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Custom inserters (e.g., conditional moves in Thumb1 can introduce

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new basic blocks, and if used as a function argument, that can cause call frame
setup / destroy pairs to be split across a basic block boundary. That prevents
us from doing a simple assertion to check that the pairs match and alloc/
dealloc the same amount of space. Modify the assertion to only check the
amount allocated when there are matching pairs in the same basic block.

rdar://8022442

llvm-svn: 107517
This commit is contained in:
Jim Grosbach 2010-07-02 21:23:37 +00:00
parent cefe3831b7
commit 3c43248560
1 changed files with 14 additions and 1 deletions
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15
llvm/lib/CodeGen/PrologEpilogInserter.cpp
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@ -642,6 +642,9 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
for (MachineFunction::iterator BB = Fn.begin(),
E = Fn.end(); BB != E; ++BB) {
#ifndef NDEBUG
int SPAdjCount = 0; // frame setup / destroy count.
#endif
int SPAdj = 0; // SP offset due to call frame setup / destroy.
if (RS && !FrameIndexVirtualScavenging) RS->enterBasicBlock(BB);
@ -649,6 +652,10 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
if (I->getOpcode() == FrameSetupOpcode ||
I->getOpcode() == FrameDestroyOpcode) {
#ifndef NDEBUG
// Track whether we see even pairs of them
SPAdjCount += I->getOpcode() == FrameSetupOpcode ? 1 : -1;
#endif
// Remember how much SP has been adjusted to create the call
// frame.
int Size = I->getOperand(0).getImm();
@ -715,7 +722,13 @@ void PEI::replaceFrameIndices(MachineFunction &Fn) {
if (RS && !FrameIndexVirtualScavenging && MI) RS->forward(MI);
}
assert(SPAdj == 0 && "Unbalanced call frame setup / destroy pairs?");
// If we have evenly matched pairs of frame setup / destroy instructions,
// make sure the adjustments come out to zero. If we don't have matched
// pairs, we can't be sure the missing bit isn't in another basic block
// due to a custom inserter playing tricks, so just asserting SPAdj==0
// isn't sufficient. See tMOVCC on Thumb1, for example.
assert((SPAdjCount || SPAdj == 0) &&
"Unbalanced call frame setup / destroy pairs?");
}
}