[Lldb-commits] [PATCH] D113163: [LLDB][Breakpad] Create a function for each compilation unit.

[Zequan Wu via Phabricator via lldb-commits]

zequanwu added inline comments.


================
Comment at: lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp:388-392
   for (llvm::StringRef line : lines(Record::Func)) {
     if (auto record = FuncRecord::parse(line))
       add_symbol(record->Address, record->Size, record->Name);
   }
 
----------------
labath wrote:
> zequanwu wrote:
> > zequanwu wrote:
> > > labath wrote:
> > > > zequanwu wrote:
> > > > > labath wrote:
> > > > > > Can you check if we can remove this now?
> > > > > > 
> > > > > > I originally thought that we can remove this entire function, but I forgot about PUBLIC records -- we don't have functions or compile units for those, so they will have to stay.
> > > > > Removing it causes FUNC records not showing up in symtab when doing `image dump symtab ...` and fails some tests.
> > > > > The Breakpad doc says (https://chromium.googlesource.com/breakpad/breakpad/+/HEAD/docs/symbol_files.md#records-4):
> > > > > 
> > > > > > If a given address is covered by both a PUBLIC record and a FUNC record, the processor uses the FUNC data.
> > > > > 
> > > > It's expected that the tests verifying symtab contents need updating after you remove some things from it. It's also possible some other tests will need minor tweaks (like the one in `line-table.test:54`) because of small differences in output format.
> > > > 
> > > > Whether this is a reasonable change cannot be judged by failing tests alone. You also need to evaluate the overall quality of the debugger output. That will have to be a judgement call, but I'm hoping it won't be a hard one. For example, the change in line-table.test was definitely for the better.
> > > > 
> > > > >> If a given address is covered by both a PUBLIC record and a FUNC record, the processor uses the FUNC data.
> > > > 
> > > > And if an address is covered both by a Symtab Symbol, and an SymbolFile Function, lldb will preferentially (in backtraces, for instance) display information from the Function, so I think (hope) that this is going to work exactly as desired.
> > > These two commands `image lookup -n ...` and `image show-unwind -n ..` also failed to give any information if the name is from FUNC records.
> > Oh, maybe those commands use `FindFunctions` to lookup for function by name?
> Yes, that will most likely be it.
> 
> If implementing FindFunctions ends up being non-trivial, we can do that (along with the symtab removal) in a separate patch.
After implementing `FindFunctions` and removing this, `image lookup -a 0x4000b0 -v` in (lldb/test/Shell/SymbolFile/Breakpad/symtab.test) shows:
```
Function: id = {0x00000001}, name = "f1_func", range = [0x00000000004000b0-0x00000000004000bc)
       Symbol: id = {0x00000000}, range = [0x00000000004000b0-0x00000000004000c0), name="f1"
```
The symbol name is different from function because symbol name is from symtab and function name is from function in CU.

And `image lookup -n f1` and `image lookup -n f1_func` both give:
```
        Address: symtab.out[0x00000000004000b0] (symtab.out.PT_LOAD[0]..text2 + 0)
        Summary: symtab.out`f1_func
```

Looks like we don't want to remove this part.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D113163/new/

https://reviews.llvm.org/D113163