First pass support for half on vk (#912)

* Look at getting half to work on vk.

* Alter half test so can always produce consistent test results.

* First pass working half on vk.

* Improve comments for vulkan extensions around half.

* Upgraded vulkan headers to v1.1.103

https://github.com/KhronosGroup/Vulkan-Headers

* * Add getFeatures on Render interface
* Vulkan renderer determines at startup if it can support half
* Parse render-features on render-test

* Small changes to half-calc.slang test.

* Structured buffer half access works as expected for Vk, but isn't for dx12, so disable for now.

* Require the half feature for renderers for the half-structured-buffer.slang test.

* * Added ToolReturnCode to be more rigerous about how a return code is passed back from a tool
* Added support for a tool being able to pass back an 'ignored' result.
* Used enum codes to indicate meanings
* Made spawnAndWait return a ToolReturnCode

* Ignore tests that don't have required render-feature

* Fix macro line continuation usage.

* Check dx12 has half support.

* Checking for half on dx12 - if CheckFeatureSupport fails, don't fail renderer initialization.

* Fix typo.

1 files changed, 44 insertions, 2 deletions

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index d2de479b4..84585f248 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -47,6 +47,8 @@ struct ExtensionUsageTracker
     StringBuilder glslExtensionRequireLines;
 
     ProfileVersion profileVersion = ProfileVersion::GLSL_110;
+
+    bool hasHalfExtension = false;
 };
 
 void requireGLSLExtension(
@@ -76,6 +78,21 @@ void requireGLSLVersionImpl(
     }
 }
 
+void requireGLSLHalfExtension(ExtensionUsageTracker* tracker)
+{
+    if (!tracker->hasHalfExtension)
+    {
+        // https://github.com/KhronosGroup/GLSL/blob/master/extensions/ext/GL_EXT_shader_16bit_storage.txt
+        requireGLSLExtension(tracker, "GL_EXT_shader_16bit_storage");
+
+        // https://github.com/KhronosGroup/GLSL/blob/master/extensions/ext/GL_EXT_shader_explicit_arithmetic_types.txt
+        // Use GL_KHX_shader_explicit_arithmetic_types because that is what appears defined in glslang 
+        requireGLSLExtension(tracker, "GL_KHX_shader_explicit_arithmetic_types");
+        
+        tracker->hasHalfExtension = true;
+    }
+}
+
 
 // Shared state for an entire emit session
 struct SharedEmitContext
@@ -810,7 +827,12 @@ struct EmitVisitor
 
         case kIROp_BoolType:    Emit("b");		break;
 
-        case kIROp_HalfType:    Emit("f16");		break;
+        case kIROp_HalfType:
+        {
+            _requireHalf();
+            Emit("f16");
+            break;
+        }
         case kIROp_DoubleType:  Emit("d");		break;
 
         case kIROp_VectorType:
@@ -1197,6 +1219,14 @@ struct EmitVisitor
         }
     }
 
+    void _requireHalf()
+    {
+        if (getTarget(context) == CodeGenTarget::GLSL)
+        {
+            requireGLSLHalfExtension(&context->shared->extensionUsageTracker);
+        }
+    }
+
     void emitSimpleTypeImpl(IRType* type)
     {
         switch (type->op)
@@ -1217,7 +1247,19 @@ struct EmitVisitor
         case kIROp_UIntType:    Emit("uint");       return;
         case kIROp_UInt64Type:  Emit("uint64_t");   return;
 
-        case kIROp_HalfType:    Emit("half");       return;
+        case kIROp_HalfType:
+        {
+            _requireHalf();
+            if (getTarget(context) == CodeGenTarget::GLSL)
+            {
+                Emit("float16_t");
+            }
+            else
+            {
+                Emit("half");
+            }
+            return;
+        }
         case kIROp_FloatType:   Emit("float");      return;
         case kIROp_DoubleType:  Emit("double");     return;