Commit Graph

102597 Commits

Author SHA1 Message Date
Duncan P. N. Exon Smith
f44eda4764 Revert "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206704, as expected.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206707 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 22:46:00 +00:00
Duncan P. N. Exon Smith
c404a5334e Revert "blockfreq: Temporarily turn on -debug-only=block-freq"
This reverts commit r206705, as planned.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206706 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 22:45:44 +00:00
Duncan P. N. Exon Smith
69552aa77e blockfreq: Temporarily turn on -debug-only=block-freq
These tests fail after my BlockFrequencyInfo rewrite on two buildbots
[1][2].  I can't reproduce it locally, so I'm temporarily turning on
-debug-only=block-freq so I can find the problem.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1860
[2]: http://llvm-amd64.freebsd.your.org/b/builders/clang-i386-freebsd/builds/18477

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206705 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 22:40:56 +00:00
Duncan P. N. Exon Smith
f465370a49 Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206677, reapplying my BlockFrequencyInfo rewrite.

I've done a careful audit, added some asserts, and fixed a couple of
bugs (unfortunately, they were in unlikely code paths).  There's a small
chance that this will appease the failing bots [1][2].  (If so, great!)

If not, I have a follow-up commit ready that will temporarily add
-debug-only=block-freq to the two failing tests, allowing me to compare
the code path between what the failing bots and what my machines (and
the rest of the bots) are doing.  Once I've triggered those builds, I'll
revert both commits so the bots go green again.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816
[2]: http://llvm-amd64.freebsd.your.org/b/builders/clang-i386-freebsd/builds/18445

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206704 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 22:34:26 +00:00
Yaron Keren
64b2297786 Patch by Vadim Chugunov
Win64 stack unwinder gets confused when execution flow "falls through" after
a call to 'noreturn' function. This fixes the "missing epilogue" problem by 
emitting a trap instruction for IR 'unreachable' on x86_x64-pc-windows.

A secondary use for it would be for anyone wanting to make double-sure that
'noreturn' functions, indeed, do not return.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206684 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 13:47:43 +00:00
Yaron Keren
2fa9e6ca34 Patch by Ray Donnelly to print register names instead of numbers.
http://reviews.llvm.org/D3422



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206683 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 05:40:09 +00:00
David Blaikie
428d601bd3 Add parens to appease GCC warning.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206678 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 00:50:15 +00:00
Duncan P. N. Exon Smith
2033057de8 Revert "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)
This reverts commit r206666, as planned.

Still stumped on why the bots are failing.  Sanitizer bots haven't
turned anything up.  If anyone can help me debug either of the failures
(referenced in r206666) I'll owe them a beer.  (In the meantime, I'll be
auditing my patch for undefined behaviour.)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206677 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 00:42:46 +00:00
Justin Bogner
55c1e1bd26 OnDiskHashTable: Audit types and use offset_type consistently
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206675 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 00:33:15 +00:00
Justin Bogner
e382065b82 ProfileData: Avoid UB when reading
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206674 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-19 00:33:12 +00:00
Justin Bogner
1907b94222 OnDiskHashTable: Fix a think-o with offset_type
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206672 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 23:50:07 +00:00
Nick Lewycky
6b2b2043c9 Check whether functions have any lines associated before emitting coverage info for them. This isn't just a size/time saving, gcov may crash on these.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206671 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 23:32:28 +00:00
Justin Bogner
aae82fb2f7 llvm-profdata: Avoid writing to /dev/null in tests
We fseek on our output file in llvm-profdata, which errors on some
systems. Avoid getting into the situation by writing to /dev/null

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206670 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 23:25:35 +00:00
Kevin Enderby
1a47d66496 Change the ARM assembler to require a :lower16: or :upper16 on non-constant
expressions for mov instructions instead of silently truncating by default.

For the ARM assembler, we want to avoid misleadingly allowing something
like "mov r0, <symbol>" especially when we turn it into a movw and the
expression <symbol> does not have a :lower16: or :upper16" as part of the
expression.  We don't want the behavior of silently truncating, which can be
unexpected and lead to bugs that are difficult to find since this is an easy
mistake to make.

This does change the previous behavior of llvm but actually matches an
older gnu assembler that would not allow this but print less useful errors
of like “invalid constant (0x927c0) after fixup” and “unsupported relocation on
symbol foo”.  The error for llvm is "immediate expression for mov requires
:lower16: or :upper16" with correct location information on the operand
as shown in the added test cases.

rdar://12342160


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206669 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 23:06:39 +00:00
Justin Bogner
ad326ae3f6 test: Add extra run lines to investigate an error on the bots
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206668 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 23:05:31 +00:00
Duncan P. N. Exon Smith
036e26bc29 Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)
This reverts commit r206628, reapplying r206622 (and r206626).

Two tests are failing only on buildbots [1][2]: i.e., I can't reproduce
on Darwin, and Chandler can't reproduce on Linux.  Asan and valgrind
don't tell us anything, but we're hoping the msan bot will catch it.

So, I'm applying this again to get more feedback from the bots.  I'll
leave it in long enough to trigger builds in at least the sanitizer
buildbots (it was failing for reasons unrelated to my commit last time
it was in), and hopefully a few others.... and then I expect to revert a
third time.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816
[2]: http://llvm-amd64.freebsd.your.org/b/builders/clang-i386-freebsd/builds/18445

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206666 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 22:30:03 +00:00
Alexey Samsonov
e0d2d7fb26 [llvm-symbolizer] Print file/line for a PC even if there is no DIE describing it.
This is important for symbolizing executables with debug info in
unavailable .dwo files. Even if all DIE entries are missing, we can
still symbolize an address: function name can be fetched from symbol table,
and file/line info can be fetched from line table.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206665 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 22:22:44 +00:00
Justin Bogner
1c60993799 ProfileData: Don't forward declare ComputeHash and make it static inline
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206663 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 22:00:22 +00:00
David Blaikie
2e3463ec43 Compress debug sections only when beneficial.
Both ZLIB and the debug info compressed section header ("ZLIB" + the
size of the uncompressed data) take some constant overhead so in some
cases the compressed data is actually larger than the uncompressed data.
In these cases, just don't compress or rename the section at all.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206659 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:52:26 +00:00
Justin Bogner
e153fb33e4 ProfileData: Add support for the indexed instrprof format
This adds support for an indexed instrumentation based profiling
format, which is just a small header and an on disk hash table.  This
format will be used by clang's -fprofile-instr-use= for PGO.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206656 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:48:40 +00:00
Reid Kleckner
4c464def6a Added Sphinx documentation generation to CMake build system.
The option LLVM_ENABLE_SPHINX option enables the "docs-llvm-html",
"docs-llvm-man" targets but does not build them by default. The
following CMake options have been added that control what targets are
made available

SPHINX_OUTPUT_HTML
SPHINX_OUTPUT_MAN

If LLVM_BUILD_DOCS is enabled then the enabled docs-llvm-* targets will
be built by default and if ``make install`` is run then docs-llvm-html
and docs-llvm-man will be installed (tested on Linux only).

The add_sphinx_target function is in its own file so it can be included
by other projects that use Sphinx for their documentation.

Patch by Daniel Liew <daniel.liew@imperial.ac.uk>!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206655 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:45:25 +00:00
Alexey Samsonov
08ef0202ce [DWARF parser] Turn DILineInfo into a struct.
Immutable DILineInfo doesn't bring any benefits and complicates
code. Also, use std::string instead of SmallString<16> for file
and function names - their length can vary significantly.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206654 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:36:39 +00:00
David Blaikie
037da24c10 Update the fragments of symbols in compressed sections.
While unnamed relocations are already cached in side tables in
ELFObjectWriter::RecordRelocation, symbols still need their fragments
updated to refer to the newly compressed fragment (even if that fragment
isn't big enough to fit the offset). Even though we only create
temporary symbols in debug info sections this comes up in 32 bit builds
where even temporary symbols in mergeable sections (such as debug_str)
have to be emitted as named symbols.

I tried a few other ways to do this but they all didn't work for various
reasons:

1) Canonicalize the MCSymbolData in RecordRelocation, nulling out the
Fragment (so it didn't have to be updated by CompressDebugSection). This
doesn't work because some code relies on symbols having fragments to
indicate that they're defined, I think.

2) Canonicalize the MCSymbolData in RecordRelocation to be "first
fragment + absolute offset" so it would be cheaper to just test and
update the fragment in CompressDebugSections. This doesn't work because
the offset computed in RecordRelocation isn't that of the symbol's
fragment, it's the passed in fragment (I haven't figured out what that
fragment is - perhaps it's the location where the relocation is to be
written). And if the fragment offset has to be computed only for this
use we might as well just do it when we need to, in
CompressDebugSection.

I also added an assert to help catch this a bit more clearly, even
though it is UB. The test case improvements would either assert fail
and/or valgrind vail without the fix, even if they wouldn't necessarily
fail the FileCheck output.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206653 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:24:12 +00:00
Chad Rosier
6c4ec69c6b [ARM64] Ports the Cortex-A53 Machine Model description from AArch64.
Summary:
This port includes the rudimentary latencies that were provided for
the Cortex-A53 Machine Model in the AArch64 backend. It also changes
the SchedAlias for COPY in the Cyclone model to an explicit
WriteRes mapping to avoid conflicts in other subtargets.

Differential Revision: http://reviews.llvm.org/D3427
Patch by Dave Estes <cestes@codeaurora.org>!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206652 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:22:04 +00:00
Reid Kleckner
ed5604850a Remove -simplify-libcalls pass form Passes documentation
This pass was removed in r184459.

Also added note that the InstCombine pass does library call
simplification.

Patch slightly modified from one by Daniel Liew
<daniel.liew@imperial.ac.uk>!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206650 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:19:06 +00:00
Yaron Keren
904f8dcaa4 Expanded test for x86-pc-windows-gnu and x86_64-pc-windows-gnu environments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206649 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 21:10:11 +00:00
Chandler Carruth
7dcb168656 [LCG] Fix the bugs that Ben pointed out in code review (and the MSan bot
caught). Sad that we don't have warnings for these things, but bleh, no
idea how to fix that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206646 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 20:44:16 +00:00
Justin Bogner
abc5eea499 OnDiskHashTable: Expect the Info type to declare the offset type
This changes the on-disk hash to get the type to use for offsets from
the Info type, so that clients can be more flexible with the size of
table they support.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206643 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 20:39:46 +00:00
Justin Bogner
acf59d9738 OnDiskHashTable: Expect the Info type to declare the hash size
This changes the on-disk hash to get the size of a hash value from the
Info type, so that clients can be more flexible with the types of hash
they use.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206642 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 20:39:43 +00:00
Alexey Samsonov
4387550026 [DWARF parser] Respect address ranges specified in compile unit DIE.
When address ranges for compile unit are specified in compile unit DIE
itself, there is no need to collect ranges from children subprogram DIEs.

This change speeds up llvm-symbolizer on Clang-produced binaries with
full debug info. For instance, symbolizing a first address in a 1Gb binary
is now 2x faster (1s vs. 2s).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206641 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 20:30:27 +00:00
Benjamin Kramer
561edae834 Remove a couple of redundant copies of SmallVector::operator==.
No functionality change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206635 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 19:48:03 +00:00
Adam Nemet
d290fa608f [X86] Improve buildFromShuffleMostly for AVX
For a 256-bit BUILD_VECTOR consisting mostly of shuffles of 256-bit vectors,
both the BUILD_VECTOR and its operands may need to be legalized in multiple
steps.  Consider:

(v8f32 (BUILD_VECTOR (extract_vector_elt (v8f32 %vreg0,) Constant<1>),
                     (extract_vector_elt %vreg0, Constant<2>),
                     (extract_vector_elt %vreg0, Constant<3>),
                     (extract_vector_elt %vreg0, Constant<4>),
                     (extract_vector_elt %vreg0, Constant<5>),
                     (extract_vector_elt %vreg0, Constant<6>),
                     (extract_vector_elt %vreg0, Constant<7>),
                     %vreg1))

a. We can't build a 256-bit vector efficiently so, we need to split it into
two 128-bit vecs and combine them with VINSERTX128.

b. Operands like (extract_vector_elt (v8f32 %vreg0), Constant<7>) needs to be
split into a VEXTRACTX128 and a further extract_vector_elt from the
resulting 128-bit vector.

c. The extract_vector_elt from b. is lowered into a shuffle to the first
element and a movss.

Depending on the order in which we legalize the BUILD_VECTOR and its
operands[1], buildFromShuffleMostly may be faced with:

(v4f32 (BUILD_VECTOR (extract_vector_elt
                      (vector_shuffle<1,u,u,u> (extract_subvector %vreg0, Constant<4>), undef),
                      Constant<0>),
                     (extract_vector_elt
                      (vector_shuffle<2,u,u,u> (extract_subvector %vreg0, Constant<4>), undef),
                      Constant<0>),
                     (extract_vector_elt
                      (vector_shuffle<3,u,u,u> (extract_subvector %vreg0, Constant<4>), undef),
                      Constant<0>),
                     %vreg1))

In order to figure out the underlying vector and their identity we need to see
through the shuffles.

[1] Note that the order in which operations and their operands are legalized is
only guaranteed in the first iteration of LegalizeDAG.

Fixes <rdar://problem/16296956>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206634 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 19:44:16 +00:00
Benjamin Kramer
842c27189a DebugInfo: Remove some initializer lists to make MSVC happy again.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206632 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 19:01:53 +00:00
David Blaikie
e7b068f9f1 Add range access to MCAssembler's symbol collection.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206631 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 18:24:25 +00:00
Reid Kleckner
b99f337151 Update comment in LLVMBitCodes.h to reflect the actual bitcode record
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206630 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 18:19:18 +00:00
Matt Arsenault
6a3c4b70ab Fix uint -> size_t conversion warning.
This warning is disabled for the LLVM build,
but external users of the header can still
run into this.

Patch by Ke Bai

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206629 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 18:08:31 +00:00
Duncan P. N. Exon Smith
ebb5d29473 Revert "blockfreq: Rewrite BlockFrequencyInfoImpl" (#2)
This reverts commit r206622 and the MSVC fixup in r206626.

Apparently the remotely failing tests are still failing, despite my
attempt to fix the nondeterminism in r206621.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206628 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:56:08 +00:00
Greg Fitzgerald
cfb2d0ea10 Fixed llvm-build when no targets are enabled
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206627 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:39:50 +00:00
Duncan P. N. Exon Smith
3a9522f7a1 Fixing MSVC after r206622?
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206626 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:38:01 +00:00
Andrew Trick
939bc92c04 Better comments to explain buffered/unbuffered processor resources.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206625 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:35:08 +00:00
Alexey Samsonov
fe030f3dcd [DWARF parser] Refactor fetching DIE address ranges.
Add a helper method to get address ranges specified in a DIE
(either by DW_AT_low_pc/DW_AT_high_pc, or by DW_AT_ranges). Use it
to untangle and simplify the code.

No functionality change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206624 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:25:46 +00:00
Duncan P. N. Exon Smith
54850bedf2 Reapply "blockfreq: Rewrite BlockFrequencyInfoImpl"
This reverts commit r206556, effectively reapplying commit r206548 and
its fixups in r206549 and r206550.

In an intervening commit I've added target triples to the tests that
were failing remotely [1] (but passing locally).  I'm hoping the mystery
is solved?  I'll revert this again if the tests are still failing
remotely.

[1]: http://bb.pgr.jp/builders/ninja-x64-msvc-RA-centos6/builds/1816

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206622 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:22:25 +00:00
Duncan P. N. Exon Smith
1e1954f749 Add some target triples for better determinism
These tests were failing on some buildbots after r206548 (reverted in
r206556), but passing locally.

They were missing target triples, so maybe that's the problem?

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206621 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 17:22:19 +00:00
Benjamin Kramer
5dd15cdb83 LineIterator: Add DataTypes.h for int64_t on MSVC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206617 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 16:57:01 +00:00
Benjamin Kramer
f2896111b5 Add some missing includes for various standard library implementations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206616 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 16:46:29 +00:00
Benjamin Kramer
98b539ae65 Make the copy member of StringRef/ArrayRef generic wrt allocators.
Doesn't make sense to restrict this to BumpPtrAllocator. While there
replace an explicit loop with std::equal. Some standard libraries know
how to compile this down to a ::memcmp call if possible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206615 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 16:36:15 +00:00
Tim Northover
7b4b261611 AArch64/ARM64: add more NEON tests.
Mostly no testing this time, since they were just wrangling
target-specific intrinsics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206613 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 14:54:53 +00:00
Benjamin Kramer
d781e40b6a Allocator: Remove ReferenceAdder hack.
This was a workaround for compilers that had issues with reference
collapsing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206612 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 14:54:51 +00:00
Tim Northover
f34a512a68 ARM64: disable generation of .loh directives outside MachO.
Part of PR19455.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206611 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 14:54:46 +00:00
Tim Northover
9cfd368302 ARM64: don't emit .subsections_via_symbols on ELF.
Part of PR19455.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206610 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-18 14:54:41 +00:00