End to end working code for dot2add

Author: sumitsays

clang/include/clang/Basic/Builtins.td

@@ -4893,8 +4893,8 @@ def HLSLDotProduct : LangBuiltin<"HLSL_LANG"> {
 
 def HLSLDot2Add : LangBuiltin<"HLSL_LANG"> {
   let Spellings = ["__builtin_hlsl_dot2add"];
-  let Attributes = [NoThrow, Const];
-  let Prototype = "void(...)";
+  let Attributes = [NoThrow, Const, CustomTypeChecking];
+  let Prototype = "float(...)";
 }
 
 def HLSLDot4AddI8Packed : LangBuiltin<"HLSL_LANG"> {

clang/lib/Sema/SemaHLSL.cpp

@@ -2490,8 +2490,10 @@ bool SemaHLSL::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
     break;
   }
   case Builtin::BI__builtin_hlsl_dot2add: {
+    // Check number of arguments should be 3
     if (SemaRef.checkArgCount(TheCall, 3))
       return true;
+    // Check first two arguments should be vectors of same length
     if (CheckVectorElementCallArgs(&SemaRef, TheCall, TheCall->getNumArgs() - 1))
       return true;
     if (CheckArgTypeMatches(&SemaRef, TheCall->getArg(2), SemaRef.getASTContext().FloatTy))

clang/test/CodeGenHLSL/builtins/dot2add.hlsl

@@ -1,14 +1,17 @@
 // RUN: %clang_cc1 -finclude-default-header -triple \
 // RUN:   dxil-pc-shadermodel6.3-compute %s -emit-llvm -disable-llvm-passes -o - | \
-// RUN:   FileCheck %s -DTARGET=dx
+// RUN:   FileCheck %s --check-prefixes=CHECK,CHECK-DXIL
+// RUN: %clang_cc1 -finclude-default-header -triple \
+// RUN:   spirv-pc-vulkan-compute %s -emit-llvm -disable-llvm-passes -o - | \
+// RUN:   FileCheck %s --check-prefixes=CHECK,CHECK-SPIRV
 
 // Test basic lowering to runtime function call.
 
-// CHECK-LABEL: test
 float test(half2 p1, half2 p2, float p3) {
-  // CHECK-DXIL:  %hlsl.dot2add = call reassoc nnan ninf nsz arcp afn float @llvm.dx.dot2add.v2f32(<2 x float> %0, <2 x float> %1, float %2)
-  // CHECK: ret float %hlsl.dot2add
+  // CHECK-SPIRV:  %[[MUL:.*]] = call {{.*}} float @llvm.spv.fdot.v2f32(<2 x float> %1, <2 x float> %2)
+  // CHECK-SPIRV:  %[[C:.*]] = load float, ptr %c.addr, align 4
+  // CHECK-SPIRV:  %[[RES:.*]] = fadd {{.*}} float %[[MUL]], %[[C]]
+  // CHECK-DXIL:  %[[RES:.*]] = call {{.*}} float @llvm.dx.dot2add.v2f32(<2 x float> %0, <2 x float> %1, float %2)
+  // CHECK:  ret float %[[RES]]
   return dot2add(p1, p2, p3);
-}
-
-// CHECK: declare [[TY]] @llvm.[[TARGET]].dot4add.i8packed([[TY]], [[TY]], [[TY]])
+}