Commit Graph

2752 Commits

Author SHA1 Message Date
Manman Ren f93ac4bfad [Debug Info] remove DITrivialType and use null to represent unspecified param.
Per feedback on r214111, we are going to use null to represent unspecified
parameter. If the type array is {null}, it means a function that returns void;
If the type array is {null, null}, it means a variadic function that returns
void. In summary if we have more than one element in the type array and the last
element is null, it is a variadic function.

rdar://17628609

llvm-svn: 214189
2014-07-29 18:20:39 +00:00
Manman Ren bd1628a595 [Debug Info] unique MDNodes in the enum types of each compile unit.
The enum types array by design contains pointers to MDNodes rather than DIRefs.
Unique them when handling the enum types in DwarfDebug.

rdar://17628609

llvm-svn: 214139
2014-07-28 23:04:20 +00:00
Manman Ren f8a1967c8c [Debug Info] add DISubroutineType and its creation takes DITypeArray.
DITypeArray is an array of DITypeRef, at its creation, we will create
DITypeRef (i.e use the identifier if the type node has an identifier).

This is the last patch to unique the type array of a subroutine type.

rdar://17628609

llvm-svn: 214132
2014-07-28 22:24:06 +00:00
Manman Ren ab8ffbaaee [Debug Info] rename getTypeArray to getElements, setTypeArray to setArrays.
This is the second of a series of patches to handle type uniqueing of the
type array for a subroutine type.

For vector and array types, getElements returns the array of subranges, so it
is a better name than getTypeArray. Even for class, struct and enum types,
getElements returns the members, which can be subprograms.

setArrays can set up to two arrays, the second is the templates.

This commit should have no functionality change.

llvm-svn: 214112
2014-07-28 19:14:13 +00:00
David Blaikie 29459ae83c Reapply "DebugInfo: Don't put fission type units in comdat sections."
This recommits r208930, r208933, and r208975 (by reverting r209338) and
reverts r209529 (the FIXME to readd this functionality once the tools
were fixed) now that DWP has been fixed to cope with a single section
for all fission type units.

Original commit message:

"Since type units in the dwo file are handled by a debug aware tool,
they don't need to leverage the ELF comdat grouping to implement
deduplication. Avoid creating all the .group sections for these as a
space optimization."

llvm-svn: 213956
2014-07-25 17:11:58 +00:00
David Blaikie 2f04011435 Recommit r212203: Don't try to construct debug LexicalScopes hierarchy for functions that do not have top level debug information.
Reverted by Eric Christopher (Thanks!) in r212203 after Bob Wilson
reported LTO issues. Duncan Exon Smith and Aditya Nandakumar helped
provide a reduced reproduction, though the failure wasn't too hard to
guess, and even easier with the example to confirm.

The assertion that the subprogram metadata associated with an
llvm::Function matches the scope data referenced by the DbgLocs on the
instructions in that function is not valid under LTO. In LTO, a C++
inline function might exist in multiple CUs and the subprogram metadata
nodes will refer to the same llvm::Function. In this case, depending on
the order of the CUs, the first intance of the subprogram metadata may
not be the one referenced by the instructions in that function and the
assertion will fail.

A test case (test/DebugInfo/cross-cu-linkonce-distinct.ll) is added, the
assertion removed and a comment added to explain this situation.

This was then reverted again in r213581 as it caused PR20367. The root
cause of this was the early exit in LiveDebugVariables meant that
spurious DBG_VALUE intrinsics that referenced dead variables were not
removed, causing an assertion/crash later on. The fix is to have
LiveDebugVariables strip all DBG_VALUE intrinsics in functions without
debug info as they're not needed anyway. Test case added to cover this
situation (that occurs when a debug-having function is inlined into a
nodebug function) in test/DebugInfo/X86/nodebug_with_debug_loc.ll

Original commit message:

If a function isn't actually in a CU's subprogram list in the debug info
metadata, ignore all the DebugLocs and don't try to build scopes, track
variables, etc.

While this is possibly a minor optimization, it's also a correctness fix
for an incoming patch that will add assertions to LexicalScopes and the
debug info verifier to ensure that all scope chains lead to debug info
for the current function.

Fix up a few test cases that had broken/incomplete debug info that could
violate this constraint.

Add a test case where this occurs by design (inlining a
debug-info-having function in an attribute nodebug function - we want
this to work because /if/ the nodebug function is then inlined into a
debug-info-having function, it should be fine (and will work fine - we
just stitch the scopes up as usual), but should the inlining not happen
we need to not assert fail either).

llvm-svn: 213952
2014-07-25 16:10:16 +00:00
Lang Hames f49bc3f1b1 [X86] Optimize stackmap shadows on X86.
This patch minimizes the number of nops that must be emitted on X86 to satisfy
stackmap shadow constraints.

To minimize the number of nops inserted, the X86AsmPrinter now records the
size of the most recent stackmap's shadow in the StackMapShadowTracker class,
and tracks the number of instruction bytes emitted since the that stackmap
instruction was encountered. Padding is emitted (if it is required at all)
immediately before the next stackmap/patchpoint instruction, or at the end of
the basic block.

This optimization should reduce code-size and improve performance for people
using the llvm stackmap intrinsic on X86.

<rdar://problem/14959522>

llvm-svn: 213892
2014-07-24 20:40:55 +00:00
David Blaikie 26f2268cc5 Revert "Recommit r212203: Don't try to construct debug LexicalScopes hierarchy for functions that do not have top level debug information."
This reverts commit r212649 while I investigate/reduce/etc PR20367.

llvm-svn: 213581
2014-07-21 20:45:59 +00:00
Eric Christopher cfd17dd2be Revert "Reapply "DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself.""""
After a successful build it seems to have come back on a later build.

This reverts commit r213391.

llvm-svn: 213432
2014-07-18 23:57:20 +00:00
David Blaikie db5371b3bb DebugInfo: Assert that all abstract scopes are subprograms, rather than conditionalizing.
There's nothing else these should ever be...

llvm-svn: 213417
2014-07-18 22:26:59 +00:00
David Blaikie 5450240219 Reapply "DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself."""
Recommits 212776 which was reverted in r212793. This has been committed
and recommitted a few times as I try to test it harder and find/fix more
issues. The most recent revert was due to an asan bot failure which I
can't seem to reproduce locally, though I believe I'm following all the
steps the buildbot does.

So I'm going to recommit this in the hopes of investigating the failure
on the buildbot itself... apologies in advance for the bot noise. If
anyone sees failures with this /please/ provide me with any
reproductions, etc.

llvm-svn: 213391
2014-07-18 17:49:10 +00:00
David Majnemer 8bce66b093 CodeGen: Stick constant pool entries in COMDAT sections for WinCOFF
COFF lacks a feature that other object file formats support: mergeable
sections.

To work around this, MSVC sticks constant pool entries in special COMDAT
sections so that each constant is in it's own section.  This permits
unused constants to be dropped and it also allows duplicate constants in
different translation units to get merged together.

This fixes PR20262.

Differential Revision: http://reviews.llvm.org/D4482

llvm-svn: 213006
2014-07-14 22:57:27 +00:00
David Majnemer 5a1c4b8283 CodeGen: Add a getSectionKind method to MachineConstantPoolEntry
This is just a helper routine, no functionality has changed.

llvm-svn: 212993
2014-07-14 22:06:29 +00:00
Saleem Abdulrasool 271ac58eb3 CodeGen: add missing include
Found during windows unwinding work.  This header is indirectly included through
a chain leading through Support/Win64EH.h.  Explicitly include the header.  NFC.

llvm-svn: 212955
2014-07-14 16:28:09 +00:00
David Blaikie de1e1a60e8 Revert "Reapply "DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself.""
This reverts commit r212776.

Nope, still seems to be failing on the sanitizer bots... but hey, not
the msan self-host anymore, it's failing in asan now. I'll start looking
there next.

llvm-svn: 212793
2014-07-11 02:42:57 +00:00
David Blaikie 3ca92d2406 Reapply "DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself."
Committed in r212205 and reverted in r212226 due to msan self-hosting
failure, I believe I've got that fixed by r212761 to Clang.

Original commit message:

"Originally committed in r211723, reverted in r211724 due to failure
cases found and fixed (ArgumentPromotion: r211872, Inlining: r212065),
committed again in r212085 and reverted again in r212089 after fixing
some other cases, such as debug info subprogram lists not keeping track
of the function they represent (r212128) and then short-circuiting
things like LiveDebugVariables that build LexicalScopes for functions
that might not have full debug info.

And again, I believe the invariant actually holds for some reasonable
amount of code (but I'll keep an eye on the buildbots and see what
happens... ).

Original commit message:

PR20038: DebugInfo: Inlined call sites where the caller has debug info
but the call itself has no debug location.

This situation does bad things when inlined, so I've fixed Clang not to
produce inlinable call sites without locations when the caller has debug
info (in the one case where I could find that this occurred). This
updates the PR20038 test case to be what clang now produces, and readds
the assertion that had to be removed due to this bug.

I've also beefed up the debug info verifier to help diagnose these
issues in the future, and I hope to add checks to the inliner to just
assert-fail if it encounters this situation. If, in the future, we
decide we have to cope with this situation, the right thing to do is
probably to just remove all the DebugLocs from the inlined
instructions."

llvm-svn: 212776
2014-07-10 22:59:39 +00:00
David Blaikie 029bd3350e Recommit r212203: Don't try to construct debug LexicalScopes hierarchy for functions that do not have top level debug information.
Reverted by Eric Christopher (Thanks!) in r212203 after Bob Wilson
reported LTO issues. Duncan Exon Smith and Aditya Nandakumar helped
provide a reduced reproduction, though the failure wasn't too hard to
guess, and even easier with the example to confirm.

The assertion that the subprogram metadata associated with an
llvm::Function matches the scope data referenced by the DbgLocs on the
instructions in that function is not valid under LTO. In LTO, a C++
inline function might exist in multiple CUs and the subprogram metadata
nodes will refer to the same llvm::Function. In this case, depending on
the order of the CUs, the first intance of the subprogram metadata may
not be the one referenced by the instructions in that function and the
assertion will fail.

A test case (test/DebugInfo/cross-cu-linkonce-distinct.ll) is added, the
assertion removed and a comment added to explain this situation.

Original commit message:

If a function isn't actually in a CU's subprogram list in the debug info
metadata, ignore all the DebugLocs and don't try to build scopes, track
variables, etc.

While this is possibly a minor optimization, it's also a correctness fix
for an incoming patch that will add assertions to LexicalScopes and the
debug info verifier to ensure that all scope chains lead to debug info
for the current function.

Fix up a few test cases that had broken/incomplete debug info that could
violate this constraint.

Add a test case where this occurs by design (inlining a
debug-info-having function in an attribute nodebug function - we want
this to work because /if/ the nodebug function is then inlined into a
debug-info-having function, it should be fine (and will work fine - we
just stitch the scopes up as usual), but should the inlining not happen
we need to not assert fail either).

llvm-svn: 212649
2014-07-09 21:02:41 +00:00
Eric Christopher 09f7131984 Temporarily revert "Don't try to construct debug LexicalScopes hierarchy for functions that do not have top level debug information." as it appears to be breaking some LTO constructs.
This reverts commit r212203.

llvm-svn: 212298
2014-07-03 22:24:54 +00:00
Ulrich Weigand f236bb1b5b Fix ppcf128 component access on little-endian systems
The PowerPC 128-bit long double data type (ppcf128 in LLVM) is in fact a
pair of two doubles, where one is considered the "high" or
more-significant part, and the other is considered the "low" or
less-significant part.  When a ppcf128 value is stored in memory or a
register pair, the high part always comes first, i.e. at the lower
memory address or in the lower-numbered register, and the low part
always comes second.  This is true both on big-endian and little-endian
PowerPC systems.  (Similar to how with a complex number, the real part
always comes first and the imaginary part second, no matter the byte
order of the system.)

This was implemented incorrectly for little-endian systems in LLVM.
This commit fixes three related issues:

- When printing an immediate ppcf128 constant to assembler output
  in emitGlobalConstantFP, emit the high part first on both big-
  and little-endian systems.

- When lowering a ppcf128 type to a pair of f64 types in SelectionDAG
  (which is used e.g. when generating code to load an argument into a
  register pair), use correct low/high part ordering on little-endian
  systems.

- In a related issue, because lowering ppcf128 into a pair of f64 must
  operate differently from lowering an int128 into a pair of i64,
  bitcasts between ppcf128 and int128 must not be optimized away by the
  DAG combiner on little-endian systems, but must effect a word-swap.

Reviewed by Hal Finkel.

llvm-svn: 212274
2014-07-03 15:06:47 +00:00
David Blaikie 9a0f7948a2 Revert "DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself."
This reverts commit r212205.

Reverting this again, still seeing crashes when building compiler-rt...
Sorry for the continued noise, not sure why I'm failing to reproduce
this locally.

llvm-svn: 212226
2014-07-02 21:42:28 +00:00
David Blaikie 9408f5282e DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself.
Originally committed in r211723, reverted in r211724 due to failure
cases found and fixed (ArgumentPromotion: r211872, Inlining: r212065),
committed again in r212085 and reverted again in r212089 after fixing
some other cases, such as debug info subprogram lists not keeping track
of the function they represent (r212128) and then short-circuiting
things like LiveDebugVariables that build LexicalScopes for functions
that might not have full debug info.

And again, I believe the invariant actually holds for some reasonable
amount of code (but I'll keep an eye on the buildbots and see what
happens... ).

Original commit message:

PR20038: DebugInfo: Inlined call sites where the caller has debug info
but the call itself has no debug location.

This situation does bad things when inlined, so I've fixed Clang not to
produce inlinable call sites without locations when the caller has debug
info (in the one case where I could find that this occurred). This
updates the PR20038 test case to be what clang now produces, and readds
the assertion that had to be removed due to this bug.

I've also beefed up the debug info verifier to help diagnose these
issues in the future, and I hope to add checks to the inliner to just
assert-fail if it encounters this situation. If, in the future, we
decide we have to cope with this situation, the right thing to do is
probably to just remove all the DebugLocs from the inlined instructions.

llvm-svn: 212205
2014-07-02 18:32:05 +00:00
David Blaikie d47fb5b339 Don't try to construct debug LexicalScopes hierarchy for functions that do not have top level debug information.
If a function isn't actually in a CU's subprogram list in the debug info
metadata, ignore all the DebugLocs and don't try to build scopes, track
variables, etc.

While this is possibly a minor optimization, it's also a correctness fix
for an incoming patch that will add assertions to LexicalScopes and the
debug info verifier to ensure that all scope chains lead to debug info
for the current function.

Fix up a few test cases that had broken/incomplete debug info that could
violate this constraint.

Add a test case where this occurs by design (inlining a
debug-info-having function in an attribute nodebug function - we want
this to work because /if/ the nodebug function is then inlined into a
debug-info-having function, it should be fine (and will work fine - we
just stitch the scopes up as usual), but should the inlining not happen
we need to not assert fail either).

llvm-svn: 212203
2014-07-02 18:31:35 +00:00
David Blaikie c8caa1702a Revert "DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself."
This reverts commit r212085.

This breaks the sanitizer bot... & I thought I'd tried pretty hard not
to do that. Guess I need to try harder.

llvm-svn: 212089
2014-07-01 04:11:45 +00:00
David Blaikie b89e6d93d9 DebugInfo: Ensure that all debug location scope chains from instructions within a function, lead to the function itself.
Originally committed in r211723, reverted in r211724 due to failure
cases found and fixed (ArgumentPromotion: r211872, Inlining: r212065),
and I now believe the invariant actually holds for some reasonable
amount of code (but I'll keep an eye on the buildbots and see what
happens... ).

Original commit message:

PR20038: DebugInfo: Inlined call sites where the caller has debug info
but the call itself has no debug location.

This situation does bad things when inlined, so I've fixed Clang not to
produce inlinable call sites without locations when the caller has debug
info (in the one case where I could find that this occurred). This
updates the PR20038 test case to be what clang now produces, and readds
the assertion that had to be removed due to this bug.

I've also beefed up the debug info verifier to help diagnose these
issues in the future, and I hope to add checks to the inliner to just
assert-fail if it encounters this situation. If, in the future, we
decide we have to cope with this situation, the right thing to do is
probably to just remove all the DebugLocs from the inlined instructions.

llvm-svn: 212085
2014-07-01 03:11:59 +00:00
Saleem Abdulrasool 67b548154e CodeGen: rename Win64 ExceptionHandling to WinEH
This exception format is not specific to Windows x64.  A similar approach is
taken on nearly all architectures.  Generalise the name to reflect reality.
This will eventually be used for Windows on ARM data emission as well.

Switch the enum and namespace into an enum class.

llvm-svn: 212000
2014-06-29 21:43:47 +00:00
Saleem Abdulrasool 7206a52522 MC: rename EmitWin64EH routines
Rename the routines to reflect the reality that they are more related to call
frame information than to Win64 EH. Although EH is implemented in an intertwined
manner by augmenting with an exception handler and an associated parameter, the
majority of these routines emit information required to unwind the frames. This
also helps identify that these routines are generic for most windows platforms
(they apply equally to nearly all architectures except x86) although the
encoding of the information is architecture dependent.

Unwinding data is emitted via EmitWinCFI* and exception handling information via
EmitWinEH*.

llvm-svn: 211994
2014-06-29 01:52:01 +00:00
David Blaikie dada538bb4 Revert "Revert "Revert "PR20038: DebugInfo: Inlined call sites where the caller has debug info but the call itself has no debug location."""
Reverting this again, didn't mean to commit it - while r211872 fixes one
of the issues here, there are still others to figure out and address.

This reverts commit r211871.

llvm-svn: 211873
2014-06-27 05:34:05 +00:00
David Blaikie 8832992df5 Revert "Revert "PR20038: DebugInfo: Inlined call sites where the caller has debug info but the call itself has no debug location.""
This reverts commit r211724.

llvm-svn: 211871
2014-06-27 05:31:49 +00:00
Alp Toker e69170a110 Revert "Introduce a string_ostream string builder facilty"
Temporarily back out commits r211749, r211752 and r211754.

llvm-svn: 211814
2014-06-26 22:52:05 +00:00
Alp Toker 614717388c Introduce a string_ostream string builder facilty
string_ostream is a safe and efficient string builder that combines opaque
stack storage with a built-in ostream interface.

small_string_ostream<bytes> additionally permits an explicit stack storage size
other than the default 128 bytes to be provided. Beyond that, storage is
transferred to the heap.

This convenient class can be used in most places an
std::string+raw_string_ostream pair or SmallString<>+raw_svector_ostream pair
would previously have been used, in order to guarantee consistent access
without byte truncation.

The patch also converts much of LLVM to use the new facility. These changes
include several probable bug fixes for truncated output, a programming error
that's no longer possible with the new interface.

llvm-svn: 211749
2014-06-26 00:00:48 +00:00
David Blaikie 2952956fd8 Revert "PR20038: DebugInfo: Inlined call sites where the caller has debug info but the call itself has no debug location."
This reverts commit r211723.

Breaks the ASan/compiler-rt build... guess I didn't test very far at all
:/.

llvm-svn: 211724
2014-06-25 18:20:54 +00:00
David Blaikie 442584588a PR20038: DebugInfo: Inlined call sites where the caller has debug info but the call itself has no debug location.
This situation does bad things when inlined, so I've fixed Clang not to
produce inlinable call sites without locations when the caller has debug
info (in the one case where I could find that this occurred). This
updates the PR20038 test case to be what clang now produces, and readds
the assertion that had to be removed due to this bug.

I've also beefed up the debug info verifier to help diagnose these
issues in the future, and I hope to add checks to the inliner to just
assert-fail if it encounters this situation. If, in the future, we
decide we have to cope with this situation, the right thing to do is
probably to just remove all the DebugLocs from the inlined instructions.

llvm-svn: 211723
2014-06-25 18:03:10 +00:00
NAKAMURA Takumi 1db5995d14 Re-apply r211399, "Generate native unwind info on Win64" with a fix to ignore SEH pseudo ops in X86 JIT emitter.
--
This patch enables LLVM to emit Win64-native unwind info rather than
DWARF CFI.  It handles all corner cases (I hope), including stack
realignment.

Because the unwind info is not flexible enough to describe stack frames
with a gap of unknown size in the middle, such as the one caused by
stack realignment, I modified register spilling code to place all spills
into the fixed frame slots, so that they can be accessed relative to the
frame pointer.

Patch by Vadim Chugunov!

Reviewed By: rnk

Differential Revision: http://reviews.llvm.org/D4081

llvm-svn: 211691
2014-06-25 12:41:52 +00:00
Rafael Espindola f491704e22 Print a=b as an assignment.
In assembly the expression a=b is parsed as an assignment, so it should be
printed as one.

This remove a truly horrible hack for producing a label with "a=.". It would
be used by codegen but would never be reached by the asm parser. Sorry I
missed this when it was first committed.

llvm-svn: 211639
2014-06-24 22:45:16 +00:00
Rafael Espindola 73f364ef5f Remove a temporary hack.
Amusingly this survived a lot longer than the CFI transition. We don't even
support non-cfi assemblers any more.

llvm-svn: 211498
2014-06-23 14:22:55 +00:00
NAKAMURA Takumi d77cefe633 Revert r211399, "Generate native unwind info on Win64"
It broke Legacy JIT Tests on x86_64-{mingw32|msvc}, aka Windows x64.

llvm-svn: 211480
2014-06-22 22:00:56 +00:00
Richard Trieu c1485223a6 Add back functionality removed in r210497.
Instead of asserting, output a message stating that a null pointer was found.

llvm-svn: 211430
2014-06-21 02:43:02 +00:00
Reid Kleckner 4a01230db4 Generate native unwind info on Win64
This patch enables LLVM to emit Win64-native unwind info rather than
DWARF CFI.  It handles all corner cases (I hope), including stack
realignment.

Because the unwind info is not flexible enough to describe stack frames
with a gap of unknown size in the middle, such as the one caused by
stack realignment, I modified register spilling code to place all spills
into the fixed frame slots, so that they can be accessed relative to the
frame pointer.

Patch by Vadim Chugunov!

Reviewed By: rnk

Differential Revision: http://reviews.llvm.org/D4081

llvm-svn: 211399
2014-06-20 20:35:47 +00:00
Yaron Keren 6d3194f7d5 The count() function for STL datatypes returns unsigned, even where it's
only 1/0 result like std::set. Some of the LLVM ADT already return unsigned
count(), while others still return bool count().

In continuation to r197879, this patch modifies DenseMap, DenseSet, 
ScopedHashTable, ValueMap:: count() to return size_type instead of bool,
1 instead of true and 0 instead of false.

size_type is typedef-ed locally within each class to size_t.

http://reviews.llvm.org/D4018

Reviewed by dblaikie.

llvm-svn: 211350
2014-06-20 10:26:56 +00:00
David Blaikie de8e12a49a DebugInfo: Fission: Ensure the address pool entries for location lists are emitted.
The address pool was being emitted before location lists. The latter
could add more entries to the pool which would be lost/never emitted.

llvm-svn: 211284
2014-06-19 17:59:14 +00:00
Oliver Stannard f7693f4c1f Emit DWARF3 call frame information when DWARF3+ debug info is requested
Currently, llvm always emits a DWARF CIE with a version of 1, even when emitting
DWARF 3 or 4, which both support CIE version 3. This patch makes it emit the
newer CIE version when we are emitting DWARF 3 or 4. This will not reduce
compatibility, as we already emit other DWARF3/4 features, and is worth doing as
the DWARF3 spec removed some ambiguities in the interpretation of call frame
information.

It also fixes a minor bug where the "return address" field of the CIE was
encoded as a ULEB128, which is only valid when the CIE version is 3. There are
no test changes for this, because (as far as I can tell) none of the platforms
that we test have a return address register with a DWARF register number >127.

llvm-svn: 211272
2014-06-19 15:39:33 +00:00
Eric Christopher 4c5bff36ad Move -dwarf-version to an MC level command line option so it's
used by all of the MC level tools and codegen. Fix up all uses
in the compiler to use this and set it on the context accordingly.

llvm-svn: 211257
2014-06-19 06:22:08 +00:00
Eric Christopher 07634e2a5b Remove unnecessary include.
llvm-svn: 211256
2014-06-19 06:22:05 +00:00
David Blaikie b9597a8e57 PR20038: DebugInfo missing DIEs for some concrete variables.
I haven't nailed this down entirely, but this is about as small of a
test case as I can seem to construct and adequately demonstrates the
crasher. I'll continue investigating the root cause/fix(es).

llvm-svn: 210993
2014-06-15 19:34:26 +00:00
David Blaikie 6f9e867c45 DebugInfo: Remove some extra handling of abstract variables and instead rely solely on the delayed handling introduced in r210946
Now that we handle finding abstract variables at the end of the module,
remove the upfront handling and just ensure the abstract variable is
built when necessary.

In theory we could have a split implementation, where inlined variables
are immediately constructed referencing the abstract definition, and
concrete variables are delayed - but let's go with one solution for now
unless there's a reason not to.

llvm-svn: 210961
2014-06-13 23:52:55 +00:00
David Blaikie e847f132f7 DebugInfo: Reference abstract definitions from variables in concrete definitions that preceed their first inline definition.
Rather than relying on abstract variables looked up at the time the
concrete variable is created, look them up at the end of the module to
ensure they're referenced even if they're created after the concrete
definition. This completes/matches the work done in r209677 to handle
this for the subprograms themselves.

llvm-svn: 210946
2014-06-13 22:35:44 +00:00
David Blaikie be7c677008 DwarfDebug::getExistingAbstractVariable: constify an existing reference parameter that didn't need to be mutated.
llvm-svn: 210944
2014-06-13 22:29:31 +00:00
David Blaikie eb1a27239c DebugInfo: Following up to r209677, refactor local variable emission to delay the choice between emitting the definition attributes or using DW_AT_abstract_definition
This doesn't fix the abstract variable handling yet, but it introduces a
similar delay mechanism as was added for subprograms, causing
DW_AT_location to be reordered to the beginning of the attribute list
for local variables, and fixes all the test fallout for that.

A subsequent commit will remove the abstract variable handling in
DbgVariable and just do the abstract variable lookup at module end to
ensure that abstract variables introduced after their concrete
counterparts are appropriately referenced by the concrete variable.

llvm-svn: 210943
2014-06-13 22:18:23 +00:00
Saleem Abdulrasool 8076cab0ce CodeGen: refactor DwarfException
DwarfException served as a base class for exception handling directive emission.
However, this is also used by other exception models (e.g. Win64EH).  Rename
this class to EHStreamer and split it out of DwarfException.h.  NFC.

Use the opportunity to fix up some of the documentation comments to match
current LLVM style.  Also rename some functions to conform better with current
LLVM coding style.

llvm-svn: 210622
2014-06-11 01:19:03 +00:00
Richard Trieu a23043cb9c Removing an "if (!this)" check from two print methods. The condition will
never be true in a well-defined context.  The checking for null pointers
has been moved into the caller logic so it does not rely on undefined behavior.

llvm-svn: 210497
2014-06-09 22:53:16 +00:00
Alexey Samsonov 8000e2734e Generate better location ranges for some register-described variables.
Don't terminate location ranges for register-described variables
at the end of machine basic block if this register is never modified
in the function body, except for the prologue and epilogue. Prologue
location is guessed by FrameSetup flags on MachineInstructions, while
epilogue location is deduced from debug locations of instructions
in the basic blocks ending with return instructions.

This patch is mostly targeted to fix non-trivial debug locations for
variables addressed via stack and frame pointers.

It is not really a generic fix. We can still produce poor debug info
for register-described variables if this register *is* modified somewhere
in the function, but in unrelated places. This might be the case for the debug
info in optimized binaries (e.g. for local variables in inlined functions).
LiveDebugVariables pass in CodeGen attempts to fix this problem by adjusting
DBG_VALUE instructions, but this pass is tied to greedy register allocator,
which is used in optimized builds only. Proper fix would likely involve
generalizing LiveDebugVariables to all register allocators. See more discussion
in http://reviews.llvm.org/D3933 review thread.

I'm proceeding with this patch to fix immediate severe problems and
important cases, e.g. fix completely broken debug info with AddressSanitizer
and fix PR19307 (missing debug info for by-value std::string arguments).

llvm-svn: 210492
2014-06-09 21:53:47 +00:00
Alp Toker 5c53639492 Fix typos
llvm-svn: 210401
2014-06-07 21:23:09 +00:00
David Blaikie 3dca59902b DebugInfo: Use the scope of the function declaration, if any, to name a function in DWARF pubnames
This ensures that member functions, for example, are entered into
pubnames with their fully qualified name, rather than inside the global
namespace.

llvm-svn: 210379
2014-06-06 22:29:05 +00:00
David Blaikie 553eb4a880 DebugInfo: pubnames: include file-local (static or anonymous namespace) variables and anonymous namespaces themselves.
Still some issues with name qualification, FIXMEs added to test cases
and fixes will come next.

llvm-svn: 210378
2014-06-06 22:16:56 +00:00
Rafael Espindola 0766ae08e5 Fix a few issues with comdat handling on COFF.
* Section association cannot use just the section name as many
sections can have the same name. With this patch, the comdat symbol in
an assoc section is interpreted to mean a symbol in the associated
section and the mapping is discovered from it.

* Comdat symbols were not being set correctly. Instead we were getting
whatever was output first for that section.

A consequence is that associative sections now must use .section to
set the association. Using .linkonce would not work since it is not
possible to change a sections comdat symbol (it is used to decide if
we should create a new section or reuse an existing one).

This includes r210298, which was reverted because it was asserting
on an associated section having the same comdat as the associated
section.

llvm-svn: 210367
2014-06-06 19:26:12 +00:00
Alexey Samsonov 45d638a3fd Fix null dereference with -debug-only=dwarfdebug
llvm-svn: 210299
2014-06-05 23:10:19 +00:00
Tom Roeder 44cb65fff1 Add a new attribute called 'jumptable' that creates jump-instruction tables for functions marked with this attribute.
It includes a pass that rewrites all indirect calls to jumptable functions to pass through these tables.

This also adds backend support for generating the jump-instruction tables on ARM and X86.
Note that since the jumptable attribute creates a second function pointer for a
function, any function marked with jumptable must also be marked with unnamed_addr.

llvm-svn: 210280
2014-06-05 19:29:43 +00:00
David Blaikie 72c3aa39b7 Revert r210221 again, due to a crash Richard Smith has provided involving self-hosting LLVM with libc++.
Test case coming, once I reduce it.

llvm-svn: 210236
2014-06-05 02:04:59 +00:00
David Blaikie 367fb01d70 DebugInfo: Reuse existing LexicalScope to retrieve the scope's MDNode, rather than looking it up through the DebugLoc.
No functional change intended, just streamlines the abstract variable
lookup/construction to use a common entry point.

llvm-svn: 210234
2014-06-05 01:30:50 +00:00
David Blaikie 087e7203a9 DebugInfo: Roll argument insertion into variable insertion to ensure arguments are correctly handled in all cases.
No functional change intended.

llvm-svn: 210233
2014-06-05 01:04:20 +00:00
David Blaikie bb6a4e2fea PR19388: DebugInfo: Emit dead arguments in their originally declared order.
Unused arguments were not being added to the argument list, but instead
treated as arbitrary scope variables. This meant they weren't carefully
added in the original argument order.

In this particular example, though, it turns out the argument is only
/mostly/ unused (well, actually it's entirely used, but in a specific
way). It's a struct that, due to ABI reasons, is decomposed into chunks
(exactly one chunk, since it has one member) and then passed. Since only
one of those chunks is used (SROA, etc, kill the original reconstitution
code) we don't have a location to describe the whole variable.

In this particular case, since the struct consists of just the one int,
once we have partial location information, this should have a location
that describes the entire variable (since the piece is the entirety of
the object).

And at some point we'll need to describe the location of even /entirely/
unused arguments so that they can at least be printed on function entry.

llvm-svn: 210231
2014-06-05 00:51:35 +00:00
David Blaikie 6cfa9e1a6d DebugInfo: Add comments/assert description to r209674 based on Eric Christopher's post-commit review feedback.
llvm-svn: 210228
2014-06-05 00:25:26 +00:00
David Blaikie 36408e7569 DebugInfo: Reapply r209984 (reverted in r210143), asserting that abstract DbgVariables have DIEs.
Abstract variables within abstract scopes that are entirely optimized
away in their first inlining are omitted because their scope is not
present so the variable is never created. Instead, we should ensure the
scope is created so the variable can be added, even if it's been
optimized away in its first inlining.

This fixes the incorrect debug info in missing-abstract-variable.ll
(added in r210143) and passes an asserts self-hosting build, so
hopefully there's not more of these issues left behind... *fingers
crossed*.

llvm-svn: 210221
2014-06-04 23:50:52 +00:00
Hans Wennborg 8e873329a1 Don't emit structors for available_externally globals (PR19933)
We would previously assert here when trying to figure out the section
for the global.

This makes us handle the situation more gracefully since the IR isn't
malformed.

Differential Revision: http://reviews.llvm.org/D4022

llvm-svn: 210215
2014-06-04 21:04:54 +00:00
David Blaikie 19a8b90763 DebugInfo: Partial revert r209984 due to more cases where abstract DbgVariables do not have associated DIEs.
Along with a test case to demonstrate that due to inlining order there
are cases where abstract variable DIEs are not constructed since the
abstract subprogram was built due to a previous inlining that optimized
away those variables. This produces incorrect debug info (the 'missing'
abstract variable causes the inlined instance of that variable to be
emitted with a full description (name, line, file) rather than
referencing the abstract origin), but this commit at least ensures that
it doesn't crash...

llvm-svn: 210143
2014-06-04 01:30:59 +00:00
Rafael Espindola 64c1e18033 Allow alias to point to an arbitrary ConstantExpr.
This  patch changes GlobalAlias to point to an arbitrary ConstantExpr and it is
up to MC (or the system assembler) to decide if that expression is valid or not.

This reduces our ability to diagnose invalid uses and how early we can spot
them, but it also lets us do things like

@test5 = alias inttoptr(i32 sub (i32 ptrtoint (i32* @test2 to i32),
                                 i32 ptrtoint (i32* @bar to i32)) to i32*)

An important implication of this patch is that the notion of aliased global
doesn't exist any more. The alias has to encode the information needed to
access it in its metadata (linkage, visibility, type, etc).

Another consequence to notice is that getSection has to return a "const char *".
It could return a NullTerminatedStringRef if there was such a thing, but when
that was proposed the decision was to just uses "const char*" for that.

llvm-svn: 210062
2014-06-03 02:41:57 +00:00
David Blaikie 23b4ecbff4 DebugInfo: Assert that DbgVariables have associated DIEs
This was previously committed in r209680 and reverted in r209683 after
it caused sanitizer builds to crash.

The issue seems to be that the DebugLoc associated with dbg.value IR
intrinsics isn't necessarily accurate. Instead, we duplicate the
DIVariables and add an InlinedAt field to them to record their
location.

We were using this InlinedAt field to compute the LexicalScope for the
variable, but not using it in the abstract DbgVariable construction and
mapping. This resulted in a formal parameter to the current concrete
function, correctly having no InlinedAt information, but incorrectly
having a DebugLoc that described an inlined location within the
function... thus an abstract DbgVariable was created for the variable,
but its DIE was never constructed (since the LexicalScope had no such
variable). This DbgVariable was silently ignored (by testing for a
non-null DIE on the abstract DbgVariable).

So, fix this by using the right scoping information when constructing
abstract DbgVariables.

In the long run, I suspect we want to undo the work that added this
second kind of location tracking and fix the places where the DebugLoc
propagation on the dbg.value intrinsic fails. This will shrink debug
info (by not duplicating DIVariables), make it more efficient (by not
having to construct new DIVariable metadata nodes to try to map back to
a single variable), and benefit all instructions.

But perhaps there are insurmountable issues with DebugLoc quality that
I'm unaware of... I just don't know how we can't /just keep the DebugLoc
from the dbg.declare to the dbg.values and never get this wrong/.

Some history context:

http://llvm.org/viewvc/llvm-project?view=revision&revision=135629
http://llvm.org/viewvc/llvm-project?view=revision&revision=137253

llvm-svn: 209984
2014-06-01 03:38:13 +00:00
Alp Toker da0c7933cf Fix typos
llvm-svn: 209982
2014-05-31 21:26:28 +00:00
Adrian Prantl c11975439c Roll DbgVariable::setMInsn into the constructor. No functional changes.
llvm-svn: 209920
2014-05-30 21:10:13 +00:00
Logan Chien c002981084 Fix MIPS exception personality encoding.
For MIPS, we have to encode the personality routine with
an indirect pointer to absptr; otherwise, some link warning
warning will be raised, and the program might crash in some
early MIPS Android device.

llvm-svn: 209907
2014-05-30 16:48:56 +00:00
Adrian Prantl fef140df96 Debug Info: Remove unused code. The MInsn of an _abstract_ variable is
never used again and updating the abstract variable for each inlined
instance of it was questionable in the first place.

llvm-svn: 209829
2014-05-29 16:56:48 +00:00
Alexey Samsonov bb2990df58 Change representation of instruction ranges where variable is accessible.
Use more straightforward way to represent the set of instruction
ranges where the location of a user variable is defined - vector of pairs
of instructions (defining start/end of each range),
instead of a flattened vector of instructions where some instructions
are supposed to start the range, and the rest are supposed to "clobber" it.

Simplify the code which generates actual .debug_loc entries.

No functionality change.

llvm-svn: 209698
2014-05-27 23:09:50 +00:00
Alexey Samsonov 8a86d6da26 Factor out looking for prologue end into a function
llvm-svn: 209697
2014-05-27 22:47:41 +00:00
Alexey Samsonov f0e0cca0c7 Don't pre-populate the set of keys in the map with variable locations history.
Current implementation of calculateDbgValueHistory already creates the
keys in the expected order (user variables are listed in order of appearance),
and should do so later by contract.

No functionality change.

llvm-svn: 209690
2014-05-27 22:35:00 +00:00
David Blaikie 6900674aaf DebugInfo: partially revert cleanup committed in r209680
I'm not sure exactly where/how we end up with an abstract DbgVariable
with a null DIE, but we do... looking into it & will add a test and/or
fix when I figure it out.

Currently shows up in selfhost or compiler-rt builds.

llvm-svn: 209683
2014-05-27 20:20:43 +00:00
David Blaikie b85f0080e7 DebugInfo: Simplify solution to avoid DW_AT_artificial on inlined parameters.
Originally committed in r207717, I clearly didn't look very closely at
the code to understand how existing things were working...

llvm-svn: 209680
2014-05-27 19:34:32 +00:00
David Blaikie 482097d098 DebugInfo: Create abstract function definitions even when concrete definitions preceed inline definitions.
After much puppetry, here's the major piece of the work to ensure that
even when a concrete definition preceeds all inline definitions, an
abstract definition is still created and referenced from both concrete
and inline definitions.

Variables are still broken in this case (see comment in
dbg-value-inlined-parameter.ll test case) and will be addressed in
follow up work.

llvm-svn: 209677
2014-05-27 18:37:55 +00:00
David Blaikie 2910f62084 DebugInfo: Avoid an extra map lookup when finding abstract subprogram DIEs.
llvm-svn: 209676
2014-05-27 18:37:51 +00:00
David Blaikie 3c2fff3fe6 DebugInfo: Lazily construct subprogram definition DIEs.
A further step to correctly emitting concrete out of line definitions
preceeding inlined instances of the same program.

To do this, emission of subprograms must be delayed until required since
we don't know which (abstract only (if there's no out of line
definition), concrete only (if there are no inlined instances), or both)
DIEs are required at the start of the module.

To reduce the test churn in the following commit that actually fixes the
bug, this commit introduces the lazy DIE construction and cleans up test
cases that are impacted by the changes in the resulting DIE ordering.

llvm-svn: 209675
2014-05-27 18:37:48 +00:00
David Blaikie f7221adb8e DebugInfo: Lazily attach definition attributes to definitions.
This is a precursor to fixing inlined debug info where the concrete,
out-of-line definition may preceed any inlined usage. To cope with this,
the attributes that may appear on the concrete definition or the
abstract definition are delayed until the end of the module. Then, if an
abstract definition was created, it is referenced (and no other
attributes are added to the out-of-line definition), otherwise the
attributes are added directly to the out-of-line definition.

In a couple of cases this causes not just reordering of attributes, but
reordering of types. When the creation of the attribute is delayed, if
that creation would create a type (such as for a DW_AT_type attribute)
then other top level DIEs may've been constructed during the delay,
causing the referenced type to be created and added after those
intervening DIEs. In the extreme case, in cross-cu-inlining.ll, this
actually causes the DW_TAG_basic_type for "int" to move from one CU to
another.

llvm-svn: 209674
2014-05-27 18:37:43 +00:00
David Blaikie 7f91686f07 DebugInfo: Separate out the addition of subprogram attribute additions so that they can be added later depending on whether or not the function is inlined.
llvm-svn: 209673
2014-05-27 18:37:38 +00:00
David Blaikie ab53c91010 DwarfUnit: Remove some misleading no-op code introduced in r204162.
Post commit review feedback from Manman called this out, but it looks
like it slipped through the cracks.

llvm-svn: 209611
2014-05-26 05:32:21 +00:00
David Blaikie 169ffe41af DebugInfo: Put concrete definitions referencing abstract definitions in the same scope as the abstract definition.
This seems like a simple cleanup/improved consistency, but also helps
lay the foundation to fix the bug mentioned in the test case: concrete
definitions preceeding any inlined usage aren't properly split into
concrete + abstract (because they're not known to need it until it's too
late).

Once we start deferring this choice until later, we won't have the
choice to put concrete definitions for inlined subroutines in a
different scope from concrete definitions for non-inlined subroutines
(since we won't know at time-of-construction which one it'll be). This
change brings those two cases into alignment ahead of that future
chaneg/fix.

llvm-svn: 209547
2014-05-23 20:25:15 +00:00
David Blaikie 05b8584f16 Add FIXME comment based on code review feedback by Hal Finkel on r209338
llvm-svn: 209529
2014-05-23 16:53:14 +00:00
David Blaikie 4860225570 Rename a couple of variables to be more accurate.
It's not really a "ScopeDIE", as such - it's the abstract function
definition's DIE. And we usually use "SP" for subprograms, rather than
"Sub".

llvm-svn: 209499
2014-05-23 05:03:23 +00:00
David Blaikie 96fb9024f2 DebugInfo: Fix cross-CU references for scopes (and variables within those scopes) in abstract definitions of cross-CU inlined functions
Found by Adrian Prantl during post-commit review of r209335.

llvm-svn: 209498
2014-05-23 04:23:06 +00:00
David Blaikie 8729bca333 DebugInfo: Simplify dead variable collection slightly.
constructSubprogramDIE was already called for every subprogram in every
CU when the module was started - there's no need to call it again at
module finalization.

llvm-svn: 209372
2014-05-22 00:48:36 +00:00
David Blaikie 2da282b860 Revert "DebugInfo: Don't put fission type units in comdat sections."
This reverts commit r208930, r208933, and r208975.

It seems not all fission consumers are ready to handle this behavior.
Reverting until tools are brought up to spec.

llvm-svn: 209338
2014-05-21 23:27:41 +00:00
David Blaikie 1ea9db2dce DebugInfo: Use the SPMap to find the parent CU of inlined functions as they may not be in the current CU
Committed in r209178 then reverted in r209251 due to LTO breakage,
here's a proper fix for the case of the missing subprogram DIE. The DIEs
were there, just in other compile units. Using the SPMap we can find the
right compile unit to search for and produce cross-unit references to
describe this kind of inlining.

One existing test case needed to be updated because it had a function
that wasn't in the CU's subprogram list, so it didn't appear in the
SPMap.

llvm-svn: 209335
2014-05-21 23:14:12 +00:00
David Blaikie 825bdd2fc6 DebugInfo: Ensure concrete out of line variables from inlined functions reference their abstract origins.
llvm-svn: 209327
2014-05-21 22:41:17 +00:00
David Blaikie ce7a1bd038 DebugInfo: Simplify subprogram declaration creation/references and accidentally refix PR11300.
Also simplifies the linkage name handling a little too.

llvm-svn: 209311
2014-05-21 18:04:33 +00:00
David Blaikie 374af662e9 Revert "DebugInfo: Assume all subprogram DIEs have been created before any abstract subprograms are constructed."
This reverts commit r209178.

This seems to be asserting in an LTO build on some internal Apple
buildbots. No upstream reproduction (and I don't have an LLVM-aware gold
built right now to reproduce it personally) but it's a small patch & the
failure's semi-plausible so I'm going to revert first while I try to
reproduce this.

llvm-svn: 209251
2014-05-20 22:33:09 +00:00
David Blaikie 93ef46b02a Unbreak the sanitizer buildbots after r209226 due to SROA issue described in http://reviews.llvm.org/D3714
Undecided whether this should include a test case - SROA produces bad
dbg.value metadata describing a value for a reference that is actually
the value of the thing the reference refers to. For now, loosening the
assert lets this not assert, but it's still bogus/wrong output...

If someone wants to tell me to add a test, I'm willing/able, just
undecided. Hopefully we'll get SROA fixed soon & we can tighten up this
assertion again.

llvm-svn: 209240
2014-05-20 21:40:13 +00:00
David Blaikie 1d9aec67b0 Fix test breakage introduced in r209223.
Oops, broke the broken enum constants again.

llvm-svn: 209226
2014-05-20 18:36:35 +00:00
Alexey Samsonov dfcaf9c8d8 Rewrite calculateDbgValueHistory to make it (hopefully) more transparent.
This change preserves the original algorithm of generating history
for user variables, but makes it more clear.

High-level description of algorithm:
Scan all the machine basic blocks and machine instructions in the order
they are emitted to the object file. Do the following:
1) If we see a DBG_VALUE instruction, add it to the history of the
corresponding user variable. Keep track of all user variables, whose
locations are described by a register.
2) If we see a regular instruction, look at all the registers it clobbers,
and terminate the location range for all variables described by these registers.
3) At the end of the basic block, terminate location ranges for all
user variables described by some register.

Although this change shouldn't be user-visible (the contents of .debug_loc section
should be the same), it changes some internal assumptions about the set
of instructions used to track the variable locations. Watching the bots.

llvm-svn: 209225
2014-05-20 18:34:54 +00:00
David Blaikie 2af1c805b4 PR19767: DebugInfo emission of pointer constants.
In refactoring DwarfUnit::isUnsignedDIType I restricted it to only work
on values with signedness (unsigned or signed), asserting on anything
else (which did uncover some bugs). But it turns out that we do need to
emit constants of signless data, such as pointer constants - only null
pointer constants are known to need this so far, but it's conceivable
that there might be non-null pointer constants at some point (hardcoded
address offsets for device drivers?).

This patch just uses 'unsigned' for signless data such as pointer
constants. Arguably we could use signless representations
(DW_FORM_dataN) instead, allowing a trinary result from isUnsignedDIType
(signed, unsigned, signless), but this seems reasonable for now.

llvm-svn: 209223
2014-05-20 18:21:51 +00:00
David Blaikie 8e1d489351 DebugInfo: Emit function definitions within their namespace scope.
This workaround (presumably for ancient GDB) doesn't appear to be
required (GDB 7.5 seems to tolerate function definition DIEs in
namespace scope just fine).

llvm-svn: 209189
2014-05-20 03:23:24 +00:00
David Blaikie 424b59b1ce DebugInfo: Assume all subprogram DIEs have been created before any abstract subprograms are constructed.
Since we visit the whole list of subprograms for each CU at module
start, this is clearly true - don't test for the case, just assert it.

A few old test cases seemed to have incomplete subprogram lists, but any
attempt to reproduce them shows full subprogram lists that even include
entities that have been completely inlined and the out of line
definition removed.

llvm-svn: 209178
2014-05-19 23:16:19 +00:00
David Blaikie 973141a035 DebugInfo: Don't include DW_AT_inline on each abstract definition multiple times.
When I refactored this in r208636 I accidentally caused this to be added
multiple times to each abstract subprogram (not accounting for the
deduplicating effect of the InlinedSubprogramDIEs set).

This got better in r208798 when the abstract definitions got the
attribute added to them at construction time, but still had the
redundant copies introduced in r208636.

This commit removes those excess DW_AT_inlines and relies solely on the
insertion in r208798.

llvm-svn: 209166
2014-05-19 22:07:16 +00:00
David Blaikie 48b056bab0 DebugInfo: Fix missing inlined_subroutines caused by r208748.
The check in DwarfDebug::constructScopeDIE was meant to consider inlined
subroutines as any non-top-level scope that was a subprogram. Instead of
checking "not top level scope" it was checking if the /subprogram's/
scope was non-top-level.

Fix this and beef up a test case to demonstrate some of the missing
inlined_subroutines are no longer missing.

In the course of fixing this I also found that r208748 (with this fix)
found one /extra/ inlined_subroutine in concrete_out_of_line.ll due to
two inlined_subroutines having the same inlinedAt location. The previous
implementation was collapsing these into a single inlined subroutine.

I'm not sure what the original code was that created this .ll file so
I'm not sure if this actually happens in practice today. Since we
deliberately include column information to disambiguate two calls on the
same line, that may've addressed this bug in the frontend, but it's good
to know that workaround isn't necessary for this particular case
anymore.

llvm-svn: 209165
2014-05-19 21:54:31 +00:00