Commit Graph

344 Commits

Author SHA1 Message Date
Matt Arsenault 255cc5a760 CodeGen: Use LLT instead of EVT in getRegisterByName
Only PPC seems to be using it, and only checks some simple cases and
doesn't distinguish between FP. Just switch to using LLT to simplify
use from GlobalISel.
2020-01-09 17:37:52 -05:00
Reid Kleckner 9c2b72821b Move tail call disabling code to target independent code
When the "disable-tail-calls" attribute was added, checks were added for
it in various backends. Now this code has proliferated, and it is
something the target is responsible for checking. Move that
responsibility back to the ISels (fast, global, and SD).

There's no major functionality change, except for targets that never
implemented this check.

This LLVM attribute was originally added in
d9699bc7bd (2015).

Reviewers: echristo, MaskRay

Differential Revision: https://reviews.llvm.org/D72118
2020-01-03 11:27:41 -08:00
QingShan Zhang 2133d3c558 [DAGCombine] Initialize the default operation action for SIGN_EXTEND_INREG for vector type as 'expand' instead of 'legal'
For now, we didn't set the default operation action for SIGN_EXTEND_INREG for
vector type, which is 0 by default, that is legal. However, most target didn't
have native instructions to support this opcode. It should be set as expand by
default, as what we did for ANY_EXTEND_VECTOR_INREG.

Differential Revision: https://reviews.llvm.org/D70000
2020-01-03 03:26:41 +00:00
Reid Kleckner 5d986953c8 [IR] Split out target specific intrinsic enums into separate headers
This has two main effects:
- Optimizes debug info size by saving 221.86 MB of obj file size in a
  Windows optimized+debug build of 'all'. This is 3.03% of 7,332.7MB of
  object file size.
- Incremental step towards decoupling target intrinsics.

The enums are still compact, so adding and removing a single
target-specific intrinsic will trigger a rebuild of all of LLVM.
Assigning distinct target id spaces is potential future work.

Part of PR34259

Reviewers: efriedma, echristo, MaskRay

Reviewed By: echristo, MaskRay

Differential Revision: https://reviews.llvm.org/D71320
2019-12-11 18:02:14 -08:00
Matt Arsenault b696b9dba7 DAG: Add function context to isFMAFasterThanFMulAndFAdd
AMDGPU needs to know the FP mode for the function to answer this
correctly when this is removed from the subtarget.

AArch64 had to make this more complicated by using this from an IR
hook, so add an IR typed overload.
2019-11-19 19:25:26 +05:30
Graham Hunter 3f08ad611a [SVE][CodeGen] Scalable vector MVT size queries
* Implements scalable size queries for MVTs, split out from D53137.

* Contains a fix for FindMemType to avoid using scalable vector type
  to contain non-scalable types.

* Explicit casts for several places where implicit integer sign
  changes or promotion from 32 to 64 bits caused problems.

* CodeGenDAGPatterns will treat scalable and non-scalable vector types
  as different.

Reviewers: greened, cameron.mcinally, sdesmalen, rovka

Reviewed By: rovka

Differential Revision: https://reviews.llvm.org/D66871
2019-11-18 12:30:59 +00:00
Krzysztof Parzyszek 99f51960fd [Hexagon] Handle remaining registers in getRegisterByName()
This fixes https://llvm.org/PR43829.
2019-10-29 08:56:01 -05:00
Matt Arsenault f24ac13aaa TLI: Remove DAG argument from getRegisterByName
Replace with the MachineFunction. X86 is the only user, and only uses
it for the function. This removes one obstacle from using this in
GlobalISel. The other is the more tolerable EVT argument.

The X86 use of the function seems questionable to me. It checks hasFP,
before frame lowering.

llvm-svn: 373292
2019-10-01 01:44:39 +00:00
Guillaume Chatelet 18f805a7ea [Alignment][NFC] Remove unneeded llvm:: scoping on Align types
llvm-svn: 373081
2019-09-27 12:54:21 +00:00
Thomas Raoux 3c8c667235 [TargetLowering] Make allowsMemoryAccess methode virtual.
Rename old function to explicitly show that it cares only about alignment.
The new allowsMemoryAccess call the function related to alignment by default
and can be overridden by target to inform whether the memory access is legal or
not.

Differential Revision: https://reviews.llvm.org/D67121

llvm-svn: 372935
2019-09-26 00:16:01 +00:00
Krzysztof Parzyszek 2b5d7e93dd [MVT] Add v256i1 to MachineValueType
This type can show up when lowering some HVX vector code on Hexagon.

llvm-svn: 372403
2019-09-20 15:19:20 +00:00
Graham Hunter 1a9195d817 [SVE][MVT] Fixed-length vector MVT ranges
* Reordered MVT simple types to group scalable vector types
    together.
  * New range functions in MachineValueType.h to only iterate over
    the fixed-length int/fp vector types.
  * Stopped backends which don't support scalable vector types from
    iterating over scalable types.

Reviewers: sdesmalen, greened

Reviewed By: greened

Differential Revision: https://reviews.llvm.org/D66339

llvm-svn: 372099
2019-09-17 10:19:23 +00:00
Guillaume Chatelet ad1cea0dda [Alignment][NFC] Use Align with TargetLowering::setPrefFunctionAlignment
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: nemanjai, javed.absar, hiraditya, kbarton, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, s.egerton, pzheng, ychen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67267

llvm-svn: 371212
2019-09-06 15:03:49 +00:00
Guillaume Chatelet 9fcf066d0c [Alignment][NFC] Use Align with TargetLowering::setPrefLoopAlignment
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: nemanjai, hiraditya, kbarton, MaskRay, jsji, ychen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67278

llvm-svn: 371210
2019-09-06 14:51:15 +00:00
Guillaume Chatelet 4fc3ad9e13 [Alignment][NFC] Use Align with TargetLowering::setMinFunctionAlignment
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: jyknight, sdardis, nemanjai, javed.absar, hiraditya, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, PkmX, jocewei, jsji, s.egerton, pzheng, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D67229

llvm-svn: 371200
2019-09-06 12:48:34 +00:00
Krzysztof Parzyszek 0ce93194fe [Hexagon] Fix type in HexagonTargetLowering::ReplaceNodeResults
llvm-svn: 371083
2019-09-05 16:19:47 +00:00
Guillaume Chatelet aff45e4b23 [LLVM][Alignment] Make functions using log of alignment explicit
Summary:
This patch renames functions that takes or returns alignment as log2, this patch will help with the transition to llvm::Align.
The renaming makes it explicit that we deal with log(alignment) instead of a power of two alignment.
A few renames uncovered dubious assignments:

 - `MirParser`/`MirPrinter` was expecting powers of two but `MachineFunction` and `MachineBasicBlock` were using deal with log2(align). This patch fixes it and updates the documentation.
 - `MachineBlockPlacement` exposes two flags (`align-all-blocks` and `align-all-nofallthru-blocks`) supposedly interpreted as power of two alignments, internally these values are interpreted as log2(align). This patch updates the documentation,
 - `MachineFunctionexposes` exposes `align-all-functions` also interpreted as power of two alignment, internally this value is interpreted as log2(align). This patch updates the documentation,

Reviewers: lattner, thegameg, courbet

Subscribers: dschuff, arsenm, jyknight, dylanmckay, sdardis, nemanjai, jvesely, nhaehnle, javed.absar, hiraditya, kbarton, fedor.sergeev, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, PkmX, jocewei, jsji, Jim, s.egerton, llvm-commits, courbet

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65945

llvm-svn: 371045
2019-09-05 10:00:22 +00:00
Krzysztof Parzyszek ac83aab035 [Hexagon] Generate min/max instructions for 64-bit vectors
llvm-svn: 369124
2019-08-16 16:16:27 +00:00
Daniel Sanders 0c47611131 Apply llvm-prefer-register-over-unsigned from clang-tidy to LLVM
Summary:
This clang-tidy check is looking for unsigned integer variables whose initializer
starts with an implicit cast from llvm::Register and changes the type of the
variable to llvm::Register (dropping the llvm:: where possible).

Partial reverts in:
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
X86FixupLEAs.cpp - Some functions return unsigned and arguably should be MCRegister
X86FrameLowering.cpp - Some functions return unsigned and arguably should be MCRegister
HexagonBitSimplify.cpp - Function takes BitTracker::RegisterRef which appears to be unsigned&
MachineVerifier.cpp - Ambiguous operator==() given MCRegister and const Register
PPCFastISel.cpp - No Register::operator-=()
PeepholeOptimizer.cpp - TargetInstrInfo::optimizeLoadInstr() takes an unsigned&
MachineTraceMetrics.cpp - MachineTraceMetrics lacks a suitable constructor

Manual fixups in:
ARMFastISel.cpp - ARMEmitLoad() now takes a Register& instead of unsigned&
HexagonSplitDouble.cpp - Ternary operator was ambiguous between unsigned/Register
HexagonConstExtenders.cpp - Has a local class named Register, used llvm::Register instead of Register.
PPCFastISel.cpp - PPCEmitLoad() now takes a Register& instead of unsigned&

Depends on D65919

Reviewers: arsenm, bogner, craig.topper, RKSimon

Reviewed By: arsenm

Subscribers: RKSimon, craig.topper, lenary, aemerson, wuzish, jholewinski, MatzeB, qcolombet, dschuff, jyknight, dylanmckay, sdardis, nemanjai, jvesely, wdng, nhaehnle, sbc100, jgravelle-google, kristof.beyls, hiraditya, aheejin, kbarton, fedor.sergeev, javed.absar, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, atanasyan, rogfer01, MartinMosbeck, brucehoult, the_o, tpr, PkmX, jocewei, jsji, Petar.Avramovic, asbirlea, Jim, s.egerton, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65962

llvm-svn: 369041
2019-08-15 19:22:08 +00:00
Krzysztof Parzyszek 8e987702b1 [Hexagon] Fix instruction selection for vselect v4i8
llvm-svn: 369040
2019-08-15 19:20:09 +00:00
Krzysztof Parzyszek 8460301d58 [Hexagon] Generate vector min/max for HVX
llvm-svn: 369014
2019-08-15 16:13:17 +00:00
Guillaume Chatelet c97a3d15d2 [LLVM][Alignment] Introduce Alignment Type
Summary:
This is patch is part of a serie to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet, jfb, jakehehrlich

Reviewed By: jfb

Subscribers: wuzish, jholewinski, arsenm, dschuff, nemanjai, jvesely, nhaehnle, javed.absar, sbc100, jgravelle-google, hiraditya, aheejin, kbarton, asb, rbar, johnrusso, simoncook, apazos, sabuasal, niosHD, jrtc27, MaskRay, zzheng, edward-jones, rogfer01, MartinMosbeck, brucehoult, the_o, dexonsmith, PkmX, jocewei, jsji, s.egerton, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65514

llvm-svn: 367828
2019-08-05 11:02:05 +00:00
Roman Lebedev 017e272c3a [Codegen] (X & (C l>>/<< Y)) ==/!= 0 --> ((X <</l>> Y) & C) ==/!= 0 fold
Summary:
This was originally reported in D62818.
https://rise4fun.com/Alive/oPH

InstCombine does the opposite fold, in hope that `C l>>/<< Y` expression
will be hoisted out of a loop if `Y` is invariant and `X` is not.
But as it is seen from the diffs here, if it didn't get hoisted,
the produced assembly is almost universally worse.

Much like with my recent "hoist add/sub by/from const" patches,
we should get almost universal win if we hoist constant,
there is almost always an "and/test by imm" instruction,
but "shift of imm" not so much, so we may avoid having to
materialize the immediate, and thus need one less register.
And since we now shift not by constant, but by something else,
the live-range of that something else may reduce.

Special care needs to be applied not to disturb x86 `BT` / hexagon `tstbit`
instruction pattern. And to not get into endless combine loop.

Reviewers: RKSimon, efriedma, t.p.northover, craig.topper, spatel, arsenm

Reviewed By: spatel

Subscribers: hiraditya, MaskRay, wuzish, xbolva00, nikic, nemanjai, jvesely, wdng, nhaehnle, javed.absar, tpr, kristof.beyls, jsji, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62871

llvm-svn: 366955
2019-07-24 22:57:22 +00:00
Krzysztof Parzyszek 5abf80cdfa [Hexagon] Custom-lower UADDO(x, 1) and USUBO(x, 1)
llvm-svn: 364790
2019-07-01 15:50:09 +00:00
Evandro Menezes 56c45e93ab [Hexagon] Change limit type to match the argument type (NFC)
llvm-svn: 363831
2019-06-19 16:12:01 +00:00
Simon Pilgrim 4e0648a541 [TargetLowering] Add MachineMemOperand::Flags to allowsMemoryAccess tests (PR42123)
As discussed on D62910, we need to check whether particular types of memory access are allowed, not just their alignment/address-space.

This NFC patch adds a MachineMemOperand::Flags argument to allowsMemoryAccess and allowsMisalignedMemoryAccesses, and wires up calls to pass the relevant flags to them.

If people are happy with this approach I can then update X86TargetLowering::allowsMisalignedMemoryAccesses to handle misaligned NT load/stores.

Differential Revision: https://reviews.llvm.org/D63075

llvm-svn: 363179
2019-06-12 17:14:03 +00:00
Simon Pilgrim 266f43964e [TargetLowering] Add allowsMemoryAccess(MachineMemOperand) helper wrapper. NFCI.
As suggested by @arsenm on D63075 - this adds a TargetLowering::allowsMemoryAccess wrapper that takes a Load/Store node's MachineMemOperand to handle the AddressSpace/Alignment arguments and will also implicitly handle the MachineMemOperand::Flags change in D63075.

llvm-svn: 363048
2019-06-11 11:00:23 +00:00
Sjoerd Meijer 180f1ae57c [TargetLowering] Change getOptimalMemOpType to take a function attribute list
The MachineFunction wasn't used in getOptimalMemOpType, but more importantly,
this allows reuse of findOptimalMemOpLowering that is calling getOptimalMemOpType.

This is the groundwork for the changes in D59766 and D59787, that allows
implementation of TTI::getMemcpyCost.

Differential Revision: https://reviews.llvm.org/D59785

llvm-svn: 359537
2019-04-30 08:38:12 +00:00
Adhemerval Zanella 664c1ef528 [TargetLowering] Add code size information on isFPImmLegal. NFC
This allows better code size for aarch64 floating point materialization
in a future patch.

Reviewers: evandro

Differential Revision: https://reviews.llvm.org/D58690

llvm-svn: 356389
2019-03-18 18:40:07 +00:00
Craig Topper 784929d045 Implementation of asm-goto support in LLVM
This patch accompanies the RFC posted here:
http://lists.llvm.org/pipermail/llvm-dev/2018-October/127239.html

This patch adds a new CallBr IR instruction to support asm-goto
inline assembly like gcc as used by the linux kernel. This
instruction is both a call instruction and a terminator
instruction with multiple successors. Only inline assembly
usage is supported today.

This also adds a new INLINEASM_BR opcode to SelectionDAG and
MachineIR to represent an INLINEASM block that is also
considered a terminator instruction.

There will likely be more bug fixes and optimizations to follow
this, but we felt it had reached a point where we would like to
switch to an incremental development model.

Patch by Craig Topper, Alexander Ivchenko, Mikhail Dvoretckii

Differential Revision: https://reviews.llvm.org/D53765

llvm-svn: 353563
2019-02-08 20:48:56 +00:00
James Y Knight 7976eb5838 [opaque pointer types] Pass function types to CallInst creation.
This cleans up all CallInst creation in LLVM to explicitly pass a
function type rather than deriving it from the pointer's element-type.

Differential Revision: https://reviews.llvm.org/D57170

llvm-svn: 352909
2019-02-01 20:43:25 +00:00
Matt Arsenault 39508331ef Reapply "IR: Add fp operations to atomicrmw"
This reapplies commits r351778 and r351782 with
RISCV test fixes.

llvm-svn: 351850
2019-01-22 18:18:02 +00:00
Chandler Carruth 285fe716c5 Revert r351778: IR: Add fp operations to atomicrmw
This broke the RISCV build, and even with that fixed, one of the RISCV
tests behaves surprisingly differently with asserts than without,
leaving there no clear test pattern to use. Generally it seems bad for
hte IR to differ substantially due to asserts (as in, an alloca is used
with asserts that isn't needed without!) and nothing I did simply would
fix it so I'm reverting back to green.

This also required reverting the RISCV build fix in r351782.

llvm-svn: 351796
2019-01-22 10:29:58 +00:00
Matt Arsenault bfdba5e4fc IR: Add fp operations to atomicrmw
Add just fadd/fsub for now.

llvm-svn: 351778
2019-01-22 03:32:36 +00:00
Chandler Carruth 2946cd7010 Update the file headers across all of the LLVM projects in the monorepo
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00
James Y Knight 62df5eed16 [opaque pointer types] Remove some calls to generic Type subtype accessors.
That is, remove many of the calls to Type::getNumContainedTypes(),
Type::subtypes(), and Type::getContainedType(N).

I'm not intending to remove these accessors -- they are
useful/necessary in some cases. However, removing the pointee type
from pointers would potentially break some uses, and reducing the
number of calls makes it easier to audit.

llvm-svn: 350835
2019-01-10 16:07:20 +00:00
Krzysztof Parzyszek 30c42e2ab6 [Hexagon] Add patterns for funnel shifts
llvm-svn: 349770
2018-12-20 16:39:20 +00:00
Krzysztof Parzyszek 545a68ca4b [Hexagon] Add instruction definitions for Hexagon V66
llvm-svn: 348411
2018-12-05 21:01:07 +00:00
Sanjay Patel 0a515595a7 [x86] allow vector load narrowing with multi-use values
This is a long-awaited follow-up suggested in D33578. Since then, we've picked up even more
opportunities for vector narrowing from changes like D53784, so there are a lot of test diffs.
Apart from 2-3 strange cases, these are all wins.

I've structured this to be no-functional-change-intended for any target except for x86
because I couldn't tell if AArch64, ARM, and AMDGPU would improve or not. All of those
targets have existing regression tests (4, 4, 10 files respectively) that would be
affected. Also, Hexagon overrides the shouldReduceLoadWidth() hook, but doesn't show
any regression test diffs. The trade-off is deciding if an extra vector load is better
than a single wide load + extract_subvector.

For x86, this is almost always better (on paper at least) because we often can fold
loads into subsequent ops and not increase the official instruction count. There's also
some unknown -- but potentially large -- benefit from using narrower vector ops if wide
ops are implemented with multiple uops and/or frequency throttling is avoided.

Differential Revision: https://reviews.llvm.org/D54073

llvm-svn: 346595
2018-11-10 20:05:31 +00:00
Craig Topper 0b5f8169b0 [TargetLowering] Change TargetLoweringBase::getPreferredVectorAction to take an MVT instead of an EVT. NFC
The main caller of this already has an MVT and several targets called getSimpleVT inside without checking isSimple. This makes the simpleness explicit.

llvm-svn: 346180
2018-11-05 23:26:13 +00:00
Krzysztof Parzyszek f070544f8e [Hexagon] Do not reduce load size for globals in small-data
Small-data (i.e. GP-relative) loads and stores allow 16-bit scaled
offset. For a load of a value of type T, the small-data area is
equivalent to an array "T sdata[65536]". This implies that objects
of smaller sizes need to be closer to the beginning of sdata,
while larger objects may be farther away, or otherwise the offset
may be insufficient to reach it. Similarly, an object of a larger
size should not be accessed via a load of a smaller size.

llvm-svn: 345975
2018-11-02 14:17:47 +00:00
Krzysztof Parzyszek 6bfc6577f2 [Hexagon] Remove support for V4
llvm-svn: 344791
2018-10-19 17:31:11 +00:00
Krzysztof Parzyszek 528aff3372 [Hexagon] Fix extracting subvectors of non-HVX vNi1
Patch by Brendon Cahoon.

llvm-svn: 343596
2018-10-02 15:05:43 +00:00
Alex Bradbury 79518b02cd [AtomicExpandPass]: Add a hook for custom cmpxchg expansion in IR
This involves changing the shouldExpandAtomicCmpXchgInIR interface, but I have 
updated the in-tree backends using this hook (ARM, AArch64, Hexagon) so they 
will see no functional change. Previously this hook returned bool, but it now 
returns AtomicExpansionKind.

This hook allows targets to select how a given cmpxchg is to be expanded. 
D48131 uses this to expand part-word cmpxchg to a target-specific intrinsic.

See my associated RFC for more info on the motivation for this change 
<http://lists.llvm.org/pipermail/llvm-dev/2018-June/123993.html>.

Differential Revision: https://reviews.llvm.org/D48130

llvm-svn: 342550
2018-09-19 14:51:42 +00:00
Sid Manning 9ad0f02749 Add support for getRegisterByName.
Support required to build the Hexagon Linux kernel.

Differential Revision: https://reviews.llvm.org/D51363

llvm-svn: 341658
2018-09-07 13:36:21 +00:00
Sid Manning 220f288720 Revert [Hexagon] Add support for getRegisterByName.
Support required to build the Hexagon Linux kernel.

llvm-svn: 341331
2018-09-03 17:59:10 +00:00
Sid Manning b1c9813042 [Hexagon] Add support for getRegisterByName.
Support required to build the Hexagon Linux kernel.

Differential Revision: https://reviews.llvm.org/D51363

llvm-svn: 341238
2018-08-31 19:08:23 +00:00
Krzysztof Parzyszek 75c2ca3638 [Hexagon] Map ISD::TRAP to J2_trap0(#0)
llvm-svn: 339365
2018-08-09 18:03:45 +00:00
Krzysztof Parzyszek 1df7059150 [Hexagon] Diagnose misaligned absolute loads and stores
Differential Revision: https://reviews.llvm.org/D50405

llvm-svn: 339272
2018-08-08 17:00:09 +00:00
Krzysztof Parzyszek 4e07509d18 [Hexagon] Properly scale bit index when extracting elements from vNi1
For example v = <2 x i1> is represented as bbbbaaaa in a predicate register,
where b = v[1], a = v[0]. Extracting v[1] is equivalent to extracting bit 4
from the predicate register.

llvm-svn: 337934
2018-07-25 16:20:59 +00:00