[HLSL] implement mad intrinsic (#83826)

This change implements #83736
The dot product lowering needs a tertiary multipy add operation. DXIL
has three mad opcodes for `fmad`(46), `imad`(48), and `umad`(49). Dot
product in DXIL only uses `imad`\ `umad`, but for completeness and
because the hlsl `mad` intrinsic requires it `fmad` was also included.
Two new intrinsics were needed to be created to complete this change.
the `fmad` case already supported by llvm via `fmuladd` intrinsic.

- `hlsl_intrinsics.h` - exposed mad api call.
- `Builtins.td` - exposed a `mad` builtin.
- `Sema.h` - make `tertiary` calls check for float types optional. 
- `CGBuiltin.cpp` - pick the intrinsic for singed\unsigned & float also
reuse `int_fmuladd`.
- `SemaChecking.cpp` - type checks for `__builtin_hlsl_mad`. 
- `IntrinsicsDirectX.td` create the two new intrinsics for
`imad`\`umad`/
- `DXIL.td` - create the llvm intrinsic to  `DXIL` opcode mapping.

---------

Co-authored-by: Farzon Lotfi <farzon@farzon.com>

clang/include/clang/Basic/Builtins.td

@@ -4572,6 +4572,12 @@ def HLSLLerp : LangBuiltin<"HLSL_LANG"> {
   let Prototype = "void(...)";
 }
 
+def HLSLMad : LangBuiltin<"HLSL_LANG"> {
+  let Spellings = ["__builtin_hlsl_mad"];
+  let Attributes = [NoThrow, Const];
+  let Prototype = "void(...)";
+}
+
 // Builtins for XRay.
 def XRayCustomEvent : Builtin {
   let Spellings = ["__xray_customevent"];

clang/include/clang/Sema/Sema.h

@@ -14146,7 +14146,8 @@ class Sema final {
   bool SemaBuiltinVectorMath(CallExpr *TheCall, QualType &Res);
   bool SemaBuiltinVectorToScalarMath(CallExpr *TheCall);
   bool SemaBuiltinElementwiseMath(CallExpr *TheCall);
-  bool SemaBuiltinElementwiseTernaryMath(CallExpr *TheCall);
+  bool SemaBuiltinElementwiseTernaryMath(CallExpr *TheCall,
+                                         bool CheckForFloatArgs = true);
   bool PrepareBuiltinElementwiseMathOneArgCall(CallExpr *TheCall);
   bool PrepareBuiltinReduceMathOneArgCall(CallExpr *TheCall);
 

clang/lib/CodeGen/CGBuiltin.cpp

@@ -18044,6 +18044,25 @@ Value *CodeGenFunction::EmitHLSLBuiltinExpr(unsigned BuiltinID,
         /*ReturnType*/ Op0->getType(), Intrinsic::dx_frac,
         ArrayRef<Value *>{Op0}, nullptr, "dx.frac");
   }
+  case Builtin::BI__builtin_hlsl_mad: {
+    Value *M = EmitScalarExpr(E->getArg(0));
+    Value *A = EmitScalarExpr(E->getArg(1));
+    Value *B = EmitScalarExpr(E->getArg(2));
+    if (E->getArg(0)->getType()->hasFloatingRepresentation()) {
+      return Builder.CreateIntrinsic(
+          /*ReturnType*/ M->getType(), Intrinsic::fmuladd,
+          ArrayRef<Value *>{M, A, B}, nullptr, "dx.fmad");
+    }
+    if (E->getArg(0)->getType()->hasSignedIntegerRepresentation()) {
+      return Builder.CreateIntrinsic(
+          /*ReturnType*/ M->getType(), Intrinsic::dx_imad,
+          ArrayRef<Value *>{M, A, B}, nullptr, "dx.imad");
+    }
+    assert(E->getArg(0)->getType()->hasUnsignedIntegerRepresentation());
+    return Builder.CreateIntrinsic(
+        /*ReturnType*/ M->getType(), Intrinsic::dx_umad,
+        ArrayRef<Value *>{M, A, B}, nullptr, "dx.umad");
+  }
   }
   return nullptr;
 }

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -511,6 +511,111 @@ double3 log2(double3);
 _HLSL_BUILTIN_ALIAS(__builtin_elementwise_log2)
 double4 log2(double4);
 
+//===----------------------------------------------------------------------===//
+// mad builtins
+//===----------------------------------------------------------------------===//
+
+/// \fn T mad(T M, T A, T B)
+/// \brief The result of \a M * \a A + \a B.
+/// \param M The multiplication value.
+/// \param A The first addition value.
+/// \param B The second addition value.
+
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+half mad(half, half, half);
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+half2 mad(half2, half2, half2);
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+half3 mad(half3, half3, half3);
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+half4 mad(half4, half4, half4);
+
+#ifdef __HLSL_ENABLE_16_BIT
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int16_t mad(int16_t, int16_t, int16_t);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int16_t2 mad(int16_t2, int16_t2, int16_t2);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int16_t3 mad(int16_t3, int16_t3, int16_t3);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int16_t4 mad(int16_t4, int16_t4, int16_t4);
+
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint16_t mad(uint16_t, uint16_t, uint16_t);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint16_t2 mad(uint16_t2, uint16_t2, uint16_t2);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint16_t3 mad(uint16_t3, uint16_t3, uint16_t3);
+_HLSL_AVAILABILITY(shadermodel, 6.2)
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint16_t4 mad(uint16_t4, uint16_t4, uint16_t4);
+#endif
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int mad(int, int, int);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int2 mad(int2, int2, int2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int3 mad(int3, int3, int3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int4 mad(int4, int4, int4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint mad(uint, uint, uint);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint2 mad(uint2, uint2, uint2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint3 mad(uint3, uint3, uint3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint4 mad(uint4, uint4, uint4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int64_t mad(int64_t, int64_t, int64_t);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int64_t2 mad(int64_t2, int64_t2, int64_t2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int64_t3 mad(int64_t3, int64_t3, int64_t3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+int64_t4 mad(int64_t4, int64_t4, int64_t4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint64_t mad(uint64_t, uint64_t, uint64_t);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint64_t2 mad(uint64_t2, uint64_t2, uint64_t2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint64_t3 mad(uint64_t3, uint64_t3, uint64_t3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+uint64_t4 mad(uint64_t4, uint64_t4, uint64_t4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+float mad(float, float, float);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+float2 mad(float2, float2, float2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+float3 mad(float3, float3, float3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+float4 mad(float4, float4, float4);
+
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+double mad(double, double, double);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+double2 mad(double2, double2, double2);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+double3 mad(double3, double3, double3);
+_HLSL_BUILTIN_ALIAS(__builtin_hlsl_mad)
+double4 mad(double4, double4, double4);
+
 //===----------------------------------------------------------------------===//
 // max builtins
 //===----------------------------------------------------------------------===//

clang/lib/Sema/SemaChecking.cpp

@@ -5298,6 +5298,14 @@ bool Sema::CheckHLSLBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
       return true;
     break;
   }
+  case Builtin::BI__builtin_hlsl_mad: {
+    if (checkArgCount(*this, TheCall, 3))
+      return true;
+    if (CheckVectorElementCallArgs(this, TheCall))
+      return true;
+    if (SemaBuiltinElementwiseTernaryMath(TheCall, /*CheckForFloatArgs*/ false))
+      return true;
+  }
   }
   return false;
 }
@@ -19798,7 +19806,8 @@ bool Sema::SemaBuiltinVectorMath(CallExpr *TheCall, QualType &Res) {
   return false;
 }
 
-bool Sema::SemaBuiltinElementwiseTernaryMath(CallExpr *TheCall) {
+bool Sema::SemaBuiltinElementwiseTernaryMath(CallExpr *TheCall,
+                                             bool CheckForFloatArgs) {
   if (checkArgCount(*this, TheCall, 3))
     return true;
 
@@ -19810,11 +19819,20 @@ bool Sema::SemaBuiltinElementwiseTernaryMath(CallExpr *TheCall) {
     Args[I] = Converted.get();
   }
 
-  int ArgOrdinal = 1;
-  for (Expr *Arg : Args) {
-    if (checkFPMathBuiltinElementType(*this, Arg->getBeginLoc(), Arg->getType(),
+  if (CheckForFloatArgs) {
+    int ArgOrdinal = 1;
+    for (Expr *Arg : Args) {
+      if (checkFPMathBuiltinElementType(*this, Arg->getBeginLoc(),
+                                        Arg->getType(), ArgOrdinal++))
+        return true;
+    }
+  } else {
+    int ArgOrdinal = 1;
+    for (Expr *Arg : Args) {
+      if (checkMathBuiltinElementType(*this, Arg->getBeginLoc(), Arg->getType(),
                                       ArgOrdinal++))
-      return true;
+        return true;
+    }
   }
 
   for (int I = 1; I < 3; ++I) {