34826 Commits

Author SHA1 Message Date
Daniel Sanders
3d06a1da65 [tablegen] Improve performance of -gen-register-info by replacing barely-necessary std::map with a sorted vector
Summary:
This particular map is hardly ever queried and has a phased usage pattern (insert,
iterate, query, insert, iterate) so it's a good candidate for a sorted vector and
std::lower_bound.

This significantly reduces the run time of runTargetDesc() in some circumstances.
One llvm-tblgen invocation in my build improves the time spent in runTargetDesc()
from 9.86s down to 0.80s (~92%) without changing the output. The same invocation
also has 2GB less allocation churn.

Reviewers: bogner, rtereshin, aditya_nandakumar, volkan

Reviewed By: rtereshin

Subscribers: mgrang, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D50272

llvm-svn: 339208
2018-08-08 00:19:59 +00:00
Vedant Kumar
b57ad60b6e [Coverage] Delete getCounterMismatches, it's dead code (NFC)
Exactly one counted region is inserted into a function record for every
region in a coverage mapping.

llvm-svn: 339193
2018-08-07 22:25:22 +00:00
Aditya Nandakumar
92fa33bc88 Refactor FileCheck to make it usable as an API
https://reviews.llvm.org/D50283
reviewed by bogner

This patch refactors FileCheck's implementation into support so it can
be used from C++ in other places (Unit tests).

llvm-svn: 339192
2018-08-07 21:58:49 +00:00
Craig Topper
bb1bde9246 [SelectionDAG][X86][SystemZ] Add a generic nonvolatile_store/nonvolatile_load pattern fragment in TargetSelectionDAG.td
Differential Revision: https://reviews.llvm.org/D50358

llvm-svn: 339156
2018-08-07 17:34:59 +00:00
Florian Hahn
49422ecfd5 [GVN,NewGVN] Keep nonnull if K does not move.
In combineMetadata, we should be able to preserve K's nonnull metadata,
if K does not move. This condition should hold for all replacements by
NewGVN/GVN, but I added a bunch of assertions to verify that.

Fixes PR35038.

There probably are additional kinds of metadata that could be preserved
using similar reasoning. This is follow-up work.

Reviewers: dberlin, davide, efriedma, nlopes

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D47339

llvm-svn: 339149
2018-08-07 15:36:11 +00:00
Florian Hahn
7ff6835194 [GVN,NewGVN] Move patchReplacementInstruction to Utils/Local.h
This function is shared between both implementations. I am not sure if
Utils/Local.h is the best place though.

Reviewers: davide, dberlin, efriedma, xbolva00

Reviewed By: efriedma, xbolva00

Differential Revision: https://reviews.llvm.org/D47337

llvm-svn: 339138
2018-08-07 13:27:33 +00:00
Andrea Di Biagio
7444c6289e [Tablegen] In TargetSchedule.td: Remove unused argument pfmCounters from ProcResourceUnits.
PFM counters don't need to be passed in input to the definition of
ProcResourceUnits. class PfmIssueCounter (see r329675) is used to map resources
to PFM counter(s).

Differential Revision: https://reviews.llvm.org/D50333

llvm-svn: 339125
2018-08-07 10:33:46 +00:00
Pavel Labath
d33177a252 [DebugInfo] Reduce debug_str_offsets section size
Summary:
The accelerator tables use the debug_str section to store their strings.
However, they do not support the indirect method of access that is
available for the debug_info section (DW_FORM_strx et al.).

Currently our code is assuming that all strings can/will be referenced
indirectly, and puts all of them into the debug_str_offsets section.
This is generally true for regular (unsplit) dwarf, but in the DWO case,
most of the strings in the debug_str section will only be used from the
accelerator tables. Therefore the contents of the debug_str_offsets
section will be largely unused and bloating the main executable.

This patch rectifies this by teaching the DwarfStringPool to
differentiate between strings accessed directly and indirectly. When a
user inserts a string into the pool it has to declare whether that
string will be referenced directly or not. If at least one user requsts
indirect access, that string will be assigned an index ID and put into
debug_str_offsets table. Otherwise, the offset table is skipped.

This approach reduces the overall binary size (when compiled with
-gdwarf-5 -gsplit-dwarf) in my tests by about 2% (debug_str_offsets is
shrunk by 99%).

Reviewers: probinson, dblaikie, JDevlieghere

Subscribers: aprantl, mgrang, llvm-commits

Differential Revision: https://reviews.llvm.org/D49493

llvm-svn: 339122
2018-08-07 09:54:52 +00:00
Simon Pilgrim
4747456e9b [TargetLowering] Add support for non-uniform vectors to BuildUDIV
This patch refactors the existing TargetLowering::BuildUDIV base implementation to support non-uniform constant vector denominators.

It also includes a fold for MULHU by pow2 constants to SRL which can now more readily occur from BuildUDIV.

Differential Revision: https://reviews.llvm.org/D49248

llvm-svn: 339121
2018-08-07 09:51:34 +00:00
George Rimar
28a885c90f [yaml2obj] - Add a support for changing EntSize.
I was trying to add a test case for LLD and found that it
is impossible to set sh_entsize via yaml.
The patch implements the missing part.

Differential revision: https://reviews.llvm.org/D50235

llvm-svn: 339113
2018-08-07 08:11:38 +00:00
Craig Topper
371c57f538 [SelectionDAG][X86] Rename MaskedLoadSDNode::getSrc0 to getPassThru.
Src0 doesn't really convey any meaning to what the operand is. Passthru matches what's used in the documentation for the intrinsic this comes from.

llvm-svn: 339101
2018-08-07 06:52:49 +00:00
Craig Topper
18bd0d4388 [SelectionDAG][X86] Rename getValue to getPassThru for gather SDNodes.
getValue is more meaningful name for scatter than it is for gather. Split them and use getPassThru for gather.

llvm-svn: 339096
2018-08-07 06:13:40 +00:00
Max Kazantsev
ee06f10f89 [NFC] Factor out implicit control flow logic from GVN
Logic for tracking implicit control flow instructions was added to GVN to
perform PRE optimizations correctly. It appears that GVN is not the only
optimization that sometimes does PRE, so this logic is required in other
places (such as Jump Threading).

This is an NFC patch that encapsulates all ICF-related logic in a dedicated
utility class separated from GVN.

Differential Revision: https://reviews.llvm.org/D40293

llvm-svn: 339086
2018-08-07 01:47:20 +00:00
Hsiangkai Wang
fd20113dad [DebugInfo] Refactor DbgInfoIntrinsic class hierarchy.
In the past, DbgInfoIntrinsic has a strong assumption that these
intrinsics all have variables and expressions attached to them.
However, it is too strong to derive the class for other debug entities.
Now, it has problems for debug labels.

In order to make DbgInfoIntrinsic as a base class for 'debug info', I
create a class for 'variable debug info', DbgVariableIntrinsic.

DbgDeclareInst, DbgAddrIntrinsic, and DbgValueInst will be derived from it.

Differential Revision: https://reviews.llvm.org/D50220

llvm-svn: 338984
2018-08-06 03:59:47 +00:00
Lang Hames
3bb5c9acd6 [ORC] Change JITSymbolFlags debug output, add a function for getting a symbol
flags map from a buffer representing an object file.

llvm-svn: 338974
2018-08-05 22:35:37 +00:00
David Bolvansky
7dcd99ba17 Enrich inline messages
Summary:
This patch improves Inliner to provide causes/reasons for negative inline decisions.
1. It adds one new message field to InlineCost to report causes for Always and Never instances. All Never and Always instantiations must provide a simple message.
2. Several functions that used to return the inlining results as boolean are changed to return InlineResult which carries the cause for negative decision.
3. Changed remark priniting and debug output messages to provide the additional messages and related inline cost.
4. Adjusted tests for changed printing.

Patch by: yrouban (Yevgeny Rouban)


Reviewers: craig.topper, sammccall, sgraenitz, NutshellySima, shchenz, chandlerc, apilipenko, javed.absar, tejohnson, dblaikie, sanjoy, eraman, xbolva00

Reviewed By: tejohnson, xbolva00

Subscribers: xbolva00, llvm-commits, arsenm, mehdi_amini, eraman, haicheng, steven_wu, dexonsmith

Differential Revision: https://reviews.llvm.org/D49412

llvm-svn: 338969
2018-08-05 14:53:08 +00:00
Chandler Carruth
069da7dcfd [ADT] Add an early-increment iterator-like type and range adaptor.
This allows us to model the common LLVM idiom of incrementing
immediately after dereferencing so that we can remove or update the
entity w/o losing our ability to reach the "next".

However, these are not real or proper iterators. They are just enough to
allow range based for loops and very simple range algorithms to work,
but should not be considered full general.

Differential Revision: https://reviews.llvm.org/D49956

llvm-svn: 338955
2018-08-04 08:17:26 +00:00
Chijun Sima
28625d59d9 [TailCallElim] Preserve DT and PDT
Summary:
Previously, in the NewPM pipeline, TailCallElim recalculates the DomTree when it modifies any instruction in the Function.
For example,
```
CallInst *CI = dyn_cast<CallInst>(&I);
...
CI->setTailCall();
Modified = true;
...
if (!Modified || ...)
  return PreservedAnalyses::all();
```
After applying this patch, the DomTree only recalculates if needed (plus an extra insertEdge() + an extra deleteEdge() call).

When optimizing SQLite with `-passes="default<O3>"` pipeline of the newPM, the number of DomTree recalculation decreases by 6.2%, the number of nodes visited by DFS decreases by 2.9%. The time used by DomTree will decrease approximately 1%~2.5% after applying the patch.
 
Statistics:
```
Before the patch:
 23010 dom-tree-stats               - Number of DomTree recalculations
489264 dom-tree-stats               - Number of nodes visited by DFS -- DomTree
After the patch:
 21581 dom-tree-stats               - Number of DomTree recalculations
475088 dom-tree-stats               - Number of nodes visited by DFS -- DomTree
```

Reviewers: kuhar, dmgreen, brzycki, grosser, davide

Reviewed By: kuhar, brzycki

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49982

llvm-svn: 338954
2018-08-04 08:13:47 +00:00
Galina Kistanova
241ffa16b1 Reverted r338825 and all the following tries to fix issues introduced by that commit (r338826, r338827, r338829, r338880).
This commit has broken build bots and has been left unattended for too long.

llvm-svn: 338948
2018-08-04 01:59:12 +00:00
Aditya Nandakumar
6188b99859 [GISel]: Add Opcodes for CTLZ/CTTZ/CTPOP
https://reviews.llvm.org/D48600

Added IRTranslator support to translate these known intrinsics into GISel opcodes.

llvm-svn: 338944
2018-08-04 01:22:12 +00:00
Rui Ueyama
f4c3d96eff Use the same constants as zlib to represent compression level.
This change allows users pass compression level that was not listed
in the enum. Also, I think using different values than zlib's
compression levels was just confusing.

Differential Revision: https://reviews.llvm.org/D50196

llvm-svn: 338939
2018-08-04 00:13:13 +00:00
Matt Arsenault
5eaf2b4fbf DAG: Enhance isKnownNeverNaN
Add a parameter for testing specifically for
sNaNs - at least one instruction pattern on AMDGPU
needs to check specifically for this.

Also handle more cases, and add a target hook
for custom nodes, similar to the hooks for known
bits.

llvm-svn: 338910
2018-08-03 18:27:52 +00:00
Nicholas Wilson
2d51b0f7e5 [WebAssembly] Cleanup of the way globals and global flags are handled
Differential Revision: https://reviews.llvm.org/D44030

llvm-svn: 338894
2018-08-03 14:33:37 +00:00
Simon Pilgrim
222b9aadec [TargetLowering] Generalise BuildSDIV function
First step towards a BuildSDIV equivalent to D49248 for non-uniform vector support - this just pushes the splat detection down into TargetLowering::BuildSDIV where its still used.

Differential Revision: https://reviews.llvm.org/D50185

llvm-svn: 338838
2018-08-03 10:00:54 +00:00
Dean Michael Berris
e289480427 [XRay] Fixup: remove 'noexcept' in defaulted move members
This is to appease stage1 builds using gcc.

Follow-up to D48370.

llvm-svn: 338826
2018-08-03 07:41:34 +00:00
Dean Michael Berris
0c7cbedfef [XRay][llvm] Load XRay Profiles
Summary:
This change implements the profile loading functionality in LLVM to
support XRay's profiling mode in compiler-rt.

We introduce a type named `llvm::xray::Profile` which allows building a
profile representation. We can load an XRay profile from a file to build
Profile instances, or do it manually through the Profile type's API.

The intent is to get the `llvm-xray` tool to generate `Profile`
instances and use that as the common abstraction through which all
conversion and analysis can be done. In the future we can generate
`Profile` instances from `Trace` instances as well, through conversion
functions.

Some of the key operations supported by the `Profile` API are:

- Path interning (`Profile::internPath(...)`) which returns a unique path
  identifier.

- Block appending (`Profile::addBlock(...)`) to add thread-associated
  profile information.

- Path ID to Path lookup (`Profile::expandPath(...)`) to look up a
  PathID and return the original interned path.

- Block iteration.

A 'Path' in this context represents the function call stack in
leaf-to-root order. This is represented as a path in an internally
managed prefix tree in the `Profile` instance. Having a handle (PathID)
to identify the unique Paths we encounter for a particular Profile
allows us to reduce the amount of memory required to associate profile
data to a particular Path.

This is the first of a series of patches to migrate the `llvm-stacks`
tool towards using a single profile representation.

Depends on D48653.

Reviewers: kpw, eizan

Reviewed By: kpw

Subscribers: mgorny, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D48370

llvm-svn: 338825
2018-08-03 07:18:39 +00:00
Chijun Sima
fba2ebc72b [Dominators] Refine the logic of recalculate() in the DomTreeUpdater
Summary:
This patch refines the logic of `recalculate()` in the `DomTreeUpdater` in the following two aspects:
1. Previously, `recalculate()` tests whether there are pending updates/BBs awaiting deletion and then do recalculation under Lazy UpdateStrategy; and do recalculation immediately under Eager UpdateStrategy. (The former behavior is inherited from the `DeferredDominance` class). This is an inconsistency between two strategies and there is no obvious reason to do this. So the behavior is changed to always recalculate available trees when calling `recalculate()`.
2. Fix the issue of when DTU under Lazy UpdateStrategy holds nothing but with BBs awaiting deletion, after calling `recalculate()`, BBs awaiting deletion aren't flushed. An additional unittest is added to cover this case.

Reviewers: kuhar, dmgreen, brzycki, grosser, davide

Reviewed By: kuhar

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D50173

llvm-svn: 338822
2018-08-03 06:51:35 +00:00
Chijun Sima
f6f16ab9ad [Dominators] Convert existing passes and utils to use the DomTreeUpdater class
Summary:
This patch is the second in a series of patches related to the [[ http://lists.llvm.org/pipermail/llvm-dev/2018-June/123883.html | RFC - A new dominator tree updater for LLVM ]].

It converts passes (e.g. adce/jump-threading) and various functions which currently accept DDT in local.cpp and BasicBlockUtils.cpp to use the new DomTreeUpdater class.
These converted functions in utils can accept DomTreeUpdater with either UpdateStrategy and can deal with both DT and PDT held by the DomTreeUpdater.

Reviewers: brzycki, kuhar, dmgreen, grosser, davide

Reviewed By: brzycki

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D48967

llvm-svn: 338814
2018-08-03 05:08:17 +00:00
Heejin Ahn
855cdeda11 [WebAssembly] Support for atomic.wait / atomic.wake instructions
Summary:
This adds support for atomic.wait / atomic.wake instructions in the wasm
thread proposal.

Reviewers: dschuff

Subscribers: sbc100, jgravelle-google, sunfish, llvm-commits

Differential Revision: https://reviews.llvm.org/D49395

llvm-svn: 338770
2018-08-02 21:44:24 +00:00
Lang Hames
54d28c92f1 [ORC] Add a re-exports fallback definition generator.
An instance of ReexportsFallbackDefinitionGenerator can be attached to a VSO
(via setFallbackDefinitionGenerator) to re-export symbols on demandy from a
backing VSO.

llvm-svn: 338764
2018-08-02 20:13:58 +00:00
George Burgess IV
d33befca30 [Support] Add an enable bit to our DebugCounters
r337748 made us start incrementing DebugCounters all of the time. This
makes tsan unhappy in multithreaded environments.

Since it doesn't make much sense to use DebugCounters with multiple
threads, this patch makes us only count anything if the user passed a
-debug-counter option or if some other piece of code explicitly asks
for it (e.g. the pass in D50031).

The amount of global state here makes writing a unittest for this
behavior somewhat awkward. So, no test is provided.

Differential Revision: https://reviews.llvm.org/D50150

llvm-svn: 338762
2018-08-02 19:50:27 +00:00
Paul Robinson
17be6b162b [DebugInfo/DWARF] Remove redundant iterator type. NFC
llvm-svn: 338759
2018-08-02 19:29:38 +00:00
Krzysztof Parzyszek
e5e129cd68 [SCEV] Properly solve quadratic equations
Differential Revision: https://reviews.llvm.org/D48283

llvm-svn: 338758
2018-08-02 19:13:35 +00:00
Stefan Granitz
f43b171255 Add include guard
Summary: Add missing include guard LLVM_DEMANGLE_DEMANGLE_H in llvm/Demangle/Demangle.h

Reviewers: erik.pilkington

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D50042

llvm-svn: 338694
2018-08-02 09:45:59 +00:00
Alexander Ivchenko
67b31b9526 [GlobalISel] Rewrite CallLowering::lowerReturn to accept multiple VRegs per Value
This is logical continuation of https://reviews.llvm.org/D46018 (r332449)

Differential Revision: https://reviews.llvm.org/D49660

llvm-svn: 338685
2018-08-02 08:33:31 +00:00
Philip Reames
f2294ec901 [LICM] Factor out fault legality from canHoistOrSinkInst [NFC]
This method has three callers, each of which wanted distinct handling:
1) Sinking into a loop is moving an instruction known to execute before a loop into the loop.  We don't need to worry about introducing a fault at all in this case.
2) Hoisting from a loop into a preheader already duplicated the check in the caller.
3) Sinking from the loop into an exit block was the only true user of the code within the routine.  For the moment, this has just been lifted into the caller, but up next is examining the logic more carefully.  Whitelisting of loads and calls - while consistent with the previous code - is rather suspicious.  Either way, a behavior change is worthy of it's own patch.  

llvm-svn: 338671
2018-08-02 04:08:04 +00:00
Tim Shen
4b8c550e74 [ADT] Add some documentation for GraphTraits.
Summary: Add some context for GraphTraits.

Reviewers: dblaikie, asbirlea

Subscribers: sanjoy, jlebar, bixia, dexonsmith, llvm-commits

Differential Revision: https://reviews.llvm.org/D50120

llvm-svn: 338660
2018-08-02 00:21:12 +00:00
Lei Liu
4779c3a4b6 [AArch64] DWARF: do not generate AT_location for thread local
AArch64 ELF ABI does not define a static relocation type for TLS offset within
a module, which makes it impossible for compiler to generate a valid
DW_AT_location content for thread local variables. Currently LLVM generates an
invalid R_AARCH64_ABS64 relocation at the DW_AT_location field for a TLS
variable. That causes trouble for linker because thread local variable does
not have an absolute address at link time. AArch64 GCC solves the problem by
not generating DW_AT_location for thread local variables. We should do the
same in LLVM.

Differential Revision: https://reviews.llvm.org/D43860

llvm-svn: 338655
2018-08-01 23:46:49 +00:00
Lang Hames
31bd6082d1 [ORC] Add a 'Callable' flag to JITSymbolFlags.
The callable flag can be used to indicate that a symbol is callable. If present,
the symbol is callable. If absent, the symbol may or may not be callable (the
client must determine this by context, for example by examining the program
representation that will provide the symbol definition).

This flag will be used in the near future to enable creation of lazy compilation
stubs based on SymbolFlagsMap instances only (without having to provide
additional information to determine which symbols need stubs).

llvm-svn: 338649
2018-08-01 22:42:23 +00:00
Paul Robinson
529af4c47d [DebugInfo/DWARF] [4/4] Unify handling of compile and type units. NFC
This is patch 4 of 4 NFC refactorings to handle type units and compile
units more consistently and with less concern about the object-file
section that they came from.

Patch 4 combines separate DWARFUnitVectors for compile and type units
into a single DWARFUnitVector that contains both.  For now the
implementation distinguishes compile units from type units by putting
all compile units at the front of the vector, reflecting the DWARF v4
distinction between .debug_info and .debug_types sections.  A future
patch will change this to allow the free mixing of unit kinds, as is
specified by DWARF v5.

Differential Revision: https://reviews.llvm.org/D49744

llvm-svn: 338633
2018-08-01 20:54:11 +00:00
Paul Robinson
a783a0cd41 [DebugInfo/DWARF] [3/4] Rename DWARFUnitSection to DWARFUnitVector. NFC
This is patch 3 of 4 NFC refactorings to handle type units and compile
units more consistently and with less concern about the object-file
section that they came from.

Patch 3 simply renames DWARFUnitSection to DWARFUnitVector, as the
object-file section of a unit is nearly irrelevant now.

Differential Revision: https://reviews.llvm.org/D49743

llvm-svn: 338632
2018-08-01 20:49:44 +00:00
Paul Robinson
b4436612d9 [DebugInfo/DWARF] [2/4] Type units no longer in a std::deque. NFC
This is patch 2 of 4 NFC refactorings to handle type units and compile
units more consistently and with less concern about the object-file
section that they came from.

Patch 2 takes the existing std::deque<DWARFUnitSection> for type units
and makes it a simple DWARFUnitSection, simplifying the handling of
type units and making it more consistent with compile units.

Differential Revision: https://reviews.llvm.org/D49742

llvm-svn: 338629
2018-08-01 20:46:46 +00:00
Paul Robinson
e86b7555f8 [DebugInfo/DWARF] [1/4] De-templatize DWARFUnitSection. NFC
This is patch 1 of 4 NFC refactorings to handle type units and compile
units more consistently and with less concern about the object-file
section that they came from.

Patch 1 replaces the templated DWARFUnitSection with a non-templated
version. That is, instead of being a SmallVector of pointers to a
specific unit kind, it is not a SmallVector of pointers to the base
class for both type and compile units.  Virtual methods are magic.

Differential Revision: https://reviews.llvm.org/D49741

llvm-svn: 338628
2018-08-01 20:43:47 +00:00
Alexey Bataev
95dd3b8ace [DEBUGINFO] Disable emission of the dwarf sections, but allow directives.
Summary:
Added an option that allows to emit only '.loc' and '.file' kind debug
directives, but disables emission of the DWARF sections. Required for
NVPTX target to support profiling. It requires '.loc' and '.file'
directives, but does not require any DWARF sections for the profiler.

Reviewers: probinson, echristo, dblaikie

Subscribers: aprantl, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D46021

llvm-svn: 338616
2018-08-01 19:38:20 +00:00
Zachary Turner
5d0ac84a37 [llvm-undname Add an option to dump back references.
This is useful for understanding how our demangler processes
back references and for investigating issues related to
back references.  But it's a feature only useful for debugging
the demangling process itself, so I'm marking it hidden.

llvm-svn: 338609
2018-08-01 18:33:04 +00:00
Simon Pilgrim
51d4ce388c [SelectionDAG] Make binop reduction matcher available to all targets
There is nothing x86-specific about this code, so it'd be nice to make this available for other targets to use in the future (and get it out of X86ISelLowering!).

Differential Revision: https://reviews.llvm.org/D50083

llvm-svn: 338586
2018-08-01 16:52:28 +00:00
Jonas Devlieghere
420ebfa10e [DebugInfo] Remove ambiguity to fix Windows bots
Should fix the MSVC bots by explicitly invoking
llvm::make_reverse_iterator to remove ambiguity with
std::make_reverse_iterator.

llvm-svn: 338511
2018-08-01 10:40:08 +00:00
Jonas Devlieghere
5d8817f05b [DebugInfo] Improve consistency in DWARFDie.h (NFC)
Follow-up for r338506 with some unrelated changes in formatting and
consistency.

llvm-svn: 338509
2018-08-01 10:30:34 +00:00
Jonas Devlieghere
42f811eb1e [DebugInfo] Have custom std::reverse_iterator<DWARFDie>
The DWARFDie is a lightweight utility wrapper that stores a pointer to a
compile unit and a debug info entry. Currently, its iterator (used for
walking over its children) stores a DWARFDie and returns a const
reference when dereferencing it.

When the iterator is modified (by incrementing or decrementing it), this
reference becomes invalid. This was happening when calling reverse on
it, because the std::reverse_iterator is keeping a temporary copy of the
iterator (see
https://en.cppreference.com/w/cpp/iterator/reverse_iterator for a good
illustration).

The relevant code in libcxx:

  reference operator*() const {_Iter __tmp = current; return *--__tmp;}

When dereferencing the reverse iterator, we decrement and return a
reference to a DWARFDie stored in the stack frame of this function,
resulting in UB at runtime.

This patch specifies the std::reverse_iterator for DWARFDie to do the
right thing.

Differential revision: https://reviews.llvm.org/D49679

llvm-svn: 338506
2018-08-01 10:24:17 +00:00
David Bolvansky
28d06c0be1 Revert "Enrich inline messages", tests fail
llvm-svn: 338496
2018-08-01 08:02:40 +00:00