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

Chris Lattner clattner at apple.com
Mon Dec 14 13:57:23 PST 2009

On Dec 14, 2009, at 1:49 PM, John Regehr wrote:

>> 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?
> Good point.  Would "generic i686" be a reasonable choice?  Does that  
> even
> mean anything these days?
> Anyway-- I'd appreciate some guidance on what you folks would find  
> most
> interesting and useful.  Then I can do some homework and figure out  
> how to
> get the rest of the compilers to assume an equivalent ISA.

I'd recommend targeting (with both -march and -mtune) a simple and  
commonly available CPU type like "core2" or "pentium4".  ICC should  
have both of these and gcc/llvm definitely do.


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