Commit Graph

98 Commits

Author SHA1 Message Date
James Y Knight 751fe286dc [opaque pointer types] Cleanup CGBuilder's Create*GEP.
The various EltSize, Offset, DataLayout, and StructLayout arguments
are all computable from the Address's element type and the DataLayout
which the CGBuilder already has access to.

After having previously asserted that the computed values are the same
as those passed in, now remove the redundant arguments from
CGBuilder's Create*GEP functions.

Differential Revision: https://reviews.llvm.org/D57767

llvm-svn: 353629
2019-02-09 22:22:28 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
Chandler Carruth e303c87e19 [TI removal] Make `getTerminator()` return a generic `Instruction`.
This removes the primary remaining API producing `TerminatorInst` which
will reduce the rate at which code is introduced trying to use it and
generally make it much easier to remove the remaining APIs across the
codebase.

Also clean up some of the stragglers that the previous mechanical update
of variables missed.

Users of LLVM and out-of-tree code generally will need to update any
explicit variable types to handle this. Replacing `TerminatorInst` with
`Instruction` (or `auto`) almost always works. Most of these edits were
made in prior commits using the perl one-liner:
```
perl -i -ple 's/TerminatorInst(\b.* = .*getTerminator\(\))/Instruction\1/g'
```

This also my break some rare use cases where people overload for both
`Instruction` and `TerminatorInst`, but these should be easily fixed by
removing the `TerminatorInst` overload.

llvm-svn: 344504
2018-10-15 10:42:50 +00:00
Fangrui Song 6907ce2f8f Remove trailing space
sed -Ei 's/[[:space:]]+$//' include/**/*.{def,h,td} lib/**/*.{cpp,h}

llvm-svn: 338291
2018-07-30 19:24:48 +00:00
Richard Smith f66e4f7dbd Support lifetime-extension of conditional temporaries.
llvm-svn: 337767
2018-07-23 22:56:45 +00:00
Yaxun Liu cbd80f49d5 Call CreateTempAllocaWithoutCast for ActiveFlag
This is partial re-commit of r332982.

llvm-svn: 334879
2018-06-16 01:20:52 +00:00
Heejin Ahn c647919933 [WebAssembly] Use Windows EH instructions for Wasm EH
Summary:
Because wasm control flow needs to be structured, using WinEH
instructions to support wasm EH brings several benefits. This patch
makes wasm EH uses Windows EH instructions, with some changes:
1. Because wasm uses a single catch block to catch all C++ exceptions,
   this merges all catch clauses into a single catchpad, within which we
   test the EH selector as in Itanium EH.
2. Generates a call to `__clang_call_terminate` in case a cleanup
   throws. Wasm does not have a runtime to handle this.
3. In case there is no catch-all clause, inserts a call to
   `__cxa_rethrow` at the end of a catchpad in order to unwind to an
   enclosing EH scope.

Reviewers: majnemer, dschuff

Subscribers: jfb, sbc100, jgravelle-google, sunfish, cfe-commits

Differential Revision: https://reviews.llvm.org/D44931

llvm-svn: 333703
2018-05-31 22:18:13 +00:00
Yaxun Liu 00ddbed298 Revert r332982 Call CreateTempMemWithoutCast for ActiveFlag
Due to regression on arm.

llvm-svn: 332991
2018-05-22 16:13:07 +00:00
Yaxun Liu 8a60e5db70 Call CreateTempMemWithoutCast for ActiveFlag
Introduced CreateMemTempWithoutCast and CreateTemporaryAllocaWithoutCast to emit alloca
without casting to default addr space.

ActiveFlag is a temporary variable emitted for clean up. It is defined as AllocaInst* type and there is
a cast to AlllocaInst in SetActiveFlag. An alloca casted to generic pointer causes assertion in
SetActiveFlag.

Since there is only load/store of ActiveFlag, it is safe to use the original alloca, therefore use
CreateMemTempWithoutCast is called.

Differential Revision: https://reviews.llvm.org/D47099

llvm-svn: 332982
2018-05-22 14:36:26 +00:00
Akira Hatanaka ccda3d2970 [CodeGen] Avoid destructing a callee-destructued struct type in a
function if a function delegates to another function.

Fix a bug introduced in r328731, which caused a struct with ObjC __weak
fields that was passed to a function to be destructed twice, once in the
callee function and once in another function the callee function
delegates to. To prevent this, keep track of the callee-destructed
structs passed to a function and disable their cleanups at the point of
the call to the delegated function.

This reapplies r331016, which was reverted in r331019 because it caused
an assertion to fail in EmitDelegateCallArg on a windows bot. I made
changes to EmitDelegateCallArg so that it doesn't try to deactivate
cleanups for structs that have trivial destructors (cleanups for those
structs are never pushed to the cleanup stack in EmitParmDecl).

rdar://problem/39194693

Differential Revision: https://reviews.llvm.org/D45382

llvm-svn: 331020
2018-04-27 06:57:00 +00:00
Akira Hatanaka b4f3637cec Revert "[CodeGen] Avoid destructing a callee-destructued struct type in a"
This reverts commit r331016, which broke a windows bot.

http://lab.llvm.org:8011/builders/clang-x86-windows-msvc2015/builds/11727

llvm-svn: 331019
2018-04-27 05:56:55 +00:00
Akira Hatanaka e712374496 [CodeGen] Avoid destructing a callee-destructued struct type in a
function if a function delegates to another function.

Fix a bug introduced in r328731, which caused a struct with ObjC __weak
fields that was passed to a function to be destructed twice, once in the
callee function and once in another function the callee function
delegates to. To prevent this, keep track of the callee-destructed
structs passed to a function and disable their cleanups at the point of
the call to the delegated function.

rdar://problem/39194693

Differential Revision: https://reviews.llvm.org/D45382

llvm-svn: 331016
2018-04-27 04:21:51 +00:00
John McCall 5cdf038374 Allocate and access NormalCleanupDest with the natural alignment of i32.
This alignment can be less than 4 on certain embedded targets, which may
not even be able to deal with 4-byte alignment on the stack.

Patch by Jacob Young!

llvm-svn: 322406
2018-01-12 22:07:01 +00:00
Nico Weber 524ae44dfa Fix typo in comment, no behavior change.
llvm-svn: 311790
2017-08-25 18:41:41 +00:00
Reid Kleckner 0449316ea0 Don't try to spill static allocas when emitting expr cleanups with branches
Credit goes to Gor Nishanov for putting together the fix in
https://reviews.llvm.org/D33733!

This patch is essentially me patching it locally and writing some test
cases to convince myself that it was necessary for GNU statement
expressions with branches as well as coroutines. I'll ask Gor to land
his patch with just the coroutines test.

During LValue expression evaluation, references can be bound to
anything, really: call results, aggregate temporaries, local variables,
global variables, or indirect arguments. We really only want to spill
instructions that were emitted as part of expression evaluation, and
static allocas are not that.

llvm-svn: 304335
2017-05-31 19:59:41 +00:00
Serge Guelton 1d993270b3 Suppress all uses of LLVM_END_WITH_NULL. NFC.
Use variadic templates instead of relying on <cstdarg> + sentinel.

This enforces better type checking and makes code more readable.

Differential revision: https://reviews.llvm.org/D32550

llvm-svn: 302572
2017-05-09 19:31:30 +00:00
Chandler Carruth 260161b8c5 Update Clang for an API change to LLVM's switch case iterator (it is now
an actual iterator and so we need to look through it to the case
handle).

llvm-svn: 300035
2017-04-12 08:12:30 +00:00
Reid Kleckner 092d065265 Don't assume cleanup emission preserves dominance in expr evaluation
Summary:
Because of the existence branches out of GNU statement expressions, it
is possible that emitting cleanups for a full expression may cause the
new insertion point to not be dominated by the result of the inner
expression. Consider this example:

  struct Foo { Foo(); ~Foo(); int x; };
  int g(Foo, int);
  int f(bool cond) {
    int n = g(Foo(), ({ if (cond) return 0; 42; }));
    return n;
  }

Before this change, result of the call to 'g' did not dominate its use
in the store to 'n'. The early return exit from the statement expression
branches to a shared cleanup block, which ends in a switch between the
fallthrough destination (the assignment to 'n') or the function exit
block.

This change solves the problem by spilling and reloading expression
evaluation results when any of the active cleanups have branches.

I audited the other call sites of enterFullExpression, and they don't
appear to keep and Values live across the site of the cleanup, except in
ARC code. I wasn't able to create a test case for ARC that exhibits this
problem, though.

Reviewers: rjmccall, rsmith

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D30590

llvm-svn: 297084
2017-03-06 22:18:34 +00:00
Benjamin Kramer c3f89253ae Retire llvm::alignOf in favor of C++11 alignof.
No functionality change intended.

llvm-svn: 284730
2016-10-20 14:27:22 +00:00
Tim Shen 421119fd89 [Temporary, Lifetime] Add lifetime marks for temporaries
With all MaterializeTemporaryExprs coming with a ExprWithCleanups, it's
easy to add correct lifetime.end marks into the right RunCleanupsScope.

Differential Revision: http://reviews.llvm.org/D20499

llvm-svn: 274385
2016-07-01 21:08:47 +00:00
Akira Hatanaka 8af7bb28aa [CodeGen] Emit lifetime.end intrinsic after objects are destructed in
landing pads.

Previously, lifetime.end intrinsics were inserted only on normal control
flows. This prevented StackColoring from merging stack slots for objects
that were destroyed on the exception handling control flow since it
couldn't tell their lifetime ranges were disjoint. This patch fixes
code-gen to emit the intrinsic on both control flows.

rdar://problem/22181976

Differential Revision: http://reviews.llvm.org/D18196

llvm-svn: 265197
2016-04-01 22:58:55 +00:00
Rui Ueyama 83aa97941f Update for LLVM function name change.
llvm-svn: 257802
2016-01-14 21:00:27 +00:00
James Y Knight 54a3b2680f Fix alignment issue in CodeGenFunction::PopCleanupBlock.
It was copying an EHCleanupStack::Cleanup object into a
SmallVector<char>, with a comment saying that SmallVector's alignment is
always large enough. Unfortunately, that isn't actually true after
r162331 in 2012.

Expand the code (somewhat distastefully) to get a stack allocation with
a correct alignment.

llvm-svn: 256619
2015-12-30 03:58:33 +00:00
David Majnemer 4e52d6f811 Update clang to use the updated LLVM EH instructions
Depends on D15139.

Reviewers: rnk

Differential Revision: http://reviews.llvm.org/D15140

llvm-svn: 255423
2015-12-12 05:39:21 +00:00
Duncan P. N. Exon Smith 9f5260ab13 CodeGen: Remove implicit ilist iterator conversions, NFC
Make ilist iterator conversions explicit in clangCodeGen.  Eventually
I'll remove them everywhere.

llvm-svn: 252358
2015-11-06 23:00:41 +00:00
Reid Kleckner a002bd544c [WinEH] Mark calls inside cleanups as noinline
This works around PR25162. The MSVC tables make it very difficult to
correctly inline a C++ destructor that contains try / catch.  We've
attempted to address PR25162 in LLVM's backend, but it feels pretty
infeasible.  MSVC and ICC both appear to avoid inlining such complex
destructors.

Long term, we want to fix this by making the inliner smart enough to
know when it is inlining into a cleanup, so it can inline simple
destructors (~unique_ptr and ~vector) while avoiding destructors
containing try / catch.

llvm-svn: 251576
2015-10-28 23:06:42 +00:00
Benjamin Kramer c2d2b4259c [CodeGen] Remove dead code. NFC.
llvm-svn: 250418
2015-10-15 15:29:40 +00:00
Reid Kleckner 5539152404 [WinEH] Push cleanupendpad scopes around exceptional cleanups
We were only doing this for SEH as a special case. Generalize it to all
cleanups.

llvm-svn: 249748
2015-10-08 21:14:56 +00:00
Reid Kleckner 129552b375 [WinEH] Remove NewMSEH and enable its behavior by default
Testing has shown that it is at least as reliable as the old landingpad
pattern matching code.

llvm-svn: 249647
2015-10-08 01:13:52 +00:00
Reid Kleckner 2586aac908 [SEH] Use cleanupendpad so that WinEHPrepare gets the coloring right
Cleanupendpad is a lot like catchendpad, so we can reuse the same
EHScopeStack type.

llvm-svn: 247349
2015-09-10 22:11:13 +00:00
John McCall 7f416cc426 Compute and preserve alignment more faithfully in IR-generation.
Introduce an Address type to bundle a pointer value with an
alignment.  Introduce APIs on CGBuilderTy to work with Address
values.  Change core APIs on CGF/CGM to traffic in Address where
appropriate.  Require alignments to be non-zero.  Update a ton
of code to compute and propagate alignment information.

As part of this, I've promoted CGBuiltin's EmitPointerWithAlignment
helper function to CGF and made use of it in a number of places in
the expression emitter.

The end result is that we should now be significantly more correct
when performing operations on objects that are locally known to
be under-aligned.  Since alignment is not reliably tracked in the
type system, there are inherent limits to this, but at least we
are no longer confused by standard operations like derived-to-base
conversions and array-to-pointer decay.  I've also fixed a large
number of bugs where we were applying the complete-object alignment
to a pointer instead of the non-virtual alignment, although most of
these were hidden by the very conservative approach we took with
member alignment.

Also, because IRGen now reliably asserts on zero alignments, we
should no longer be subject to an absurd but frustrating recurring
bug where an incomplete type would report a zero alignment and then
we'd naively do a alignmentAtOffset on it and emit code using an
alignment equal to the largest power-of-two factor of the offset.

We should also now be emitting much more aggressive alignment
attributes in the presence of over-alignment.  In particular,
field access now uses alignmentAtOffset instead of min.

Several times in this patch, I had to change the existing
code-generation pattern in order to more effectively use
the Address APIs.  For the most part, this seems to be a strict
improvement, like doing pointer arithmetic with GEPs instead of
ptrtoint.  That said, I've tried very hard to not change semantics,
but it is likely that I've failed in a few places, for which I
apologize.

ABIArgInfo now always carries the assumed alignment of indirect and
indirect byval arguments.  In order to cut down on what was already
a dauntingly large patch, I changed the code to never set align
attributes in the IR on non-byval indirect arguments.  That is,
we still generate code which assumes that indirect arguments have
the given alignment, but we don't express this information to the
backend except where it's semantically required (i.e. on byvals).
This is likely a minor regression for those targets that did provide
this information, but it'll be trivial to add it back in a later
patch.

I partially punted on applying this work to CGBuiltin.  Please
do not add more uses of the CreateDefaultAligned{Load,Store}
APIs; they will be going away eventually.

llvm-svn: 246985
2015-09-08 08:05:57 +00:00
Joseph Tremoulet ce536a596b [WinEH] Update to new EH pad/ret signatures (with tokens required)
Summary:
The signatures of the methods in LLVM for creating EH pads/rets are changing
to require token arguments on rets and assume token return type on pads.
Update creation code accordingly.

Reviewers: majnemer, rnk

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D12109

llvm-svn: 245798
2015-08-23 00:26:48 +00:00
David Majnemer e888a2f655 [MS ABI] Switch catchpad/cleanuppad to use tokens
llvm-svn: 245153
2015-08-15 03:21:08 +00:00
Benjamin Kramer 6c3e4ec449 [CodeGen] Don't write into a SmallVector's uninitialized memory.
That's just ugly and not needed in this case. No functionality change.

llvm-svn: 243973
2015-08-04 12:34:30 +00:00
David Majnemer dbf1045ad7 [MS ABI] Hook clang up to the new EH instructions
The new EH instructions make it possible for LLVM to generate .xdata
tables that the MSVC personality routines will be happy about.  Because
this is experimental, hide it behind a -cc1 flag (-fnew-ms-eh).

Differential Revision: http://reviews.llvm.org/D11405

llvm-svn: 243767
2015-07-31 17:58:45 +00:00
James Y Knight 53c7616e2e Fix alignment issues in Clang.
Some const-correctness changes snuck in here too, since they were in the
area of code I was modifying.

This seems to make Clang actually work without Bus Error on
32bit-sparc.

Follow-up patches will factor out a trailing-object helper class, to
make classes using the idiom of appending objects to other objects
easier to understand, and to ensure (with static_assert) that required
alignment guarantees continue to hold.

Differential Revision: http://reviews.llvm.org/D10272

llvm-svn: 242554
2015-07-17 18:21:37 +00:00
David Majnemer dc012fa266 Revert "Revert r234581, it might have caused a few miscompiles in Chromium."
This reverts commit r234700.  It turns out that the lifetime markers
were not the cause of Chromium failing but a bug which was uncovered by
optimizations exposed by the markers.

llvm-svn: 235553
2015-04-22 21:38:15 +00:00
Nico Weber 1c565c31b1 Revert r234581, it might have caused a few miscompiles in Chromium.
If the revert helps, I'll get a repro this Monday.  Else I'll put the change
back in.

llvm-svn: 234700
2015-04-11 23:51:38 +00:00
Arnaud A. de Grandmaison 047a686d53 Remove threshold for inserting lifetime markers for named temporaries
Now that TailRecursionElimination has been fixed with r222354, the
threshold on size for lifetime marker insertion can be removed. This
only affects named temporary though, as the patch for unnamed temporaries
is still in progress.

My previous commit (r222993) was not handling debuginfo correctly, but
this could only be seen with some asan tests. Basically, lifetime markers
are just instrumentation for the compiler's usage and should not affect
debug information; however, the cleanup infrastructure was assuming it
contained only destructors, i.e. actual code to be executed, and was
setting the breakpoint for the end of the function to the closing '}', and
not the return statement, in order to show some destructors have been
called when leaving the function. This is wrong when the cleanups are only
lifetime markers, and this is now fixed.

llvm-svn: 234581
2015-04-10 10:13:52 +00:00
Reid Kleckner e5b064205a [WinEH] Don't wrap cleanups in terminate actions
_CxxFrameHandler3 calls terminate if a cleanup action throws, regardless
of what bits you put in the xdata tables. There's no need to model this
in the IR, since we just have to take it out later.

llvm-svn: 234448
2015-04-08 22:48:50 +00:00
David Blaikie 2e80428dc5 clang-format my last commit
(sorry, keep forgetting that)

llvm-svn: 234129
2015-04-05 22:47:07 +00:00
David Blaikie 1ed728c499 [opaque pointer type] More GEP API migrations
Looks like the VTable code in particular will need some work to pass
around the pointee type explicitly.

llvm-svn: 234128
2015-04-05 22:45:47 +00:00
Benjamin Kramer c749745bac Revert accidental commit.
llvm-svn: 229510
2015-02-17 16:53:08 +00:00
Benjamin Kramer f989042f18 Prefer SmallVector::append/insert over push_back loops. Clang edition.
Same functionality, but hoists the vector growth out of the loop.

llvm-svn: 229508
2015-02-17 16:48:30 +00:00
David Blaikie 4d52443c0e DebugInfo: Attribute cleanup code to the end of the scope, not the end of the function.
Now if you break on a dtor and go 'up' in your debugger (or you get an
asan failure in a dtor) during an exception unwind, you'll have more
context. Instead of all dtors appearing to be called from the '}' of the
function, they'll be attributed to the end of the scope of the variable,
the same as the non-exceptional dtor call.

This doesn't /quite/ remove all uses of CurEHLocation (which might be
nice to remove, for a few reasons) - it's still used to choose the
location for some other work in the landing pad. It'd be nice to
attribute that code to the same location as the exception calls within
the block and to remove CurEHLocation.

llvm-svn: 228181
2015-02-04 19:47:54 +00:00
Adrian Prantl 95b24e9b59 Address review feedback for r228003.
- use named constructors
- get rid of MarkAsPrologue

llvm-svn: 228021
2015-02-03 20:00:54 +00:00
Adrian Prantl 39428e74a0 Merge ArtificialLocation into ApplyDebugLocation and make a clear
distinction between the different use-cases. With the previous default
behavior we would occasionally emit empty debug locations in situations
where they actually were strictly required (= on invoke insns).
We now have a choice between defaulting to an empty location or an
artificial location.

Specifically, this fixes a bug caused by a missing debug location when
emitting C++ EH cleanup blocks from within an artificial function, such as
an ObjC destroy helper function.

rdar://problem/19670595

llvm-svn: 228003
2015-02-03 18:40:42 +00:00
David Blaikie 66e4197f07 Reapply r225000 (reverted in r225555): DebugInfo: Generalize debug info location handling (and follow-up commits).
Several pieces of code were relying on implicit debug location setting
which usually lead to incorrect line information anyway. So I've fixed
those (in r225955 and r225845) separately which should pave the way for
this commit to be cleanly reapplied.

The reason these implicit dependencies resulted in crashes with this
patch is that the debug location would no longer implicitly leak from
one place to another, but be set back to invalid. Once a call with
no/invalid location was emitted, if that call was ever inlined it could
produce invalid debugloc chains and assert during LLVM's codegen.

There may be further cases of such bugs in this patch - they're hard to
flush out with regression testing, so I'll keep an eye out for reports
and investigate/fix them ASAP if they come up.

Original commit message:

Reapply "DebugInfo: Generalize debug info location handling"

Originally committed in r224385 and reverted in r224441 due to concerns
this change might've introduced a crash. Turns out this change fixes the
crash introduced by one of my earlier more specific location handling
changes (those specific fixes are reverted by this patch, in favor of
the more general solution).

Recommitted in r224941 and reverted in r224970 after it caused a crash
when building compiler-rt. Looks to be due to this change zeroing out
the debug location when emitting default arguments (which were meant to
inherit their outer expression's location) thus creating call
instructions without locations - these create problems for inlining and
must not be created. That is fixed and tested in this version of the
change.

Original commit message:

This is a more scalable (fixed in mostly one place, rather than many
places that will need constant improvement/maintenance) solution to
several commits I've made recently to increase source fidelity for
subexpressions.

This resetting had to be done at the DebugLoc level (not the
SourceLocation level) to preserve scoping information (if the resetting
was done with CGDebugInfo::EmitLocation, it would've caused the tail end
of an expression's codegen to end up in a potentially different scope
than the start, even though it was at the same source location). The
drawback to this is that it might leave CGDebugInfo out of sync. Ideally
CGDebugInfo shouldn't have a duplicate sense of the current
SourceLocation, but for now it seems it does... - I don't think I'm
going to tackle removing that just now.

I expect this'll probably cause some more buildbot fallout & I'll
investigate that as it comes up.

Also these sort of improvements might be starting to show a weakness/bug
in LLVM's line table handling: we don't correctly emit is_stmt for
statements, we just put it on every line table entry. This means one
statement split over multiple lines appears as multiple 'statements' and
two statements on one line (without column info) are treated as one
statement.

I don't think we have any IR representation of statements that would
help us distinguish these cases and identify the beginning of each
statement - so that might be something we need to add (possibly to the
lexical scope chain - a scope for each statement). This does cause some
problems for GDB and possibly other DWARF consumers.

llvm-svn: 225956
2015-01-14 07:38:27 +00:00
David Blaikie f353d3ecd0 Revert "DebugInfo: Generalize debug info location handling" and related commits
This reverts commit r225000, r225021, r225083, r225086, r225090.

The root change (r225000) still has several issues where it's caused
calls to be emitted without debug locations. This causes assertion
failures if/when those calls are inlined.

I'll work up some test cases and fixes before recommitting this.

llvm-svn: 225555
2015-01-09 23:00:28 +00:00
David Blaikie 84fe79cfc3 Reapply "DebugInfo: Generalize debug info location handling"
Originally committed in r224385 and reverted in r224441 due to concerns
this change might've introduced a crash. Turns out this change fixes the
crash introduced by one of my earlier more specific location handling
changes (those specific fixes are reverted by this patch, in favor of
the more general solution).

Recommitted in r224941 and reverted in r224970 after it caused a crash
when building compiler-rt. Looks to be due to this change zeroing out
the debug location when emitting default arguments (which were meant to
inherit their outer expression's location) thus creating call
instructions without locations - these create problems for inlining and
must not be created. That is fixed and tested in this version of the
change.

Original commit message:

This is a more scalable (fixed in mostly one place, rather than many
places that will need constant improvement/maintenance) solution to
several commits I've made recently to increase source fidelity for
subexpressions.

This resetting had to be done at the DebugLoc level (not the
SourceLocation level) to preserve scoping information (if the resetting
was done with CGDebugInfo::EmitLocation, it would've caused the tail end
of an expression's codegen to end up in a potentially different scope
than the start, even though it was at the same source location). The
drawback to this is that it might leave CGDebugInfo out of sync. Ideally
CGDebugInfo shouldn't have a duplicate sense of the current
SourceLocation, but for now it seems it does... - I don't think I'm
going to tackle removing that just now.

I expect this'll probably cause some more buildbot fallout & I'll
investigate that as it comes up.

Also these sort of improvements might be starting to show a weakness/bug
in LLVM's line table handling: we don't correctly emit is_stmt for
statements, we just put it on every line table entry. This means one
statement split over multiple lines appears as multiple 'statements' and
two statements on one line (without column info) are treated as one
statement.

I don't think we have any IR representation of statements that would
help us distinguish these cases and identify the beginning of each
statement - so that might be something we need to add (possibly to the
lexical scope chain - a scope for each statement). This does cause some
problems for GDB and possibly other DWARF consumers.

llvm-svn: 225000
2014-12-30 19:39:33 +00:00