[clang][hlsl] Add atan2 intrinsic part 1

Issue: llvm#70096

Changes:
- Doc updates:
  - `clang/docs/LanguageExtensions.rst` - Document the new elementwise atan2 builtin.
  - `llvm/docs/LangRef.rst` - Document the atan2 intrinsic
- TableGen:
  - `clang/include/clang/Basic/Builtins.td` - Implement the atan2 builtin.
  - `llvm/include/llvm/IR/Intrinsics.td` - Create the atan2 intrinsic
- Sema checking:
  - `clang/lib/Sema/SemaChecking.cpp` - Add generic sema checks to the atan2 builtin
  - `clang/lib/Sema/SemaHLSL` Add HLSL specifc sema checks to the atan2 builtin
- `clang/lib/CodeGen/CGBuiltin.cpp` - invoke the atan2 intrinsic on uses of the builtin
- `clang/lib/Headers/hlsl/hlsl_intrinsics.h` - Associate the atan2 builtin with the equivalent hlsl apis

clang/docs/LanguageExtensions.rst

@@ -660,6 +660,7 @@ Unless specified otherwise operation(±0) = ±0 and operation(±infinity) = ±in
  T __builtin_elementwise_asin(T x)           return the arcsine of x interpreted as an angle in radians       floating point types
  T __builtin_elementwise_acos(T x)           return the arccosine of x interpreted as an angle in radians     floating point types
  T __builtin_elementwise_atan(T x)           return the arctangent of x interpreted as an angle in radians    floating point types
+ T __builtin_elementwise_atan2(T y, T x)     return the arctangent of y/x                                     floating point types
  T __builtin_elementwise_sinh(T x)           return the hyperbolic sine of angle x in radians                 floating point types
  T __builtin_elementwise_cosh(T x)           return the hyperbolic cosine of angle x in radians               floating point types
  T __builtin_elementwise_tanh(T x)           return the hyperbolic tangent of angle x in radians              floating point types

clang/include/clang/Basic/Builtins.td

@@ -1250,6 +1250,12 @@ def ElementwiseATan : Builtin {
   let Prototype = "void(...)";
 }
 
+def ElementwiseATan2 : Builtin {
+  let Spellings = ["__builtin_elementwise_atan2"];
+  let Attributes = [NoThrow, Const, CustomTypeChecking];
+  let Prototype = "void(...)";
+}
+
 def ElementwiseBitreverse : Builtin {
   let Spellings = ["__builtin_elementwise_bitreverse"];
   let Attributes = [NoThrow, Const, CustomTypeChecking];

clang/lib/CodeGen/CGBuiltin.cpp

@@ -3800,6 +3800,9 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI__builtin_elementwise_atan:
     return RValue::get(emitBuiltinWithOneOverloadedType<1>(
         *this, E, llvm::Intrinsic::atan, "elt.atan"));
+  case Builtin::BI__builtin_elementwise_atan2:
+    return RValue::get(emitBuiltinWithOneOverloadedType<2>(
+        *this, E, llvm::Intrinsic::atan2, "elt.atan2"));
   case Builtin::BI__builtin_elementwise_ceil:
     return RValue::get(emitBuiltinWithOneOverloadedType<1>(
         *this, E, llvm::Intrinsic::ceil, "elt.ceil"));

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -415,6 +415,36 @@ float3 atan(float3);
 _HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan)
 float4 atan(float4);
 
+//===----------------------------------------------------------------------===//
+// atan2 builtins
+//===----------------------------------------------------------------------===//
+
+/// \fn T atan2(T y, T x)
+/// \brief Returns the arctangent of y/x, using the signs of the arguments to
+/// determine the correct quadrant.
+/// \param y The y-coordinate.
+/// \param x The x-coordinate.
+
+#ifdef __HLSL_ENABLE_16_BIT
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+half atan2(half y, half x);
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+half2 atan2(half2 y, half2 x);
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+half3 atan2(half3 y, half3 x);
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+half4 atan2(half4 y, half4 x);
+#endif
+
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+float atan2(float y, float x);
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+float2 atan2(float2 y, float2 x);
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+float3 atan2(float3 y, float3 x);
+_HLSL_BUILTIN_ALIAS(__builtin_elementwise_atan2)
+float4 atan2(float4 y, float4 x);
+
 //===----------------------------------------------------------------------===//
 // ceil builtins
 //===----------------------------------------------------------------------===//

clang/lib/Sema/SemaChecking.cpp

@@ -2755,6 +2755,7 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
 
   // These builtins restrict the element type to floating point
   // types only, and take in two arguments.
+  case Builtin::BI__builtin_elementwise_atan2:
   case Builtin::BI__builtin_elementwise_pow: {
     if (BuiltinElementwiseMath(TheCall))
       return ExprError();

clang/lib/Sema/SemaHLSL.cpp

@@ -1736,6 +1736,7 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   case Builtin::BI__builtin_elementwise_acos:
   case Builtin::BI__builtin_elementwise_asin:
   case Builtin::BI__builtin_elementwise_atan:
+  case Builtin::BI__builtin_elementwise_atan2:
   case Builtin::BI__builtin_elementwise_ceil:
   case Builtin::BI__builtin_elementwise_cos:
   case Builtin::BI__builtin_elementwise_cosh:

clang/test/CodeGen/builtins-elementwise-math.c

@@ -441,6 +441,26 @@ void test_builtin_elementwise_atan(float f1, float f2, double d1, double d2,
   vf2 = __builtin_elementwise_atan(vf1);
 }
 
+void test_builtin_elementwise_atan2(float f1, float f2, float f3, double d1,
+                                    double d2, double d3, float4 vf1,
+                                    float4 vf2, float4 vf3) {
+  // CHECK-LABEL: define void @test_builtin_elementwise_atan2(
+  // CHECK:      [[F1:%.+]] = load float, ptr %f1.addr, align 4
+  // CHECK-NEXT: [[F2:%.+]] = load float, ptr %f2.addr, align 4
+  // CHECK-NEXT: call float @llvm.atan2.f32(float [[F1]], float [[F2]])
+  f3 = __builtin_elementwise_atan2(f1, f2);
+
+  // CHECK:      [[D1:%.+]] = load double, ptr %d1.addr, align 8
+  // CHECK-NEXT: [[D2:%.+]] = load double, ptr %d2.addr, align 8
+  // CHECK-NEXT: call double @llvm.atan2.f64(double [[D1]], double [[D2]])
+  d3 = __builtin_elementwise_atan2(d1, d2);
+
+  // CHECK:      [[VF1:%.+]] = load <4 x float>, ptr %vf1.addr, align 16
+  // CHECK-NEXT: [[VF2:%.+]] = load <4 x float>, ptr %vf2.addr, align 16
+  // CHECK-NEXT: call <4 x float> @llvm.atan2.v4f32(<4 x float> [[VF1]], <4 x float> [[VF2]])
+  vf3 = __builtin_elementwise_atan2(vf1, vf2);
+}
+
 void test_builtin_elementwise_cos(float f1, float f2, double d1, double d2,
                                   float4 vf1, float4 vf2) {
   // CHECK-LABEL: define void @test_builtin_elementwise_cos(

clang/test/CodeGen/strictfp-elementwise-bulitins.cpp

@@ -257,6 +257,16 @@ float4 strict_elementwise_tanh(float4 a) {
   return __builtin_elementwise_tanh(a);
 }
 
+// CHECK-LABEL: define dso_local noundef <4 x float> @_Z24strict_elementwise_atan2Dv4_fS_
+// CHECK-SAME: (<4 x float> noundef [[A:%.*]], <4 x float> noundef [[B:%.*]]) local_unnamed_addr #[[ATTR2]] {
+// CHECK-NEXT:  entry:
+// CHECK-NEXT:    [[ELT_ATAN2:%.*]] = tail call <4 x float> @llvm.atan2.v4f32(<4 x float> [[A]], <4 x float> [[B]]) #[[ATTR4]]
+// CHECK-NEXT:    ret <4 x float> [[ELT_ATAN2]]
+//
+float4 strict_elementwise_atan2(float4 a, float4 b) {
+  return __builtin_elementwise_atan2(a, b);
+}
+
 // CHECK-LABEL: define dso_local noundef <4 x float> @_Z24strict_elementwise_truncDv4_f
 // CHECK-SAME: (<4 x float> noundef [[A:%.*]]) local_unnamed_addr #[[ATTR2]] {
 // CHECK-NEXT:  entry:

clang/test/CodeGenHLSL/builtins/atan2.hlsl

@@ -0,0 +1,59 @@
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   dxil-pc-shadermodel6.3-library %s -fnative-half-type \
+// RUN:   -emit-llvm -disable-llvm-passes -o - | FileCheck %s \ 
+// RUN:   --check-prefixes=CHECK,NATIVE_HALF
+// RUN: %clang_cc1 -finclude-default-header -x hlsl -triple \
+// RUN:   spirv-unknown-vulkan-compute %s -emit-llvm -disable-llvm-passes \
+// RUN:   -o - | FileCheck %s --check-prefixes=CHECK,NO_HALF
+
+// CHECK-LABEL: test_atan2_half
+// NATIVE_HALF: call half @llvm.atan2.f16
+// NO_HALF: call float @llvm.atan2.f32
+half test_atan2_half (half p0, half p1) {
+  return atan2(p0, p1);
+}
+
+// CHECK-LABEL: test_atan2_half2
+// NATIVE_HALF: call <2 x half> @llvm.atan2.v2f16
+// NO_HALF: call <2 x float> @llvm.atan2.v2f32
+half2 test_atan2_half2 (half2 p0, half2 p1) {
+  return atan2(p0, p1);
+}
+
+// CHECK-LABEL: test_atan2_half3
+// NATIVE_HALF: call <3 x half> @llvm.atan2.v3f16
+// NO_HALF: call <3 x float> @llvm.atan2.v3f32
+half3 test_atan2_half3 (half3 p0, half3 p1) {
+  return atan2(p0, p1);
+}
+
+// CHECK-LABEL: test_atan2_half4
+// NATIVE_HALF: call <4 x half> @llvm.atan2.v4f16
+// NO_HALF: call <4 x float> @llvm.atan2.v4f32
+half4 test_atan2_half4 (half4 p0, half4 p1) {
+  return atan2(p0, p1);
+}
+
+// CHECK-LABEL: test_atan2_float
+// CHECK: call float @llvm.atan2.f32
+float test_atan2_float (float p0, float p1) {
+  return atan2(p0, p1);
+}
+
+// CHECK-LABEL: test_atan2_float2
+// CHECK: call <2 x float> @llvm.atan2.v2f32
+float2 test_atan2_float2 (float2 p0, float2 p1) {
+  return atan2(p0, p1);
+}
+
+// CHECK-LABEL: test_atan2_float3
+// CHECK: call <3 x float> @llvm.atan2.v3f32
+float3 test_atan2_float3 (float3 p0, float3 p1) {
+  return atan2(p0, p1);
+}
+
+// CHECK-LABEL: test_atan2_float4
+// CHECK: call <4 x float> @llvm.atan2.v4f32
+float4 test_atan2_float4 (float4 p0, float4 p1) {
+  return atan2(p0, p1);
+}

clang/test/Sema/aarch64-sve-vector-trig-ops.c

@@ -22,6 +22,12 @@ svfloat32_t test_atan_vv_i8mf8(svfloat32_t v) {
   // expected-error@-1 {{1st argument must be a vector, integer or floating point type}}
 }
 
+svfloat32_t test_atan2_vv_i8mf8(svfloat32_t v) {
+
+  return __builtin_elementwise_atan2(v);
+  // expected-error@-1 {{1st argument must be a vector, integer or floating point type}}
+}
+
 svfloat32_t test_sin_vv_i8mf8(svfloat32_t v) {
 
   return __builtin_elementwise_sin(v);

clang/test/Sema/builtins-elementwise-math.c

@@ -731,6 +731,30 @@ void test_builtin_elementwise_atan(int i, float f, double d, float4 v, int3 iv,
   // expected-error@-1 {{1st argument must be a floating point type (was 'unsigned4' (vector of 4 'unsigned int' values))}}
 }
 
+void test_builtin_elementwise_atan2(int i, float f, double d, float4 v, int3 iv, unsigned u, unsigned4 uv) {
+
+  struct Foo s = __builtin_elementwise_atan2(f, f);
+  // expected-error@-1 {{initializing 'struct Foo' with an expression of incompatible type 'float'}}
+
+  i = __builtin_elementwise_atan2();
+  // expected-error@-1 {{too few arguments to function call, expected 2, have 0}}
+
+  i = __builtin_elementwise_atan2(f);
+  // expected-error@-1 {{too few arguments to function call, expected 2, have 1}}
+
+  i = __builtin_elementwise_atan2(i, i);
+  // expected-error@-1 {{1st argument must be a floating point type (was 'int')}}
+
+  i = __builtin_elementwise_atan2(f, f, f);
+  // expected-error@-1 {{too many arguments to function call, expected 2, have 3}}
+
+  u = __builtin_elementwise_atan2(u, u);
+  // expected-error@-1 {{1st argument must be a floating point type (was 'unsigned int')}}
+
+  uv = __builtin_elementwise_atan2(uv, uv);
+  // expected-error@-1 {{1st argument must be a floating point type (was 'unsigned4' (vector of 4 'unsigned int' values))}}
+}
+
 void test_builtin_elementwise_tan(int i, float f, double d, float4 v, int3 iv, unsigned u, unsigned4 uv) {
 
   struct Foo s = __builtin_elementwise_tan(f);

clang/test/Sema/riscv-rvv-vector-trig-ops.c

@@ -23,6 +23,12 @@ vfloat32mf2_t test_asin_vv_i8mf8(vfloat32mf2_t v) {
     // expected-error@-1 {{1st argument must be a vector, integer or floating point type}}
   }
 
+vfloat32mf2_t test_atan2_vv_i8mf8(vfloat32mf2_t v) {
+
+  return __builtin_elementwise_atan2(v, v);
+  // expected-error@-1 {{1st argument must be a vector, integer or floating point type}}
+}
+
 vfloat32mf2_t test_sin_vv_i8mf8(vfloat32mf2_t v) {
 
   return __builtin_elementwise_sin(v);

clang/test/SemaCXX/builtins-elementwise-math.cpp

@@ -146,6 +146,13 @@ void test_builtin_elementwise_atan() {
   static_assert(!is_const<decltype(__builtin_elementwise_atan(b))>::value);
 }
 
+void test_builtin_elementwise_atan2() {
+  const float a = 42.0;
+  float b = 42.3;
+  static_assert(!is_const<decltype(__builtin_elementwise_atan2(a, a))>::value);
+  static_assert(!is_const<decltype(__builtin_elementwise_atan2(b, b))>::value);
+}
+
 void test_builtin_elementwise_tan() {
   const float a = 42.0;
   float b = 42.3;

clang/test/SemaHLSL/BuiltIns/half-float-only-errors2.hlsl

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -fnative-half-type -emit-llvm-only -disable-llvm-passes -verify -DTEST_FUNC=__builtin_elementwise_atan2
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.6-library %s -fnative-half-type -emit-llvm-only -disable-llvm-passes -verify -DTEST_FUNC=__builtin_elementwise_pow
+
+double2 test_double_builtin(double2 p0, double2 p1) {
+    return TEST_FUNC(p0, p1);
+  // expected-error@-1 {{passing 'double2' (aka 'vector<double, 2>') to parameter of incompatible type '__attribute__((__vector_size__(2 * sizeof(float)))) float' (vector of 2 'float' values)}}
+}

llvm/docs/LangRef.rst

@@ -15568,6 +15568,43 @@ trapping or setting ``errno``.
 When specified with the fast-math-flag 'afn', the result may be approximated
 using a less accurate calculation.
 
+'``llvm.atan2.*``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+This is an overloaded intrinsic. You can use ``llvm.atan2`` on any
+floating-point or vector of floating-point type. Not all targets support
+all types however.
+
+::
+
+      declare float     @llvm.atan2.f32(float  %X, float %Y)
+      declare double    @llvm.atan2.f64(double %X, double %Y)
+      declare x86_fp80  @llvm.atan2.f80(x86_fp80  %X, x86_fp80 %Y)
+      declare fp128     @llvm.atan2.f128(fp128 %X, fp128 %Y)
+      declare ppc_fp128 @llvm.atan2.ppcf128(ppc_fp128  %X, ppc_fp128 %Y)
+
+Overview:
+"""""""""
+
+The '``llvm.atan2.*``' intrinsics return the arctangent of the operand.
+
+Arguments:
+""""""""""
+
+The arguments and return value are floating-point numbers of the same type.
+
+Semantics:
+""""""""""
+
+Return the same value as a corresponding libm '``atan2``' function but without
+trapping or setting ``errno``.
+
+When specified with the fast-math-flag 'afn', the result may be approximated
+using a less accurate calculation.
+
 '``llvm.sinh.*``' Intrinsic
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

llvm/include/llvm/IR/Intrinsics.td

@@ -1016,6 +1016,7 @@ let IntrProperties = [IntrNoMem, IntrSpeculatable, IntrWillReturn] in {
   def int_asin : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>]>;
   def int_acos : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>]>;
   def int_atan : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>]>;
+  def int_atan2 : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>, LLVMMatchType<0>]>;
   def int_sin  : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>]>;
   def int_cos  : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>]>;
   def int_tan  : DefaultAttrsIntrinsic<[llvm_anyfloat_ty], [LLVMMatchType<0>]>;