Hi Gang-Ryung!
Your reverse iteration of instructions in the BB
* for (BasicBlock::iterator II = BB->end(); II != BB->begin(); ) *{
Instruction &I = *--II;
if (isLoopInvariantInst(I) && canSinkOrHoistInst(I) &&
isSafeToExecuteUnconditionally(I))
* hoist(I);*
}
looks perfectly valid.
If I remember correctly, the (operator--) on Instruction has a buggy
assert, but that should not trigger in your case. (Adding unit tests for
reverse iteration is on my TODO list.)
I suspect that your "hoist(I)" call removes the instruction "I" from the
BB and puts it into the first position of another basic block. This could
mess up the "II != BB->begin()" test.
Hope this helps!
Cheers,
Gabor