First off, is anyone working on providing GCC or libm with a (complete)
set of C99 math functions with SSE/SSE2 calling conventions? If not, I
will start with something like the following plan:
1. There is already support for switching the ABI function-wise in
the backend for local static functions. As a first step I'd like
to expose this functionality as a function attribute.
2. In the -mfpmath=sse case I'd like to attach this attribute to GCCs
builtin math functions, either dependent on availability of such
function in libgcc(?) or glibc libm (detected by some configure
magic).
3. Emit calls to alternate the functions during RTL expansion, possibly
following the naming scheme from the Intel compiler (to be able to
use their libm replacement for testing).
4. Provide either libgcc or libm with SSE/SSE2 implementations for
the math functions, possibly with both ABIs as entry point.
5. Eventually provide GCC with RTL inline intrinsics for commonly used
math functions in the -ffast-math case.
Does this sound reasonable and profitable? As far as I see glibc libm
currently has no SSE/SSE2 implementations, neither for amd64 nor for
ia32.
Thanks,
Richard.
