[CodeGen] Fix string literal address space casting.

[hliao]

Summary

• If a string literal is reused directly, need to add necessary address space casting if the target requires that.

[yaxunl]

LGTM. Thanks!

lib/CodeGen/CodeGenModule.cpp

CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S,
 
   llvm::Constant *C = GetConstantArrayFromStringLiteral(S);
   llvm::GlobalVariable **Entry = nullptr;
   if (!LangOpts.WritableStrings) {
     Entry = &ConstantStringMap[C];
     if (auto GV = *Entry) {
       if (Alignment.getQuantity() > GV->getAlignment())
         GV->setAlignment(Alignment.getQuantity());
-      return ConstantAddress(GV, Alignment);
+      return ConstantAddress(castStringLiteralToDefaultAddressSpace(*this, GV),
+                             Alignment);
     }
   }
 
   SmallString<256> MangledNameBuffer;
   StringRef GlobalVariableName;
   llvm::GlobalValue::LinkageTypes LT;
 
   // Mangle the string literal if that's how the ABI merges duplicate strings.
ConstantAddress CodeGenModule::GetAddrOfConstantCString(
 
   // Don't share any string literals if strings aren't constant.
   llvm::GlobalVariable **Entry = nullptr;
   if (!LangOpts.WritableStrings) {
     Entry = &ConstantStringMap[C];
     if (auto GV = *Entry) {
       if (Alignment.getQuantity() > GV->getAlignment())
         GV->setAlignment(Alignment.getQuantity());
-      return ConstantAddress(GV, Alignment);
+      return ConstantAddress(castStringLiteralToDefaultAddressSpace(*this, GV),
+                             Alignment);
     }
   }
 
   // Get the default prefix if a name wasn't specified.
   if (!GlobalName)
     GlobalName = ".str";
   // Create a global variable for this.
   auto GV = GenerateStringLiteral(C, llvm::GlobalValue::PrivateLinkage, *this,

test/CodeGenCXX/amdgcn-string-literal.cpp

 // RUN: %clang_cc1 -triple amdgcn-amd-amdhsa -emit-llvm %s -o - | FileCheck %s
 
 // CHECK: @.str = private unnamed_addr addrspace(4) constant [6 x i8] c"g_str\00", align 1
 // CHECK: @g_str = addrspace(1) global i8* addrspacecast (i8 addrspace(4)* getelementptr inbounds ([6 x i8], [6 x i8] addrspace(4)* @.str, i32 0, i32 0) to i8*), align 8
 // CHECK: @g_array = addrspace(1) global [8 x i8] c"g_array\00", align 1
 // CHECK: @.str.1 = private unnamed_addr addrspace(4) constant [6 x i8] c"l_str\00", align 1
 // CHECK: @__const._Z1fv.l_array = private unnamed_addr addrspace(4) constant [8 x i8] c"l_array\00", align 1
 
 const char* g_str = "g_str";
 char g_array[] = "g_array";
 
 void g(const char* p);
 
 // CHECK-LABEL: define void @_Z1fv()
 void f() {
   const char* l_str = "l_str";
-  
   // CHECK: call void @llvm.memcpy.p0i8.p4i8.i64
   char l_array[] = "l_array";
 
   g(g_str);
   g(g_array);
   g(l_str);
   g(l_array);
 
   const char* p = g_str;
   g(p);
 }
+
+// CHECK-LABEL: define void @_Z1ev
+void e() {
+  g("string literal");
+  g("string literal");
+}