Implement texture functions for Metal target (#4158)

* Impl texture APIs for Metal target

This commit is to implement texture functions for Metal target.

The following functions are implemented and tested.
 - GetDimensions()
 - CalculateLevelOfDetail()
 - CalculateLevelOfDetailUnclamped()
 - Sample()
 - SampleBias()
 - SampleLevel()
 - SampleCmp()
 - SampleCmpLevelZero()
 - Gather()
 - SampleGrad()
 - Load()

Metal has limited support for the texture functions compared to HLSL.
 - LOD is not supported for 1D texture,
 - Depth textures are limited to 2D, 2DArray, Cube and CubeArray
   textures.
 - "Offset" variants are limited to 2D, 2DArray, 2D-Depth,
   2DArray-Depth and 3D textures.

The functions that cannot be implemented for Metal should properly
be handled by the capability system later.

* Fix the failing test, multi-file.hlsl

I am not sure why this change is needed.

* Fix compile errors on macOS 2nd try

* Remove a typo character to fix the compile error

* Trivial clean up

* Remove `as_type` where it was intended as static_cast

* Use a simpler sytax for __intrinsic_asm

* Trivial clean up

* Remove TEST_AFTER_FIXING_CAPABILITY_PROBLEM after fixing normalize

* Fix the failing test properly

* Fix an incorrect setup of Depth-cube texture

---------

Co-authored-by: Yong He <yonghe@outlook.com>

1 files changed, 53 insertions, 6 deletions

diff --git a/source/slang/slang-stdlib-textures.cpp b/source/slang/slang-stdlib-textures.cpp
index f874c5da9..380ed1677 100644
--- a/source/slang/slang-stdlib-textures.cpp
+++ b/source/slang/slang-stdlib-textures.cpp
@@ -68,7 +68,8 @@ void TextureTypeInfo::writeFuncBody(
     const String& cuda,
     const String& spirvDefault,
     const String& spirvRWDefault,
-    const String& spirvCombined)
+    const String& spirvCombined,
+    const String& metal)
 {
     BraceScope funcScope{i, sb};
     {
@@ -90,6 +91,11 @@ void TextureTypeInfo::writeFuncBody(
             sb << i << "case cuda:\n";
             sb << i << "__intrinsic_asm \"" << cuda << "\";\n";
         }
+        if (metal.getLength())
+        {
+            sb << i << "case metal:\n";
+            sb << i << "__intrinsic_asm \"" << metal << "\";\n";
+        }
         if(spirvDefault.getLength() && spirvCombined.getLength())
         {
             sb << i << "case spirv:\n";
@@ -127,14 +133,14 @@ void TextureTypeInfo::writeFuncWithSig(
     const String& spirvRWDefault,
     const String& spirvCombined,
     const String& cuda,
+    const String& metal,
     const ReadNoneMode readNoneMode)
 {
     if (readNoneMode == ReadNoneMode::Always)
         sb << i << "[__readNone]\n";
-    sb << i << "[__readNone]\n";
     sb << i << "[ForceInline]\n";
     sb << i << sig << "\n";
-    writeFuncBody(funcName, glsl, cuda, spirvDefault, spirvRWDefault, spirvCombined);
+    writeFuncBody(funcName, glsl, cuda, spirvDefault, spirvRWDefault, spirvCombined, metal);
     sb << "\n";
 }
 
@@ -147,6 +153,7 @@ void TextureTypeInfo::writeFunc(
     const String& spirvRWDefault,
     const String& spirvCombined,
     const String& cuda,
+    const String& metal,
     const ReadNoneMode readNoneMode)
 {
     writeFuncWithSig(
@@ -157,6 +164,7 @@ void TextureTypeInfo::writeFunc(
         spirvRWDefault,
         spirvCombined,
         cuda,
+        metal,
         readNoneMode
     );
 }
@@ -184,27 +192,56 @@ void TextureTypeInfo::writeGetDimensionFunctions()
 
             int sizeDimCount = 0;
             StringBuilder params;
+            int paramCount = 0;
+
+            StringBuilder metal;
+            const char* metalMipLevel = "0";
+
             if (includeMipInfo)
-                params << "uint mipLevel, ";
+            {
+                ++paramCount;
+                params << "uint mipLevel,";
+
+                if (baseShape != SLANG_TEXTURE_1D)
+                    metalMipLevel = "$1";
+            }
 
             switch (baseShape)
             {
             case SLANG_TEXTURE_1D:
+                ++paramCount;
                 params << t << "width";
+                metal << "(*($" << String(paramCount) << ") = $0.get_width(" << String(metalMipLevel) << ")),";
+
                 sizeDimCount = 1;
                 break;
 
             case SLANG_TEXTURE_2D:
             case SLANG_TEXTURE_CUBE:
+                ++paramCount;
                 params << t << "width,";
+                metal << "(*($" << String(paramCount) << ") = $0.get_width(" << String(metalMipLevel) << ")),";
+
+                ++paramCount;
                 params << t << "height";
+                metal << "(*($" << String(paramCount) << ") = $0.get_height(" << String(metalMipLevel) << ")),";
+
                 sizeDimCount = 2;
                 break;
 
             case SLANG_TEXTURE_3D:
+                ++paramCount;
                 params << t << "width,";
+                metal << "(*($" << String(paramCount) << ") = $0.get_width(" << String(metalMipLevel) << ")),";
+
+                ++paramCount;
                 params << t << "height,";
+                metal << "(*($" << String(paramCount) << ") = $0.get_height(" << String(metalMipLevel) << ")),";
+
+                ++paramCount;
                 params << t << "depth";
+                metal << "(*($" << String(paramCount) << ") = $0.get_depth(" << String(metalMipLevel) << ")),";
+
                 sizeDimCount = 3;
                 break;
 
@@ -215,18 +252,27 @@ void TextureTypeInfo::writeGetDimensionFunctions()
 
             if (isArray)
             {
+                ++sizeDimCount;
+                ++paramCount;
                 params << ", " << t << "elements";
-                sizeDimCount++;
+                metal << "(*($" << String(paramCount) << ") = $0.get_array_size()),";
             }
 
             if (isMultisample)
             {
+                ++paramCount;
                 params << ", " << t << "sampleCount";
+                metal << "(*($" << String(paramCount) << ") = $0.get_num_samples()),";
             }
 
             if (includeMipInfo)
+            {
+                ++paramCount;
                 params << ", " << t << "numberOfLevels";
+                metal << "(*($" << String(paramCount) << ") = $0.get_num_mip_levels()),";
+            }
 
+            metal.reduceLength(metal.getLength() - 1); // drop the last comma
 
             StringBuilder glsl;
             {
@@ -407,7 +453,7 @@ void TextureTypeInfo::writeGetDimensionFunctions()
 
             sb << "    __glsl_version(450)\n";
             sb << "    __glsl_extension(GL_EXT_samplerless_texture_functions)\n";
-            sb << "    [require(glsl_spirv, texture_sm_4_1)]\n";
+            sb << "    [require(glsl_hlsl_metal_spirv, texture_sm_4_1)]\n";
             writeFunc(
                 "void",
                 "GetDimensions",
@@ -417,6 +463,7 @@ void TextureTypeInfo::writeGetDimensionFunctions()
                 spirvRWDefault,
                 spirvCombined,
                 "",
+                metal,
                 ReadNoneMode::Always);
         }
     }