[HLSL] Global resource arrays element access (#152454)

Adds support for accessing individual resources from fixed-size global resource arrays.

Design proposal:
https://github.com/llvm/wg-hlsl/blob/main/proposals/0028-resource-arrays.md

Enables indexing into globally scoped, fixed-size resource arrays to retrieve individual resources. The initialization logic is primarily handled during codegen. When a global resource array is indexed, the
codegen translates the `ArraySubscriptExpr` AST node into a constructor call for the corresponding resource record type and binding.

To support this behavior, Sema needs to ensure that:
- The constructor for the specific resource type is instantiated.
- An implicit binding attribute is added to resource arrays that lack explicit bindings (#152452).

Closes #145424

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGExpr.cpp b/clang/lib/CodeGen/CGExpr.cpp
index d5df6dd3e303..d229d81d6b93 100644
--- a/clang/lib/CodeGen/CGExpr.cpp
+++ b/clang/lib/CodeGen/CGExpr.cpp
@@ -16,6 +16,7 @@
 #include "CGCall.h"
 #include "CGCleanup.h"
 #include "CGDebugInfo.h"
+#include "CGHLSLRuntime.h"
 #include "CGObjCRuntime.h"
 #include "CGOpenMPRuntime.h"
 #include "CGRecordLayout.h"
@@ -4534,6 +4535,15 @@ LValue CodeGenFunction::EmitArraySubscriptExpr(const ArraySubscriptExpr *E,
                                  LHS.getBaseInfo(), TBAAAccessInfo());
   }
 
+  // The HLSL runtime handle the subscript expression on global resource arrays.
+  if (getLangOpts().HLSL && (E->getType()->isHLSLResourceRecord() ||
+                             E->getType()->isHLSLResourceRecordArray())) {
+    std::optional<LValue> LV =
+        CGM.getHLSLRuntime().emitResourceArraySubscriptExpr(E, *this);
+    if (LV.has_value())
+      return *LV;
+  }
+
   // All the other cases basically behave like simple offsetting.
 
   // Handle the extvector case we ignored above.