[SPIRV] Add atan2 function lowering (p2) (llvm#110037)

This change is part of this proposal:
https://discourse.llvm.org/t/rfc-all-the-math-intrinsics/78294

- Add generic opcode for atan2
- Add SPIRV lowering for atan2

Part 2 for Implement the atan2 HLSL Function llvm#70096.

Author: tex3d

llvm/docs/GlobalISel/GenericOpcode.rst

@@ -633,8 +633,8 @@ G_FCEIL, G_FSQRT, G_FFLOOR, G_FRINT, G_FNEARBYINT
 
 These correspond to the standard C functions of the same name.
 
-G_FCOS, G_FSIN, G_FTAN, G_FACOS, G_FASIN, G_FATAN, G_FCOSH, G_FSINH, G_FTANH
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+G_FCOS, G_FSIN, G_FTAN, G_FACOS, G_FASIN, G_FATAN, G_FATAN2, G_FCOSH, G_FSINH, G_FTANH
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 These correspond to the standard C trigonometry functions of the same name.
 

llvm/include/llvm/Support/TargetOpcodes.def

@@ -821,6 +821,9 @@ HANDLE_TARGET_OPCODE(G_FASIN)
 /// Floating point arctangent.
 HANDLE_TARGET_OPCODE(G_FATAN)
 
+/// Floating point arctangent of y/x.
+HANDLE_TARGET_OPCODE(G_FATAN2)
+
 /// Floating point hyperbolic cosine.
 HANDLE_TARGET_OPCODE(G_FCOSH)
 

llvm/include/llvm/Target/GenericOpcodes.td

@@ -1048,6 +1048,13 @@ def G_FATAN : GenericInstruction {
   let hasSideEffects = false;
 }
 
+// Floating point arctangent of a value.
+def G_FATAN2 : GenericInstruction {
+  let OutOperandList = (outs type0:$dst);
+  let InOperandList = (ins type0:$src1, type0:$src2);
+  let hasSideEffects = false;
+}
+
 // Floating point hyperbolic cosine of a value.
 def G_FCOSH : GenericInstruction {
   let OutOperandList = (outs type0:$dst);

llvm/lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -1885,6 +1885,8 @@ unsigned IRTranslator::getSimpleIntrinsicOpcode(Intrinsic::ID ID) {
       return TargetOpcode::G_FASIN;
     case Intrinsic::atan:
       return TargetOpcode::G_FATAN;
+    case Intrinsic::atan2:
+      return TargetOpcode::G_FATAN2;
     case Intrinsic::bswap:
       return TargetOpcode::G_BSWAP;
     case Intrinsic::bitreverse:

llvm/lib/Target/SPIRV/SPIRVInstructionSelector.cpp

@@ -540,6 +540,8 @@ bool SPIRVInstructionSelector::spvSelect(Register ResVReg,
     return selectExtInst(ResVReg, ResType, I, CL::asin, GL::Asin);
   case TargetOpcode::G_FATAN:
     return selectExtInst(ResVReg, ResType, I, CL::atan, GL::Atan);
+  case TargetOpcode::G_FATAN2:
+    return selectExtInst(ResVReg, ResType, I, CL::atan2, GL::Atan2);
   case TargetOpcode::G_FCOSH:
     return selectExtInst(ResVReg, ResType, I, CL::cosh, GL::Cosh);
   case TargetOpcode::G_FSINH:

llvm/lib/Target/SPIRV/SPIRVLegalizerInfo.cpp

@@ -321,6 +321,7 @@ SPIRVLegalizerInfo::SPIRVLegalizerInfo(const SPIRVSubtarget &ST) {
                                G_FACOS,
                                G_FASIN,
                                G_FATAN,
+                               G_FATAN2,
                                G_FCOSH,
                                G_FSINH,
                                G_FTANH,

llvm/test/CodeGen/AArch64/GlobalISel/legalizer-info-validation.mir

@@ -717,6 +717,9 @@
 # DEBUG-NEXT: .. opcode {{[0-9]+}} is aliased to {{[0-9]+}}
 # DEBUG-NEXT: .. the first uncovered type index: 1, OK
 # DEBUG-NEXT: .. the first uncovered imm index: 0, OK
+# DEBUG-NEXT: G_FATAN2 (opcode {{[0-9]+}}): 1 type index, 0 imm indices
+# DEBUG-NEXT: .. type index coverage check SKIPPED: no rules defined 
+# DEBUG-NEXT: .. imm index coverage check SKIPPED: no rules defined
 # DEBUG-NEXT: G_FCOSH (opcode {{[0-9]+}}): 1 type index, 0 imm indices
 # DEBUG-NEXT: .. opcode {{[0-9]+}} is aliased to {{[0-9]+}}
 # DEBUG-NEXT: .. the first uncovered type index: 1, OK

llvm/test/CodeGen/SPIRV/hlsl-intrinsics/atan2.ll

@@ -0,0 +1,49 @@
+; RUN: llc -verify-machineinstrs -O0 -mtriple=spirv-unknown-unknown %s -o - | FileCheck %s
+; RUN: %if spirv-tools %{ llc -O0 -mtriple=spirv-unknown-unknown %s -o - -filetype=obj | spirv-val %}
+
+; CHECK-DAG: %[[#op_ext_glsl:]] = OpExtInstImport "GLSL.std.450"
+; CHECK-DAG: %[[#float_32:]] = OpTypeFloat 32
+; CHECK-DAG: %[[#float_16:]] = OpTypeFloat 16
+; CHECK-DAG: %[[#vec4_float_32:]] = OpTypeVector %[[#float_32]] 4
+; CHECK-DAG: %[[#vec4_float_16:]] = OpTypeVector %[[#float_16]] 4
+
+define noundef float @atan2_float(float noundef %a, float noundef %b) {
+entry:
+; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#arg1:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#]] = OpExtInst %[[#float_32]] %[[#op_ext_glsl]] Atan2 %[[#arg0]] %[[#arg1]]
+  %elt.atan2 = call float @llvm.atan2.f32(float %a, float %b)
+  ret float %elt.atan2
+}
+
+define noundef half @atan2_half(half noundef %a, half noundef %b) {
+entry:
+; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#arg1:]] = OpFunctionParameter %[[#]]
+; CHECK: %[[#]] = OpExtInst %[[#float_16]] %[[#op_ext_glsl]] Atan2 %[[#arg0]] %[[#arg1]]
+  %elt.atan2 = call half @llvm.atan2.f16(half %a, half %b)
+  ret half %elt.atan2
+}
+
+define noundef <4 x float> @atan2_float4(<4 x float> noundef %a, <4 x float> noundef %b) {
+entry:
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#]]
+  ; CHECK: %[[#arg1:]] = OpFunctionParameter %[[#]]
+  ; CHECK: %[[#]] = OpExtInst %[[#vec4_float_32]] %[[#op_ext_glsl]] Atan2 %[[#arg0]] %[[#arg1]]
+  %elt.atan2 = call <4 x float> @llvm.atan2.v4f32(<4 x float> %a, <4 x float> %b)
+  ret <4 x float> %elt.atan2
+}
+
+define noundef <4 x half> @atan2_half4(<4 x half> noundef %a, <4 x half> noundef %b) {
+entry:
+  ; CHECK: %[[#arg0:]] = OpFunctionParameter %[[#]]
+  ; CHECK: %[[#arg1:]] = OpFunctionParameter %[[#]]
+  ; CHECK: %[[#]] = OpExtInst %[[#vec4_float_16]] %[[#op_ext_glsl]] Atan2 %[[#arg0]] %[[#arg1]]
+  %elt.atan2 = call <4 x half> @llvm.atan2.v4f16(<4 x half> %a, <4 x half> %b)
+  ret <4 x half> %elt.atan2
+}
+
+declare half @llvm.atan2.f16(half, half)
+declare float @llvm.atan2.f32(float, float)
+declare <4 x half> @llvm.atan2.v4f16(<4 x half>, <4 x half>)
+declare <4 x float> @llvm.atan2.v4f32(<4 x float>, <4 x float>)