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, 17 insertions, 0 deletions

diff --git a/source/slang/lower-to-ir.cpp b/source/slang/lower-to-ir.cpp
index 7b63f510f..5f3b00b24 100644
--- a/source/slang/lower-to-ir.cpp
+++ b/source/slang/lower-to-ir.cpp
@@ -5112,6 +5112,23 @@ struct DeclLoweringVisitor : DeclVisitor<DeclLoweringVisitor, LoweredValInfo>
         // for a particular target, then handle that here.
         addTargetIntrinsicDecorations(irFunc, decl);
 
+        // If this declaration requires certain GLSL extension (or a particular GLSL version)
+        // for it to be usable, then declare that here.
+        //
+        // TODO: We should wrap this an `SpecializedForTargetModifier` together into a single
+        // case for enumerating the "capabilities" that a declaration requires.
+        //
+        for(auto extensionMod : decl->GetModifiersOfType<RequiredGLSLExtensionModifier>())
+        {
+            auto decoration = getBuilder()->addDecoration<IRRequireGLSLExtensionDecoration>(irFunc);
+            decoration->extensionName = getBuilder()->addStringToFree(extensionMod->extensionNameToken.Content);
+        }
+        for(auto versionMod : decl->GetModifiersOfType<RequiredGLSLVersionModifier>())
+        {
+            auto decoration = getBuilder()->addDecoration<IRRequireGLSLVersionDecoration>(irFunc);
+            decoration->languageVersion = Int(getIntegerLiteralValue(versionMod->versionNumberToken));
+        }
+
         // For convenience, ensure that any additional global
         // values that were emitted while outputting the function
         // body appear before the function itself in the list