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

llvm-svn: 255555

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/test/Transforms/InstCombine/no_cgscc_assert.ll b/llvm/test/Transforms/InstCombine/no_cgscc_assert.ll
index cec5297695b..3df04d2c890 100644
--- a/llvm/test/Transforms/InstCombine/no_cgscc_assert.ll
+++ b/llvm/test/Transforms/InstCombine/no_cgscc_assert.ll
@@ -10,7 +10,7 @@ define float @bar(float %f) #0 {
   ret float %call1
 
 ; CHECK-LABEL: @bar(
-; CHECK-NEXT: call float @llvm.fabs.f32
+; CHECK-NEXT: call fast float @llvm.fabs.f32
 ; CHECK-NEXT: ret float
 }