[llvm-dev] Status of debuginfo-tests

Zachary Turner via llvm-dev llvm-dev at lists.llvm.org
Thu Sep 7 13:15:54 PDT 2017

I was thinking of something along the lines of:

// SCRIPT-POSIX: posix/aggregate-indirect-arg.s
// SCRIPT-WIN: win/aggregate-indirect-arg.s

class SVal {
  ~SVal() {}
  const void* Data;
  unsigned Kind;

void bar(SVal &v) {}
class A {
  void foo(SVal v) { bar(v); }

int main() {
  SVal v;
  v.Data = 0;
  v.Kind = 2142;
  A a;
  return 0;

Then, you could have:

// posix/aggregate-indirect-arg.s

// RUN: %clangxx %target_itanium_abi_host_triple -O0 -g %i   -c -o %t.o
// RUN: %clangxx %target_itanium_abi_host_triple %t.o -o %t.out
// RUN: %test_debuginfo %s  %t.out
// Radar 8945514
// DEBUGGER: break 22
// DEBUGGER: p v
// CHECK: ${{[0-9]+}} =
// CHECK:  Data ={{.*}} 0x0{{(0*)}}
// CHECK:  Kind = 2142

// win/aggregate-indirect-arg.s

// RUN: %clangcl /Z7 %i /c /Fo%t.obj
// RUN: %lld-link /DEBUG %t.obj /out:%t.lld.exe
// RUN: %run_windbg %t.lld.exe %s
// RUN: %ms-link /DEBUG:FASTLINK %t.obj /out:%t.fastlink.exe
// RUN: %run_windbg %t.fastlink.exe %s
// DEBUGGER: bp 22
// DEBUGGER: dt v
// CHECK: Local var {{.*}} Type SVal
// CHECK:  +0x000 Data : (null)
// CHECK: +0x004 Kind : 0x85e

Eventually, some tests will inevitably need to Windows or Posix specific,
so you're going to have to have all this extra stuff (the new
substitutions, the different command lines, the custom output formats,
etc.  So I think something like this provides maximal encouragement of
sharing whenever possible (since you can almost always share source code),
while still allowing each format to test real input and real output.

In rare cases where command lines, input, and output formats match up, just
replace the SCRIPT-POSIX and SCRIPT-WIN directives with the actual run and
check lines.

On Thu, Sep 7, 2017 at 12:41 PM Adrian Prantl <aprantl at apple.com> wrote:

> 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> wrote:
>> On Sep 7, 2017, at 12:11 PM, Adrian Prantl <aprantl at apple.com> wrote:
>> On Sep 7, 2017, at 12:01 PM, Zachary Turner <zturner at google.com> wrote:
>> On Thu, Sep 7, 2017 at 11:49 AM Adrian Prantl <aprantl at apple.com> wrote:
>>> On Sep 7, 2017, at 11:37 AM, Zachary Turner via llvm-dev <
>>> 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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