[PATCH] D48419: [OpenCL] Fixed parsing of address spaces for C++

[Yaxun Liu via Phabricator via cfe-commits]

yaxunl added a comment.

In https://reviews.llvm.org/D48419#1139749, @Anastasia wrote:

> In https://reviews.llvm.org/D48419#1139601, @yaxunl wrote:
>
> > Did you notice the bug that C++ silently allows implicit casting of a pointer to a pointer type with different address space?
> >
> > Do you have a fix for that?
>
>
> I didn't think it did because if I run  `test/SemaOpenCL/address-spaces-conversions-cl2.0.cl` in `-cl-std=c++` it gives me errors when I initialize a pointer with different AS pointer:
>
>   error: cannot initialize a variable of type '__global int *' with an lvalue of type '__local int *'
>   error: assigning to '__global int *' from incompatible type '__local int *'
>   error: comparison of distinct pointer types ('__global int *' and '__local int *')
>   
>
> Do you have an example code somewhere?


Actually this only happens when there is an explicit cast:

  $ cat address-space-cast.cpp
  // RUN: %clang_cc1 %s -triple=amdgcn-amd-amdhsa -emit-llvm -o - | FileCheck %s
  
  #define __private__ __attribute__((address_space(5)))
  
  void f(char* q) {
    // CHECK: addrspacecast
    __private__ char* p = (__private__ char*)q;
    //__private__ char* p = q;
  }
  $clang -cc1 -triple=amdgcn-amd-amdhsa address-space-cast.cpp -ast-dump
  TranslationUnitDecl 0x699f418 <<invalid sloc>> <invalid sloc>
  |-TypedefDecl 0x699fab0 <<invalid sloc>> <invalid sloc> implicit __int128_t '__int128'
  | `-BuiltinType 0x699f770 '__int128'
  |-TypedefDecl 0x699fb18 <<invalid sloc>> <invalid sloc> implicit __uint128_t 'unsigned __int128'
  | `-BuiltinType 0x699f790 'unsigned __int128'
  |-TypedefDecl 0x699fe58 <<invalid sloc>> <invalid sloc> implicit __NSConstantString '__NSConstantString_tag'
  | `-RecordType 0x699fc00 '__NSConstantString_tag'
  |   `-CXXRecord 0x699fb68 '__NSConstantString_tag'
  |-TypedefDecl 0x699fef0 <<invalid sloc>> <invalid sloc> implicit __builtin_va_list 'char *'
  | `-PointerType 0x699feb0 'char *'
  |   `-BuiltinType 0x699f4b0 'char'
  `-FunctionDecl 0x69a0020 <address-space-cast.cpp:5:1, line:9:1> line:5:6 f 'void (char *)'
    |-ParmVarDecl 0x699ff58 <col:8, col:14> col:14 used q 'char *'
    `-CompoundStmt 0x69e4130 <col:17, line:9:1>
      `-DeclStmt 0x69e4118 <line:3:21, line:7:45>
        `-VarDecl 0x69e4000 <line:3:21, line:7:44> col:21 p '__attribute__((address_space(5))) char *' cinit
          `-CStyleCastExpr 0x69e40f0 <col:25, col:44> '__attribute__((address_space(5))) char *' <NoOp>
            `-ImplicitCastExpr 0x69e40d8 <col:44> '__attribute__((address_space(5))) char *' <NoOp>
              `-ImplicitCastExpr 0x69e40c0 <col:44> 'char *' <LValueToRValue>
                `-DeclRefExpr 0x69e4080 <col:44> 'char *' lvalue ParmVar 0x699ff58 'q' 'char *'

In the AST there is a CStyleCast and an ImplicitCast, both are NoOp, which will becomes bitcast in codegen and causes invalid bitcast instruction.


https://reviews.llvm.org/D48419