[LLVMdev] Problem with InsertPointGuard ABI?

[Paweł Bylica]

Hi,

I have problem with IRBuilderBase::InsertPointGuard class that simply does
not work in the release build of my project. The class does not restore the
IRBuilder's insert point correctly when NDEBUG macro is set. It happens on
OSX system only, trunk version of the LLVM built with brew.

I suspect it is the ABI problem. InsertPointGuard uses AssertingVT for
debug builds.

LLDB gets confused also. The first listing shows that the instance of
InsertPointGuard is messed up:

   96   auto check = _builder.GetInsertBlock();
   97   {
   98   llvm::IRBuilderBase::InsertPointGuard guard{_builder};
-> 99   _builder.SetInsertPoint(checkBB);
   100 }
   101
   102 if (_builder.GetInsertBlock() != check)
(lldb) p _builder
(llvm::IRBuilder<true, llvm::ConstantFolder,
llvm::IRBuilderDefaultInserter<true> >) $4 = {
  llvm::IRBuilderBase = {
    CurDbgLocation = {
      Loc = {
        Ref = {
          MD = 0x0000000000000000
        }
      }
    }
    BB = 0x000000010642ecf0
    InsertPt = {
      NodePtr = 0x000000010642ed00
    }
    Context = 0x000000010642d170
    DefaultFPMathTag = 0x0000000000000000
    FMF = (Flags = 0)
  }
  Folder = {}
}
(lldb) p guard
(llvm::IRBuilderBase::InsertPointGuard) $5 = {
  Builder = 0x00007fff5fbf46d8
  Block = {
    ThePtr = 0x0000000107800398
  }
  Point = {
    NodePtr = 0x0000000000000000
  }
  DbgLoc = {
    Loc = {
      Ref = {
        MD = 0x000000010642ecf0
      }
    }
  }
}

Moreover, if I start printing the guard from InsertPointGuard constructor
it shows different data layout. LLDB also crashes after step out and
printing the guard again.

   195   public:
   196     InsertPointGuard(IRBuilderBase &B)
   197         : Builder(B), Block(B.GetInsertBlock()),
Point(B.GetInsertPoint()),
-> 198           DbgLoc(B.getCurrentDebugLocation()) {}
   199
   200     ~InsertPointGuard() {
   201       Builder.restoreIP(InsertPoint(Block, Point));
(lldb) p *this
(llvm::IRBuilderBase::InsertPointGuard) $6 = {
  Builder = 0x00007fff5fbf4440
  Block = {
    llvm::ValueHandleBase = {
      PrevPair = (Value = 4337803886)
      Next = 0x000000010615b0a8
      V = 0x000000010615b170
    }
  }
  Point = {
    NodePtr = 0x000000010615b140
  }
  DbgLoc = {
    Loc = {
      Ref = {
        MD = 0x000000010324444b
      }
    }
  }
}
(lldb) n
Process 1498 stopped
* thread #1: tid = 0x493aa8, 0x0000000102920b22
libevmjit.0.0.dylib`dev::eth::jit::test(_builder=0x00007fff5fbf46d8) + 258
at RuntimeManager.cpp:99, queue = 'com.apple.main-thread', stop reason =
step over
    frame #0: 0x0000000102920b22
libevmjit.0.0.dylib`dev::eth::jit::test(_builder=0x00007fff5fbf46d8) + 258
at RuntimeManager.cpp:99
   96   auto check = _builder.GetInsertBlock();
   97   {
   98   llvm::IRBuilderBase::InsertPointGuard guard{_builder};
-> 99   _builder.SetInsertPoint(checkBB);
   100 }
   101
   102 if (_builder.GetInsertBlock() != check)
(lldb) p guard
Assertion failed: (field_idx < record_layout.getFieldCount()), function
GetChildClangTypeAtIndex, file
/SourceCache/lldb/lldb-320.4.156/source/Symbol/ClangASTType.cpp, line 6615.
Abort trap: 6

It's hard to create a small executable where the problem can be reproduced.

Cheers,
- Paweł Bylica
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