Commit Graph

382 Commits

Author SHA1 Message Date
Dehao Chen 6e0c8446db Invoke add-discriminator at -g0 -fsample-profile
Summary: -fsample-profile needs discriminator, which will not be added if built with -g0. This patch makes sure the discriminator is added for sample-profile at -g0. A followup patch will be send out to update clang tests.

Reviewers: davidxl, dblaikie, echristo, dnovillo

Subscribers: mehdi_amini, probinson, llvm-commits

Differential Revision: https://reviews.llvm.org/D25132

llvm-svn: 283565
2016-10-07 15:21:31 +00:00
Peter Collingbourne d4135bbc30 DebugInfo: New metadata representation for global variables.
This patch reverses the edge from DIGlobalVariable to GlobalVariable.
This will allow us to more easily preserve debug info metadata when
manipulating global variables.

Fixes PR30362. A program for upgrading test cases is attached to that
bug.

Differential Revision: http://reviews.llvm.org/D20147

llvm-svn: 281284
2016-09-13 01:12:59 +00:00
David Majnemer 28c3646f82 [COFF, Dwarf] Don't emit DW_AT_location for dllimported entities
There exists no relocation which can describe the address of a
dllimported variable: do not try to describe their location.

llvm-svn: 274986
2016-07-09 20:47:48 +00:00
David Blaikie c53e18d93a DWARF: Omit DW_AT_APPLE attributes (except ObjC ones) when not targeting LLDB
These attributes aren't used by other debuggers (& may be confused with
other DWARF extensions) so they just waste space (about 1.5% on .dwo
file size on a random large program I tested).

We could remove the ObjC property ones too, but I figured they were
probably more necessary when trying to understand ObjC (I could be wrong
though) & so any debugger interested in working with ObjC would use
them, perhaps? (also, there are some legacy tests in Clang that test for
them - making it one of those annoying cross-project commits and/or
cleanup to refactor those tests)

llvm-svn: 270613
2016-05-24 21:19:28 +00:00
Peter Collingbourne 96c9ae6a20 CodeGen: Do not require a MachineFunction just to create a DIEDwarfExpression.
We are about to start using DIEDwarfExpression to create global variable
DIEs, which happens before we generate code for functions.

Differential Revision: http://reviews.llvm.org/D20412

llvm-svn: 270257
2016-05-20 19:35:17 +00:00
Amjad Aboud 72da9391f0 Reverting 268054 & 268063 as they caused PR27579.
llvm-svn: 268150
2016-04-30 01:44:07 +00:00
Amjad Aboud 293ee8bba1 Recommitted r264280 "Supporting all entities declared in lexical scope in LLVM debug info."
After fixing PR26942 in r267004.

llvm-svn: 268054
2016-04-29 16:07:55 +00:00
Paul Robinson 43d1e45347 [DWARF] Force a linkage_name on an inlined subprogram's abstract origin.
When we suppress linkage names, for a non-inlined subprogram the name
can still be found in the object-file symbol table, because we have
the code address of the subprogram.  This is not necessarily the case
for an inlined subprogram, so we still want to emit the linkage name
in the DWARF.  Put this on the abstract-origin DIE because it's common
to all inlined instances.

Differential Revision: http://reviews.llvm.org/D18706

llvm-svn: 266692
2016-04-18 22:41:41 +00:00
Adrian Prantl 3891e9e859 Drop debug info for DISubprograms that are not referenced by anything
This patch drops the debug info for all DISubprograms that are
(a) not attached to an llvm::Function and
(b) not indirectly reachable via inline scopes from any surviving Function and
(c) not reachable from a type (i.e.: member functions).

Background: I'm currently working on a patch to reverse the pointers
between DICompileUnit and DISubprogram (for more info check Duncan's RFC
on lazy-loading of debug info metadata
http://lists.llvm.org/pipermail/llvm-dev/2016-March/097419.html).
The idea is to remove the list of subprograms from DICompileUnit and
instead point to the owning compile unit from each DISubprogram.
After doing this all DISubprograms fulfilling the above criteria will be
implicitly dropped unless we go through an extra effort to preserve them.

http://reviews.llvm.org/D18477
<rdar://problem/25256815>

llvm-svn: 265876
2016-04-09 18:10:22 +00:00
Adrian Prantl b939a25707 Move the DebugEmissionKind enum from DIBuilder into DICompileUnit.
This mostly cosmetic patch moves the DebugEmissionKind enum from DIBuilder
into DICompileUnit. DIBuilder is not the right place for this enum to live
in — a metadata consumer should not have to include DIBuilder.h.
I also added a Verifier check that checks that the emission kind of a
DICompileUnit is actually legal.

http://reviews.llvm.org/D18612
<rdar://problem/25427165>

llvm-svn: 265077
2016-03-31 23:56:58 +00:00
Reid Kleckner 01bc66a8ce Revert "Recommitted r263424 "Supporting all entities declared in lexical scope in LLVM debug info." After fixing PR26942 (the fix is included in this commit)."
This reverts commit r264280.

This broke building Chromium for iOS. We'll upload a reproducer to the
PR soon.

llvm-svn: 264334
2016-03-24 20:38:49 +00:00
Amjad Aboud 6ff7e10052 Recommitted r263424 "Supporting all entities declared in lexical scope in LLVM debug info."
After fixing PR26942 (the fix is included in this commit).

Differential Revision: http://reviews.llvm.org/D18350

llvm-svn: 264280
2016-03-24 13:30:16 +00:00
Benjamin Kramer 1082fa66a5 Revert "Recommitted r261633 "Supporting all entities declared in lexical scope in LLVM debug info." After fixing PR26715 at r263379."
This reverts commit r263424. Breaks self-host.

llvm-svn: 263437
2016-03-14 14:58:36 +00:00
Amjad Aboud ab0378b16c Recommitted r261633 "Supporting all entities declared in lexical scope in LLVM debug info."
After fixing PR26715 at r263379.

llvm-svn: 263424
2016-03-14 12:03:20 +00:00
Hans Wennborg d3661cd140 Revert r261633 "Supporting all entities declared in lexical scope in LLVM debug info."
This and the corresponding Clang change caused PR26715.

llvm-svn: 261671
2016-02-23 19:17:03 +00:00
Amjad Aboud fc8f296782 Supporting all entities declared in lexical scope in LLVM debug info.
Differential Revision: http://reviews.llvm.org/D15976

llvm-svn: 261633
2016-02-23 13:36:51 +00:00
Adrian Prantl 3b89e6634c DwarfDebug: Don't drop the DIExpression just because a variable is
described by an immediate.

Found via http://reviews.llvm.org/D16867
Thanks to Paul Robinson for pointing this out.

<rdar://problem/24456528>

llvm-svn: 261168
2016-02-17 22:20:08 +00:00
Adrian Prantl 6f4746b11a DbgVariable: Add an accessor for the common case of a single expression
belonging to a single DBG_VALUE instruction.

NFC

llvm-svn: 261167
2016-02-17 22:19:59 +00:00
Peter Collingbourne 7c384ccea2 DwarfDebug: emit type units immediately.
Rather than storing type units in a vector and emitting them at the end
of code generation, emit them immediately and destroy them, reclaiming the
memory we were using for their DIEs.

In one benchmark carried out against Chromium's 50 largest (by bitcode
file size) translation units, total peak memory consumption with type units
decreased by median 17%, or by 7% when compared against disabling type units.

Tested using check-{llvm,clang}, the GDB 7.5 test suite (with
'-fdebug-types-section') and by eyeballing llvm-dwarfdump output on those
Chromium translation units with split DWARF both disabled and enabled, and
verifying that the only changes were to addresses and abbreviation ordering.

Differential Revision: http://reviews.llvm.org/D17118

llvm-svn: 260578
2016-02-11 19:57:46 +00:00
Amjad Aboud 8bbce8ad8e Improved macro emission in dwarf.
Changed emitting offset of macinfo entry into compiler unit DIE to use "addSectionLabel" method rather than explicitly calculating size/offset of macro entry.

Differential Revision: http://reviews.llvm.org/D16292

llvm-svn: 259358
2016-02-01 14:09:41 +00:00
Eduard Burtescu 68e7f49f8e [opaque pointer types] [NFC] DataLayout::getIndexedOffset: take source element type instead of pointer type and rename to getIndexedOffsetInType.
Summary:

Reviewers: mjacob, dblaikie

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D16282

llvm-svn: 258478
2016-01-22 03:08:27 +00:00
Manuel Jacob 5f6eaac611 GlobalValue: use getValueType() instead of getType()->getPointerElementType().
Reviewers: mjacob

Subscribers: jholewinski, arsenm, dsanders, dblaikie

Patch by Eduard Burtescu.

Differential Revision: http://reviews.llvm.org/D16260

llvm-svn: 257999
2016-01-16 20:30:46 +00:00
Dehao Chen 54511353e3 clang-format lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
llvm-svn: 252769
2015-11-11 18:09:47 +00:00
Dehao Chen 72fdf444b7 Emit discriminator for inlined callsites.
Summary: Inlined callsites need to be emitted in debug info so that sample profile can be annotated to the correct inlined instance.

Reviewers: dnovillo, dblaikie

Subscribers: dblaikie, llvm-commits

Differential Revision: http://reviews.llvm.org/D14511

llvm-svn: 252768
2015-11-11 18:08:18 +00:00
Ivan Krasin 465fbe25c4 Fix indents. It's a follow up to r251353.
llvm-svn: 251364
2015-10-26 22:35:40 +00:00
Ivan Krasin 298639a5fd Move imported entities into DwarfCompilationUnit to speed up LTO linking.
Summary:
In particular, this CL speeds up the official Chrome linking with LTO by
1.8x.

See more details in https://crbug.com/542426

Reviewers: dblaikie

Subscribers: jevinskie

Differential Revision: http://reviews.llvm.org/D13918

llvm-svn: 251353
2015-10-26 21:36:35 +00:00
Chih-Hung Hsieh 1e859582d6 Implement target independent TLS compatible with glibc's emutls.c.
The 'common' section TLS is not implemented.
Current C/C++ TLS variables are not placed in common section.
DWARF debug info to get the address of TLS variables is not generated yet.

clang and driver changes in http://reviews.llvm.org/D10524

  Added -femulated-tls flag to select the emulated TLS model,
  which will be used for old targets like Android that do not
  support ELF TLS models.

Added TargetLowering::LowerToTLSEmulatedModel as a target-independent
function to convert a SDNode of TLS variable address to a function call
to __emutls_get_address.

Added into lib/Target/*/*ISelLowering.cpp to call LowerToTLSEmulatedModel
for TLSModel::Emulated. Although all targets supporting ELF TLS models are
enhanced, emulated TLS model has been tested only for Android ELF targets.
Modified AsmPrinter.cpp to print the emutls_v.* and emutls_t.* variables for
emulated TLS variables.
Modified DwarfCompileUnit.cpp to skip some DIE for emulated TLS variabls.

TODO: Add proper DIE for emulated TLS variables.
      Added new unit tests with emulated TLS.

Differential Revision: http://reviews.llvm.org/D10522

llvm-svn: 243438
2015-07-28 16:24:05 +00:00
David Blaikie d51dea67b3 Revert "[DWARF] Fix debug info generation for function static variables, typedefs, and records"
Caused PR24008

This reverts commit 37cb5f1c2db9f42d29f26b215585f56bb64ae4f5.

llvm-svn: 241176
2015-07-01 18:07:16 +00:00
Michael Kuperstein 01e8185c31 [DWARF] Fix debug info generation for function static variables, typedefs, and records
Function static variables, typedefs and records (class, struct or union) declared inside
a lexical scope were associated with the function as their parent scope, rather than the
lexical scope they are defined or declared in.

This fixes PR19238

Patch by: amjad.aboud@intel.com
Differential Revision: http://reviews.llvm.org/D9758

llvm-svn: 241153
2015-07-01 12:33:11 +00:00
Adrian Prantl 08a388ba8f Debug info: Add dwarf backend support for DIModule.
rdar://problem/20965932

llvm-svn: 241034
2015-06-30 02:13:04 +00:00
Duncan P. N. Exon Smith 827200c822 AsmPrinter: Use an intrusively linked list for DIE::Children
Replace the `std::vector<>` for `DIE::Children` with an intrusively
linked list.  This is a strict memory improvement: it requires no
auxiliary storage, and reduces `sizeof(DIE)` by one pointer.  It also
factors out the DIE-related malloc traffic.

This drops llc memory usage from 735 MB down to 718 MB, or ~2.3%.

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

llvm-svn: 240736
2015-06-25 23:52:10 +00:00
Duncan P. N. Exon Smith 4fb1f9cda6 AsmPrinter: Convert DIE::Values to a linked list
Change `DIE::Values` to a singly linked list, where each node is
allocated on a `BumpPtrAllocator`.  In order to support `push_back()`,
the list is circular, and points at the tail element instead of the
head.  I abstracted the core list logic out to `IntrusiveBackList` so
that it can be reused for `DIE::Children`, which also cares about
`push_back()`.

This drops llc memory usage from 799 MB down to 735 MB, about 8%.

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

llvm-svn: 240733
2015-06-25 23:46:41 +00:00
Alexander Kornienko f00654e31b Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)
Apparently, the style needs to be agreed upon first.

llvm-svn: 240390
2015-06-23 09:49:53 +00:00
Duncan P. N. Exon Smith e6cc531b1a AsmPrinter: Rewrite initialization of DbgVariable, NFC
There are three types of `DbgVariable`:
  - alloca variables, created based on the MMI table,
  - register variables, created based on DBG_VALUE instructions, and
  - optimized-out variables.

This commit reconfigures `DbgVariable` to make it easier to tell which
kind we have, and make initialization a little clearer.

For MMI/alloca variables, `FrameIndex.size()` must always equal
`Expr.size()`, and there shouldn't be an `MInsn`.  For register
variables (with a `MInsn`), `FrameIndex` must be empty, and `Expr`
should have 0 or 1 element depending on whether it has a complex
expression (registers with multiple locations use `DebugLocListIndex`).
Optimized-out variables shouldn't have any of these fields.

Moreover, this separates DBG_VALUE initialization until after the
variable is created, simplifying logic in a future commit that changes
`collectVariableInfo()` to stop creating empty .debug_loc entries/lists.

llvm-svn: 240243
2015-06-21 16:50:43 +00:00
Alexander Kornienko 70bc5f1398 Fixed/added namespace ending comments using clang-tidy. NFC
The patch is generated using this command:

tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
  -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
  llvm/lib/


Thanks to Eugene Kosov for the original patch!

llvm-svn: 240137
2015-06-19 15:57:42 +00:00
Duncan P. N. Exon Smith b04fb5ed25 AsmPrinter: Rename begin_values() => values_begin(), NFC
llvm-svn: 238456
2015-05-28 18:55:38 +00:00
Duncan P. N. Exon Smith 88a8fc5448 AsmPrinter: Stop exposing underlying DIEValue list, NFC
Change the `DIE` API to hide the implementation of the list of
`DIEValue`s.

llvm-svn: 238369
2015-05-27 22:44:06 +00:00
Duncan P. N. Exon Smith 815a6eb55d AsmPrinter: Store abbreviation data directly in DIE and DIEValue
Stop storing a `DIEAbbrev` in `DIE`, since the data fits neatly inside
the `DIEValue` list.  Besides being a cleaner data structure (avoiding
the parallel arrays), this gives us more freedom to rearrange the
`DIEValue` list.

This fixes the temporary memory regression from 845 MB up to 879 MB, and
drops it further to 829 MB for a net memory decrease of around 1.9%
(incremental decrease around 5.7%).

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

llvm-svn: 238364
2015-05-27 22:31:41 +00:00
Duncan P. N. Exon Smith e7e1d0c706 Reapply "AsmPrinter: Change DIEValue to be stored by value"
This reverts commit r238350, effectively reapplying r238349 after fixing
(all?) the problems, all somehow related to how I was using
`AlignedArrayCharUnion<>` inside `DIEValue`:

  - MSVC can only handle `sizeof()` on types, not values.  Change the
    assert.
  - GCC doesn't know the `is_trivially_copyable` type trait.  Instead of
    asserting it, add destructors.
  - Call placement new even when constructing POD (i.e., the pointers).
  - Instead of copying the char buffer, copy the casted classes.

I've left in a couple of `static_assert`s that I think both MSVC and GCC
know how to handle.  If the bots disagree with me, I'll remove them.

  - Check that the constructed type is either standard layout or a
    pointer.  This protects against a programming error: we really want
    the "small" `DIEValue`s to be small and simple, so don't
    accidentally change them not to be.
  - Similarly, check that the size of the buffer is no bigger than a
    `uint64_t` or a pointer.  (I thought checking against
    `sizeof(uint64_t)` would be good enough, but Chandler suggested that
    pointers might sometimes be bigger than that in the context of
    sanitizers.)

I've also committed r238359 in the meantime, which introduces a
DIEValue.def to simplify dispatching between the various types (thanks
to a review comment by David Blaikie).  Without that, this commit would
be almost unintelligible.

Here's the original commit message:
--
Change `DIEValue` to be stored/passed/etc. by value, instead of
reference.  It's now a discriminated union, with a `Val` field storing
the actual type.  The classes that used to inherit from `DIEValue` no
longer do.  There are two categories of these:

  - Small values fit in a single pointer and are stored by value.
  - Large values require auxiliary storage, and are stored by reference.

The only non-mechanical change is to tools/dsymutil/DwarfLinker.cpp.  It
was relying on `DIEInteger`s being passed around by reference, so I
replaced that assumption with a `PatchLocation` type that stores a safe
reference to where the `DIEInteger` lives instead.

This commit causes a temporary regression in memory usage, since I've
left merging `DIEAbbrevData` into `DIEValue` for a follow-up commit.  I
measured an increase from 845 MB to 879 MB, around 3.9%.  The follow-up
drops it lower than the starting point, and I've only recently brought
the memory this low anyway, so I'm committing these changes separately
to keep them incremental.  (I also considered swapping the commits, but
the other one first would cause a lot more code churn.)

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)
--

llvm-svn: 238362
2015-05-27 22:14:58 +00:00
Duncan P. N. Exon Smith 583bc03829 Revert "AsmPrinter: Change DIEValue to be stored by value"
This reverts commit r238349, since it caused some errors on bots:
  - std::is_trivially_copyable isn't available until GCC 5.0.
  - It was complaining about strict aliasing with my use of
    ArrayCharUnion.

llvm-svn: 238350
2015-05-27 19:30:27 +00:00
Duncan P. N. Exon Smith 7735b48a8b AsmPrinter: Change DIEValue to be stored by value
Change `DIEValue` to be stored/passed/etc. by value, instead of
reference.  It's now a discriminated union, with a `Val` field storing
the actual type.  The classes that used to inherit from `DIEValue` no
longer do.  There are two categories of these:

  - Small values fit in a single pointer and are stored by value.
  - Large values require auxiliary storage, and are stored by reference.

The only non-mechanical change is to tools/dsymutil/DwarfLinker.cpp.  It
was relying on `DIEInteger`s being passed around by reference, so I
replaced that assumption with a `PatchLocation` type that stores a safe
reference to where the `DIEInteger` lives instead.

This commit causes a temporary regression in memory usage, since I've
left merging `DIEAbbrevData` into `DIEValue` for a follow-up commit.  I
measured an increase from 845 MB to 879 MB, around 3.9%.  The follow-up
drops it lower than the starting point, and I've only recently brought
the memory this low anyway, so I'm committing these changes separately
to keep them incremental.  (I also considered swapping the commits, but
the other one first would cause a lot more code churn.)

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

llvm-svn: 238349
2015-05-27 19:22:50 +00:00
Duncan P. N. Exon Smith a9308c49ef 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.

llvm-svn: 236120
2015-04-29 16:38:44 +00:00
Lang Hames 9ff69c8f4d [AsmPrinter] Make AsmPrinter's OutStreamer member a unique_ptr.
AsmPrinter owns the OutStreamer, so an owning pointer makes sense here. Using a
reference for this is crufty.

llvm-svn: 235752
2015-04-24 19:11:51 +00:00
Duncan P. N. Exon Smith aa861aa483 DebugInfo: Remove DIArray and DITypeArray typedefs
Remove the `DIArray` and `DITypeArray` typedefs, preferring the
underlying types (`DebugNodeArray` and `MDTypeRefArray`, respectively).

llvm-svn: 235413
2015-04-21 20:07:38 +00:00
Duncan P. N. Exon Smith 60635e39b6 DebugInfo: Drop rest of DIDescriptor subclasses
Delete the remaining subclasses of (the already deleted) `DIDescriptor`.
Part of PR23080.

llvm-svn: 235404
2015-04-21 18:44:06 +00:00
Duncan P. N. Exon Smith 2fbe13540a DebugInfo: Delete subclasses of DIScope
Delete subclasses of (the already defunct) `DIScope`, updating users to
use the raw pointers from the `Metadata` hierarchy directly.

llvm-svn: 235356
2015-04-20 22:10:08 +00:00
Duncan P. N. Exon Smith be9e4fe768 DebugInfo: Remove DIScope
Replace uses of `DIScope` with `MDScope*`.  There was one spot where
I've left an `MDScope*` uninitialized (where `DIScope` would have been
default-initialized to `nullptr`) -- this is intentional, since the
if/else that follows should unconditional assign it to a value.

llvm-svn: 235327
2015-04-20 18:32:29 +00:00
Duncan P. N. Exon Smith 7c60f20e49 DebugInfo: Delete DIDescriptor (but not its subclasses)
Delete `DIDescriptor` and update the remaining users.  I'll follow-up by
deleting subclasses in manageable groups (top-down).

llvm-svn: 235248
2015-04-18 00:35:36 +00:00
Duncan P. N. Exon Smith 364a3005f2 AsmPrinter: Create a unified .debug_loc stream
This commit removes `DebugLocList` and replaces it with
`DebugLocStream`.

  - `DebugLocEntry` no longer contains its byte/comment streams.
  - The `DebugLocEntry` list for a variable/inlined-at pair is allocated
    on the stack, and released right after `DebugLocEntry::finalize()`
    (possible because of the refactoring in r231023).  Now, only one
    list is in memory at a time now.
  - There's a single unified stream for the `.debug_loc` section that
    persists, stored in the new `DebugLocStream` data structure.

The last point is important: this collapses the nested `SmallVector<>`s
from `DebugLocList` into unified streams.  We previously had something
like the following:

    vec<tuple<Label, CU,
              vec<tuple<BeginSym, EndSym,
                        vec<Value>,
                        vec<char>,
                        vec<string>>>>>

A `SmallVector` can avoid allocations, but is statically fairly large
for a vector: three pointers plus the size of the small storage, which
is the number of elements in small mode times the element size).
Nesting these is expensive, since an inner vector's size contributes to
the element size of an outer one.  (Nesting any vector is expensive...)

In the old data structure, the outer vector's *element* size was 632B,
excluding allocation costs for when the middle and inner vectors
exceeded their small sizes.  312B of this was for the "three" pointers
in the vector-tree beneath it.  If you assume 1M functions with an
average of 10 variable/inlined-at pairs each (in an LTO scenario),
that's almost 6GB (besides inner allocations), with almost 3GB for the
"three" pointers.

This came up in a heap profile a little while ago of a `clang -flto -g`
bootstrap, with `DwarfDebug::collectVariableInfo()` using something like
10-15% of the total memory.

With this commit, we have:

    tuple<vec<tuple<Label, CU, Offset>>,
          vec<tuple<BeginSym, EndSym, Offset, Offset>>,
          vec<char>,
          vec<string>>

The offsets are used to create `ArrayRef` slices of adjacent
`SmallVector`s.  This reduces the number of vectors to four (unrelated
to the number of variable/inlined-at pairs), and caps the number of
allocations at the same number.

Besides saving memory and limiting allocations, this is NFC.

I don't know my way around this code very well yet, but I wonder if we
could go further: why stream to a side-table, instead of directly to the
output stream?

llvm-svn: 235229
2015-04-17 21:34:47 +00:00
Duncan P. N. Exon Smith b105564015 DebugInfo: Gut DIType and subclasses
Continuing PR23080, gut `DIType` and its various subclasses, leaving
behind thin wrappers around the pointer types in the new debug info
hierarchy.

llvm-svn: 235064
2015-04-16 01:01:28 +00:00