[clang][CodeGen] Put constant initializer globals into constant addrspace (#90048)

Place constant initializer globals into the constant address space.
Clang generates such globals for e.g. larger array member initializers
of classes and then emits copy operations from the global to the
object(s). The globals are never written so they ought to be in the
constant address space.

Author: svenvh

clang/lib/CodeGen/CGExprAgg.cpp

@@ -537,20 +537,23 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
       elementType.isTriviallyCopyableType(CGF.getContext())) {
     CodeGen::CodeGenModule &CGM = CGF.CGM;
     ConstantEmitter Emitter(CGF);
-    LangAS AS = ArrayQTy.getAddressSpace();
+    QualType GVArrayQTy = CGM.getContext().getAddrSpaceQualType(
+        CGM.getContext().removeAddrSpaceQualType(ArrayQTy),
+        CGM.GetGlobalConstantAddressSpace());
+    LangAS AS = GVArrayQTy.getAddressSpace();
     if (llvm::Constant *C =
-            Emitter.tryEmitForInitializer(ExprToVisit, AS, ArrayQTy)) {
+            Emitter.tryEmitForInitializer(ExprToVisit, AS, GVArrayQTy)) {
       auto GV = new llvm::GlobalVariable(
           CGM.getModule(), C->getType(),
           /* isConstant= */ true, llvm::GlobalValue::PrivateLinkage, C,
           "constinit",
           /* InsertBefore= */ nullptr, llvm::GlobalVariable::NotThreadLocal,
           CGM.getContext().getTargetAddressSpace(AS));
       Emitter.finalize(GV);
-      CharUnits Align = CGM.getContext().getTypeAlignInChars(ArrayQTy);
+      CharUnits Align = CGM.getContext().getTypeAlignInChars(GVArrayQTy);
       GV->setAlignment(Align.getAsAlign());
       Address GVAddr(GV, GV->getValueType(), Align);
-      EmitFinalDestCopy(ArrayQTy, CGF.MakeAddrLValue(GVAddr, ArrayQTy));
+      EmitFinalDestCopy(ArrayQTy, CGF.MakeAddrLValue(GVAddr, GVArrayQTy));
       return;
     }
   }

clang/test/CodeGenOpenCLCXX/addrspace-with-class.clcpp

@@ -5,7 +5,7 @@
 // for constructors, member functions and destructors.
 // See also atexit.cl and global_init.cl for other specific tests.
 
-// CHECK: %struct.MyType = type { i32 }
+// CHECK: %struct.MyType = type { i32, [5 x i32] }
 struct MyType {
   MyType(int i) : i(i) {}
   MyType(int i) __constant : i(i) {}
@@ -14,6 +14,7 @@ struct MyType {
   int bar() { return i + 2; }
   int bar() __constant { return i + 1; }
   int i;
+  int a[5] = {42, 43, 44, 45, 46};
 };
 
 // CHECK: @const1 ={{.*}} addrspace(2) global %struct.MyType zeroinitializer
@@ -23,6 +24,8 @@ __constant MyType const2(2);
 // CHECK: @glob ={{.*}} addrspace(1) global %struct.MyType zeroinitializer
 MyType glob(1);
 
+// CHECK: @constinit ={{.*}} addrspace(2) constant [5 x i32] [i32 42, i32 43, i32 44, i32 45, i32 46]
+
 // CHECK: call spir_func void @_ZNU3AS26MyTypeC1Ei(ptr addrspace(2) {{[^,]*}} @const1, i32 noundef 1)
 // CHECK: call spir_func void @_ZNU3AS26MyTypeC1Ei(ptr addrspace(2) {{[^,]*}} @const2, i32 noundef 2)
 // CHECK: call spir_func void @_ZNU3AS46MyTypeC1Ei(ptr addrspace(4) {{[^,]*}} addrspacecast (ptr addrspace(1) @glob to ptr addrspace(4)), i32 noundef 1)