[clang] [clang] Lower non-builtin sincos[f|l] calls to llvm.sincos.* when -fno-math-errno is set (PR #121763)

[Benjamin Maxwell via cfe-commits]

https://github.com/MacDue created https://github.com/llvm/llvm-project/pull/121763

This will allow vectorizing these calls (after a few more patches). This should not change the codegen for targets that enable the use of AA during the codegen (in `TargetSubtargetInfo::useAA()`). This includes targets such as AArch64. This notably does not include x86 but can be worked around by passing `-mllvm -combiner-global-alias-analysis=true` to clang.

Follow up to #114086.

>From 2cadacae4359f8d67bdff850738441fba455a8bc Mon Sep 17 00:00:00 2001
From: Benjamin Maxwell <benjamin.maxwell at arm.com>
Date: Mon, 6 Jan 2025 11:49:48 +0000
Subject: [PATCH] [clang] Lower non-builtin sincos[f|l] calls to llvm.sincos.*
 when -fno-math-errno is set

This will allow vectorizing these calls (after a few more patches). This
should not change the codegen for targets that enable the use of AA
during the codegen (in `TargetSubtargetInfo::useAA()`). This includes
targets such as AArch64. This notably does not include x86 but can be
worked around by passing `-mllvm -combiner-global-alias-analysis=true`
to clang.
---
 clang/lib/CodeGen/CGBuiltin.cpp     |  3 +++
 clang/test/CodeGen/AArch64/sincos.c | 24 +++++++++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index c419fb0cc055e0..9a859e7a22f5e3 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -3264,6 +3264,9 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
       return RValue::get(emitUnaryMaybeConstrainedFPBuiltin(
           *this, E, Intrinsic::sinh, Intrinsic::experimental_constrained_sinh));
 
+    case Builtin::BIsincos:
+    case Builtin::BIsincosf:
+    case Builtin::BIsincosl:
     case Builtin::BI__builtin_sincos:
     case Builtin::BI__builtin_sincosf:
     case Builtin::BI__builtin_sincosf16:
diff --git a/clang/test/CodeGen/AArch64/sincos.c b/clang/test/CodeGen/AArch64/sincos.c
index b77d98ceab4869..fde277716ddddb 100644
--- a/clang/test/CodeGen/AArch64/sincos.c
+++ b/clang/test/CodeGen/AArch64/sincos.c
@@ -1,5 +1,19 @@
-// RUN: %clang_cc1 -triple=aarch64-gnu-linux -emit-llvm -O1 %s -o - | FileCheck --check-prefix=NO-MATH-ERRNO %s
-// RUN: %clang_cc1 -triple=aarch64-gnu-linux -emit-llvm -fmath-errno %s -o - | FileCheck --check-prefix=MATH-ERRNO %s
+// RUN: %clang_cc1 -triple=aarch64-gnu-linux -emit-llvm -O1 %s -o - -DUSE_BUILTIN | FileCheck --check-prefix=NO-MATH-ERRNO %s
+// RUN: %clang_cc1 -triple=aarch64-gnu-linux -emit-llvm -fmath-errno %s -o - -DUSE_BUILTIN | FileCheck --check-prefix=MATH-ERRNO %s
+// RUN: %clang_cc1 -triple=aarch64-gnu-linux -emit-llvm -O1 %s -o - -DUSE_C_DECL | FileCheck --check-prefix=NO-MATH-ERRNO %s
+// RUN: %clang_cc1 -triple=aarch64-gnu-linux -emit-llvm -fmath-errno %s -o - -DUSE_C_DECL | FileCheck --check-prefix=MATH-ERRNO %s
+
+#if defined(USE_BUILTIN)
+  #define sincos __builtin_sincos
+  #define sincosf __builtin_sincosf
+  #define sincosl __builtin_sincosl
+#elif defined(USE_C_DECL)
+  void sincos(double, double*, double*);
+  void sincosf(float, float*, float*);
+  void sincosl(long double, long double*, long double*);
+#else
+    #error Expected USE_BUILTIN or USE_C_DECL to be defined.
+#endif
 
 // NO-MATH-ERRNO-LABEL: @sincos_f32
 //      NO-MATH-ERRNO:    [[SINCOS:%.*]] = tail call { float, float } @llvm.sincos.f32(float {{.*}})
@@ -12,7 +26,7 @@
 //      MATH-ERRNO:    call void @sincosf(
 //
 void sincos_f32(float x, float* fp0, float* fp1) {
-  __builtin_sincosf(x, fp0, fp1);
+  sincosf(x, fp0, fp1);
 }
 
 // NO-MATH-ERRNO-LABEL: @sincos_f64
@@ -26,7 +40,7 @@ void sincos_f32(float x, float* fp0, float* fp1) {
 //      MATH-ERRNO:    call void @sincos(
 //
 void sincos_f64(double x, double* dp0, double* dp1) {
-  __builtin_sincos(x, dp0, dp1);
+  sincos(x, dp0, dp1);
 }
 
 // NO-MATH-ERRNO-LABEL: @sincos_f128
@@ -40,5 +54,5 @@ void sincos_f64(double x, double* dp0, double* dp1) {
 //      MATH-ERRNO:    call void @sincosl(
 //
 void sincos_f128(long double x, long double* ldp0, long double* ldp1) {
-  __builtin_sincosl(x, ldp0, ldp1);
+  sincosl(x, ldp0, ldp1);
 }