Vulkan implicit sampler fixups (#686)

* Fix sampler-less texture functions (#685)

* Fix sampler-less texeture functions

I'm honestly not sure how the original work on this feature in #648 worked at all (probably insufficient testing).

We have these front-end modifiers to indicate that a particular function definition requires a certain GLSL version, or a GLSL extension in order to be used, and they are supposed to be automatically employed by the logic in `emit.cpp` to output `#extension` lines in the output GLSL. However, it turns out that nothing is actually wired up right now, so that adding the modifiers to a declaration is a placebo.

This change propagates the modifiers through as decorations, and then uses them during GLSL code emit, which allows the functions that require `EXT_samplerless_texture_functions` to work.

* fixup: 32-bit warning

* Add serialization support for GLSL extension/version decorations

1 files changed, 30 insertions, 1 deletions

diff --git a/source/slang/emit.cpp b/source/slang/emit.cpp
index 4961518f1..c9e19dffc 100644
--- a/source/slang/emit.cpp
+++ b/source/slang/emit.cpp
@@ -3466,9 +3466,38 @@ struct EmitVisitor
         IREmitMode      mode,
         EOpInfo         outerPrec)
     {
+        auto funcValue = inst->getOperand(0);
+
+        // Does this function declare any requirements on GLSL version or
+        // extensions, which should affect our output?
+        if(getTarget(ctx) == CodeGenTarget::GLSL)
+        {
+            auto decoratedValue = funcValue;
+            while (auto specInst = as<IRSpecialize>(decoratedValue))
+            {
+                decoratedValue = getSpecializedValue(specInst);
+            }
+
+            for( auto decoration = decoratedValue->firstDecoration; decoration; decoration = decoration->next )
+            {
+                switch(decoration->op)
+                {
+                default:
+                    break;
+
+                case kIRDecorationOp_RequireGLSLExtension:
+                    requireGLSLExtension(String(((IRRequireGLSLExtensionDecoration*)decoration)->extensionName));
+                    break;
+
+                case kIRDecorationOp_RequireGLSLVersion:
+                    requireGLSLVersion(int(((IRRequireGLSLVersionDecoration*)decoration)->languageVersion));
+                    break;
+                }
+            }
+        }
+
         // We want to detect any call to an intrinsic operation,
         // that we can emit it directly without mangling, etc.
-        auto funcValue = inst->getOperand(0);
         if(auto irFunc = asTargetIntrinsic(ctx, funcValue))
         {
             emitIntrinsicCallExpr(ctx, inst, irFunc, mode, outerPrec);