One of the things that I've been interested in is adding support to GCC to compile individual functions with specific target options. I first presented a draft at the Google mini-summit, and then another draft at the GCC developer summit last July.
In the x86 world this would mean saying that an individual function can use SSE5 instructions or SSE4.1 instructions. This would simplify things for people who need to write high performance libraries that run on different architectures, and need to be optimal on each platform. Ultimately, the goal is to allow hotspot functions to be compiled several times with different target specific optimizations. I would welcome any thoughts or suggestions about this proposal. The proposal is at: http://gcc.gnu.org/wiki/FunctionSpecificOpt Part of the infrastructure work for doing this is already addressed in function adaption project and we will work together with that team: http://gcc.gnu.org/wiki/functionAdaptation One of the things that I have considered and not added to the current proposal is to change most of the -f, -O, -W options for a function. This would be relatively simple to add once the infrastructure is in place, but it can really complicate things, since various optimizations depend on other optimizations having been done. Similarly, the -mtune= and -march= options can overly complicate matters. In addition, attribute(cold) and attribute(hot) will set the optimization level to -Os and -O3. I will be away on vacation from December 3-8th, and not reading mail during that time. -- Michael Meissner, AMD 90 Central Street, MS 83-29, Boxborough, MA, 01719, USA [EMAIL PROTECTED]
