[clang] [HLSL] Buffer handle globals should not be constants (PR #130231)

[Helena Kotas via cfe-commits]

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@@ -214,12 +213,12 @@ void CGHLSLRuntime::addBuffer(const HLSLBufferDecl *BufDecl) {
   llvm::TargetExtType *TargetTy =
       cast<llvm::TargetExtType>(convertHLSLSpecificType(
           ResHandleTy, BufDecl->hasValidPackoffset() ? &Layout : nullptr));
-  llvm::GlobalVariable *BufGV =
-      new GlobalVariable(TargetTy, /*isConstant*/ true,
-                         GlobalValue::LinkageTypes::ExternalLinkage, nullptr,
-                         llvm::formatv("{0}{1}", BufDecl->getName(),
-                                       BufDecl->isCBuffer() ? ".cb" : ".tb"),
-                         GlobalValue::NotThreadLocal);
+  llvm::GlobalVariable *BufGV = new GlobalVariable(
+      TargetTy, /*isConstant*/ false,
+      GlobalValue::LinkageTypes::ExternalLinkage, PoisonValue::get(TargetTy),
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hekota wrote:

The global BufGV will be initialized with a resource handle based on resource bindings at the start of the entry function (or in module init function). A resource class with uninitialized handle is an error state, so poison is the right choice here.

https://github.com/llvm/llvm-project/pull/130231