add fast-math-flags to 'call' instructions (PR21290)

Description

add fast-math-flags to 'call' instructions (PR21290)

This patch adds optional fast-math-flags (the same that apply to fmul/fadd/fsub/fdiv/frem/fcmp)
to call instructions in IR. Follow-up patches would use these flags in LibCallSimplifier, add
support to clang, and extend FMF to the DAG for calls.

Motivating example:

%y = fmul fast float %x, %x
%z = tail call float @sqrtf(float %y)

We'd like to be able to optimize sqrt(x*x) into fabs(x). We do this today using a function-wide
attribute for unsafe-math, but we really want to trigger on the instructions themselves:

%z = tail call fast float @sqrtf(float %y)

because in an LTO build it's possible that calls with fast semantics have been inlined into a
function with non-fast semantics.

The code changes and tests are based on the recent commits that added "notail":
http://reviews.llvm.org/rL252368

and added FMF to fcmp:
http://reviews.llvm.org/rL241901

Differential Revision: http://reviews.llvm.org/D14707

Details

Committed
spatelDec 14 2015, 1:59 PM
Differential Revision
D14707: add fast-math-flags to 'call' instructions (PR21290)
Parents
rL255554: Reordering fields to reduce padding in LLVM. NFC
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