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

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-codegen

Author: Sven van Haastregt (svenvh)

<details>
<summary>Changes</summary>

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.

---
Full diff: https://github.com/llvm/llvm-project/pull/90048.diff


2 Files Affected:

- (modified) clang/lib/CodeGen/CGExprAgg.cpp (+2) 
- (modified) clang/test/CodeGenOpenCLCXX/addrspace-with-class.clcpp (+4-1) 


``````````diff
diff --git a/clang/lib/CodeGen/CGExprAgg.cpp b/clang/lib/CodeGen/CGExprAgg.cpp
index 355fec42be4489..30cde245cc837c 100644
--- a/clang/lib/CodeGen/CGExprAgg.cpp
+++ b/clang/lib/CodeGen/CGExprAgg.cpp
@@ -536,6 +536,8 @@ void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
     CodeGen::CodeGenModule &CGM = CGF.CGM;
     ConstantEmitter Emitter(CGF);
     LangAS AS = ArrayQTy.getAddressSpace();
+    if (CGF.getLangOpts().OpenCL)
+      AS = LangAS::opencl_constant;
     if (llvm::Constant *C =
             Emitter.tryEmitForInitializer(ExprToVisit, AS, ArrayQTy)) {
       auto GV = new llvm::GlobalVariable(
diff --git a/clang/test/CodeGenOpenCLCXX/addrspace-with-class.clcpp b/clang/test/CodeGenOpenCLCXX/addrspace-with-class.clcpp
index 18d97a989a4364..a0ed03b25535c8 100644
--- a/clang/test/CodeGenOpenCLCXX/addrspace-with-class.clcpp
+++ b/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)

``````````

</details>


https://github.com/llvm/llvm-project/pull/90048