Commit Graph

29823 Commits

Author SHA1 Message Date
Colin LeMahieu
5ec52ca1bf [Hexagon] r236351 fix does not work on builder configurations yet.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236358 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 22:39:20 +00:00
Quentin Colombet
32675bbfd0 [AArch64][FastISel] Variant of the logical instructions that use two input
registers cannot write on SP.

rdar://problem/20748715


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236352 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 21:34:57 +00:00
Colin LeMahieu
a036240a88 [Hexagon] Adding expression MC emission and removing XFAIL from test that hits this code path.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236348 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 21:14:21 +00:00
Quentin Colombet
4688a0507c [AArch64][FastISel] Fix the setting of kill flags for MUL -> UMULH sequences.
rdar://problem/20748715


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236346 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 20:57:11 +00:00
Zachary Turner
7c69a58214 [llvm-pdbdump] Support dynamic load address and external symbols.
This patch adds the --load-address command line option to
llvm-pdbdump, which dumps all addresses assuming the module has
loaded at the specified address.

Additionally, this patch adds an option to llvm-pdbdump to support
dumping of public symbols (i.e. symbols with external linkage).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236342 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 20:24:26 +00:00
Reid Kleckner
053f7d148e Revert "[WinEH] Add an EH registration and state insertion pass for 32-bit x86"
This reverts commit r236339, it breaks the win32 clang-cl self-host.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236340 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 20:14:04 +00:00
Reid Kleckner
018ed7b68b [WinEH] Add an EH registration and state insertion pass for 32-bit x86
This pass is responsible for constructing the EH registration object
that gets linked into fs:00, which is all it does in this change. In the
future, it will also insert stores to update the EH state number.

I considered keeping this functionality in WinEHPrepare, but it's pretty
separable and X86 specific. It has conceptually very little to do with
the task of WinEHPrepare, which is currently outlining.  WinEHPrepare is
also in theory useful on ARM, but this logic is pretty x86 specific.

Reviewers: andrew.w.kaylor, majnemer

Differential Revision: http://reviews.llvm.org/D9422

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236339 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 20:04:54 +00:00
Peter Collingbourne
dc1a030aec ARM: Align functions containing Thumb-2 jump tables to 4 bytes.
Functions with jump tables need an alignment of 4 because they use the ADR
instruction, which aligns the PC to 4 bytes before adding an offset.

Differential Revision: http://reviews.llvm.org/D9424

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236327 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 18:05:59 +00:00
James Y Knight
a2dd41dead [Sparc] Repair fixups in little endian mode.
Differential Revision: http://reviews.llvm.org/D9434

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236324 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 17:13:02 +00:00
Toma Tabacu
62e5ebfaef [mips] [IAS] Fix error messages for using LI with 64-bit immediates.
Summary:
LI should never accept immediates larger than 32 bits.
The additional Is32BitImm boolean also paves the way for unifying the functionality that LA and LI have in common.

Reviewers: dsanders

Reviewed By: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9289

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236313 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 12:19:27 +00:00
Toma Tabacu
80683c0be6 [mips] [IAS] Slightly improve shift instruction generation in expandLoadImm.
Summary:
Generate one DSLL32 of 0 instead of two consecutive DSLL of 16.
In order to do this I had to change createLShiftOri's template argument from a bool to an unsigned.

This also gave me the opportunity to rewrite the mips64-expansions.s test, as it was testing the same cases multiple times and skipping over other cases.
It was also somewhat unreadable, as the CHECK lines were grouped in a huge block of text at the beginning of the file.

Reviewers: dsanders

Reviewed By: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D8974

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236311 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 10:26:47 +00:00
Simon Pilgrim
509fb2c84c [SelectionDAG] Unary vector constant folding integer legality fixes
This patch fixes issues with vector constant folding not correctly handling scalar input operands if they require implicit truncation - this was tested with llvm-stress as recommended by Patrik H Hagglund.

The patch ensures that integer input scalars from a build vector are correctly truncated before folding, and that constant integer scalar results are promoted to a legal type before inclusion in the new folded build vector.

I have added another crash test case and also a test for UINT_TO_FP / SINT_TO_FP using an non-truncated scalar input, which was failing before this patch.

Differential Revision: http://reviews.llvm.org/D9282

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236308 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 08:20:04 +00:00
Tom Stellard
f17a95a681 R600/SI: Add VCC as an implict def of SI_KILL
When SI_KILL has a register operand, its lowered form writes to vcc.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236307 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 03:44:09 +00:00
Tom Stellard
89d0e99f86 R600/SI: Fix verifier errors from the SIAnnotateControlFlow pass
This pass was generating 'Instruction does not dominate all uses!'
errors for programs which had loops with a condition variable that
depended on the result of a phi instruction from outside of the loop.

The pass was inserting new phi nodes outside of the loop which used values
defined inside the loop.

http://bugs.freedesktop.org/show_bug.cgi?id=90056

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236306 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 03:44:08 +00:00
Quentin Colombet
d57216e763 [ARM][TEST] Strengthen test against smarter reg alloc.
Follow-up of r236247.

rdar://problem/20770899


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236296 91177308-0d34-0410-b5e6-96231b3b80d8
2015-05-01 00:45:55 +00:00
Pete Cooper
9ff32d2fe5 [ARM] optimizeSelect should clear kill flags.
If we move an instruction from one block down to a MOVC and predicate it,
then the original instruction could be moved in to a loop.  In this case,
its invalid for any kill flags to remain on there.

Fails with -verfy-machineinstrs.

rdar://problem/20752113

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236290 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 23:57:47 +00:00
Pete Cooper
a4f66d25fc Commute the internal flag on MachineOperands.
When commuting a thumb instruction in the size reduction pass, thumb
instructions are represented as a bundle and so some operands may be marked
as internal.  The internal flag has to move with the operand when commuting.

This test is sensitive to register allocation so can't specifically check that
this error was happening, but so long as it continues to pass with -verify then
hopefully its still ok.

rdar://problem/20752113

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236282 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 23:14:14 +00:00
Davide Italiano
0c54b7abc7 [Object] Teach Object and llvm-objdump about ".hidden"
Differential Revision:	http://reviews.llvm.org/D9416
Reviewed by:	rafael


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236279 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 23:08:53 +00:00
Quentin Colombet
3a0fccf6a0 [AArch64] Fix bad register class constraint in fast-isel for TST instruction.
rdar://problem/20748715


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236273 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 22:27:20 +00:00
Pete Cooper
d47066e86b Don't always apply kill flag in thumb2 ABS pseudo expansion.
The expansion for t2ABS was always setting the kill flag on the rsb instruction.
It should instead only be set on rsb if it was set on the original ABS instruction.

rdar://problem/20752113

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236272 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 22:15:59 +00:00
Reid Kleckner
7a1b190bcd [X86] Use 4 byte preferred aggregate alignment on Win32
This helps reduce the frequency of stack realignment prologues in 32-bit
X86 Windows code. Before this change and the corresponding clang change,
we would take the max of the type preferred alignment and the explicit
alignment on the alloca.

If you don't override aggregate alignment in datalayout, you get a
default of 8. This dates back to 2007 / r34356, and changing it seems
prohibitively difficult at this point.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236270 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 22:11:59 +00:00
Matthias Braun
af2e236c11 InstCombineSimplifyDemanded: Remove nsw/nuw flags when optimizing demanded bits
When optimizing demanded bits of the operands of an Add we have to
remove the nsw/nuw flags as we have no guarantee anymore that we don't
wrap.  This is legal here because the top bit is not demanded.  In fact
this operaion was already performed but missed in the case of an Add
with a constant on the right side.  To fix this this patch refactors the
code to unify the code paths in SimplifyDemandedUseBits() handling of
Add/Sub:

- The transformation of Add->Or is removed from the simplify demand
  code because the equivalent transformation exists in
  InstCombiner::visitAdd()
- KnownOnes/KnownZero are not adjusted for Add x, C anymore as
  computeKnownBits() already performs these computations.
- The simplification of the operands is unified. In this new version
  constant on the right side of a Sub are shrunk now as I could not find
  a reason why not to do so.
- The special case for clearing nsw/nuw in ShrinkDemandedConstant() is
  not necessary anymore as the caller does that already.

Differential Revision: http://reviews.llvm.org/D9415

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236269 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 22:05:30 +00:00
Andrea Di Biagio
cdc4c42bac Fix comment in test. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236262 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 21:22:28 +00:00
Andrea Di Biagio
3b15669938 Fix for PR23103. Correctly propagate the 'IsUndef' flag to the register operands of a commuted instruction.
Revision 220239 exposed a latent bug in method
'TargetInstrInfo::commuteInstruction'. When commuting the operands of a machine
instruction, method 'commuteInstruction' didn't correctly propagate the
'IsUndef' flag to the register operands of the new (commuted) instruction.

Before this patch, the following instruction:
  %vreg4<def> = VADDSDrr  %vreg14, %vreg5<undef>; FR64:%vreg4,%vreg14,%vreg5

was wrongly converted by method 'commuteInstruction' into:
  %vreg4<def> = VADDSDrr  %vreg5, %vreg14<undef>; FR64:%vreg4,%vreg5,%vreg14

The correct instruction should have been:
  %vreg4<def> = VADDSDrr  %vreg5<undef>, %vreg14; FR64:%vreg4,%vreg5,%vreg14

This patch fixes the problem in method 'TargetInstrInfo::commuteInstruction'.
When swapping the operands of a machine instruction, we now make sure that
'IsUndef' flags are correctly set.
Added test case 'pr23103.ll'.

Differential Revision: http://reviews.llvm.org/D9406


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236258 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 21:03:29 +00:00
Kevin Enderby
28b8dea315 For llvm-objdump, with the -archive-headers and -macho options, use the -non-verbose
option to print the archive headers using raw numeric values.  Also add the -archive-member-offsets
for use with these to also trigger printing of the offset of the archive member from the start
of the archive.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236252 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 20:30:42 +00:00
Pete Cooper
1870668beb Don't rewrite jumps to empty BBs to landing pads.
In the test case here, the 'unreachable' BB was removed by BranchFolding because its empty.

It then rewrote the jump from 'entry' to jump to its fallthrough, which was a landing pad.

This results in 'entry' jumping to 2 different landing pads, which fails the machine verifier.

rdar://problem/20750162

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236248 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 18:58:23 +00:00
Quentin Colombet
131da40ffd [ARM] Do not generate invalid encoding for stack adjust, even if this is just
temporary.

Because of that:
1. The machine verifier was complaining on such code.
2. The generate code worked just because the thumb reduction size pass fixed the
opcode.

rdar://problem/20749824


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236247 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 18:52:49 +00:00
Tim Northover
6ff3ac67e0 AArch64: add BFC alias for the BFI/BFM instructions.
Unlike 32-bit ARM, AArch64 can use wzr/xzr to implement this without the need
for a separate instruction.

rdar://18679590

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236245 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 18:28:58 +00:00
Jan Vesely
e3d17d7e9c Reinstate revisions r234755, r234759, r234760
changes:
  Don't apply on hexagon and NVPTX since they no longer claim to support UADDO/USUBO
  Add location to getConstant
  Drop comment about the ops being turned into expand

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236240 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 17:15:56 +00:00
Rafael Espindola
76e71bd66e Write sections mostly in one pass.
During ELF writing, there is no need to further relax the sections, so we
should not be creating fragments. This patch avoids doing so in all cases
but debug section compression (that is next).

Also, the ELF format is fairly simple to write. We can do a single pass over
the sections to write them out and compute the section header table.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236235 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 14:21:49 +00:00
Rafael Espindola
7fc9422362 Don't check for offsets in tests where it is not relevant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236233 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 13:57:06 +00:00
Rafael Espindola
c846f35a04 Check the entire content of the comdat group.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236230 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 13:08:09 +00:00
Daniel Sanders
2e2b1db4d2 [mips] Sorted instructions in mips64r6 disassembly tests. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236223 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 10:52:42 +00:00
Daniel Sanders
9707b674d0 [mips][mips64r6] Sorted instructions in test. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236221 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 10:23:48 +00:00
Daniel Sanders
cd511a5714 [mips][msa] Rename main check prefix to 'ALL' in basic operations tests. NFC
Summary:
The majority of the checks are subtarget independent. The few that aren't
will be corrected shortly.

Reviewers: vkalintiris

Reviewed By: vkalintiris

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9340


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236220 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 09:57:37 +00:00
Daniel Sanders
f424f1da46 [mips][msa] Use CHECK-LABEL where missing, and remove checks matching the .size directive. NFC.
Summary: 

Reviewers: vkalintiris

Reviewed By: vkalintiris

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9339


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236219 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 09:56:30 +00:00
Daniel Sanders
d63766eb03 [mips] Add missing signext attributes to MSA basic operations tests. NFC.
Summary:
This doesn't make much difference to MIPS32, but it will simplify a
MIPS64r6 bugfix which will follow shortly by removing unnecessary
sign-extension of parameters.

Reviewers: vkalintiris

Reviewed By: vkalintiris

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9338

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236216 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 09:24:09 +00:00
Simon Pilgrim
c8ee30be4f [SSE] Fix for MUL v16i8 on pre-SSE41 targets (PR23369).
Sign extension of i8 to i16 was placing the unpacked bytes in the lower byte instead of the upper byte.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236209 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 08:23:16 +00:00
Sanjoy Das
a34038226e [InstCombine] Add new rule for MIN(MAX(~A, ~B), ~C) et. al.
Summary:
Optimizing these well are especially interesting for IRCE since it
"clamps" values by generating this sort of pattern through SCEV
expressions.

Depends on D9352.

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9353

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236203 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 04:56:04 +00:00
Sanjoy Das
c0730628a4 [InstCombine] Add a new formula for SMIN.
Summary:
After this change `MatchSelectPattern` recognizes the following form
of SMIN:

  Y >s C ? ~Y : ~C == ~Y <s ~C ? ~Y : ~C = SMIN(~Y, ~C)

Reviewers: majnemer

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9352

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236202 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 04:56:00 +00:00
Filipe Cabecinhas
deedba2a36 Don't overflow GCTable
Summary: Bug found with AFL fuzz.

Reviewers: rafael, dexonsmith

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9361

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236200 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 04:09:41 +00:00
Owen Anderson
36a398fe70 Semantically revert r236031, which is not a good idea for in-order targets.
At the least it should be guarded by some kind of target hook.
It also introduced catastrophic compile time and code quality
regressions on some out of tree targets (test case still being
reduced/sanitized).

Sanjay agreed with reverting this patch until these issues can be
resolved.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236199 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 04:06:32 +00:00
Hans Wennborg
5ad26af732 XFAIL test/CodeGen/Generic/MachineBranchProb.ll on Hexagon (PR23377)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236196 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 01:59:04 +00:00
Filipe Cabecinhas
8b2199e2a2 Make sure Op->getType() is a PointerType before we cast<> it.
Bug found with AFL fuzz.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236193 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 01:13:31 +00:00
Hans Wennborg
49baa9f896 Switch lowering: use profile info to build weight-balanced binary search trees
This will cause hot nodes to appear closer to the root.

The literature says building the tree like this makes it a near-optimal (in
terms of search time given key frequencies) binary search tree. In LLVM's case,
we can do up to 3 comparisons in each leaf node, so it might be better to opt
for lower tree height in some cases; that's something to look into in the
future.

Differential Revision: http://reviews.llvm.org/D9318

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236192 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 00:57:37 +00:00
Filipe Cabecinhas
a607be94ca Make sure we don't resize(0) when we get a fwdref with Idx == UINT_MAX
Make it an error instead.

Bug found with AFL fuzz.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236190 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 00:52:42 +00:00
Ahmed Bougacha
06f9f1056e Flip r236172 testcase RUN option ordering for BSD sed(1). NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236186 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-30 00:07:34 +00:00
Pete Cooper
224f06e5dd Change x86 CMOVE_F to read it source, not write it.
This was breaking sqlite with the machine verifier because operand 0 was a def according to tablegen, but didn't have the 'isDef' flag set.

Looking at the ISA, its clear that this operand is a source as writing to st(0) is implicit.  So move the operand to the correct place in the td file.

rdar://problem/20751584

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236183 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-29 23:51:33 +00:00
Reid Kleckner
85b9ebb7e8 [WinEH] Start EH preparation for 32-bit x86, it uses no arguments
32-bit x86 MSVC-style exceptions are functionaly similar to 64-bit, but
they take no arguments. Instead, they implicitly use the value of EBP
passed in by the caller as a pointer to the parent's frame. In LLVM, we
can represent this as llvm.frameaddress(1), and feed that into all of
our calls to llvm.framerecover.

The next steps are:
- Add an alloca to the fs:00 linked list of handlers
- Add something like llvm.sjlj.lsda or generalize it to store in the
  alloca
- Move state number calculation to WinEHPrepare, arrange for
  FunctionLoweringInfo to call it
- Use the state numbers to insert explicit loads and stores in the IR

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236172 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-29 22:49:54 +00:00
Rafael Espindola
58a854d447 Write the section header string table directly to the output stream.
Instead of accumulating the content in a fragment first, just write it
to the output stream.

Also put it first in the section table, so that we never have to worry
about its index being >= SHN_LORESERVE.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236145 91177308-0d34-0410-b5e6-96231b3b80d8
2015-04-29 20:25:24 +00:00