[lldb-dev] [Bug 26790] New: IRForTarget

via lldb-dev lldb-dev at lists.llvm.org
Tue Mar 1 11:02:22 PST 2016


https://llvm.org/bugs/show_bug.cgi?id=26790

            Bug ID: 26790
           Summary: IRForTarget
           Product: lldb
           Version: unspecified
          Hardware: PC
                OS: All
            Status: NEW
          Severity: release blocker
          Priority: P
         Component: All Bugs
          Assignee: lldb-dev at lists.llvm.org
          Reporter: luke.drummond at codeplay.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

It looks like the recent changes committed in r260768 have caused regressions
when trying to call functions that take any arguments whose typename is the
result of a `typedef` involving untagged struct types.

e.g

```c++
typedef {
    float f;
    int i;
} mystruct;

mystruct s;
void somefunc(mystruct *s){}


int $__lldb_expr()
{
    ;
    somefunc(&s);
}
```

lldb versions previous to r260768 resolved the anonymous struct without a
problem, though r260768 and later fail to match the function instead failing
with the following error:

> "error: Couldn't lookup symbols:
>    multiply($_0*)
.

It seems that calling functions through pointers returned by
`IRForTarget::ResolveFunctionPointers` has been removed in favor of direct
calls through the function by name. That function previously called
IRForTarget::GetFunctionAddress` to resolve a function, and seems to have had
more robust lookups for matching functions did symbol/type resolution through.

I've attached a diff for a failing testcase, that I think would be helpful to
catch this regression in future. I haven't committed this test to the lldb
source tree yet, as I understand this may unduly upset the buildbots.

Apologies for the delay here, but it was a few days after this change went in
that we got this change locally.

Let me know if there's anything I can do to help test this, as I'm keen to get
this resolved as soon as possible - therwise it seems like the best course of
action is to revert r260768 as it seems there might still be some teething
problems with this commit (https://llvm.org/bugs/show_bug.cgi?id=26694

FindCodeSymbolInContext

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