[CIR][CIRGen] Support for __builtin_elementwise_atan2 (#1655)

Implement atan2 intrinsic as part of #1192

Author: mariusdr

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -4797,6 +4797,7 @@ def FMaximumOp : BinaryFPToFPBuiltinOp<"fmaximum", "MaximumOp">;
 def FMinimumOp : BinaryFPToFPBuiltinOp<"fminimum", "MinimumOp">;
 def FModOp : BinaryFPToFPBuiltinOp<"fmod", "FRemOp">;
 def PowOp : BinaryFPToFPBuiltinOp<"pow", "PowOp">;
+def ATan2Op : BinaryFPToFPBuiltinOp<"atan2", "ATan2Op">;
 
 def IsFPClassOp : CIR_Op<"is_fp_class"> {
   let summary = "Corresponding to the `__builtin_fpclassify` builtin function in clang";

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -1499,7 +1499,7 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BI__builtin_elementwise_atan:
     return emitUnaryFPBuiltin<cir::ATanOp>(*this, *E);
   case Builtin::BI__builtin_elementwise_atan2:
-    llvm_unreachable("BI__builtin_elementwise_atan2 NYI");
+    return emitBinaryFPBuiltin<cir::ATan2Op>(*this, *E);
   case Builtin::BI__builtin_elementwise_ceil:
     llvm_unreachable("BI__builtin_elementwise_ceil NYI");
   case Builtin::BI__builtin_elementwise_exp:

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

@@ -100,6 +100,27 @@ void test_builtin_elementwise_atan(float f, double d, vfloat4 vf4,
   vd4 = __builtin_elementwise_atan(vd4);
 }
 
+void test_builtin_elementwise_atan2(float f, double d, vfloat4 vf4,
+  vdouble4  vd4) {
+  // CIR-LABEL: test_builtin_elementwise_atan2
+  // LLVM-LABEL: test_builtin_elementwise_atan2
+  // CIR: {{%.*}} = cir.atan2 {{%.*}}, {{%.*}} : !cir.float
+  // LLVM: {{%.*}} = call float @llvm.atan2.f32(float {{%.*}}, float {{%.*}})
+  f = __builtin_elementwise_atan2(f, f);
+
+  // CIR: {{%.*}} = cir.atan2 {{%.*}}, {{%.*}} : !cir.double
+  // LLVM: {{%.*}} = call double @llvm.atan2.f64(double {{%.*}}, double {{%.*}})
+  d = __builtin_elementwise_atan2(d, d);
+
+  // CIR: {{%.*}} = cir.atan2 {{%.*}}, {{%.*}} : !cir.vector<!cir.float x 4>
+  // LLVM: {{%.*}} = call <4 x float> @llvm.atan2.v4f32(<4 x float> {{%.*}}, <4 x float> {{%.*}})
+  vf4 = __builtin_elementwise_atan2(vf4, vf4);
+
+  // CIR: {{%.*}} = cir.atan2 {{%.*}}, {{%.*}} : !cir.vector<!cir.double x 4>
+  // LLVM: {{%.*}} = call <4 x double> @llvm.atan2.v4f64(<4 x double> {{%.*}}, <4 x double> {{%.*}})
+  vd4 = __builtin_elementwise_atan2(vd4, vd4);
+}
+
 void test_builtin_elementwise_exp(float f, double d, vfloat4 vf4,
                                   vdouble4  vd4) {
   // CIR-LABEL: test_builtin_elementwise_exp