[LLVMdev] detailed comparison of generated code size for LLVM and other compilers

[Dale Johannesen]

On Dec 14, 2009, at 12:23 PMPST, John Regehr wrote:

>>> There are probably other differing defaults besides frame  
>>> pointers.  Stack
>>> protectors, perhaps.
>>
>> Yes, that's another good example,
>
> Ok-- I assume I should just add '-fno-stack-protector' to the llvm- 
> gcc and
> clang command lines?  I had totally missed that something like this  
> was
> turned on by default.

Yes.

> I'll re-run everything with this change, with frame pointers  
> omitted, and
> dropping testcases that contain uses of uninititalized locals and post
> here again when that's done.

You'll probably need to  some digging to make sure the defaults are  
exactly comparable.  Are SSE and/or MMX used?  This affects floating  
point codegen quite a bit.  Are the target CPUs the same?

I think some useful information is going to come out of this, but  
there's some cruft to clear out first.