Add GLSL intrinsics for f32tof16() and f16tof32() (shader-slang#883)

Author: chuckgenome

source/slang/hlsl.meta.slang

@@ -717,12 +717,20 @@ __generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> exp2(vector<T
 __generic<T : __BuiltinFloatingPointType, let N : int, let M : int> matrix<T,N,M> exp2(matrix<T,N,M> x);
 
 // Convert 16-bit float stored in low bits of integer
+__target_intrinsic(glsl, "unpackHalf2x16($0).x")
 float f16tof32(uint value);
-__generic<let N : int> vector<float,N> f16tof32(vector<uint,N> value);
+
+__generic<let N : int>
+__target_intrinsic(glsl, "unpackHalf2x16($0).x")
+vector<float,N> f16tof32(vector<uint,N> value);
 
 // Convert to 16-bit float stored in low bits of integer
+__target_intrinsic(glsl, "packHalf2x16(vec2($0,0.0))")
 uint f32tof16(float value);
-__generic<let N : int> vector<uint,N> f32tof16(vector<float,N> value);
+
+__generic<let N : int>
+__target_intrinsic(glsl, "packHalf2x16(vec2($0,0.0))")
+vector<uint,N> f32tof16(vector<float,N> value);
 
 // Flip surface normal to face forward, if needed
 __generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> faceforward(vector<T,N> n, vector<T,N> i, vector<T,N> ng);

source/slang/hlsl.meta.slang.h

@@ -793,12 +793,20 @@ SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> ex
 SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int, let M : int> matrix<T,N,M> exp2(matrix<T,N,M> x);\n")
 SLANG_RAW("\n")
 SLANG_RAW("// Convert 16-bit float stored in low bits of integer\n")
+SLANG_RAW("__target_intrinsic(glsl, \"unpackHalf2x16($0).x\")\n")
 SLANG_RAW("float f16tof32(uint value);\n")
-SLANG_RAW("__generic<let N : int> vector<float,N> f16tof32(vector<uint,N> value);\n")
+SLANG_RAW("\n")
+SLANG_RAW("__generic<let N : int>\n")
+SLANG_RAW("__target_intrinsic(glsl, \"unpackHalf2x16($0).x\")\n")
+SLANG_RAW("vector<float,N> f16tof32(vector<uint,N> value);\n")
 SLANG_RAW("\n")
 SLANG_RAW("// Convert to 16-bit float stored in low bits of integer\n")
+SLANG_RAW("__target_intrinsic(glsl, \"packHalf2x16(vec2($0,0.0))\")\n")
 SLANG_RAW("uint f32tof16(float value);\n")
-SLANG_RAW("__generic<let N : int> vector<uint,N> f32tof16(vector<float,N> value);\n")
+SLANG_RAW("\n")
+SLANG_RAW("__generic<let N : int>\n")
+SLANG_RAW("__target_intrinsic(glsl, \"packHalf2x16(vec2($0,0.0))\")\n")
+SLANG_RAW("vector<uint,N> f32tof16(vector<float,N> value);\n")
 SLANG_RAW("\n")
 SLANG_RAW("// Flip surface normal to face forward, if needed\n")
 SLANG_RAW("__generic<T : __BuiltinFloatingPointType, let N : int> vector<T,N> faceforward(vector<T,N> n, vector<T,N> i, vector<T,N> ng);\n")
@@ -1513,7 +1521,7 @@ for (int aa = 0; aa < kBaseBufferAccessLevelCount; ++aa)
 
     sb << "};\n";
 }
-SLANG_RAW("#line 1440 \"hlsl.meta.slang\"")
+SLANG_RAW("#line 1448 \"hlsl.meta.slang\"")
 SLANG_RAW("\n")
 SLANG_RAW("\n")
 SLANG_RAW("\n")