GLSL SSBO Support (#3400)

* Squash warnings and fix build with SLANG_EMBED_STDLIB

* Add GLSLShaderStorageBuffer magic wrapper

* Make GLSLSSBO not a uniform type

* Buffers are global variables

* Allow creating ssbo aggregate types

* Allow reading from RWSB using builder

* Nicer debug printing for ssbos

* Lower SSBO to RWSB

* Parse interface blocks into wrapped structs

* Lower Interface Block Decls to structs

* remove comment

* Two simple ssbo tests

* Move ssbo pass earlier

* Correct mutable buffer detection

* Do not replace ssbo usages outside of blocks

* Treat GLSLSSBO as a mutable buffer for type layouts

* regenerate vs projects

* Correctly detect ssbo types

* Diagnose illegal ssbo

* remove unreachable code

* neaten

* ci wobble

* Make GLSLSSBO ast handling more uniform

* Add modifier cases for glsl

* Use empty val info for unhandled interface blocks

necessary for ./tests/glsl/out-binding-redeclaration.slang

* more sophisticated modifier check

* Correct ssbo wrapper name

1 files changed, 19 insertions, 15 deletions

diff --git a/source/slang/slang-check-expr.cpp b/source/slang/slang-check-expr.cpp
index 59f7f2aa1..3aaeade74 100644
--- a/source/slang/slang-check-expr.cpp
+++ b/source/slang/slang-check-expr.cpp
@@ -299,21 +299,25 @@ namespace Slang
 
     static bool isMutableGLSLBufferBlockVarExpr(Expr* expr)
     {
-        if(const auto varExpr = as<VarExpr>(expr))
-        {
-            if(const auto declRefType = as<DeclRefType>(varExpr->type->getCanonicalType()))
-            {
-                if(declRefType->getDeclRef().getDecl()->isDerivedFrom(ASTNodeType::GLSLInterfaceBlockDecl))
-                {
-                    const auto d = varExpr->declRef.getDecl();
-                    if(d->hasModifier<GLSLBufferModifier>() && !d->hasModifier<GLSLReadOnlyModifier>())
-                    {
-                        return true;
-                    }
-                }
-            }
-        }
-        return false;
+        const auto derefExpr = as<DerefExpr>(expr);
+        if(!derefExpr)
+            return false;
+        const auto varExpr = as<VarExpr>(derefExpr->base);
+        // Check the declaration type
+        if(!varExpr)
+            return false;
+
+        const auto varExprType = varExpr->type->getCanonicalType();
+        const auto ssbt = as<GLSLShaderStorageBufferType>(varExprType);
+        if(!ssbt)
+            return false;
+
+        // Check the modifiers on the declaration
+        const auto d = varExpr->declRef.getDecl();
+        if(d->hasModifier<GLSLReadOnlyModifier>())
+            return false;
+
+        return true;
     }
 
     DeclRefExpr* SemanticsVisitor::ConstructDeclRefExpr(