[HLSL][DXIL] Implement refract intrinsic

clang/include/clang/Basic/BuiltinsSPIRV.td

@@ -26,6 +26,12 @@ def SPIRVReflect : Builtin {
   let Prototype = "void(...)";
 }
 
+def SPIRVRefract : Builtin {
+  let Spellings = ["__builtin_spirv_refract"];
+  let Attributes = [NoThrow, Const];
+  let Prototype = "void(...)";
+}
+
 def SPIRVSmoothStep : Builtin {
   let Spellings = ["__builtin_spirv_smoothstep"];
   let Attributes = [NoThrow, Const, CustomTypeChecking];

clang/lib/CodeGen/TargetBuiltins/SPIR.cpp

@@ -58,6 +58,21 @@ Value *CodeGenFunction::EmitSPIRVBuiltinExpr(unsigned BuiltinID,
         /*ReturnType=*/I->getType(), Intrinsic::spv_reflect,
         ArrayRef<Value *>{I, N}, nullptr, "spv.reflect");
   }
+  case SPIRV::BI__builtin_spirv_refract: {
+    Value *I = EmitScalarExpr(E->getArg(0));
+    Value *N = EmitScalarExpr(E->getArg(1));
+    Value *eta = EmitScalarExpr(E->getArg(2));
+    assert(E->getArg(0)->getType()->hasFloatingRepresentation() &&
+           E->getArg(1)->getType()->hasFloatingRepresentation() &&
+           E->getArg(2)->getType()->hasFloatingRepresentation() &&
+           "refract operands must have a float representation");
+    assert(E->getArg(0)->getType()->isVectorType() &&
+           E->getArg(1)->getType()->isVectorType() &&
+           "refract I and N operands must be a vector");
+    return Builder.CreateIntrinsic(
+        /*ReturnType=*/I->getType(), Intrinsic::spv_refract,
+        ArrayRef<Value *>{I, N, eta}, nullptr, "spv.refract");
+  }
   case SPIRV::BI__builtin_spirv_smoothstep: {
     Value *Min = EmitScalarExpr(E->getArg(0));
     Value *Max = EmitScalarExpr(E->getArg(1));

clang/lib/Headers/hlsl/hlsl_intrinsic_helpers.h

@@ -10,7 +10,7 @@
 #define _HLSL_HLSL_INTRINSIC_HELPERS_H_
 
 namespace hlsl {
-namespace __detail {
+namespace __dETAil {
 
 constexpr vector<uint, 4> d3d_color_to_ubyte4_impl(vector<float, 4> V) {
   // Use the same scaling factor used by FXC, and DXC for DXIL
@@ -71,6 +71,27 @@ constexpr vector<T, L> reflect_vec_impl(vector<T, L> I, vector<T, L> N) {
 #endif
 }
 
+template <typename T> constexpr T refract_impl(T I, T N, T Eta) {
+  T K = 1 - Eta * Eta * (1 - (N * I * N * I));
+  if (K < 0)
+    return 0;
+  else
+    return (Eta * I - (Eta * N * I + sqrt(K)) * N);
+}
+
+template <typename T, int L>
+constexpr vector<T, L> refract_vec_impl(vector<T, L> I, vector<T, L> N, T Eta) {
+#if (__has_builtin(__builtin_spirv_refract))
+  return __builtin_spirv_refract(I, N, Eta);
+#else
+  vector<T, L> K = 1 - Eta * Eta * (1 - dot(N, I) * dot(N, I));
+  if (K < 0)
+    return 0;
+  else
+    return (Eta * I - (Eta * dot(N, I) + sqrt(K)) * N);
+#endif
+}
+
 template <typename T> constexpr T fmod_impl(T X, T Y) {
 #if !defined(__DIRECTX__)
   return __builtin_elementwise_fmod(X, Y);
@@ -126,7 +147,7 @@ template <typename T> constexpr vector<T, 4> lit_impl(T NDotL, T NDotH, T M) {
   return Result;
 }
 
-} // namespace __detail
+} // namespace __dETAil
 } // namespace hlsl
 
 #endif // _HLSL_HLSL_INTRINSIC_HELPERS_H_

clang/lib/Headers/hlsl/hlsl_intrinsics.h

@@ -386,6 +386,65 @@ reflect(__detail::HLSL_FIXED_VECTOR<float, L> I,
   return __detail::reflect_vec_impl(I, N);
 }
 
+//===----------------------------------------------------------------------===//
+// refract builtin
+//===----------------------------------------------------------------------===//
+
+/// \fn T refract(T I, T N, T eta)
+/// \brief Returns a refraction using an entering ray, \a I, a surface
+/// normal, \a N and refraction index \a eta
+/// \param I The entering ray.
+/// \param N The surface normal.
+/// \param eta The refraction index.
+///
+/// The return value is a floating-point vector that represents the refraction
+/// using the refraction index, \a eta, for the direction of the entering ray,
+/// \a I, off a surface with the normal \a N.
+///
+/// This function calculates the refraction vector using the following formulas:
+/// k = 1.0 - eta * eta * (1.0 - dot(N, I) * dot(N, I))
+/// if k < 0.0 the result is 0.0
+/// otherwise, the result is eta * I - (eta * dot(N, I) + sqrt(k)) * N
+///
+/// I and N must already be normalized in order to achieve the desired result.
+///
+/// I and N must be a scalar or vector whose component type is
+/// floating-point.
+///
+/// eta must be a 16-bit or 32-bit floating-point scalar.
+///
+/// Result type, the type of I, and the type of N must all be the same type.
+
+template <typename T>
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+const inline __detail::enable_if_t<__detail::is_arithmetic<T>::Value &&
+                                       __detail::is_same<half, T>::value,
+                                   T> refract(T I, T N, T eta) {
+  return __detail::refract_impl(I, N, eta);
+}
+
+template <typename T>
+const inline __detail::enable_if_t<
+    __detail::is_arithmetic<T>::Value && __detail::is_same<float, T>::value, T>
+refract(T I, T N, T eta) {
+  return __detail::refract_impl(I, N, eta);
+}
+
+template <int L>
+_HLSL_16BIT_AVAILABILITY(shadermodel, 6.2)
+const inline __detail::HLSL_FIXED_VECTOR<half, L> refract(
+    __detail::HLSL_FIXED_VECTOR<half, L> I,
+    __detail::HLSL_FIXED_VECTOR<half, L> N, half eta) {
+  return __detail::refract_vec_impl(I, N, eta);
+}
+
+template <int L>
+const inline __detail::HLSL_FIXED_VECTOR<float, L>
+refract(__detail::HLSL_FIXED_VECTOR<float, L> I,
+        __detail::HLSL_FIXED_VECTOR<float, L> N, float eta) {
+  return __detail::refract_vec_impl(I, N, eta);
+}
+
 //===----------------------------------------------------------------------===//
 // smoothstep builtin
 //===----------------------------------------------------------------------===//

clang/lib/Sema/SemaSPIRV.cpp

@@ -39,7 +39,7 @@ bool SemaSPIRV::CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID,
     QualType ArgTyB = B.get()->getType();
     auto *VTyB = ArgTyB->getAs<VectorType>();
     if (VTyB == nullptr) {
-      SemaRef.Diag(A.get()->getBeginLoc(),
+      SemaRef.Diag(B.get()->getBeginLoc(),
                    diag::err_typecheck_convert_incompatible)
           << ArgTyB
           << SemaRef.Context.getVectorType(ArgTyB, 2, VectorKind::Generic) << 1
@@ -69,6 +69,47 @@ bool SemaSPIRV::CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID,
     TheCall->setType(RetTy);
     break;
   }
+  case SPIRV::BI__builtin_spirv_refract: {
+    if (SemaRef.checkArgCount(TheCall, 3))
+      return true;
+
+    ExprResult A = TheCall->getArg(0);
+    QualType ArgTyA = A.get()->getType();
+    auto *VTyA = ArgTyA->getAs<VectorType>();
+    if (VTyA == nullptr) {
+      SemaRef.Diag(A.get()->getBeginLoc(),
+                   diag::err_typecheck_convert_incompatible)
+          << ArgTyA
+          << SemaRef.Context.getVectorType(ArgTyA, 2, VectorKind::Generic) << 1
+          << 0 << 0;
+      return true;
+    }
+
+    ExprResult B = TheCall->getArg(1);
+    QualType ArgTyB = B.get()->getType();
+    auto *VTyB = ArgTyB->getAs<VectorType>();
+    if (VTyB == nullptr) {
+      SemaRef.Diag(B.get()->getBeginLoc(),
+                   diag::err_typecheck_convert_incompatible)
+          << ArgTyB
+          << SemaRef.Context.getVectorType(ArgTyB, 2, VectorKind::Generic) << 1
+          << 0 << 0;
+      return true;
+    }
+
+    ExprResult C = TheCall->getArg(2);
+    QualType ArgTyC = C.get()->getType();
+    if (!ArgTyC->hasFloatingRepresentation()) {
+      SemaRef.Diag(C.get()->getBeginLoc(), diag::err_builtin_invalid_arg_type)
+          << 3 << /* scalar or vector */ 5 << /* no int */ 0 << /* fp */ 1
+          << ArgTyC;
+      return true;
+    }
+
+    QualType RetTy = ArgTyA;
+    TheCall->setType(RetTy);
+    break;
+  }
   case SPIRV::BI__builtin_spirv_reflect: {
     if (SemaRef.checkArgCount(TheCall, 2))
       return true;
@@ -89,7 +130,7 @@ bool SemaSPIRV::CheckSPIRVBuiltinFunctionCall(unsigned BuiltinID,
     QualType ArgTyB = B.get()->getType();
     auto *VTyB = ArgTyB->getAs<VectorType>();
     if (VTyB == nullptr) {
-      SemaRef.Diag(A.get()->getBeginLoc(),
+      SemaRef.Diag(B.get()->getBeginLoc(),
                    diag::err_typecheck_convert_incompatible)
           << ArgTyB
           << SemaRef.Context.getVectorType(ArgTyB, 2, VectorKind::Generic) << 1