shafik marked an inline comment as done.
shafik added inline comments.
================
Comment at: clang/lib/CodeGen/CGDebugInfo.cpp:3659
// Use llvm function name.
- Name = Fn->getName();
+ if (Fn->getName().startswith("___Z"))
+ LinkageName = Fn->getName();
----------------
dblaikie wrote:
> shafik wrote:
> > dblaikie wrote:
> > > shafik wrote:
> > > > dblaikie wrote:
> > > > > aprantl wrote:
> > > > > > aprantl wrote:
> > > > > > > Could you please add a comment that Clang Blocks are generated as
> > > > > > > raw llvm::Functions but do have a mangled name and that is
> > > > > > > handling this case? Otherwise this would look suspicious.
> > > > > > Should *all* raw LLVM functions have their name as the linkage
> > > > > > name? Perhaps a raw LLVM function should only have a linkage name
> > > > > > and no human-readable name?
> > > > > Seems plausible to me - do we have any data on other types of
> > > > > functions that hit this codepath?
> > > > So it was not obvious to me what other cases would this branch so I
> > > > added an assert and ran `check-clang` and from that I saw four cases
> > > > that ended up here:
> > > >
> > > > `GenerateCapturedStmtFunction`
> > > > `GenerateOpenMPCapturedStmtFunction`
> > > > `GenerateBlockFunction`
> > > > `generateDestroyHelper`
> > > >
> > > > It is not obvious to me we want to alter the behavior of any of the
> > > > other cases.
> > > Could you show any small source examples & their corresponding DWARF &
> > > how that DWARF would change? (what names are we using, what names would
> > > we end up using/what sort of things are they naming)
> > Ok, I understand the objections to special casing like this. We ended up
> > setting both the `Name` and `LinkageName` unconditionally in this branch
> > because not setting the name for subroutines end up with us generating
> > `DW_TAG_subprogram` without a `DW_AT_name` which is not valid. We
> > discovered this when running the LLDB test suite.
> If we need to have a name, and these are mangled names - were they mangled
> /from/ something & have an unmangled name we should be using, then?
>
> llvm-cxxfilt demangles the example/test as "invocation function for block in
> f(void (int) block_pointer)" - perhaps we should name this "invocation
> function"? & let the scope of the DIE communicate the rest of the information
> about this thing (like the "operator()" for a lambda is just "operator()")?
If we take the example from the test I added it demangles to:
```
invocation function for block in f(void (int) block_pointer)
```
There is no usable "short" name there, it is a complex description of the block
and what wraps it. In general from the LLDB perspective we would want a name to
set a breakpoint or display it during a back trace. In this case we care about
displaying this properly in a back trace and it would not be reasonable to use
such a name to set a breakpoint.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D73282/new/
https://reviews.llvm.org/D73282
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