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1852 Commits

Author SHA1 Message Date
Chris Dewhurst
028d2e0885 [Sparc] This provides support for itineraries on Sparc.
Specifically, itineraries for LEON processors has been added, along with several LEON processor Subtargets. Although currently all these targets are pretty much identical, support for features that will differ among these processors will be added in the very near future.

The different Instruction Itinerary Classes (IICs) added are sufficient to differentiate between the instruction timings used by LEON and, quite probably, by generic Sparc processors too, but the focus of the exercise has been for LEON processors, as the requirement of my project. If the IICs are not sufficient for other Sparc processor types and you want to add a new itinerary for one of those, it should be relatively trivial to adapt this.

As none of the LEON processors has Quad Floats, or is a Version 9 processor, none of those instructions have itinerary classes defined and revert to the default "NoItinerary" instruction itinerary.

Phabricator Review: http://reviews.llvm.org/D19359

llvm-svn: 267121
2016-04-22 08:17:17 +00:00
Chris Dewhurst
a841bbdbcd The following code would not work before this patch, due to the inability to take the address of a global object:
void func1() {

...
}

int main(int argc, char** argv) {

void (*pFunc)();
pFunc = &func1
pFunc();
...
}

Phabricator review: http://reviews.llvm.org/D19368

llvm-svn: 267120
2016-04-22 08:13:47 +00:00
Mehdi Amini
9ff867f98c [NFC] Header cleanup
Removed some unused headers, replaced some headers with forward class declarations.

Found using simple scripts like this one:
clear && ack --cpp -l '#include "llvm/ADT/IndexedMap.h"' | xargs grep -L 'IndexedMap[<]' | xargs grep -n --color=auto 'IndexedMap'

Patch by Eugene Kosov <claprix@yandex.ru>

Differential Revision: http://reviews.llvm.org/D19219

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266595
2016-04-18 09:17:29 +00:00
James Y Knight
a55b68a75e Add __atomic_* lowering to AtomicExpandPass.
(Recommit of r266002, with r266011, r266016, and not accidentally
including an extra unused/uninitialized element in LibcallRoutineNames)

AtomicExpandPass can now lower atomic load, atomic store, atomicrmw, and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266115
2016-04-12 20:18:48 +00:00
Rafael Espindola
b04bc032f0 This reverts commit r266002, r266011 and r266016.
They broke the msan bot.

Original message:

Add __atomic_* lowering to AtomicExpandPass.

AtomicExpandPass can now lower atomic load, atomic store, atomicrmw,and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266062
2016-04-12 12:30:25 +00:00
James Y Knight
003ee915ba Add __atomic_* lowering to AtomicExpandPass.
AtomicExpandPass can now lower atomic load, atomic store, atomicrmw, and
cmpxchg instructions to __atomic_* library calls, when the target
doesn't support atomics of a given size.

This is the first step towards moving all atomic lowering from clang
into llvm. When all is done, the behavior of __sync_* builtins,
__atomic_* builtins, and C11 atomics will be unified.

Previously LLVM would pass everything through to the ISelLowering
code. There, unsupported atomic instructions would turn into __sync_*
library calls. Because of that behavior, Clang currently avoids emitting
llvm IR atomic instructions when this would happen, and emits __atomic_*
library functions itself, in the frontend.

This change makes LLVM able to emit __atomic_* libcalls, and thus will
eventually allow clang to depend on LLVM to do the right thing.

It is advantageous to do the new lowering to atomic libcalls in
AtomicExpandPass, before ISel time, because it's important that all
atomic operations for a given size either lower to __atomic_*
libcalls (which may use locks), or native instructions which won't. No
mixing and matching.

At the moment, this code is enabled only for SPARC, as a
demonstration. The next commit will expand support to all of the other
targets.

Differential Revision: http://reviews.llvm.org/D18200

llvm-svn: 266002
2016-04-11 22:22:33 +00:00
Hans Wennborg
f1f7a0ce15 Fix broken assert, PR24624
llvm-svn: 265989
2016-04-11 20:35:41 +00:00
JF Bastien
f4f5b32f44 NFC: make AtomicOrdering an enum class
Summary:
In the context of http://wg21.link/lwg2445 C++ uses the concept of
'stronger' ordering but doesn't define it properly. This should be fixed
in C++17 barring a small question that's still open.

The code currently plays fast and loose with the AtomicOrdering
enum. Using an enum class is one step towards tightening things. I later
also want to tighten related enums, such as clang's
AtomicOrderingKind (which should be shared with LLVM as a 'C++ ABI'
enum).

This change touches a few lines of code which can be improved later, I'd
like to keep it as NFC for now as it's already quite complex. I have
related changes for clang.

As a follow-up I'll add:
  bool operator<(AtomicOrdering, AtomicOrdering) = delete;
  bool operator>(AtomicOrdering, AtomicOrdering) = delete;
  bool operator<=(AtomicOrdering, AtomicOrdering) = delete;
  bool operator>=(AtomicOrdering, AtomicOrdering) = delete;
This is separate so that clang and LLVM changes don't need to be in sync.

Reviewers: jyknight, reames

Subscribers: jyknight, llvm-commits

Differential Revision: http://reviews.llvm.org/D18775

llvm-svn: 265602
2016-04-06 21:19:33 +00:00
Derek Schuff
e26993d076 Add MachineFunctionProperty checks for AllVRegsAllocated for target passes
Summary:
This adds the same checks that were added in r264593 to all
target-specific passes that run after register allocation.

Reviewers: qcolombet

Subscribers: jyknight, dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D18525

llvm-svn: 265313
2016-04-04 17:09:25 +00:00
Hans Wennborg
07d10a6e30 Change eliminateCallFramePseudoInstr() to return an iterator
This will become necessary in a subsequent change to make this method
merge adjacent stack adjustments, i.e. it might erase the previous
and/or next instruction.

It also greatly simplifies the calls to this function from Prolog-
EpilogInserter. Previously, that had a bunch of logic to resume iteration
after the call; now it just continues with the returned iterator.

Note that this changes the behaviour of PEI a little. Previously,
it attempted to re-visit the new instruction created by
eliminateCallFramePseudoInstr(). That code was added in r36625,
but I can't see any reason for it: the new instructions will obviously
not be pseudo instructions, they will not have FrameIndex operands,
and we have already accounted for the stack adjustment.

Differential Revision: http://reviews.llvm.org/D18627

llvm-svn: 265036
2016-03-31 18:33:38 +00:00
James Y Knight
be5fed0669 [SPARC] Use AtomicExpandPass to expand AtomicRMW instructions.
They were previously expanded to CAS loops in a custom isel expansion,
but AtomicExpandPass knows how to do that generically.

Testing is covered by the existing sparc atomics.ll testcases.

llvm-svn: 264771
2016-03-29 19:09:54 +00:00
Douglas Katzman
990a4765e9 Sparc: silently ignore .proc assembler directive
Differential Revision: http://reviews.llvm.org/D18463

llvm-svn: 264579
2016-03-28 14:00:11 +00:00
James Y Knight
4b163a5aa3 Tweak some atomics functions in preparation for larger changes; NFC.
- Rename getATOMIC to getSYNC, as llvm will soon be able to emit both
  '__sync' libcalls and '__atomic' libcalls, and this function is for
  the '__sync' ones.

- getInsertFencesForAtomic() has been replaced with
  shouldInsertFencesForAtomic(Instruction), so that the decision can be
  made per-instruction. This functionality will be used soon.

- emitLeadingFence/emitTrailingFence are no longer called if
  shouldInsertFencesForAtomic returns false, and thus don't need to
  check the condition themselves.

llvm-svn: 263665
2016-03-16 22:12:04 +00:00
Douglas Katzman
d81fc2168d Myriad: Add new sparc CPU kinds.
llvm-svn: 263557
2016-03-15 16:41:47 +00:00
Sanjay Patel
f22bc14a47 [DAG] use isUndef() ; NFCI
llvm-svn: 263448
2016-03-14 17:28:46 +00:00
Chris Dewhurst
1fde07b2dc This change adds co-processor condition branching and conditional traps to the Sparc back-end.
This will allow inline assembler code to utilize these features, but no automatic lowering is provided, except for the previously provided @llvm.trap, which lowers to "ta 5".

The change also separates out the different assembly language syntaxes for V8 and V9 Sparc. Previously, only V9 Sparc assembly syntax was provided.

The change also corrects the selection order of trap disassembly, allowing, e.g. "ta %g0 + 15" to be rendered, more readably, as "ta 15", ignoring the %g0 register. This is per the sparc v8 and v9 manuals.

Check-in includes many extra unit tests to check this works correctly on both V8 and V9 Sparc processors.

Code Reviewed at http://reviews.llvm.org/D17960.

llvm-svn: 263044
2016-03-09 18:20:21 +00:00
Chris Dewhurst
7df4542eb7 The patch adds missing registers and instructions to complete all the registers supported by the Sparc v8 manual.
These are all co-processor registers, with the exception of the floating-point deferred-trap queue register.
Although these will not be lowered automatically by any instructions, it allows the use of co-processor
instructions implemented by inline-assembly.

Code Reviewed at http://reviews.llvm.org/D17133, with the exception of a very small change in brace placement in SparcInstrInfo.td,
which was formerly causing a problem in the disassembly of the %fq register.

llvm-svn: 262133
2016-02-27 12:49:59 +00:00
Nirav Dave
9dd7b9a38b Fix Sparc 32bit Lowering to rebundle up v2i32 values.
Summary: Fix LowerCall to rebundle v2i32 values after lowering and add testcase

Reviewers: jyknight

Subscribers: llvm-commits, jyknight

Differential Revision: http://reviews.llvm.org/D17615

llvm-svn: 262048
2016-02-26 18:55:22 +00:00
Chris Dewhurst
1127527bb7 Reverting breaking change. Sorry.
llvm-svn: 262007
2016-02-26 12:20:10 +00:00
Chris Dewhurst
5c895f8b77 Reviewed at reviews.llvm.org/D17133
llvm-svn: 262005
2016-02-26 11:46:47 +00:00
Chris Dewhurst
a09327f2ce Initial test commit only
llvm-svn: 262003
2016-02-26 11:38:24 +00:00
Duncan P. N. Exon Smith
53cb4596f6 CodeGen: TII: Take MachineInstr& in predicate API, NFC
Change TargetInstrInfo API to take `MachineInstr&` instead of
`MachineInstr*` in the functions related to predicated instructions
(I'll try to come back later and get some of the rest).  All of these
functions require non-null parameters already, so references are more
clear.  As a bonus, this happens to factor away a host of implicit
iterator => pointer conversions.

No functionality change intended.

llvm-svn: 261605
2016-02-23 02:46:52 +00:00
Duncan P. N. Exon Smith
0fa6439bcd Revert "CodeGen: MachineInstr::getIterator() => getInstrIterator(), NFC"
This reverts commit r261504, since it's not obvious the new name is
better:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20160222/334298.html

I'll recommit if we get consensus that it's the right direction.

llvm-svn: 261567
2016-02-22 20:49:58 +00:00
Duncan P. N. Exon Smith
b2dab65ba3 CodeGen: MachineInstr::getIterator() => getInstrIterator(), NFC
Delete MachineInstr::getIterator(), since the term "iterator" is
overloaded when talking about MachineInstr.

- Downcast to ilist_node in iplist::getNextNode() and getPrevNode() so
  that ilist_node::getIterator() is still available.
- Add it back as MachineInstr::getInstrIterator().  This matches the
  naming in MachineBasicBlock.
- Add MachineInstr::getBundleIterator().  This is explicitly called
  "bundle" (not matching MachineBasicBlock) to disintinguish it clearly
  from ilist_node::getIterator().
- Update all calls.  Some of these I switched to `auto` to remove
  boiler-plate, since the new name is clear about the type.

There was one call I updated that looked fishy, but it wasn't clear what
the right answer was.  This was in X86FrameLowering::inlineStackProbe(),
added in r252578 in lib/Target/X86/X86FrameLowering.cpp.  I opted to
leave the behaviour unchanged, but I'll reply to the original commit on
the list in a moment.

llvm-svn: 261504
2016-02-21 22:58:35 +00:00
James Y Knight
529a53c338 [SPARC] Repair floating-point condition encodings in assembly parser.
The encodings for floating point conditions A(lways) and N(ever) were
incorrectly specified for the assembly parser, per Sparc manual v8 page
121. This change corrects that mistake.

Also, strangely, all of the branch instructions already had MC test
cases, except for the broken ones. Added the tests.

Patch by Chris Dewhurst

Differential Revision: http://reviews.llvm.org/D17074

llvm-svn: 260390
2016-02-10 17:47:20 +00:00
Benjamin Kramer
1d1115c0c4 Rename TargetSelectionDAGInfo into SelectionDAGTargetInfo and move it to CodeGen/
It's a SelectionDAG thing, not a Target thing.

llvm-svn: 258939
2016-01-27 16:32:26 +00:00
Benjamin Kramer
e3023baf50 Move MCTargetAsmParser.h to llvm/MC/MCParser where it belongs.
llvm-svn: 258917
2016-01-27 10:01:28 +00:00
Chris Bieneman
1b8d4f74aa Remove autoconf support
Summary:
This patch is provided in preparation for removing autoconf on 1/26. The proposal to remove autoconf on 1/26 was discussed on the llvm-dev thread here: http://lists.llvm.org/pipermail/llvm-dev/2016-January/093875.html

"I felt a great disturbance in the [build system], as if millions of [makefiles] suddenly cried out in terror and were suddenly silenced. I fear something [amazing] has happened."
- Obi Wan Kenobi

Reviewers: chandlerc, grosbach, bob.wilson, tstellarAMD, echristo, whitequark

Subscribers: chfast, simoncook, emaste, jholewinski, tberghammer, jfb, danalbert, srhines, arsenm, dschuff, jyknight, dsanders, joker.eph, llvm-commits

Differential Revision: http://reviews.llvm.org/D16471

llvm-svn: 258861
2016-01-26 21:29:08 +00:00
Benjamin Kramer
75511fc092 Reflect the MC/MCDisassembler split on the include/ level.
No functional change, just moving code around.

llvm-svn: 258818
2016-01-26 16:44:37 +00:00
Rui Ueyama
dca64dbccc Update to use new name alignTo().
llvm-svn: 257804
2016-01-14 21:06:47 +00:00
Rafael Espindola
7f81c885ac Convert a few assert failures into proper errors.
Fixes PR25944.

llvm-svn: 257697
2016-01-13 22:56:57 +00:00
James Y Knight
42de23f7fd [SPARC] Revamp AnalyzeBranch and add ReverseBranchCondition.
AnalyzeBranch on X86 (and, previously, SPARC, which implementation was
copied from X86) tries to modify the branches based on block
layout (e.g. checking isLayoutSuccessor), when AllowModify is true.

The rest of the architectures leave that up to the caller, which can
call InsertBranch, RemoveBranch, and ReverseBranchCondition as
appropriate. That appears to be the preferred way to do it nowadays.

This commit makes SPARC like the rest: replaces AnalyzeBranch with an
implementation cribbed from AArch64, and adds a ReverseBranchCondition
implementation.

Additionally, a test-case has been added (also cribbed from AArch64)
demonstrating that redundant branch sequences no longer get emitted.

E.g., it used to emit code like this:
         bne .LBB1_2
         nop
         ba .LBB1_1
         nop
 .LBB1_2:

And now emits:
        cmp %i0, 42
        be .LBB1_1
        nop

llvm-svn: 257572
2016-01-13 04:44:14 +00:00
Craig Topper
8ac345d153 Remove extra forward declarations and scrub includes for all in tree InstPrinters. NFC
llvm-svn: 256427
2015-12-25 22:10:01 +00:00
James Y Knight
9261eab6db [Sparc] Tweak r255668: Use llvm_unreachable.
llvm-svn: 255698
2015-12-15 23:07:16 +00:00
James Y Knight
b8d3c93b60 [Sparc] Fix handling of double incoming arguments on sparc little-endian.
On SparcV8, doubles get passed in two 32-bit integer registers. The call
code was already handling endianness correctly, but the incoming
argument code was not -- it got the two halves in opposite order.

Also remove some dead code in LowerFormalArguments_32 to handle
less-than-32bit values, which can't actually happen.

Finally, add some test cases for the 32-bit calling convention, cribbed
from the 64abi.ll test, and run for both big and little-endian.

llvm-svn: 255668
2015-12-15 19:23:12 +00:00
Matt Arsenault
fad94dae85 Start replacing vector_extract/vector_insert with extractelt/insertelt
These are redundant pairs of nodes defined for
INSERT_VECTOR_ELEMENT/EXTRACT_VECTOR_ELEMENT.
insertelement/extractelement are slightly closer to the corresponding
C++ node name, and has stricter type checking so prefer it.

Update targets to only use these nodes where it is trivial to do so.
AArch64, ARM, and Mips all have various type errors on simple replacement,
so they will need work to fix.

Example from AArch64:

def : Pat<(sext_inreg (vector_extract (v16i8 V128:$Rn), VectorIndexB:$idx), i8),
          (i32 (SMOVvi8to32 V128:$Rn, VectorIndexB:$idx))>;

Which is trying to do sext_inreg i8, i8.

llvm-svn: 255359
2015-12-11 19:20:16 +00:00
Joerg Sonnenberger
34bfbf3aa5 Add a TODO item that the nop handling before FP conditional branches is
not enough for SPARCv7.

llvm-svn: 254580
2015-12-03 02:35:24 +00:00
Artyom Skrobov
3803dae0a6 Expose isXxxConstant() functions from SelectionDAGNodes.h (NFC)
Summary:
Many target lowerings copy-paste the code to test SDValues for known constants.
This code can instead be shared in SelectionDAG.cpp, and reused in the targets.

Reviewers: MatzeB, andreadb, tstellarAMD

Subscribers: arsenm, jyknight, llvm-commits

Differential Revision: http://reviews.llvm.org/D14945

llvm-svn: 254085
2015-11-25 19:41:11 +00:00
Akira Hatanaka
0fb89f87e0 Reduce the size of MCRelaxableFragment.
MCRelaxableFragment previously kept a copy of MCSubtargetInfo and
MCInst to enable re-encoding the MCInst later during relaxation. A copy
of MCSubtargetInfo (instead of a reference or pointer) was needed
because the feature bits could be modified by the parser.

This commit replaces the MCSubtargetInfo copy in MCRelaxableFragment
with a constant reference to MCSubtargetInfo. The copies of
MCSubtargetInfo are kept in MCContext, and the target parsers are now
responsible for asking MCContext to provide a copy whenever the feature
bits of MCSubtargetInfo have to be toggled.
 
With this patch, I saw a 4% reduction in peak memory usage when I
compiled verify-uselistorder.lto.bc using llc.

rdar://problem/21736951

Differential Revision: http://reviews.llvm.org/D14346

llvm-svn: 253127
2015-11-14 06:35:56 +00:00
Akira Hatanaka
3093820c02 [MCTargetAsmParser] Move the member varialbes that reference
MCSubtargetInfo in the subclasses into MCTargetAsmParser and define a
member function getSTI.

This is done in preparation for making changes to shrink the size of
MCRelaxableFragment. (see http://reviews.llvm.org/D14346).

llvm-svn: 253124
2015-11-14 05:20:05 +00:00
Joseph Tremoulet
6a3a04f00f [WinEH] Update exception pointer registers
Summary:
The CLR's personality routine passes these in rdx/edx, not rax/eax.

Make getExceptionPointerRegister a virtual method parameterized by
personality function to allow making this distinction.

Similarly make getExceptionSelectorRegister a virtual method parameterized
by personality function, for symmetry.


Reviewers: pgavlin, majnemer, rnk

Subscribers: jyknight, dsanders, llvm-commits

Differential Revision: http://reviews.llvm.org/D14344

llvm-svn: 252383
2015-11-07 01:11:31 +00:00
Tim Northover
227737c0c9 Remove windows line endings introduced by r252177. NFC.
llvm-svn: 252217
2015-11-05 21:54:58 +00:00
Oleg Ranevskyy
839befd4e4 [DebugInfo] Fix ARM/AArch64 prologue_end position. Related to D11268.
Summary:
This review is related to another review request http://reviews.llvm.org/D11268, does the same and merely fixes a couple of issues with it.

D11268 is quite old and has merge conflicts against the current trunk.
This request 
 - rebases D11268 onto the new trunk;
 - resolves the merge conflicts;
 - fixes the prologue_end tests, which do not pass due to the subprogram definitions not marked as distinct.

Reviewers: echristo, rengolin, kubabrecka

Subscribers: aemerson, rengolin, jyknight, dsanders, llvm-commits, asl

Differential Revision: http://reviews.llvm.org/D14338

llvm-svn: 252177
2015-11-05 17:50:17 +00:00
Craig Topper
853fdeb009 Change makeLibCall to take an ArrayRef<SDValue> instead of pointer and size. This removes the need to pass a hardcoded size in many places. NFC
llvm-svn: 251032
2015-10-22 17:05:00 +00:00
Joerg Sonnenberger
314bf5d434 Drop assert that a call with struct return goes to a function with sret
attribute. Clang incorrectly misses it on __muldc3 and friends and the
type system doesn't include it properly either.

llvm-svn: 250938
2015-10-21 20:05:01 +00:00
Duncan P. N. Exon Smith
becbc54dca Sparc: Remove implicit ilist iterator conversions, NFC
llvm-svn: 250781
2015-10-20 00:59:43 +00:00
Craig Topper
e8b9c46ea0 [Sparc] Use MCPhysReg instead of unsigned to size static arrays of registers. Should reduce the table size.
llvm-svn: 250644
2015-10-18 05:29:05 +00:00
Craig Topper
c8409f4435 Make a bunch of static arrays const.
llvm-svn: 250642
2015-10-18 05:15:34 +00:00
James Y Knight
5a3ef042dd Fix assert when emitting llvm.pow.f86.
This occurred due to introducing the invalid i64 type after type
legalization had already finished, in an attempt to workaround bitcast
f64 -> v2i32 not doing constant folding.

The *right* thing is to actually fix bitcast, but that has other
complications. So, for now, just get rid of the broken workaround, and
check in a test-case showing that it doesn't crash, with TODOs for
emitting proper code.

llvm-svn: 249908
2015-10-09 21:36:19 +00:00
Rafael Espindola
d32e304f9c Fix pr24486.
This extends the work done in r233995 so that now getFragment (in addition to
getSection) also works for variable symbols.

With that the existing logic to decide if a-b can be computed works even if
a or b are variables. Given that, the expression evaluation can avoid expanding
variables as aggressively and that in turn lets the relocation code see the
original variable.

In order for this to work with the asm streamer, there is now a dummy fragment
per section. It is used to assign a section to a symbol when no other fragment
exists.

This patch is a joint work by Maxim Ostapenko andy myself.

llvm-svn: 249303
2015-10-05 12:07:05 +00:00