[llvm-commits] [llvm] r112597 - in /llvm/trunk: include/llvm/CodeGen/Passes.h lib/CodeGen/DwarfEHPrepare.cpp lib/CodeGen/LLVMTargetMachine.cpp
Duncan Sands
baldrick at free.fr
Tue Aug 31 13:11:07 PDT 2010
Hi Bill,
>>> I'm fine with this, but please do the alloca promotion using SSAUpdater soon. Otherwise my horrible hack won't work for all of the cases I need it to. As John mentioned, I need to do reachability and not dominance. I'll fix it so that the DomTree stuff isn't needed.
>>
>> we never did any alloca promotion at -O0, so does that mean this already
>> sometimes wasn't working properly at -O0? Also, I wasn't actually planning
>> to do alloca promotion for your 'orrible hack code because it makes my head
>> hurt, but perhaps I can be persuaded...
>>
> The horrible hack is there mostly for inlining, which doesn't occur at -O0.
aren't you confusing -O0 at the IR level and -O0 codegen? I can optimize some
bitcode with -std-compile-opts and then pass it to "llc -O0"... So in theory
llc needs to deal correctly with inlined code even at -O0.
We can get away with it in most cases. But it's quite easy to generate a case
where it won't work. My guess is that it's a hand-written case that would fail.
Sounds like a good testcase to have in the testsuite!
> I just don't want a regression, and since you took the code out I thought you would replace it. :-)
There is something to what you say :)
But if it works, then it's fine being omitted.
I think I'd better test it harder...
Ciao,
Duncan.
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