Commit Graph

6 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith
e56023a059 IR: Give 'DI' prefix to debug info metadata
Finish off PR23080 by renaming the debug info IR constructs from `MD*`
to `DI*`.  The last of the `DIDescriptor` classes were deleted in
r235356, and the last of the related typedefs removed in r235413, so
this has all baked for about a week.

Note: If you have out-of-tree code (like a frontend), I recommend that
you get everything compiling and tests passing with the *previous*
commit before updating to this one.  It'll be easier to keep track of
what code is using the `DIDescriptor` hierarchy and what you've already
updated, and I think you're extremely unlikely to insert bugs.  YMMV of
course.

Back to *this* commit: I did this using the rename-md-di-nodes.sh
upgrade script I've attached to PR23080 (both code and testcases) and
filtered through clang-format-diff.py.  I edited the tests for
test/Assembler/invalid-generic-debug-node-*.ll by hand since the columns
were off-by-three.  It should work on your out-of-tree testcases (and
code, if you've followed the advice in the previous paragraph).

Some of the tests are in badly named files now (e.g.,
test/Assembler/invalid-mdcompositetype-missing-tag.ll should be
'dicompositetype'); I'll come back and move the files in a follow-up
commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236120 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-29 16:38:44 +00:00
Duncan P. N. Exon Smith
387a89bb36 Reapply "Linker: Drop function pointers for overridden subprograms"
This reverts commit r233254, effectively reapplying r233164 (and its
successors), with an additional testcase for when subprograms match
exactly.  This fixes PR22792 (again).

I'm using the same approach, but I've moved up the call to
`stripReplacedSubprograms()`.  The function pointers need to be dropped
before mapping any metadata from the source module, or else this can
drop the function from new subprograms that have merged (via Metadata
uniquing) with the old ones.  Dropping the pointers first prevents them
from merging.

**** The original commit message follows. ****

Linker: Drop function pointers for overridden subprograms

Instead of dropping subprograms that have been overridden, just set
their function pointers to `nullptr`.  This is a minor adjustment to the
stop-gap fix for PR21910 committed in r224487, and fixes the crasher
from PR22792.

The problem that r224487 put a band-aid on: how do we find the canonical
subprogram for a `Function`?  Since the backend currently relies on
`DebugInfoFinder` (which does a naive in-order traversal of compile
units and picks the first subprogram) for this, r224487 tried dropping
non-canonical subprograms.

Dropping subprograms fails because the backend *also* builds up a map
from subprogram to compile unit (`DwarfDebug::SPMap`) based on the
subprogram lists.  A missing subprogram causes segfaults later when an
inlined reference (such as in this testcase) is created.

Instead, just drop the `Function` pointer to `nullptr`, which nicely
mirrors what happens when an already-inlined `Function` is optimized
out.  We can't really be sure that it's the same definition anyway, as
the testcase demonstrates.

This still isn't completely satisfactory.  Two flaws at least that I can
think of:

  - I still haven't found a straightforward way to make this symmetric
    in the IR.  (Interestingly, the DWARF output is already symmetric,
    and I've tested for that to be sure we don't regress.)
  - Using `DebugInfoFinder` to find the canonical subprogram for a
    function is kind of crazy.  We should just attach metadata to the
    function, like this:

        define weak i32 @foo(i32, i32) !dbg !MDSubprogram(...) {

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233302 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-26 18:35:30 +00:00
Duncan P. N. Exon Smith
a977f7e771 Revert "Linker: Drop function pointers for overridden subprograms"
This reverts commit r233164 and its testcase follow-ups in r233165,
r233207, r233214, and r233221.  It apparently unleashed an LTO bootstrap
failure, at least on Darwin:

http://lab.llvm.org:8080/green/job/clang-stage2-configure-Rlto_build/3376/

I'm reproducing now.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233254 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-26 05:27:45 +00:00
Duncan P. N. Exon Smith
00aafa5d73 Linker: Stop using -gmlt test/Linker/subprogram-linkonce-weak.ll
As dblaikie pointed out, if I stop setting `emissionKind: 2` then the
backend won't do magical things on Linux vs. Darwin.  I had wrongly
assumed that there were stricter requirements on the input if we weren't
in line-tables-only mode, but apparently not.

With that knowledge, clean up this testcase a little more.

  - Set `emissionKind: 1`.
  - Add back checks for the weak version of @foo.
  - Check more robustly that we have the right subprograms by checking
    the `DW_AT_decl_file` and `DW_AT_decl_line` which now show up.
  - Check the line table in isolation (since it's no longer doubling as
    an indirect test for the subprogram of the weak version of @foo).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233221 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-25 21:36:41 +00:00
Duncan P. N. Exon Smith
151bc36220 Linker: Rewrite dwarfdump checks from r233164
Rewrite the checks from r233164 that I temporarily disabled in r233165.

It turns out that the line-tables only debug info we emit from `llc` is
(intentionally) different on Linux than on Darwin.  r218129 started
skipping emission of subprograms with no inlined subroutines, and
r218702 was a spiritual revert of that behaviour for Darwin.

I think we can still test this in a platform-neutral way.

  - Stop checking for the possibly missing `DW_TAG_subprogram` defining
    the debug info for the real version of `@foo`.
  - Start checking the line tables, ensuring that the right debug info
    was used to generate them (grabbing `DW_AT_low_pc` from the compile
    unit).
  - I changed up the line numbers used in the "weak" version so it's
    easier to follow.

This should hopefully finish off PR22792.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233207 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-25 19:57:42 +00:00
Duncan P. N. Exon Smith
c89369a941 Linker: Drop function pointers for overridden subprograms
Instead of dropping subprograms that have been overridden, just set
their function pointers to `nullptr`.  This is a minor adjustment to the
stop-gap fix for PR21910 committed in r224487, and fixes the crasher
from PR22792.

The problem that r224487 put a band-aid on: how do we find the canonical
subprogram for a `Function`?  Since the backend currently relies on
`DebugInfoFinder` (which does a naive in-order traversal of compile
units and picks the first subprogram) for this, r224487 tried dropping
non-canonical subprograms.

Dropping subprograms fails because the backend *also* builds up a map
from subprogram to compile unit (`DwarfDebug::SPMap`) based on the
subprogram lists.  A missing subprogram causes segfaults later when an
inlined reference (such as in this testcase) is created.

Instead, just drop the `Function` pointer to `nullptr`, which nicely
mirrors what happens when an already-inlined `Function` is optimized
out.  We can't really be sure that it's the same definition anyway, as
the testcase demonstrates.

This still isn't completely satisfactory.  Two flaws at least that I can
think of:

  - I still haven't found a straightforward way to make this symmetric
    in the IR.  (Interestingly, the DWARF output is already symmetric,
    and I've tested for that to be sure we don't regress.)
  - Using `DebugInfoFinder` to find the canonical subprogram for a
    function is kind of crazy.  We should just attach metadata to the
    function, like this:

        define weak i32 @foo(i32, i32) !dbg !MDSubprogram(...) {

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233164 91177308-0d34-0410-b5e6-96231b3b80d8
2015-03-25 02:26:32 +00:00