[llvm-dev] Status of debuginfo-tests

[Adrian Prantl via llvm-dev]

> On Sep 7, 2017, at 12:31 PM, Zachary Turner <zturner at google.com> wrote:
> 
> That's true, but it still requires the person writing the test to be familiar with both formats. Also anything more trivial than dumping a single local variable will probably run into even more issues. 
> 
> For example, The expression parsers each have their own unique quirks, and it might not always be easy to translate.

The vocabulary used by the tests is extremely limited, it is basically "b <line>", "r", "p <var>", "c", and twice "ptype" (which I would guess may be hard to support).
Do any of these lack an equivalent under WinDbg?

> 
> Besides all the format compatibility issues, there's the more general issue that massaging one format into another format just introduces another place for things to go wrong and/or be flaky. But as we are the ones that have to do the massaging, we get the short end of the stick.
> 
> One possible bridge is to make some sort of special directive that identifies a certain fragment of the test file as gcc input & checks, and another directive that identifies windbg input & checks.

One way to implement this (especially if it only affects few tests) is to mark the test as unsupported under windows and then have a test script in, e.g., the pdb directory that has a new RUN command and CHECK lines but uses the same source code.
> 
> This way each could have their own native run lines, debugger commands, and check statements, but share the same source code. The runner then chooses which mode to run based on which directives are present and whether a debugger to run the corresponding fragment in is found.

-- adrian
> 
> This way you could have one or both directives in a file, and we'd run whichever version(s) are appropriate 
> On Thu, Sep 7, 2017 at 12:19 PM Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
>> On Sep 7, 2017, at 12:11 PM, Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
>> 
>>> 
>>> On Sep 7, 2017, at 12:01 PM, Zachary Turner <zturner at google.com <mailto:zturner at google.com>> wrote:
>>> 
>>> 
>>> 
>>> On Thu, Sep 7, 2017 at 11:49 AM Adrian Prantl <aprantl at apple.com <mailto:aprantl at apple.com>> wrote:
>>>> On Sep 7, 2017, at 11:37 AM, Zachary Turner via llvm-dev <llvm-dev at lists.llvm.org <mailto:llvm-dev at lists.llvm.org>> wrote:
>>>> 
>>>> To be clear, the tests I'm proposing will have no resemblance whatsoever to GDB, so I would be intentionally forking the set of tests in this regards.  So there would very clearly be a paradigm shift in writing CodeView debug info tests (which would be written in JavaScript using WinDbg specific debugger commands) and DWARF debug info tests (which would be written in whatever / using GDB style commands)
>>> 
>>> That sounds like an unfortunate direction. Can you explain why it wouldn't be possible to write a wrapper (in JavaScript) that interprets the 3ish gdb commands used by the tests in terms of WinDbg? Similar to how LLDB is supported?
>>> 
>>> 
>>> I can think of a couple of reasons:
>>> 
>>> 1) We're already going to need entirely different runlines.  clang and clang-cl don't use the same command line options, or for that matter even styles.
>> 
>> I'm not familiar with clang-cl so please bear with me if this is a stupid question: Is clang-cl just an MSVC compatible driver? Can you not produce the same result by using the "standard" clang driver and a windows target triple?
>> 
>>> 
>>> 2) The output format is going to be different.  whereas the current tests look for things like 
>> 
>> If you are going to write a wrapper script for the debugger commands, that wrapper script could also transform the output to look more like the GDB output that the CHECK-lines are looking for.
>>> 
>>> // CHECK: ${{[0-9]+}} =
>>> // CHECK:  Data ={{.*}} 0x0{{(0*)}}
>>> // CHECK:  Kind = 2142
>>> 
>>> In WinDbg this is going to be more like:
>>> 
>>> Local var @ 0x6ffa50 Type SVal
>>>    +0x000 Data             : (null) 
>>>    +0x004 Kind             : 0x85e
>>> 
> 
> Alternatively, this is still similar enough that we could relax the check to look like
>   CHECK: Data{{.*[:=].*(0x0|.null.)}}
>   CHECK: Kind{{.*[:=].*(2142|0x85e)}}
> without much loss.
> 
> -- adrian
>>> So we're also going to need different check lines.
>>> At this point, the only similarities in the PDB / DWARF tests is going to be the source code, as I don't see an easy way to automatically translate command lines, input commands, and output text.
>> By the way, I'm fine with adding, e.g., a PDB subdirectory with a lit filter that contains tests that will only work under Windows, but it would be very unfortunate if there was no common set of tests, since then the Windows folks wouldn't benefit from new tests being added for GDB and vice versa.
>> 
>> -- adrian
> 

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