llvm-mirror/test/CodeGen/X86/recip-fastmath.ll
Sanjay Patel 164919e49c [x86] set default reciprocal (division and square root) codegen to match GCC
D8982 ( checked in at http://reviews.llvm.org/rL239001 ) added command-line 
options to allow reciprocal estimate instructions to be used in place of
divisions and square roots.

This patch changes the default settings for x86 targets to allow that recip
codegen (except for scalar division because that breaks too much code) when
using -ffast-math or its equivalent. 

This matches GCC behavior for this kind of codegen.

Differential Revision: http://reviews.llvm.org/D10396

llvm-svn: 240310
2015-06-22 18:29:44 +00:00

110 lines
2.7 KiB
LLVM

; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=sse2 -recip=!divf,!vec-divf | FileCheck %s --check-prefix=NORECIP
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=avx -recip=divf,vec-divf | FileCheck %s --check-prefix=RECIP
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=avx -recip=divf:2,vec-divf:2 | FileCheck %s --check-prefix=REFINE
; If the target's divss/divps instructions are substantially
; slower than rcpss/rcpps with a Newton-Raphson refinement,
; we should generate the estimate sequence.
; See PR21385 ( http://llvm.org/bugs/show_bug.cgi?id=21385 )
; for details about the accuracy, speed, and implementation
; differences of x86 reciprocal estimates.
define float @reciprocal_estimate(float %x) #0 {
%div = fdiv fast float 1.0, %x
ret float %div
; NORECIP-LABEL: reciprocal_estimate:
; NORECIP: movss
; NORECIP-NEXT: divss
; NORECIP-NEXT: movaps
; NORECIP-NEXT: retq
; RECIP-LABEL: reciprocal_estimate:
; RECIP: vrcpss
; RECIP: vmulss
; RECIP: vsubss
; RECIP: vmulss
; RECIP: vaddss
; RECIP-NEXT: retq
; REFINE-LABEL: reciprocal_estimate:
; REFINE: vrcpss
; REFINE: vmulss
; REFINE: vsubss
; REFINE: vmulss
; REFINE: vaddss
; REFINE: vmulss
; REFINE: vsubss
; REFINE: vmulss
; REFINE: vaddss
; REFINE-NEXT: retq
}
define <4 x float> @reciprocal_estimate_v4f32(<4 x float> %x) #0 {
%div = fdiv fast <4 x float> <float 1.0, float 1.0, float 1.0, float 1.0>, %x
ret <4 x float> %div
; NORECIP-LABEL: reciprocal_estimate_v4f32:
; NORECIP: movaps
; NORECIP-NEXT: divps
; NORECIP-NEXT: movaps
; NORECIP-NEXT: retq
; RECIP-LABEL: reciprocal_estimate_v4f32:
; RECIP: vrcpps
; RECIP: vmulps
; RECIP: vsubps
; RECIP: vmulps
; RECIP: vaddps
; RECIP-NEXT: retq
; REFINE-LABEL: reciprocal_estimate_v4f32:
; REFINE: vrcpps
; REFINE: vmulps
; REFINE: vsubps
; REFINE: vmulps
; REFINE: vaddps
; REFINE: vmulps
; REFINE: vsubps
; REFINE: vmulps
; REFINE: vaddps
; REFINE-NEXT: retq
}
define <8 x float> @reciprocal_estimate_v8f32(<8 x float> %x) #0 {
%div = fdiv fast <8 x float> <float 1.0, float 1.0, float 1.0, float 1.0, float 1.0, float 1.0, float 1.0, float 1.0>, %x
ret <8 x float> %div
; NORECIP-LABEL: reciprocal_estimate_v8f32:
; NORECIP: movaps
; NORECIP: movaps
; NORECIP-NEXT: divps
; NORECIP-NEXT: divps
; NORECIP-NEXT: movaps
; NORECIP-NEXT: movaps
; NORECIP-NEXT: retq
; RECIP-LABEL: reciprocal_estimate_v8f32:
; RECIP: vrcpps
; RECIP: vmulps
; RECIP: vsubps
; RECIP: vmulps
; RECIP: vaddps
; RECIP-NEXT: retq
; REFINE-LABEL: reciprocal_estimate_v8f32:
; REFINE: vrcpps
; REFINE: vmulps
; REFINE: vsubps
; REFINE: vmulps
; REFINE: vaddps
; REFINE: vmulps
; REFINE: vsubps
; REFINE: vmulps
; REFINE: vaddps
; REFINE-NEXT: retq
}
attributes #0 = { "unsafe-fp-math"="true" }