[HLSL][SPIR-V] Add hlsl_private address space for SPIR-V (#133464)

This is an alternative to
#122103

In SPIR-V, private global variables have the Private storage class. This
PR adds a new address space which allows frontend to emit variable with
this storage class when targeting this backend.

This is covered in this proposal: llvm/wg-hlsl@4c9e11a

This PR will cause addrspacecast to show up in several cases, like class
member functions or assignment. Those will have to be handled in the
backend later on, particularly to fixup pointer storage classes in some
functions.

Before this change, global variable were emitted with the 'Function'
storage class, which was wrong.

Author: Keenuts

clang/include/clang/Basic/AddressSpaces.h

@@ -59,6 +59,7 @@ enum class LangAS : unsigned {
   // HLSL specific address spaces.
   hlsl_groupshared,
   hlsl_constant,
+  hlsl_private,
 
   // Wasm specific address spaces.
   wasm_funcref,

clang/include/clang/Sema/Sema.h

@@ -4328,6 +4328,7 @@ class Sema final : public SemaBase {
   NamedDecl *findLocallyScopedExternCDecl(DeclarationName Name);
 
   void deduceOpenCLAddressSpace(ValueDecl *decl);
+  void deduceHLSLAddressSpace(VarDecl *decl);
 
   /// Adjust the \c DeclContext for a function or variable that might be a
   /// function-local external declaration.

clang/include/clang/Sema/SemaHLSL.h

@@ -154,6 +154,8 @@ class SemaHLSL : public SemaBase {
   bool TransformInitList(const InitializedEntity &Entity,
                          const InitializationKind &Kind, InitListExpr *Init);
 
+  void deduceAddressSpace(VarDecl *Decl);
+
 private:
   // HLSL resource type attributes need to be processed all at once.
   // This is a list to collect them.

clang/lib/AST/Type.cpp

@@ -94,6 +94,10 @@ bool Qualifiers::isTargetAddressSpaceSupersetOf(LangAS A, LangAS B,
          (A == LangAS::Default &&
           (B == LangAS::cuda_constant || B == LangAS::cuda_device ||
            B == LangAS::cuda_shared)) ||
+         // `this` overloading depending on address space is not ready,
+         // so this is a hack to allow generating addrspacecasts.
+         // IR legalization will be required when this address space is used.
+         (A == LangAS::Default && B == LangAS::hlsl_private) ||
          // Conversions from target specific address spaces may be legal
          // depending on the target information.
          Ctx.getTargetInfo().isAddressSpaceSupersetOf(A, B);

clang/lib/AST/TypePrinter.cpp

@@ -2581,6 +2581,8 @@ std::string Qualifiers::getAddrSpaceAsString(LangAS AS) {
     return "groupshared";
   case LangAS::hlsl_constant:
     return "hlsl_constant";
+  case LangAS::hlsl_private:
+    return "hlsl_private";
   case LangAS::wasm_funcref:
     return "__funcref";
   default:

clang/lib/Basic/TargetInfo.cpp

@@ -47,6 +47,8 @@ static const LangASMap FakeAddrSpaceMap = {
     11, // ptr32_uptr
     12, // ptr64
     13, // hlsl_groupshared
+    14, // hlsl_constant
+    15, // hlsl_private
     20, // wasm_funcref
 };
 

clang/lib/Basic/Targets/AArch64.h

@@ -45,6 +45,7 @@ static const unsigned ARM64AddrSpaceMap[] = {
     static_cast<unsigned>(AArch64AddrSpace::ptr64),
     0, // hlsl_groupshared
     0, // hlsl_constant
+    0, // hlsl_private
     // Wasm address space values for this target are dummy values,
     // as it is only enabled for Wasm targets.
     20, // wasm_funcref

clang/lib/Basic/Targets/AMDGPU.cpp

@@ -60,6 +60,9 @@ const LangASMap AMDGPUTargetInfo::AMDGPUDefIsGenMap = {
     llvm::AMDGPUAS::FLAT_ADDRESS,     // ptr64
     llvm::AMDGPUAS::FLAT_ADDRESS,     // hlsl_groupshared
     llvm::AMDGPUAS::CONSTANT_ADDRESS, // hlsl_constant
+    // FIXME(pr/122103): hlsl_private -> PRIVATE is wrong, but at least this
+    // will break loudly.
+    llvm::AMDGPUAS::PRIVATE_ADDRESS, // hlsl_private
 };
 
 const LangASMap AMDGPUTargetInfo::AMDGPUDefIsPrivMap = {
@@ -85,6 +88,7 @@ const LangASMap AMDGPUTargetInfo::AMDGPUDefIsPrivMap = {
     llvm::AMDGPUAS::FLAT_ADDRESS,     // ptr64
     llvm::AMDGPUAS::FLAT_ADDRESS,     // hlsl_groupshared
     llvm::AMDGPUAS::CONSTANT_ADDRESS, // hlsl_constant
+    llvm::AMDGPUAS::PRIVATE_ADDRESS,  // hlsl_private
 };
 } // namespace targets
 } // namespace clang

clang/lib/Basic/Targets/DirectX.h

@@ -43,6 +43,7 @@ static const unsigned DirectXAddrSpaceMap[] = {
     0, // ptr64
     3, // hlsl_groupshared
     2, // hlsl_constant
+    0, // hlsl_private
     // Wasm address space values for this target are dummy values,
     // as it is only enabled for Wasm targets.
     20, // wasm_funcref

clang/lib/Basic/Targets/NVPTX.h

@@ -47,6 +47,7 @@ static const unsigned NVPTXAddrSpaceMap[] = {
     0, // ptr64
     0, // hlsl_groupshared
     0, // hlsl_constant
+    0, // hlsl_private
     // Wasm address space values for this target are dummy values,
     // as it is only enabled for Wasm targets.
     20, // wasm_funcref