[Lldb-commits] [PATCH] D110571: [lldb] Add omitted abstract formal parameters in DWARF symbol files

[David Blaikie via Phabricator via lldb-commits]

dblaikie added a comment.

>> - We could supply a test written in C, but it needs -O1 and is fairly sensitive to the meaning of -O1 (e.g., clang started inlining and omitting unsued inlined parameters only recently, so changes to -O1 could make a C test easily meaningless). Any concerns here?
>
> It is really hard to make sure the compiler generates what you want for a test case as it will change over time and you might not end up testing what you think you are testing. The easiest way to avoid this is to emit the assembly from the compiler and then use that as the source for the test since that will guarantee the same output.

If anyone ever needs a hand constructing a stable debug info test case using clang (or other compilers for that matter) - I'm totally happy to help. It's quite possible to constrain the compiler enough and give it easy enough things to inline to make it pretty reliable - for instance for this sort of issue, I'd expect something like this is what I'd use to demonstrate a missing parameter:

  __attribute__((optnone)) __attribute__((nodebug)) void use(int*) { }
  inline void f1(int a, int b) {
    use(&b);
  }
  int main() {
    f1(5,  6);
  }

This compiled with some optimizations (-O1 or above should be adequate) should result in a single concrete subprogram for main, a single inlined subroutine with a single formal parameter in the inlined subroutine (for 'b') and the abstract origin will have both 'a' and 'b'.


Repository:
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  https://reviews.llvm.org/D110571/new/

https://reviews.llvm.org/D110571