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[x86] set default reciprocal (division and square root) codegen to match GCC

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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
This commit is contained in:
Sanjay Patel 2015-06-22 18:29:44 +00:00
parent ce613c8a7a
commit 164919e49c
3 changed files with 63 additions and 60 deletions
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15
lib/Target/X86/X86TargetMachine.cpp
View File

@ -110,12 +110,15 @@ X86TargetMachine::X86TargetMachine(const Target &T, const Triple &TT,
if (Subtarget.isTargetWin64()) if (Subtarget.isTargetWin64())
this->Options.TrapUnreachable = true; this->Options.TrapUnreachable = true;
// TODO: By default, all reciprocal estimate operations are off because // By default (and when -ffast-math is on), enable estimate codegen for
// that matches the behavior before TargetRecip was added (except for btver2 // everything except scalar division. By default, use 1 refinement step for
// which used subtarget features to enable this type of codegen). // all operations. Defaults may be overridden by using command-line options.
// We should change this to match GCC behavior where everything but // Scalar division estimates are disabled because they break too much
// scalar division estimates are turned on by default with -ffast-math. // real-world code. These defaults match GCC behavior.
this->Options.Reciprocals.setDefaults("all", false, 1); this->Options.Reciprocals.setDefaults("sqrtf", true, 1);
this->Options.Reciprocals.setDefaults("divf", false, 1);
this->Options.Reciprocals.setDefaults("vec-sqrtf", true, 1);
this->Options.Reciprocals.setDefaults("vec-divf", true, 1);
initAsmInfo(); initAsmInfo();
} }

38
test/CodeGen/X86/recip-fastmath.ll
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@ -1,4 +1,4 @@
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=sse2 | FileCheck %s ; 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,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 ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=avx -recip=divf:2,vec-divf:2 | FileCheck %s --check-prefix=REFINE
@ -14,11 +14,11 @@ define float @reciprocal_estimate(float %x) #0 {
%div = fdiv fast float 1.0, %x %div = fdiv fast float 1.0, %x
ret float %div ret float %div
; CHECK-LABEL: reciprocal_estimate: ; NORECIP-LABEL: reciprocal_estimate:
; CHECK: movss ; NORECIP: movss
; CHECK-NEXT: divss ; NORECIP-NEXT: divss
; CHECK-NEXT: movaps ; NORECIP-NEXT: movaps
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; RECIP-LABEL: reciprocal_estimate: ; RECIP-LABEL: reciprocal_estimate:
; RECIP: vrcpss ; RECIP: vrcpss
@ -45,11 +45,11 @@ 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 %div = fdiv fast <4 x float> <float 1.0, float 1.0, float 1.0, float 1.0>, %x
ret <4 x float> %div ret <4 x float> %div
; CHECK-LABEL: reciprocal_estimate_v4f32: ; NORECIP-LABEL: reciprocal_estimate_v4f32:
; CHECK: movaps ; NORECIP: movaps
; CHECK-NEXT: divps ; NORECIP-NEXT: divps
; CHECK-NEXT: movaps ; NORECIP-NEXT: movaps
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; RECIP-LABEL: reciprocal_estimate_v4f32: ; RECIP-LABEL: reciprocal_estimate_v4f32:
; RECIP: vrcpps ; RECIP: vrcpps
@ -76,14 +76,14 @@ 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 %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 ret <8 x float> %div
; CHECK-LABEL: reciprocal_estimate_v8f32: ; NORECIP-LABEL: reciprocal_estimate_v8f32:
; CHECK: movaps ; NORECIP: movaps
; CHECK: movaps ; NORECIP: movaps
; CHECK-NEXT: divps ; NORECIP-NEXT: divps
; CHECK-NEXT: divps ; NORECIP-NEXT: divps
; CHECK-NEXT: movaps ; NORECIP-NEXT: movaps
; CHECK-NEXT: movaps ; NORECIP-NEXT: movaps
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; RECIP-LABEL: reciprocal_estimate_v8f32: ; RECIP-LABEL: reciprocal_estimate_v8f32:
; RECIP: vrcpps ; RECIP: vrcpps

70
test/CodeGen/X86/sqrt-fastmath.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=sse2 | FileCheck %s ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=sse2 -recip=!sqrtf,!vec-sqrtf,!divf,!vec-divf | FileCheck %s --check-prefix=NORECIP
; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=avx -recip=sqrtf,vec-sqrtf | FileCheck %s --check-prefix=ESTIMATE ; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=avx -recip=sqrtf,vec-sqrtf | FileCheck %s --check-prefix=ESTIMATE
declare double @__sqrt_finite(double) #0 declare double @__sqrt_finite(double) #0
@ -10,10 +10,10 @@ declare <8 x float> @llvm.sqrt.v8f32(<8 x float>) #0
define double @fd(double %d) #0 { define double @fd(double %d) #0 {
; CHECK-LABEL: fd: ; NORECIP-LABEL: fd:
; CHECK: # BB#0: ; NORECIP: # BB#0:
; CHECK-NEXT: sqrtsd %xmm0, %xmm0 ; NORECIP-NEXT: sqrtsd %xmm0, %xmm0
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; ;
; ESTIMATE-LABEL: fd: ; ESTIMATE-LABEL: fd:
; ESTIMATE: # BB#0: ; ESTIMATE: # BB#0:
@ -25,10 +25,10 @@ define double @fd(double %d) #0 {
define float @ff(float %f) #0 { define float @ff(float %f) #0 {
; CHECK-LABEL: ff: ; NORECIP-LABEL: ff:
; CHECK: # BB#0: ; NORECIP: # BB#0:
; CHECK-NEXT: sqrtss %xmm0, %xmm0 ; NORECIP-NEXT: sqrtss %xmm0, %xmm0
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; ;
; ESTIMATE-LABEL: ff: ; ESTIMATE-LABEL: ff:
; ESTIMATE: # BB#0: ; ESTIMATE: # BB#0:
@ -49,11 +49,11 @@ define float @ff(float %f) #0 {
define x86_fp80 @fld(x86_fp80 %ld) #0 { define x86_fp80 @fld(x86_fp80 %ld) #0 {
; CHECK-LABEL: fld: ; NORECIP-LABEL: fld:
; CHECK: # BB#0: ; NORECIP: # BB#0:
; CHECK-NEXT: fldt {{[0-9]+}}(%rsp) ; NORECIP-NEXT: fldt {{[0-9]+}}(%rsp)
; CHECK-NEXT: fsqrt ; NORECIP-NEXT: fsqrt
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; ;
; ESTIMATE-LABEL: fld: ; ESTIMATE-LABEL: fld:
; ESTIMATE: # BB#0: ; ESTIMATE: # BB#0:
@ -67,12 +67,12 @@ define x86_fp80 @fld(x86_fp80 %ld) #0 {
define float @reciprocal_square_root(float %x) #0 { define float @reciprocal_square_root(float %x) #0 {
; CHECK-LABEL: reciprocal_square_root: ; NORECIP-LABEL: reciprocal_square_root:
; CHECK: # BB#0: ; NORECIP: # BB#0:
; CHECK-NEXT: sqrtss %xmm0, %xmm1 ; NORECIP-NEXT: sqrtss %xmm0, %xmm1
; CHECK-NEXT: movss {{.*#+}} xmm0 = mem[0],zero,zero,zero ; NORECIP-NEXT: movss {{.*#+}} xmm0 = mem[0],zero,zero,zero
; CHECK-NEXT: divss %xmm1, %xmm0 ; NORECIP-NEXT: divss %xmm1, %xmm0
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; ;
; ESTIMATE-LABEL: reciprocal_square_root: ; ESTIMATE-LABEL: reciprocal_square_root:
; ESTIMATE: # BB#0: ; ESTIMATE: # BB#0:
@ -89,12 +89,12 @@ define float @reciprocal_square_root(float %x) #0 {
} }
define <4 x float> @reciprocal_square_root_v4f32(<4 x float> %x) #0 { define <4 x float> @reciprocal_square_root_v4f32(<4 x float> %x) #0 {
; CHECK-LABEL: reciprocal_square_root_v4f32: ; NORECIP-LABEL: reciprocal_square_root_v4f32:
; CHECK: # BB#0: ; NORECIP: # BB#0:
; CHECK-NEXT: sqrtps %xmm0, %xmm1 ; NORECIP-NEXT: sqrtps %xmm0, %xmm1
; CHECK-NEXT: movaps {{.*#+}} xmm0 = [1.000000e+00,1.000000e+00,1.000000e+00,1.000000e+00] ; NORECIP-NEXT: movaps {{.*#+}} xmm0 = [1.000000e+00,1.000000e+00,1.000000e+00,1.000000e+00]
; CHECK-NEXT: divps %xmm1, %xmm0 ; NORECIP-NEXT: divps %xmm1, %xmm0
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; ;
; ESTIMATE-LABEL: reciprocal_square_root_v4f32: ; ESTIMATE-LABEL: reciprocal_square_root_v4f32:
; ESTIMATE: # BB#0: ; ESTIMATE: # BB#0:
@ -111,15 +111,15 @@ define <4 x float> @reciprocal_square_root_v4f32(<4 x float> %x) #0 {
} }
define <8 x float> @reciprocal_square_root_v8f32(<8 x float> %x) #0 { define <8 x float> @reciprocal_square_root_v8f32(<8 x float> %x) #0 {
; CHECK-LABEL: reciprocal_square_root_v8f32: ; NORECIP-LABEL: reciprocal_square_root_v8f32:
; CHECK: # BB#0: ; NORECIP: # BB#0:
; CHECK-NEXT: sqrtps %xmm1, %xmm2 ; NORECIP-NEXT: sqrtps %xmm1, %xmm2
; CHECK-NEXT: sqrtps %xmm0, %xmm3 ; NORECIP-NEXT: sqrtps %xmm0, %xmm3
; CHECK-NEXT: movaps {{.*#+}} xmm1 = [1.000000e+00,1.000000e+00,1.000000e+00,1.000000e+00] ; NORECIP-NEXT: movaps {{.*#+}} xmm1 = [1.000000e+00,1.000000e+00,1.000000e+00,1.000000e+00]
; CHECK-NEXT: movaps %xmm1, %xmm0 ; NORECIP-NEXT: movaps %xmm1, %xmm0
; CHECK-NEXT: divps %xmm3, %xmm0 ; NORECIP-NEXT: divps %xmm3, %xmm0
; CHECK-NEXT: divps %xmm2, %xmm1 ; NORECIP-NEXT: divps %xmm2, %xmm1
; CHECK-NEXT: retq ; NORECIP-NEXT: retq
; ;
; ESTIMATE-LABEL: reciprocal_square_root_v8f32: ; ESTIMATE-LABEL: reciprocal_square_root_v8f32:
; ESTIMATE: # BB#0: ; ESTIMATE: # BB#0: