[Lldb-commits] [PATCH] D79491: [lldb] Revive TestBasicEntryValuesX86_64

Thu May 7 04:29:21 PDT 2020

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In D79491#2024647 <https://reviews.llvm.org/D79491#2024647>, @djtodoro wrote:

> Thanks a lot for this!
>
> > Nevertheless, I am still interested in making assembly-based tests for this (and similar features) because it enables testing scenarios that we could not get (reliably or at all) a compiler to produce.
>
> I also think this would be more stable if we can make assembler-based tests (but we'll need to address all archs from {x86_64, arm, aarch64}).
>  I am just wondering, what are the obstacles for writing the assembler-based tests? Is it LLDB testing infrastructure or writing tests itself?

A bit of both, maybe. Writing a test which works on a single target (os+arch) was relatively easy (for me, because I've done a lot of this stuff lately, maybe not so easy for others), but the difficulties started when I wanted to make that test run on other oses (which have different asm dialects). I was ok with leaving the test x86-specific, since most developers have an x86 machine and there is nothing arch-specific about this functionality. However, I did not want to restrict the test to any single OS, and since this test requires a running program, the asm needed to match what the host expects.

I did manage to ifdef around the asm platform quirks, but I still haven't managed to get the darwin linker to recognize my hand-written dwarf. I am sure this can be fixed (I think it's  because I reduced the input too much), and I do want to try it out, but I am not sure the result will be something we can recommend as a general practice.

A different way to address this would be to remove the requirement for a running process. The test doesn't really require that, it just needs a relatively complex static snapshot of the process. A core file is just that, but we currently don't have any good way of creating such core files. If we had that, we could run this test over a core file. That would still be platform specific, but then it wouldn't matter (so much) because it wouldn't be tied to the host platform.

Repository:
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https://reviews.llvm.org/D79491