Commit Graph

320 Commits

Author SHA1 Message Date
Jonas Paulsson 6228aeda65 [LSR / TTI / SystemZ] Eliminate TargetTransformInfo::isFoldableMemAccess()
isLegalAddressingMode() has recently gained the extra optional Instruction*
parameter, and therefore it can now do the job that previously only
isFoldableMemAccess() could do.

The SystemZ implementation of isLegalAddressingMode() has gained the
functionality of checking for offsets, which used to be done with
isFoldableMemAccess().

The isFoldableMemAccess() hook has been removed everywhere.

Review: Quentin Colombet, Ulrich Weigand
https://reviews.llvm.org/D35933

llvm-svn: 310463
2017-08-09 11:28:01 +00:00
Ulrich Weigand a11f63a952 [SystemZ] Add support for 128-bit atomic load/store/cmpxchg
This adds support for the main 128-bit atomic operations,
using the SystemZ instructions LPQ, STPQ, and CDSG.

Generating these instructions is a bit more complex than usual
since the i128 type is not legal for the back-end.  Therefore,
we have to hook the LowerOperationWrapper and ReplaceNodeResults
TargetLowering callbacks.

llvm-svn: 310094
2017-08-04 18:57:58 +00:00
Ulrich Weigand 02f1c02c27 [SystemZ] Eliminate unnecessary serialization operations
We currently emit a serialization operation (bcr 14, 0) before every
atomic load and after every atomic store.  This is overly conservative.
The SystemZ architecture actually does not require any serialization
for atomic loads, and a serialization after an atomic store only if
we need to enforce sequential consistency.  This is what other compilers
for the platform implement as well.

llvm-svn: 310093
2017-08-04 18:53:35 +00:00
Jonas Paulsson 024e319489 [SystemZ, LoopStrengthReduce]
This patch makes LSR generate better code for SystemZ in the cases of memory
intrinsics, Load->Store pairs or comparison of immediate with memory.

In order to achieve this, the following common code changes were made:

 * New TTI hook: LSRWithInstrQueries(), which defaults to false. Controls if
 LSR should do instruction-based addressing evaluations by calling
 isLegalAddressingMode() with the Instruction pointers.
 * In LoopStrengthReduce: handle address operands of memset, memmove and memcpy
 as address uses, and call isFoldableMemAccessOffset() for any LSRUse::Address,
 not just loads or stores.

SystemZ changes:

 * isLSRCostLess() implemented with Insns first, and without ImmCost.
 * New function supportedAddressingMode() that is a helper for TTI methods
 looking at Instructions passed via pointers.

Review: Ulrich Weigand, Quentin Colombet
https://reviews.llvm.org/D35262
https://reviews.llvm.org/D35049

llvm-svn: 308729
2017-07-21 11:59:37 +00:00
Ulrich Weigand f2968d58cb [SystemZ] Add support for IBM z14 processor (3/3)
This adds support for the new 128-bit vector float instructions of z14.
Note that these instructions actually only operate on the f128 type,
since only each 128-bit vector register can hold only one 128-bit
float value.  However, this is still preferable to the legacy 128-bit
float instructions, since those operate on pairs of floating-point
registers (so we can hold at most 8 values in registers), while the
new instructions use single vector registers (so we hold up to 32
value in registers).

Adding support includes:
- Enabling the instructions for the assembler/disassembler.
- CodeGen for the instructions.  This includes allocating the f128
  type now to the VR128BitRegClass instead of FP128BitRegClass.
- Scheduler description support for the instructions.

Note that for a small number of operations, we have no new vector
instructions (like integer <-> 128-bit float conversions), and so
we use the legacy instruction and then reformat the operand
(i.e. copy between a pair of floating-point registers and a
vector register).

llvm-svn: 308196
2017-07-17 17:44:20 +00:00
Ulrich Weigand 33435c4c9c [SystemZ] Add support for IBM z14 processor (2/3)
This adds support for the new 32-bit vector float instructions of z14.
This includes:
- Enabling the instructions for the assembler/disassembler.
- CodeGen for the instructions, including new LLVM intrinsics.
- Scheduler description support for the instructions.
- Update to the vector cost function calculations.

In general, CodeGen support for the new v4f32 instructions closely
matches support for the existing v2f64 instructions.

llvm-svn: 308195
2017-07-17 17:42:48 +00:00
Ulrich Weigand 2b3482fe85 [SystemZ] Add support for IBM z14 processor (1/3)
This patch series adds support for the IBM z14 processor.  This part includes:
- Basic support for the new processor and its features.
- Support for new instructions (except vector 32-bit float and 128-bit float).
- CodeGen for new instructions, including new LLVM intrinsics.
- Scheduler description for the new processor.
- Detection of z14 as host processor.

Support for the new 32-bit vector float and 128-bit vector float
instructions is provided by separate patches.

llvm-svn: 308194
2017-07-17 17:41:11 +00:00
Konstantin Zhuravlyov bb80d3e1d3 Enhance synchscope representation
OpenCL 2.0 introduces the notion of memory scopes in atomic operations to
  global and local memory. These scopes restrict how synchronization is
  achieved, which can result in improved performance.

  This change extends existing notion of synchronization scopes in LLVM to
  support arbitrary scopes expressed as target-specific strings, in addition to
  the already defined scopes (single thread, system).

  The LLVM IR and MIR syntax for expressing synchronization scopes has changed
  to use *syncscope("<scope>")*, where <scope> can be "singlethread" (this
  replaces *singlethread* keyword), or a target-specific name. As before, if
  the scope is not specified, it defaults to CrossThread/System scope.

  Implementation details:
    - Mapping from synchronization scope name/string to synchronization scope id
      is stored in LLVM context;
    - CrossThread/System and SingleThread scopes are pre-defined to efficiently
      check for known scopes without comparing strings;
    - Synchronization scope names are stored in SYNC_SCOPE_NAMES_BLOCK in
      the bitcode.

Differential Revision: https://reviews.llvm.org/D21723

llvm-svn: 307722
2017-07-11 22:23:00 +00:00
Simon Pilgrim 8c4069e842 [SystemZ] Fix -Wimplicit-fallthrough warnings. NFCI.
llvm-svn: 307376
2017-07-07 10:07:09 +00:00
Ulrich Weigand 43579cf4a0 [SystemZ] Simplify handling of 128-bit multiply/divide instruction
Several integer multiply/divide instructions require use of a
register pair as input and output.  This patch moves setting
up the input register pair from C++ code to TableGen, simplifying
the whole process and making it more easily extensible.

No functional change.

llvm-svn: 307155
2017-07-05 13:17:31 +00:00
Jonas Paulsson 8c33647ba1 [SystemZ] Add a check against zero before calling getTestUnderMaskCond()
Csmith discovered that this function can be called with a zero argument,
in which case an assert for this triggered.

This patch also adds a guard before the other call to this function since
it was missing, although the test only covers the case where it was
discovered.

Reduced test case attached as CodeGen/SystemZ/int-cmp-54.ll.

Review: Ulrich Weigand
llvm-svn: 306287
2017-06-26 13:38:27 +00:00
Ulrich Weigand eaf0051ba3 [SystemZ] Remove unnecessary serialization before volatile loads
This reverts the use of TargetLowering::prepareVolatileOrAtomicLoad
introduced by r196905.  Nothing in the semantics of the "volatile"
keyword or the definition of the z/Architecture actually requires
that volatile loads are preceded by a serialization operation, and
no other compiler on the platform actually implements this.

Since we've now seen a use case where this additional serialization
causes noticable performance degradation, this patch removes it.

The patch still leaves in the serialization before atomic loads,
which is now implemented directly in lowerATOMIC_LOAD.  (This also
seems overkill, but that can be addressed separately.)

llvm-svn: 306117
2017-06-23 15:56:14 +00:00
Jonas Paulsson ae8d22cee2 [SystemZ] Propagate MachineMemOperands
In emitCondStore() and emitMemMemWrapper().

Review: Ulrich Weigand
llvm-svn: 304913
2017-06-07 14:08:34 +00:00
Jonas Paulsson fe0c0935c8 [SystemZ] Improve buildVector() in SystemZISelLowering.cpp.
Use VLREP when inserting one or more loads into a vector. This is more
efficient than to first load and then use a VLVGP.

Review: Ulrich Weigand
llvm-svn: 304152
2017-05-29 13:22:23 +00:00
Jonas Paulsson 11d251c05c [SystemZ] Implement getRepRegClassFor()
This method must return a valid register class, or the list-ilp isel
scheduler will crash. For MVT::Untyped nullptr was previously returned, but
now ADDR128BitRegClass is returned instead. This is needed just as long as
list-ilp (and probably also list-hybrid) is still there.

Review: Ulrich Weigand, A Trick
https://reviews.llvm.org/D32802

llvm-svn: 302649
2017-05-10 13:03:25 +00:00
Serge Pavlov d526b13e61 Add extra operand to CALLSEQ_START to keep frame part set up previously
Using arguments with attribute inalloca creates problems for verification
of machine representation. This attribute instructs the backend that the
argument is prepared in stack prior to  CALLSEQ_START..CALLSEQ_END
sequence (see http://llvm.org/docs/InAlloca.htm for details). Frame size
stored in CALLSEQ_START in this case does not count the size of this
argument. However CALLSEQ_END still keeps total frame size, as caller can
be responsible for cleanup of entire frame. So CALLSEQ_START and
CALLSEQ_END keep different frame size and the difference is treated by
MachineVerifier as stack error. Currently there is no way to distinguish
this case from actual errors.

This patch adds additional argument to CALLSEQ_START and its
target-specific counterparts to keep size of stack that is set up prior to
the call frame sequence. This argument allows MachineVerifier to calculate
actual frame size associated with frame setup instruction and correctly
process the case of inalloca arguments.

The changes made by the patch are:
- Frame setup instructions get the second mandatory argument. It
  affects all targets that use frame pseudo instructions and touched many
  files although the changes are uniform.
- Access to frame properties are implemented using special instructions
  rather than calls getOperand(N).getImm(). For X86 and ARM such
  replacement was made previously.
- Changes that reflect appearance of additional argument of frame setup
  instruction. These involve proper instruction initialization and
  methods that access instruction arguments.
- MachineVerifier retrieves frame size using method, which reports sum of
  frame parts initialized inside frame instruction pair and outside it.

The patch implements approach proposed by Quentin Colombet in
https://bugs.llvm.org/show_bug.cgi?id=27481#c1.
It fixes 9 tests failed with machine verifier enabled and listed
in PR27481.

Differential Revision: https://reviews.llvm.org/D32394

llvm-svn: 302527
2017-05-09 13:35:13 +00:00
Craig Topper d0af7e8ab8 [SelectionDAG] Use KnownBits struct in DAG's computeKnownBits and simplifyDemandedBits
This patch replaces the separate APInts for KnownZero/KnownOne with a single KnownBits struct. This is similar to what was done to ValueTracking's version recently.

This is largely a mechanical transformation from KnownZero to Known.Zero.

Differential Revision: https://reviews.llvm.org/D32569

llvm-svn: 301620
2017-04-28 05:31:46 +00:00
Matt Arsenault 3138075dd4 DAG: Make mayBeEmittedAsTailCall parameter const
llvm-svn: 300603
2017-04-18 21:16:46 +00:00
Jonas Paulsson fccc7d66c3 [SystemZ] TargetTransformInfo cost functions implemented.
getArithmeticInstrCost(), getShuffleCost(), getCastInstrCost(),
getCmpSelInstrCost(), getVectorInstrCost(), getMemoryOpCost(),
getInterleavedMemoryOpCost() implemented.

Interleaved access vectorization enabled.

BasicTTIImpl::getCastInstrCost() improved to check for legal extending loads,
in which case the cost of the z/sext instruction becomes 0.

Review: Ulrich Weigand, Renato Golin.
https://reviews.llvm.org/D29631

llvm-svn: 300052
2017-04-12 11:49:08 +00:00
Jonas Paulsson cad72efee6 [SystemZ] Check for presence of vector support in SystemZISelLowering
A test case was found with llvm-stress that caused DAGCombiner to crash
when compiling for an older subtarget without vector support.

SystemZTargetLowering::combineTruncateExtract() should do nothing for older
subtargets.

This check was placed in canTreatAsByteVector(), which also helps in a few
other places.

Review: Ulrich Weigand
llvm-svn: 299763
2017-04-07 12:35:11 +00:00
Jonas Paulsson 16100c637e [SystemZ] Remove confusing comment in combineEXTRACT_VECTOR_ELT()
It isn't just one-element vectors that can appear here.

llvm-svn: 299762
2017-04-07 12:11:41 +00:00
Nirav Dave aa65a2beb8 [SystemZ] Prevent Merging Bitcast with non-normal loads
Fixes PR32505.

Reviewers: uweigand, jonpa

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31609

llvm-svn: 299552
2017-04-05 15:42:48 +00:00
Jonas Paulsson 56bb0857e9 [SystemZ] Skip DAGCombining of vector node for older subtargets.
Even on older subtargets that lack vector support, there may be vector values
with just one element in the input program. These are converted during DAG
legalization to scalar values.

The pre-legalize SystemZ DAGCombiner methods should in this circumstance not
touch these nodes. This patch adds a check for this in
SystemZTargetLowering::combineEXTRACT_VECTOR_ELT().

Review: Ulrich Weigand
llvm-svn: 299213
2017-03-31 13:22:59 +00:00
Jonas Paulsson 1d33cd3988 [SystemZ] Add check VT.isSimple() in canTreateAsByteVector()
Since BB-vectorizer can produce vectors of for example 3 elements,
this check is needed.

Review: Ulrich Weigand
llvm-svn: 297136
2017-03-07 09:49:31 +00:00
Jonas Paulsson b7a2ef8375 [SystemZ] Add comment for ISD::FP_TO_UINT expansion.
(Copied from the fp-conv-10.ll test to SystemZISelLowering.cpp)

Review: Ulrich Weigand
llvm-svn: 293900
2017-02-02 15:42:14 +00:00
Jonas Paulsson 463e2a6f3d [SystemZ] Gracefully fail in GeneralShuffle::add() instead of assertion.
The GeneralShuffle::add() method used to have an assert that made sure that
source elements were at least as big as the destination elements. This was
wrong, since it is actually expected that an EXTRACT_VECTOR_ELT node with a
smaller source element type than the return type gets extended.

Therefore, instead of asserting this, it is just checked and if this is the
case 'false' is returned from the GeneralShuffle::add() method. This case
should be very rare and is not handled further by the backend.

Review: Ulrich Weigand.
llvm-svn: 292888
2017-01-24 05:43:03 +00:00
Diana Picus 116bbab4e4 [CodeGen] Rename MachineInstrBuilder::addOperand. NFC
Rename from addOperand to just add, to match the other method that has been
added to MachineInstrBuilder for adding more than just 1 operand.

See https://reviews.llvm.org/D28057 for the whole discussion.

Differential Revision: https://reviews.llvm.org/D28556

llvm-svn: 291891
2017-01-13 09:58:52 +00:00
Jonas Paulsson c282975604 [SystemZ] Improve isFoldableMemAccessOffset().
A store of an extracted element or a load which gets inserted into a vector,
will be combined into a vector load/store element instruction.

Therefore, isFoldableMemAccessOffset(), which is called by LSR, should
return false in these cases.

Reviewer: Ulrich Weigand
llvm-svn: 291673
2017-01-11 14:40:39 +00:00
Ulrich Weigand 524f276c74 [SystemZ] Improve use of conditional instructions
This patch moves formation of LOC-type instructions from (late)
IfConversion to the early if-conversion pass, and in some cases
additionally creates them directly from select instructions
during DAG instruction selection.

To make early if-conversion work, the patch implements the
canInsertSelect / insertSelect callbacks.  It also implements
the commuteInstructionImpl and FoldImmediate callbacks to
enable generation of the full range of LOC instructions.

Finally, the patch adds support for all instructions of the
load-store-on-condition-2 facility, which allows using LOC
instructions also for high registers.

Due to the use of the GRX32 register class to enable high registers,
we now also have to handle the cases where there are still no single
hardware instructions (conditional move from a low register to a high
register or vice versa).  These are converted back to a branch sequence
after register allocation.  Since the expandRAPseudos callback is not
allowed to create new basic blocks, this requires a simple new pass,
modelled after the ARM/AArch64 ExpandPseudos pass.

Overall, this patch causes significantly more LOC-type instructions
to be used, and results in a measurable performance improvement.

llvm-svn: 288028
2016-11-28 13:34:08 +00:00
Ulrich Weigand fffc7110d6 [SystemZ] Model access registers as LLVM registers
Add the 16 access registers as LLVM registers.  This allows removing
a lot of special cases in the assembler and disassembler where we
were handling access registers; this can all just use the generic
register code now.

Also add a bunch of instructions to operate on access registers,
for assembler/disassembler use only.  No change in code generation
intended.

llvm-svn: 286283
2016-11-08 20:15:26 +00:00
Konstantin Zhuravlyov 8ea0246e93 [MachineMemOperand] Move synchronization scope and atomic orderings from SDNode to MachineMemOperand, and remove redundant getAtomic* member functions from SelectionDAG.
Differential Revision: https://reviews.llvm.org/D24577

llvm-svn: 284312
2016-10-15 22:01:18 +00:00
Sanjay Patel 1ed771f5d7 getVectorElementType().getSizeInBits() -> getScalarSizeInBits() ; NFCI
llvm-svn: 281495
2016-09-14 16:37:15 +00:00
Sanjay Patel b1f0a0f4a8 getValueType().getSizeInBits() -> getValueSizeInBits() ; NFCI
llvm-svn: 281493
2016-09-14 16:05:51 +00:00
Elliot Colp a4092104cb Fix SystemZ hang caused by r279105
The change in r279105 causes an infinite loop in some cases, as it sets the upper bits of an AND mask constant, which DAGCombiner::SimplifyDemandedBits then unsets.
This patch reverts that part of the behaviour, instead relying on .td peepholes to perform the transformation to NILL. I reapplied my original fix for the problem addressed by r279105 (unsetting the upper bits, which prevents a compiler abort for a different reason).

Differential Revision: https://reviews.llvm.org/D23781

llvm-svn: 279515
2016-08-23 14:03:02 +00:00
Michael Kuperstein 2bc3d4d46c [SelectionDAG] Rename fextend -> fpextend, fround -> fpround, frnd -> fround
The names of the tablegen defs now match the names of the ISD nodes.
This makes the world a slightly saner place, as previously "fround" matched
ISD::FP_ROUND and not ISD::FROUND.

Differential Revision: https://reviews.llvm.org/D23597

llvm-svn: 279129
2016-08-18 20:08:15 +00:00
Elliot Colp 687691aeac Fix SystemZ compilation abort caused by negative AND mask
Normally, when an AND with a constant is lowered to NILL, the constant value is truncated to 16 bits. However, since r274066, ANDs whose results are used in a shift are caught by a different pattern that does not truncate. The instruction printer expects a 16-bit unsigned immediate operand for NILL, so this results in an abort.

This patch adds code to manually truncate the constant in this situation. The rest of the bits are then set, so we will detect a case for NILL "naturally" rather than using peephole optimizations.

Differential Revision: http://reviews.llvm.org/D21854

llvm-svn: 279105
2016-08-18 18:04:26 +00:00
Jonas Paulsson 7a79422536 [LoopStrenghtReduce] Refactoring and addition of a new target cost function.
Refactored so that a LSRUse owns its fixups, as oppsed to letting the
LSRInstance own them. This makes it easier to rate formulas for
LSRUses, since the fixups are available directly. The Offsets vector
has been removed since it was no longer necessary.

New target hook isFoldableMemAccessOffset(), which is used during formula
rating.

For SystemZ, this is useful to express that loads and stores with
float or vector types with a big/negative offset should be avoided in
loops. Without this, LSR will generate a lot of negative offsets that
would require extra instructions for loading the address.

Updated tests:
test/CodeGen/SystemZ/loop-01.ll

Reviewed by: Quentin Colombet and Ulrich Weigand.
https://reviews.llvm.org/D19152

llvm-svn: 278927
2016-08-17 13:24:19 +00:00
Matthias Braun 941a705b7b MachineFunction: Return reference for getFrameInfo(); NFC
getFrameInfo() never returns nullptr so we should use a reference
instead of a pointer.

llvm-svn: 277017
2016-07-28 18:40:00 +00:00
Justin Lebar 9c375817ac [SelectionDAG] Get rid of bool parameters in SelectionDAG::getLoad, getStore, and friends.
Summary:
Instead, we take a single flags arg (a bitset).

Also add a default 0 alignment, and change the order of arguments so the
alignment comes before the flags.

This greatly simplifies many callsites, and fixes a bug in
AMDGPUISelLowering, wherein the order of the args to getLoad was
inverted.  It also greatly simplifies the process of adding another flag
to getLoad.

Reviewers: chandlerc, tstellarAMD

Subscribers: jholewinski, arsenm, jyknight, dsanders, nemanjai, llvm-commits

Differential Revision: http://reviews.llvm.org/D22249

llvm-svn: 275592
2016-07-15 18:27:10 +00:00
Marcin Koscielnicki cf7cc724a7 [SystemZ] Utilize Test Data Class instructions.
This adds a new SystemZ-specific intrinsic, llvm.s390.tdc.f(32|64|128),
which maps straight to the test data class instructions.  A new IR pass
is added to recognize instructions that can be converted to TDC and
perform the necessary replacements.

Differential Revision: http://reviews.llvm.org/D21949

llvm-svn: 275016
2016-07-10 14:41:22 +00:00
Elliot Colp bc2cfc2291 [SystemZ] Remove AND mask of bottom 6 bits when result is used for shift/rotate
On SystemZ, shift and rotate instructions only use the bottom 6 bits of the shift/rotate amount.
Therefore, if the amount is ANDed with an immediate mask that has all of the bottom 6 bits set, we
can remove the AND operation entirely.

Differential Revision: http://reviews.llvm.org/D21854

llvm-svn: 274650
2016-07-06 18:13:11 +00:00
Marcin Koscielnicki 32e8734e41 [SystemZ] Move misplaced SystemZ::TDC to non-memory opcode range.
llvm-svn: 274417
2016-07-02 02:20:40 +00:00
Duncan P. N. Exon Smith e4f5e4f4d1 CodeGen: Use MachineInstr& in TargetLowering, NFC
This is a mechanical change to make TargetLowering API take MachineInstr&
(instead of MachineInstr*), since the argument is expected to be a valid
MachineInstr.  In one case, changed a parameter from MachineInstr* to
MachineBasicBlock::iterator, since it was used as an insertion point.

As a side effect, this removes a bunch of MachineInstr* to
MachineBasicBlock::iterator implicit conversions, a necessary step
toward fixing PR26753.

llvm-svn: 274287
2016-06-30 22:52:52 +00:00
Marcin Koscielnicki 68747ac78e [SystemZ] Split up PerformDAGCombine. [NFC]
This function is already a bit too long, and I'm about to make it worse.

llvm-svn: 274191
2016-06-30 00:08:54 +00:00
Marcin Koscielnicki 518cbc7cc3 [SystemZ] Add floating-point test data class instructions.
These are not used by CodeGen yet - ISD combiners creating the new node
will come in subsequent patches.

llvm-svn: 274108
2016-06-29 07:29:07 +00:00
Rafael Espindola 3beef8d6db Move shouldAssumeDSOLocal to Target.
Should fix the shared library build.

llvm-svn: 273958
2016-06-27 23:15:57 +00:00
Benjamin Kramer bdc4956bac Pass DebugLoc and SDLoc by const ref.
This used to be free, copying and moving DebugLocs became expensive
after the metadata rewrite. Passing by reference eliminates a ton of
track/untrack operations. No functionality change intended.

llvm-svn: 272512
2016-06-12 15:39:02 +00:00
Zhan Jun Liau ab42cbce98 [SystemZ] Support Compare and Traps
Support and generate Compare and Traps like CRT, CIT, etc.

Support Trap as legal DAG opcodes and generate "j .+2" for them by default.
Add support for Conditional Traps and use the If Converter to convert them into
the corresponding compare and trap opcodes.

Differential Revision: http://reviews.llvm.org/D21155

llvm-svn: 272419
2016-06-10 19:58:10 +00:00
Bryan Chan 28b759c4c8 [SystemZ] Support LRVH and STRVH opcodes
Summary: On Linux, /usr/include/bits/byteswap-16.h defines __byteswap_16(x) as an inlined LRVH (Load Reversed Half-word) instruction. The SystemZ back-end did not support this opcode and the inlined assembly would cause a fatal error.

Reviewers: bryanpkc, uweigand

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D18732

llvm-svn: 269688
2016-05-16 20:32:22 +00:00
Marcin Koscielnicki ad1482c6f1 [SystemZ] Implement backchain attribute (recommit with fix).
This introduces a SystemZ-specific "backchain" attribute on function, which
enables writing the frame backchain link as specified by the ABI.  This will
be used to implement -mbackchain option in clang.

Differential Revision: http://reviews.llvm.org/D19889

Fixed in this version: added RegState::Define and RegState::Kill on R1D
in prologue.

llvm-svn: 268581
2016-05-05 00:37:30 +00:00