (I2==MBB2->begin()) {
++I1;
// I1==non-DBG, or first of DBGs not at begin; I2==DBG at begin
if (I2==MBB2->begin())
return TailLen;
}
--I2;
}
// I1, I2==first (untested) non-DBGs preceding known match
if (!I1->isIdenticalTo(I2) ||
// FIXME: This check is dubious. It's used to get around a problem where
// people incorrectly expect inline asm directives to remain in the same
@ -382,29 +368,6 @@ static unsigned ComputeCommonTailLength(MachineBasicBlock *MBB1,
}
++TailLen;
}
// Back past possible debugging pseudos at beginning of block. This matters
// when one block differs from the other only by whether debugging pseudos
// are present at the beginning. (This way, the various checks later for
// I1==MBB1->begin() work as expected.)
if (I1 == MBB1->begin() && I2 != MBB2->begin()) {
--I2;
while (I2->isDebugValue()) {
if (I2 == MBB2->begin()) {
return TailLen;
}
--I2;
}
++I2;
}
if (I2 == MBB2->begin() && I1 != MBB1->begin()) {
--I1;
while (I1->isDebugValue()) {
if (I1 == MBB1->begin())
return TailLen;
--I1;
}
++I1;
}
return TailLen;
}
@ -1200,23 +1163,7 @@ ReoptimizeBlock:
// be 'non-branch terminators' in the block, try removing the branch and
// then seeing if the block is empty.
TII->RemoveBranch(*MBB);
// If the only things remaining in the block are debug info, remove these
// as well, so this will behave the same as an empty block in non-debug
// mode.
if (!MBB->empty()) {
bool NonDebugInfoFound = false;
for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
I != E; ++I) {
if (!I->isDebugValue()) {
NonDebugInfoFound = true;
break;
}
}
if (!NonDebugInfoFound)
// Make the block empty, losing the debug info (we could probably
// improve this in some cases.)
MBB->erase(MBB->begin(), MBB->end());
}
// If this block is just an unconditional branch to CurTBB, we can
// usually completely eliminate the block. The only case we cannot
// completely eliminate the block is when the block before this one