Commit Graph

360 Commits

Author SHA1 Message Date
Lei Huang c29229a644 [PowerPC] Unify handling for conversion of FP_TO_INT feeding a store
Existing DAG combine only handles conversions for FP_TO_SINT:
"{f32, f64} x { i32, i16 }"

This patch simplifies the code to handle:
"{ FP_TO_SINT, FP_TO_UINT } x { f64, f32 } x { i64, i32, i16, i8 }"

Differential Revision: https://reviews.llvm.org/D46102

llvm-svn: 331778
2018-05-08 17:36:40 +00:00
Nemanja Ivanovic 01e2e79abf [PowerPC] Implement isMaskAndCmp0FoldingBeneficial
Sinking the and closer to a compare against zero is beneficial on PPC as it
allows us to emit record-form instructions. In the future, we may expand this
to a larger set of operations that feed compares against zero since PPC has
lots of record-form instructions.

Differential revision: https://reviews.llvm.org/D46060

llvm-svn: 331416
2018-05-02 23:55:23 +00:00
Adrian Prantl 5f8f34e459 Remove \brief commands from doxygen comments.
We've been running doxygen with the autobrief option for a couple of
years now. This makes the \brief markers into our comments
redundant. Since they are a visual distraction and we don't want to
encourage more \brief markers in new code either, this patch removes
them all.

Patch produced by

  for i in $(git grep -l '\\brief'); do perl -pi -e 's/\\brief //g' $i & done

Differential Revision: https://reviews.llvm.org/D46290

llvm-svn: 331272
2018-05-01 15:54:18 +00:00
Craig Topper 2fa1436206 [IR][CodeGen] Remove dependency on EVT from IR/Function.cpp. Move EVT to CodeGen layer.
Currently EVT is in the IR layer only because of Function.cpp needing a very small piece of the functionality of EVT::getEVTString(). The rest of EVT is used in codegen making CodeGen a better place for it.

The previous code converted a Type* to EVT and then called getEVTString. This was only expected to handle the primitive types from Type*. Since there only a few primitive types, we can just print them as strings directly.

Differential Revision: https://reviews.llvm.org/D45017

llvm-svn: 328806
2018-03-29 17:21:10 +00:00
David Blaikie 36a0f226b1 Fix layering by moving ValueTypes.h from CodeGen to IR
ValueTypes.h is implemented in IR already.

llvm-svn: 328397
2018-03-23 23:58:31 +00:00
David Blaikie 13e77db2df Fix layering of MachineValueType.h by moving it from CodeGen to Support
This is used by llvm tblgen as well as by LLVM Targets, so the only
common place is Support for now. (maybe we need another target for these
sorts of things - but for now I'm at least making them correct & we can
make them better if/when people have strong feelings)

llvm-svn: 328395
2018-03-23 23:58:25 +00:00
Nemanja Ivanovic d9d5bd3067 [PowerPC] Make AddrSpaceCast noop
PowerPC targets do not use address spaces. As a result, we can get selection
failures with address space casts. This patch makes those casts noops.

Patch by Valentin Churavy.

Differential revision: https://reviews.llvm.org/D43781

llvm-svn: 327877
2018-03-19 18:50:02 +00:00
Nemanja Ivanovic ebb23078e9 [PowerPC] Zero-extend the compare operand for ATOMIC_CMP_SWAP
Part of the fix for https://bugs.llvm.org/show_bug.cgi?id=35812.
This patch ensures that the compare operand for the atomic compare and swap
is properly zero-extended to 32 bits if applicable.
A follow-up commit will fix the extension for the SETCC node generated when
expanding an ATOMIC_CMP_SWAP_WITH_SUCCESS. That will complete the bug fix.

Differential Revision: https://reviews.llvm.org/D41856

llvm-svn: 322372
2018-01-12 14:58:41 +00:00
Matthias Braun f1caa2833f MachineFunction: Return reference from getFunction(); NFC
The Function can never be nullptr so we can return a reference.

llvm-svn: 320884
2017-12-15 22:22:58 +00:00
Matt Arsenault 7d7adf4f2e TLI: Allow using PSV for intrinsic mem operands
llvm-svn: 320756
2017-12-14 22:34:10 +00:00
Francis Visoiu Mistrih 9d7bb0cb40 [CodeGen] Print register names in lowercase in both MIR and debug output
As part of the unification of the debug format and the MIR format,
always print registers as lowercase.

* Only debug printing is affected. It now follows MIR.

Differential Revision: https://reviews.llvm.org/D40417

llvm-svn: 319187
2017-11-28 17:15:09 +00:00
David Blaikie b3bde2ea50 Fix a bunch more layering of CodeGen headers that are in Target
All these headers already depend on CodeGen headers so moving them into
CodeGen fixes the layering (since CodeGen depends on Target, not the
other way around).

llvm-svn: 318490
2017-11-17 01:07:10 +00:00
Sean Fertile 0f0837e84e [PowerPC] Implement mayBeEmittedAsTailCall for PPC
Implements TargetLowering callback 'mayBeEmittedAsTailCall' that enables
CodeGenPrepare to duplicate returns when they might enable a tail-call.

Differential Revision: https://reviews.llvm.org/D39777

llvm-svn: 318321
2017-11-15 18:58:27 +00:00
Graham Yiu 030621bbcb Adds code to PPC ISEL lowering to recognize byte inserts from vector_shuffles, and use P9 shift and vector insert byte instructions instead of vperm. Extends tests from vector insert half-word.
Differential Revision: https://reviews.llvm.org/D34497

llvm-svn: 317503
2017-11-06 20:18:30 +00:00
Guozhi Wei e3b8d9a312 [PPC] Use xxbrd to speed up bswap64
Power doesn't have bswap instructions, so llvm generates following code sequence for bswap64.

  rotldi   5, 3, 16
  rotldi   4, 3, 8
  rotldi   9, 3, 24
  rotldi   10, 3, 32
  rotldi   11, 3, 48
  rotldi   12, 3, 56
  rldimi 4, 5, 8, 48
  rldimi 4, 9, 16, 40
  rldimi 4, 10, 24, 32
  rldimi 4, 11, 40, 16
  rldimi 4, 12, 48, 8
  rldimi 4, 3, 56, 0

But Power9 has vector bswap instructions, they can also be used to speed up scalar bswap intrinsic. With this patch, bswap64 can be translated to:

  mtvsrdd 34, 3, 3
  xxbrd 34, 34
  mfvsrld 3, 34

Differential Revision: https://reviews.llvm.org/D39510

llvm-svn: 317499
2017-11-06 19:09:38 +00:00
Graham Yiu 671526148c Adds code to PPC ISEL lowering to recognize half-word inserts from vector_shuffles, and use P9 shift and vector insert instructions instead of vperm.
Differential Revision: https://reviews.llvm.org/D34160

llvm-svn: 317111
2017-11-01 18:06:56 +00:00
Matt Arsenault f2db97d8fa DAG: Add opcode and source type to isFPExtFree
This is only currently used for mad/fma transforms.
This is the only case where it should be used for AMDGPU,
so add an opcode to be sure.

llvm-svn: 315740
2017-10-13 19:55:45 +00:00
Tony Jiang 61ef1c540c [PPC][NFC] Renaming things with 'xxinsert' moniker to 'vecinsert' to make it more general.
Commit on behalf of Graham Yiu (gyiu@ca.ibm.com)

llvm-svn: 312547
2017-09-05 18:08:02 +00:00
Sanjay Patel e404cbff66 [DAG] convert vector select-of-constants to logic/math
This goes back to a discussion about IR canonicalization. We'd like to preserve and convert
more IR to 'select' than we currently do because that's likely the best choice in IR:
http://lists.llvm.org/pipermail/llvm-dev/2016-September/105335.html
...but that's often not true for codegen, so we need to account for this pattern coming in
to the backend and transform it to better DAG ops.

Steps in this patch:

  1. Add an EVT param to the existing convertSelectOfConstantsToMath() TLI hook to more finely
     enable this transform. Other targets will probably want that anyway to distinguish scalars
     from vectors. We're using that here to exclude AVX512 targets, but it may not be necessary.

  2. Convert a vselect to ext+add. This eliminates a constant load/materialization, and the
     vector ext is often free.

Implementing a more general fold using xor+and can be a follow-up for targets that don't have
a legal vselect. It's also possible that we can remove the TLI hook for the special case fold
implemented here because we're eliminating a constant, but it needs to be tested on other
targets.

Differential Revision: https://reviews.llvm.org/D36840

llvm-svn: 311731
2017-08-24 23:24:43 +00:00
Peter Collingbourne 081ffe2ff2 Change CallLoweringInfo::CS to be an ImmutableCallSite instead of a pointer. NFCI.
This was a use-after-free waiting to happen.

llvm-svn: 309159
2017-07-26 19:15:29 +00:00
Stefan Pintilie df0ee9e1b9 [NFC] test commit.
Added a comment to explain how to add a PPCISD node.

llvm-svn: 309114
2017-07-26 13:44:59 +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
Nemanja Ivanovic 3c7e276d24 [PowerPC] Ensure displacements for DQ-Form instructions are multiples of 16
As outlined in the PR, we didn't ensure that displacements for DQ-Form
instructions are multiples of 16. Since the instruction encoding encodes
a quad-word displacement, a sub-16 byte displacement is meaningless and
ends up being encoded incorrectly.

Fixes https://bugs.llvm.org/show_bug.cgi?id=33671.

Differential Revision: https://reviews.llvm.org/D35007

llvm-svn: 307934
2017-07-13 18:17:10 +00:00
Hiroshi Inoue 70b1af5921 fix formatting; NFC
llvm-svn: 307523
2017-07-10 06:32:52 +00:00
Lei Huang 317104183d [PowerPC] NFC : Common up definitions of isIntS16Immediate and update parameter to int16_t
llvm-svn: 307442
2017-07-07 21:12:35 +00:00
Tony Jiang 9a91a18110 [Power9] Exploit vector integer extend instructions when indices aren't correct.
This patch adds on to the exploitation added by https://reviews.llvm.org/D33510.
This now catches build vector nodes where the inputs are coming from sign
extended vector extract elements where the indices used by the vector extract
are not correct. We can still use the new hardware instructions by adding a
shuffle to move the elements to the correct indices. I introduced a new PPCISD
node here because adding a vector_shuffle and changing the elements of the
vector_extracts was getting undone by another DAG combine.

Commit on behalf of Zaara Syeda (syzaara@ca.ibm.com)
Differential Revision: https://reviews.llvm.org/D34009

llvm-svn: 307169
2017-07-05 16:00:38 +00:00
Tony Jiang 1a8eec141a [PowerPC] Match vec_revb builtins to P9 instructions.
Power9 has instructions that will reverse the bytes within an element for all
sizes (half-word, word, double-word and quad-word). These can be used for the
vec_revb builtins in altivec.h. However, we implement these to match vector
shuffle nodes as that will cover both the builtins and vector shuffles that
occur in the SDAG through other means.

Differential Revision: https://reviews.llvm.org/D33690

llvm-svn: 305214
2017-06-12 18:24:36 +00:00
Tony Jiang 30a49d1a3d [Power9] Added support for the modsw, moduw, modsd, modud hardware instructions.
Note that if we need the result of both the divide and the modulo then we
compute the modulo based on the result of the divide and not using the new
hardware instruction.

Commit on behalf of STEFAN PINTILIE.
Differential Revision: https://reviews.llvm.org/D33940

llvm-svn: 305210
2017-06-12 17:58:42 +00:00
Tony Jiang 60c247de18 [PowerPC] Fix a performance bug for PPC::XXPERMDI.
There are some VectorShuffle Nodes in SDAG which can be selected to XXPERMDI
Instruction, this patch recognizes them and does the selection to improve
the PPC performance.

Differential Revision: https://reviews.llvm.org/D33404

llvm-svn: 304298
2017-05-31 13:09:57 +00:00
Tony Jiang 0a429f040e [PowerPC] Fix a performance bug for PPC::XXSLDWI.
There are some VectorShuffle Nodes in SDAG which can be selected to XXSLDWI
instruction, this patch recognizes them and does the selection to improve the
PPC performance.

llvm-svn: 303822
2017-05-24 23:48:29 +00:00
Tim Shen 3bef27cc6f [PPC] Lower load acquire/seq_cst trailing fence to cmp + bne + isync.
Summary:
This fixes pr32392.

The lowering pipeline is:
llvm.ppc.cfence in IR -> PPC::CFENCE8 in isel -> Actual instructions in
expandPostRAPseudo.

The reason why expandPostRAPseudo is chosen is because previous passes
are likely eliminating instructions like cmpw 3, 3 (early CSE) and bne-
7, .+4 (some branch pass(s)).

Differential Revision: https://reviews.llvm.org/D32763

llvm-svn: 303205
2017-05-16 20:18:06 +00:00
Tim Shen 10c64e6aea [PPC] Move the combine "a << (b % (sizeof(a) * 8)) -> (PPCshl a, b)" to the backend. NFC.
Summary:
Eli pointed out that it's unsafe to combine the shifts to ISD::SHL etc.,
because those are not defined for b > sizeof(a) * 8, even after some of
the combiners run.

However, PPCISD::SHL defines that behavior (as the instructions themselves).
Move the combination to the backend.

The tests in shift_mask.ll still pass.

Reviewers: echristo, hfinkel, efriedma, iteratee

Subscribers: nemanjai, llvm-commits

Differential Revision: https://reviews.llvm.org/D33076

llvm-svn: 302937
2017-05-12 19:25:37 +00:00
Tim Shen 04de70d3a7 [Atomic] Remove IsStore/IsLoad in the interface, and pass the instruction instead. NFC.
Now both emitLeadingFence and emitTrailingFence take the instruction
itself, instead of taking IsLoad/IsStore pairs.
Instruction::mayReadFromMemory and Instrucion::mayWriteToMemory are used
for determining those two booleans.

The instruction argument is also useful for later D32763, in
emitTrailingFence. For emitLeadingFence, it seems to have cleaner
interface with the proposed change.

Differential Revision: https://reviews.llvm.org/D32762

llvm-svn: 302539
2017-05-09 15:27:17 +00:00
Tim Shen e59d06fe78 [PowerPC, DAGCombiner] Fold a << (b % (sizeof(a) * 8)) back to a single instruction
Summary:
This is the corresponding llvm change to D28037 to ensure no performance
regression.

Reviewers: bogner, kbarton, hfinkel, iteratee, echristo

Subscribers: nemanjai, llvm-commits

Differential Revision: https://reviews.llvm.org/D28329

llvm-svn: 301990
2017-05-03 00:07:02 +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
Sanjay Patel b2f1621bb1 [DAGCombiner] add and use TLI hook to convert and-of-seteq / or-of-setne to bitwise logic+setcc (PR32401)
This is a generic combine enabled via target hook to reduce icmp logic as discussed in:
https://bugs.llvm.org/show_bug.cgi?id=32401

It's likely that other targets will want to enable this hook for scalar transforms, 
and there are probably other patterns that can use bitwise logic to reduce comparisons.

Note that we are missing an IR canonicalization for these patterns, and we will probably
prefer the pair-of-compares form in IR (shorter, more likely to fold).

Differential Revision: https://reviews.llvm.org/D31483

llvm-svn: 299542
2017-04-05 14:09:39 +00:00
Simon Pilgrim 37b536e4b3 [DAGCombiner] Add vector demanded elements support to computeKnownBitsForTargetNode
Follow up to D25691, this sets up the plumbing necessary to support vector demanded elements support in known bits calculations in target nodes.

Differential Revision: https://reviews.llvm.org/D31249

llvm-svn: 299201
2017-03-31 11:24:16 +00:00
Sanjay Patel 066f3208bf [DAGCombiner] allow transforming (select Cond, C +/- 1, C) to (add(ext Cond), C)
select Cond, C +/- 1, C --> add(ext Cond), C -- with a target hook.

This is part of the ongoing process to obsolete D24480.  The motivation is to 
canonicalize to select IR in InstCombine whenever possible, so we need to have a way to
undo that easily in codegen.
 
PowerPC is an obvious winner for this kind of transform because it has fast and complete 
bit-twiddling abilities but generally lousy conditional execution perf (although this might
have changed in recent implementations).

x86 also sees some wins, but the effect is limited because these transforms already mostly
exist in its target-specific combineSelectOfTwoConstants(). The fact that we see any x86 
changes just shows that that code is a mess of special-case holes. We may be able to remove 
some of that logic now.

My guess is that other targets will want to enable this hook for most cases. The likely 
follow-ups would be to add value type and/or the constants themselves as parameters for the
hook. As the tests in select_const.ll show, we can transform any select-of-constants to 
math/logic, but the general transform for any 2 constants needs one more instruction 
(multiply or 'and').

ARM is one target that I think may not want this for most cases. I see infinite loops there
because it wants to use selects to enable conditionally executed instructions.

Differential Revision: https://reviews.llvm.org/D30537

llvm-svn: 296977
2017-03-04 19:18:09 +00:00
Eugene Zelenko 8187c192c6 [PowerPC] Fix some Clang-tidy modernize and Include What You Use warnings; other minor fixes (NFC).
llvm-svn: 291872
2017-01-13 00:58:58 +00:00
Tony Jiang 3a2f00b024 [PowerPC] Implement missing ISA 2.06 instructions.
Instructions: fctidu[.], fctiwu[.], ftdiv, ftsqrt are not implemented. Implement
them and add corresponding test cases in this patch.

llvm-svn: 291116
2017-01-05 15:00:45 +00:00
Guozhi Wei 1fd553c934 [PPC] Prefer direct move on power8 if load 1 or 2 bytes to VSR
Power8 has MTVSRWZ but no LXSIBZX/LXSIHZX, so move 1 or 2 bytes to VSR through MTVSRWZ is much faster than store the extended value into stack and load it with LXSIWZX.
This patch fixes pr31144.

Differential Revision: https://reviews.llvm.org/D27287

llvm-svn: 289473
2016-12-12 22:09:02 +00:00
Nemanja Ivanovic 8c11e79b17 [PowerPC] Improvements for BUILD_VECTOR Vol. 2
This patch corresponds to review:
https://reviews.llvm.org/D25980

This is the 2nd patch in a series of 4 that improve the lowering and combining
for BUILD_VECTOR nodes on PowerPC. This particular patch combines a build vector
of fp-to-int conversions into an fp-to-int conversion of a build vector of fp
values. For example:
Converts (build_vector (fp_to_[su]i $A), (fp_to_[su]i $B), ...)
Into (fp_to_[su]i (build_vector $A, $B, ...))).
Which is a natural match for much cleaner code.

llvm-svn: 288218
2016-11-29 23:36:03 +00:00
Ehsan Amiri 85818684c6 [PPC][DAGCombine] Convert SETCC to subtract when the result is zero extended
When we see a SETCC whose only users are zero extend operations, we can replace
it with a subtraction. This results in doing all calculations in GPRs and
avoids CR use.

Currently we do this only for ULT, ULE, UGT and UGE condition codes. There are
ways that this can be extended. For example for signed condition codes. In that
case we will be introducing additional sign extend instructions, so more careful
profitability analysis may be required.

Another direction to extend this is for equal, not equal conditions. Also when
users of SETCC are any_ext or sign_ext, we might be able to do something 
similar.

llvm-svn: 287329
2016-11-18 10:41:44 +00:00
Joerg Sonnenberger 8c1a9ac52b Always use relative jump table encodings on PowerPC64.
For the default, small and medium code model, use the existing
difference from the jump table towards the label. For all other code
models, setup the picbase and use the difference between the picbase and
the block address.

Overall, this results in smaller data tables at the expensive of one or
two more arithmetic operation at the jump site. Given that we only create
jump tables with a lot more than two entries, it is a net win in size.
For larger code models the assumption remains that individual functions
are no larger than 2GB.

Differential Revision: https://reviews.llvm.org/D26336

llvm-svn: 287059
2016-11-16 00:37:30 +00:00
Evandro Menezes 21f9ce1a0d [DAG Combiner] Fix the native computation of the Newton series for reciprocals
The generic infrastructure to compute the Newton series for reciprocal and
reciprocal square root was conceived to allow a target to compute the series
itself.  However, the original code did not properly consider this condition
if returned by a target.  This patch addresses the issues to allow a target
to compute the series on its own.

Differential revision: https://reviews.llvm.org/D22975

llvm-svn: 286523
2016-11-10 23:31:06 +00:00
Ehsan Amiri c90b02cf50 [PPC] Generate positive FP zero using xor insn instead of loading from constant area
https://reviews.llvm.org/D23614

Currently we load +0.0 from constant area. That can change to be generated using
XOR instruction.

llvm-svn: 284995
2016-10-24 17:31:09 +00:00
Sanjay Patel 0051efcf97 [Target] remove TargetRecip class; 2nd try
This is a retry of r284495 which was reverted at r284513 due to use-after-scope bugs
caused by faulty usage of StringRef.

This version also renames a pair of functions:
getRecipEstimateDivEnabled()
getRecipEstimateSqrtEnabled()
as suggested by Eric Christopher.

original commit msg:

[Target] remove TargetRecip class; move reciprocal estimate isel functionality to TargetLowering

This is a follow-up to https://reviews.llvm.org/D24816 - where we changed reciprocal estimates to be function attributes
rather than TargetOptions.

This patch is intended to be a structural, but not functional change. By moving all of the
TargetRecip functionality into TargetLowering, we can remove all of the reciprocal estimate
state, shield the callers from the string format implementation, and simplify/localize the
logic needed for a target to enable this.

If a function has a "reciprocal-estimates" attribute, those settings may override the target's
default reciprocal preferences for whatever operation and data type we're trying to optimize.
If there's no attribute string or specific setting for the op/type pair, just use the target
default settings.

As noted earlier, a better solution would be to move the reciprocal estimate settings to IR
instructions and SDNodes rather than function attributes, but that's a multi-step job that
requires infrastructure improvements. I intend to work on that, but it's not clear how long
it will take to get all the pieces in place.

Differential Revision: https://reviews.llvm.org/D25440

llvm-svn: 284746
2016-10-20 16:55:45 +00:00
Sanjay Patel 19601fa587 revert r284495: [Target] remove TargetRecip class
There's something wrong with the StringRef usage while parsing the attribute string.

llvm-svn: 284513
2016-10-18 18:36:49 +00:00
Sanjay Patel 08fff9ca81 [Target] remove TargetRecip class; move reciprocal estimate isel functionality to TargetLowering
This is a follow-up to D24816 - where we changed reciprocal estimates to be function attributes
rather than TargetOptions.

This patch is intended to be a structural, but not functional change. By moving all of the
TargetRecip functionality into TargetLowering, we can remove all of the reciprocal estimate
state, shield the callers from the string format implementation, and simplify/localize the
logic needed for a target to enable this.

If a function has a "reciprocal-estimates" attribute, those settings may override the target's
default reciprocal preferences for whatever operation and data type we're trying to optimize.
If there's no attribute string or specific setting for the op/type pair, just use the target
default settings.

As noted earlier, a better solution would be to move the reciprocal estimate settings to IR
instructions and SDNodes rather than function attributes, but that's a multi-step job that
requires infrastructure improvements. I intend to work on that, but it's not clear how long
it will take to get all the pieces in place.

Differential Revision: https://reviews.llvm.org/D25440

llvm-svn: 284495
2016-10-18 17:05:05 +00:00
Nemanja Ivanovic 11049f8f07 [Power9] Part-word VSX integer scalar loads/stores and sign extend instructions
This patch corresponds to review:
https://reviews.llvm.org/D23155

This patch removes the VSHRC register class (based on D20310) and adds
exploitation of the Power9 sub-word integer loads into VSX registers as well
as vector sign extensions.
The new instructions are useful for a few purposes:

    Int to Fp conversions of 1 or 2-byte values loaded from memory
    Building vectors of 1 or 2-byte integers with values loaded from memory
    Storing individual 1 or 2-byte elements from integer vectors

This patch implements all of those uses.

llvm-svn: 283190
2016-10-04 06:59:23 +00:00