[all-commits] [llvm/llvm-project] 80a9fc: [clang][Sema] Fix a clang crash with btf_type_tag

[yonghong-song via All-commits]

  Branch: refs/heads/release/15.x
  Home:   https://github.com/llvm/llvm-project
  Commit: 80a9fc840b1b0c5bdd6509578283af3b02782d48
      https://github.com/llvm/llvm-project/commit/80a9fc840b1b0c5bdd6509578283af3b02782d48
  Author: Yonghong Song <yhs at fb.com>
  Date:   2022-11-01 (Tue, 01 Nov 2022)

  Changed paths:
    M clang/docs/ReleaseNotes.rst
    M clang/lib/Sema/SemaType.cpp
    A clang/test/CodeGen/attr-btf_type_tag-func-ptr.c

  Log Message:
  -----------
  [clang][Sema] Fix a clang crash with btf_type_tag

For the following program,
  $ cat t.c
  struct t {
   int (__attribute__((btf_type_tag("rcu"))) *f)();
   int a;
  };
  int foo(struct t *arg) {
    return arg->a;
  }
Compiling with 'clang -g -O2 -S t.c' will cause a failure like below:
  clang: /home/yhs/work/llvm-project/clang/lib/Sema/SemaType.cpp:6391: void {anonymous}::DeclaratorLocFiller::VisitParenTypeLoc(clang::ParenTypeLoc):
         Assertion `Chunk.Kind == DeclaratorChunk::Paren' failed.
  PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
  Stack dump:
  ......
  #5 0x00007f89e4280ea5 abort (/lib64/libc.so.6+0x21ea5)
  #6 0x00007f89e4280d79 _nl_load_domain.cold.0 (/lib64/libc.so.6+0x21d79)
  #7 0x00007f89e42a6456 (/lib64/libc.so.6+0x47456)
  #8 0x00000000045c2596 GetTypeSourceInfoForDeclarator((anonymous namespace)::TypeProcessingState&, clang::QualType, clang::TypeSourceInfo*) SemaType.cpp:0:0
  #9 0x00000000045ccfa5 GetFullTypeForDeclarator((anonymous namespace)::TypeProcessingState&, clang::QualType, clang::TypeSourceInfo*) SemaType.cpp:0:0
  ......

The reason of the failure is due to the mismatch of TypeLoc and D.getTypeObject().Kind. For example,
the TypeLoc is
  BTFTagAttributedType 0x88614e0 'int  btf_type_tag(rcu)()' sugar
  |-ParenType 0x8861480 'int ()' sugar
  | `-FunctionNoProtoType 0x8861450 'int ()' cdecl
  |   `-BuiltinType 0x87fd500 'int'
while corresponding D.getTypeObject().Kind points to DeclaratorChunk::Paren, and
this will cause later assertion.

To fix the issue, similar to AttributedTypeLoc, let us skip BTFTagAttributedTypeLoc in
GetTypeSourceInfoForDeclarator().

Differential Revision: https://reviews.llvm.org/D136807