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Trait object debug #45897

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merged 2 commits into from
Nov 17, 2017
Merged

Trait object debug #45897

merged 2 commits into from
Nov 17, 2017

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tromey
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@tromey tromey commented Nov 9, 2017

This enables better debugging of trait objects. See the individual commits for explanations. This required an LLVM bump.

@kennytm kennytm added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Nov 10, 2017
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bors commented Nov 11, 2017

☔ The latest upstream changes (presumably #45806) made this pull request unmergeable. Please resolve the merge conflicts.

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r? @michaelwoerister

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michaelwoerister approved these changes Nov 13, 2017
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Looks good to me, thanks @tromey!

@tromey tromey force-pushed the trait-object-debug branch 2 times, most recently from 8c9a797 to ab4da8c Compare November 13, 2017 19:11
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tromey commented Nov 14, 2017

So far I haven't managed to reproduce that failure.

@kennytm kennytm added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 14, 2017
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tromey commented Nov 14, 2017

My current theory is that this is failing due to an unmodified LLVM; and so the patch will need some tweaks.

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tromey commented Nov 14, 2017

Looking at the patches, I still don't see how that would be possible, but I'm rebuilding without the LLVM patch to be sure.

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tromey commented Nov 14, 2017

I rebuilt without the LLVM bump and didn't see this failure. Now I don't have a theory about what is going wrong. Maybe I need to build specifically against whatever LLVM travis is using.

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cuviper commented Nov 14, 2017

The first CI run uses Ubuntu's llvm-3.9. The rest should use rust's own llvm.

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tromey commented Nov 15, 2017

The first CI run uses Ubuntu's llvm-3.9

Thanks. I got it to fail with my system llvm.

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tromey commented Nov 15, 2017

The bug is that the patch is passing in NULL for the linkage name of the vtable.

@tromey
Allow minimum system LLVM version in tests
a512228 
This adds a "min-system-llvm-version" directive, so that a test can
indicate that it will either work with rust-llvm or with some minimal
system LLVM.  This makes it simpler to write a test that requires an
LLVM patch that landed upstream and was then backported to rust-llvm.
@tromey
Emit debug info for trait object pointer
ae4cc60 
Emit better debugging information for a trait object pointer.  In
particular, now:

* The fields are explicitly represented in the DWARF;
* DWARF for the vtable itself is emitted; and
* The DWARF for the vtable's type has a DW_AT_containing_type which
  points to the concrete type for which the vtable was emitted.  This is
  a small DWARF extension, that allows debuggers to determine the real
  type of the object to which a trait object points.

I'll submit the gdb patch to take advantage of this new debuginfo once
this lands.

The vtable type is not currently complete -- it doesn't include members
for the pointers it contains.  This information was not needed for this
feature.

This addresses part 1 of rust-lang#1563.
@tromey tromey force-pushed the trait-object-debug branch from ab4da8c to ae4cc60 Compare November 15, 2017 08:48
@kennytm kennytm added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Nov 15, 2017
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kennytm commented Nov 15, 2017

@tromey I think this is ready to be reviewed or merged? cc @michaelwoerister

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tromey commented Nov 15, 2017

@kennytm yes - it was reviewed once, then I made a small change to address the test failures. A re-review would be good.

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@bors r+

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bors commented Nov 16, 2017

📌 Commit ae4cc60 has been approved by michaelwoerister

@kennytm kennytm added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 16, 2017
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bors commented Nov 16, 2017

⌛ Testing commit ae4cc60 with merge d59f66d...

bors added a commit that referenced this pull request Nov 16, 2017
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Auto merge of #45897 - tromey:trait-object-debug, r=michaelwoerister
d59f66d 
Trait object debug

This enables better debugging of trait objects.  See the individual commits for explanations.  This required an LLVM bump.
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bors commented Nov 17, 2017

☀️ Test successful - status-appveyor, status-travis
Approved by: michaelwoerister
Pushing d59f66d to master...

@bors bors merged commit ae4cc60 into rust-lang:master Nov 17, 2017
@bors bors mentioned this pull request Nov 17, 2017
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@tromey tromey deleted the trait-object-debug branch November 17, 2017 05:34
@cuviper cuviper mentioned this pull request Jun 29, 2018
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