Implement HLSL resource bindings and default type `float4` to `SubpassInput<T>` (#4462)

* Add case to `emitVectorReshape` for `vector<>` type, `scalar` value

1. Add new case
2. Add test

* fix warning

* fix warning

* Implement HLSL resource bindings and default type `float4` to `SubpassInput<T>`

fixes: #4440

1. Removed GLSLInputAttachmentIndexLayout modifier and the somewhat 'hacky' binding model 'Input Attachment' previously relied upon. This was changed to work with the slang-type-layout rules system. This change allows Slang automatic bindings, HLSL bindings, GLSL bindings, and translation of GLSL to and from HLSL bindings to work.
2. Added default argument `float4` to SubpassInput<T>.
3. Merged glsl.meta and hlsl.meta SubpassInput logic.

* fix InputAttachment attribute checks

fix InputAttachment attribute checks for HLSL and GLSL syntax

* remove unused var

* validate attribute correctly

Attributes do not have type information. We must check the type expression to validate attribute usage.

* remove hacky validation

type based validation before types are fully resolved is quite hacky and unstable to changes and wrapped types

* fix warning

* remove redundant `!= nullptr`

* remove extra `!= nullptr`

* fix some warnings/errors

* subpass capability to limit to dxc & remove default values in some functions

* revert logic to previous logic

revert logic to return if we have a binding regardless of if a VarDecl is given the binding

1 files changed, 11 insertions, 4 deletions

diff --git a/source/slang/slang-emit-c-like.cpp b/source/slang/slang-emit-c-like.cpp
index 6062875b3..66ee12ca6 100644
--- a/source/slang/slang-emit-c-like.cpp
+++ b/source/slang/slang-emit-c-like.cpp
@@ -3160,9 +3160,14 @@ void CLikeSourceEmitter::emitSemantics(IRInst* inst, bool allowOffsetLayout)
     emitSemanticsImpl(inst, allowOffsetLayout);
 }
 
+void CLikeSourceEmitter::emitDecorationLayoutSemantics(IRInst* inst, char const* uniformSemanticSpelling)
+{
+    emitLayoutSemanticsImpl(inst, uniformSemanticSpelling, EmitLayoutSemanticOption::kPreType);
+}
+
 void CLikeSourceEmitter::emitLayoutSemantics(IRInst* inst, char const* uniformSemanticSpelling)
 {
-    emitLayoutSemanticsImpl(inst, uniformSemanticSpelling);
+    emitLayoutSemanticsImpl(inst, uniformSemanticSpelling, EmitLayoutSemanticOption::kPostType);
 }
 
 void CLikeSourceEmitter::emitRegion(Region* inRegion)
@@ -3959,7 +3964,7 @@ void CLikeSourceEmitter::emitVar(IRVar* varDecl)
     emitType(varType, getName(varDecl));
 
     emitSemantics(varDecl);
-    emitLayoutSemantics(varDecl);
+    emitLayoutSemantics(varDecl, "register");
     emitPostDeclarationAttributesForType(varType);
 
     // TODO: ideally this logic should scan ahead to see if it can find a `store`
@@ -4092,7 +4097,7 @@ void CLikeSourceEmitter::emitGlobalVar(IRGlobalVar* varDecl)
     // global variables.
     //
     emitSemantics(varDecl);
-    emitLayoutSemantics(varDecl);
+    emitLayoutSemantics(varDecl, "register");
 
     if (varDecl->getFirstBlock())
     {
@@ -4155,13 +4160,15 @@ void CLikeSourceEmitter::emitGlobalParam(IRGlobalParam* varDecl)
     SLANG_ASSERT(layout);
 
     emitVarModifiers(layout, varDecl, varType);
+    
+    emitDecorationLayoutSemantics(varDecl, "register");
 
     emitRateQualifiersAndAddressSpace(varDecl);
     emitType(varType, getName(varDecl));
 
     emitSemantics(varDecl);
 
-    emitLayoutSemantics(varDecl);
+    emitLayoutSemantics(varDecl, "register");
 
     // A shader parameter cannot have an initializer,
     // so we do need to consider emitting one here.