[SelectionDAG] Allow sin/cos -> sincos optimization on GNU triples w/ just -fno-math-errno

Summary:
This change enables the sin(x) cos(x) -> sincos(x) optimization on GNU
target triples.  This optimization was being inhibited when -ffast-math
wasn't set because sincos in GLibC does not set errno, while sin and cos
do.  However, this optimization will only run if the attributes on the
sin/cos calls include readnone, which is how clang represents the fact
that it doesn't care about the errno values set by these functions (via
the -fno-math-errno flag).

Reviewers: hfinkel, bogner

Subscribers: mcrosier, javed.absar, llvm-commits, paul.redmond

Differential Revision: https://reviews.llvm.org/D32921

llvm-svn: 305204

1 files changed, 39 insertions, 16 deletions

diff --git a/llvm/test/CodeGen/SystemZ/fp-sincos-01.ll b/llvm/test/CodeGen/SystemZ/fp-sincos-01.ll
index cd182a590ee..4a38d7afba2 100644
--- a/llvm/test/CodeGen/SystemZ/fp-sincos-01.ll
+++ b/llvm/test/CodeGen/SystemZ/fp-sincos-01.ll
@@ -1,6 +1,6 @@
 ; Test that combined sin/cos library call is emitted when appropriate
 
-; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s --check-prefix=CHECK-NOOPT
+; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s --check-prefix=CHECK-OPT
 ; RUN: llc < %s -mtriple=s390x-linux-gnu -enable-unsafe-fp-math | FileCheck %s --check-prefix=CHECK-OPT
 
 define float @f1(float %x) {
@@ -8,10 +8,18 @@ define float @f1(float %x) {
 ; CHECK-OPT: brasl %r14, sincosf@PLT
 ; CHECK-OPT: le %f0, 164(%r15)
 ; CHECK-OPT: aeb %f0, 160(%r15)
+  %tmp1 = call float @sinf(float %x) readnone
+  %tmp2 = call float @cosf(float %x) readnone
+  %add = fadd float %tmp1, %tmp2
+  ret float %add
+}
 
-; CHECK-NOOPT-LABEL: f1:
-; CHECK-NOOPT: brasl %r14, sinf@PLT
-; CHECK-NOOPT: brasl %r14, cosf@PLT
+define float @f1_errno(float %x) {
+; CHECK-OPT-LABEL: f1_errno:
+; CHECK-OPT: brasl %r14, sinf@PLT
+; CHECK-OPT: ler %f9, %f0
+; CHECK-OPT: brasl %r14, cosf@PLT
+; CHECK-OPT: aebr %f0, %f9
   %tmp1 = call float @sinf(float %x)
   %tmp2 = call float @cosf(float %x)
   %add = fadd float %tmp1, %tmp2
@@ -23,10 +31,18 @@ define double @f2(double %x) {
 ; CHECK-OPT: brasl %r14, sincos@PLT
 ; CHECK-OPT: ld %f0, 168(%r15)
 ; CHECK-OPT: adb %f0, 160(%r15)
+  %tmp1 = call double @sin(double %x) readnone
+  %tmp2 = call double @cos(double %x) readnone
+  %add = fadd double %tmp1, %tmp2
+  ret double %add
+}
 
-; CHECK-NOOPT-LABEL: f2:
-; CHECK-NOOPT: brasl %r14, sin@PLT
-; CHECK-NOOPT: brasl %r14, cos@PLT
+define double @f2_errno(double %x) {
+; CHECK-OPT-LABEL: f2_errno:
+; CHECK-OPT: brasl %r14, sin@PLT
+; CHECK-OPT: ldr %f9, %f0
+; CHECK-OPT: brasl %r14, cos@PLT
+; CHECK-OPT: adbr %f0, %f9
   %tmp1 = call double @sin(double %x)
   %tmp2 = call double @cos(double %x)
   %add = fadd double %tmp1, %tmp2
@@ -37,20 +53,27 @@ define fp128 @f3(fp128 %x) {
 ; CHECK-OPT-LABEL: f3:
 ; CHECK-OPT: brasl %r14, sincosl@PLT
 ; CHECK-OPT: axbr
+  %tmp1 = call fp128 @sinl(fp128 %x) readnone
+  %tmp2 = call fp128 @cosl(fp128 %x) readnone
+  %add = fadd fp128 %tmp1, %tmp2
+  ret fp128 %add
+}
 
-; CHECK-NOOPT-LABEL: f3:
-; CHECK-NOOPT: brasl %r14, sinl@PLT
-; CHECK-NOOPT: brasl %r14, cosl@PLT
+define fp128 @f3_errno(fp128 %x) {
+; CHECK-OPT-LABEL: f3_errno:
+; CHECK-OPT: brasl %r14, sinl@PLT
+; CHECK-OPT: brasl %r14, cosl@PLT
+; CHECK-OPT: axbr
   %tmp1 = call fp128 @sinl(fp128 %x)
   %tmp2 = call fp128 @cosl(fp128 %x)
   %add = fadd fp128 %tmp1, %tmp2
   ret fp128 %add
 }
 
-declare float @sinf(float) readonly
-declare double @sin(double) readonly
-declare fp128 @sinl(fp128) readonly
-declare float @cosf(float) readonly
-declare double @cos(double) readonly
-declare fp128 @cosl(fp128) readonly
+declare float @sinf(float)
+declare double @sin(double)
+declare fp128 @sinl(fp128)
+declare float @cosf(float)
+declare double @cos(double)
+declare fp128 @cosl(fp128)