Commit Graph

69 Commits

Author SHA1 Message Date
Stanislav Mekhanoshin e67cc380a8 [AMDGPU] gfx908 mfma support
Differential Revision: https://reviews.llvm.org/D64584

llvm-svn: 365824
2019-07-11 21:19:33 +00:00
Matt Arsenault c04aab9c06 AMDGPU: Look through bundles for existing waitcnts
These aren't produced now, but will be in a future patch.

llvm-svn: 364983
2019-07-03 00:30:44 +00:00
Matt Arsenault 740322f1eb AMDGPU: Add intrinsics for DS GWS semaphore instructions
llvm-svn: 363983
2019-06-20 21:11:42 +00:00
Matt Arsenault e4c2e9b016 AMDGPU: Consolidate some getGeneration checks
This is incomplete, and ideally these would all be removed, but it's
better to localize them to the subtarget first with comments about
what they're for.

llvm-svn: 363902
2019-06-19 23:54:58 +00:00
Matt Arsenault 4d55d024be Reapply "AMDGPU: Add ds_gws_init / ds_gws_barrier intrinsics"
This reapplies r363678, using the correct chain for the CopyToReg for
v0. glueCopyToM0 counterintuitively changes the operands of the
original node.

llvm-svn: 363870
2019-06-19 19:55:27 +00:00
Simon Pilgrim 128ce93c60 Revert rL363678 : AMDGPU: Add ds_gws_init / ds_gws_barrier intrinsics
There may or may not be additional work to handle this correctly on
SI/CI.
........
Breaks EXPENSIVE_CHECKS buildbots - http://lab.llvm.org:8011/builders/llvm-clang-x86_64-expensive-checks-win/builds/78/

llvm-svn: 363797
2019-06-19 13:00:54 +00:00
Matt Arsenault 8d35dcd703 AMDGPU: Add ds_gws_init / ds_gws_barrier intrinsics
There may or may not be additional work to handle this correctly on
SI/CI.

llvm-svn: 363678
2019-06-18 13:19:57 +00:00
Stanislav Mekhanoshin 5250021672 [AMDGPU] gfx10 conditional registers handling
This is cpp source part of wave32 support, excluding overriden
getRegClass().

Differential Revision: https://reviews.llvm.org/D63351

llvm-svn: 363513
2019-06-16 17:13:09 +00:00
Matt Arsenault aa41e92e17 AMDGPU: Avoid most waitcnts before calls
Currently you get extra waits, because waits are inserted for the
register dependencies of the call, and the function prolog waits on
everything.

Currently waits are still inserted on returns. It may make sense to
not do this, and wait in the caller instead.

llvm-svn: 363465
2019-06-14 21:52:26 +00:00
Stanislav Mekhanoshin d9dcf392c7 [AMDGPU] gfx1010 wait count insertion
Differential Revision: https://reviews.llvm.org/D61534

llvm-svn: 359938
2019-05-03 21:53:53 +00:00
Stanislav Mekhanoshin 956b0be72e [AMDGPU] gfx1010 utility functions
Differential Revision: https://reviews.llvm.org/D61094

llvm-svn: 359224
2019-04-25 18:53:41 +00:00
Matt Arsenault 0b31b24c13 AMDGPU: Correct type for waitcnt debug flag
llvm-svn: 356206
2019-03-14 21:23:59 +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
Marek Olsak c5cec5e1fa AMDGPU: Add llvm.amdgcn.ds.ordered.add & swap
Reviewers: arsenm, nhaehnle

Subscribers: kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits

Differential Revision: https://reviews.llvm.org/D52944

llvm-svn: 351351
2019-01-16 15:43:53 +00:00
Carl Ritson c521ac3a44 AMDGPU/InsertWaitcnts: Update VGPR/SGPR bounds when brackets are merged
Summary:
Fix an issue where VGPR/SGPR bounds are not properly extended when brackets are merged.
This manifests as missing waitcnt insertions when multiple brackets are forwarded to a successor block and the first forward has lower VGPR/SGPR bounds.

Irreducible loop test has been extended based on a CTS failure detected for GFX9.

Reviewers: nhaehnle

Reviewed By: nhaehnle

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D55602

llvm-svn: 349611
2018-12-19 10:17:49 +00:00
Nicolai Haehnle 7bed696915 AMDGPU/InsertWaitcnts: Remove the dependence on MachineLoopInfo
Summary:
MachineLoopInfo cannot be relied on for correctness, because it cannot
properly recognize loops in irreducible control flow which can be
introduced by late machine basic block optimization passes. See the new
test case for the reduced form of an example that occurred in practice.

Use a simple fixpoint iteration instead.

In order to facilitate this change, refactor WaitcntBrackets so that it
only tracks pending events and registers, rather than also maintaining
state that is relevant for the high-level algorithm. Various accessor
methods can be removed or made private as a consequence.

Affects (in radv):
- dEQP-VK.glsl.loops.special.{for,while}_uniform_iterations.select_iteration_count_{fragment,vertex}

Fixes: r345719 ("AMDGPU: Rewrite SILowerI1Copies to always stay on SALU")

Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits, hakzsam

Differential Revision: https://reviews.llvm.org/D54231

llvm-svn: 347853
2018-11-29 11:06:26 +00:00
Nicolai Haehnle ab43bf60fe AMDGPU/InsertWaitcnt: Consistently use uint32_t for scores / time points
Summary:
There is one obsolete reference to using -1 as an indication of "unknown",
but this isn't actually used anywhere.

Using unsigned makes robust wrapping checks easier.

Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, llvm-commits, tpr, t-tye, hakzsam

Differential Revision: https://reviews.llvm.org/D54230

llvm-svn: 347852
2018-11-29 11:06:21 +00:00
Nicolai Haehnle f96456c611 AMDGPU/InsertWaitcnt: Remove unused WaitAtBeginning
Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits, hakzsam

Differential Revision: https://reviews.llvm.org/D54229

llvm-svn: 347851
2018-11-29 11:06:18 +00:00
Nicolai Haehnle d1f45dad84 AMDGPU/InsertWaitcnts: Simplify pending events tracking
Summary:
Instead of storing the "score" (last time point) of the various relevant
events, only store whether an event is pending or not.

This is sufficient, because whenever only one event of a count type is
pending, its last time point is naturally the upper bound of all time
points of this count type, and when multiple event types are pending,
the count type has gone out of order and an s_waitcnt to 0 is required
to clear any pending event type (and will then clear all pending event
types for that count type).

This also removes the special handling of GDS_GPR_LOCK and EXP_GPR_LOCK.
I do not understand what this special handling ever attempted to achieve.
It has existed ever since the original port from an internal code base,
so my best guess is that it solved a problem related to EXEC handling in
that internal code base.

Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits, hakzsam

Differential Revision: https://reviews.llvm.org/D54228

llvm-svn: 347850
2018-11-29 11:06:14 +00:00
Nicolai Haehnle ae369d70c3 AMDGPU/InsertWaitcnts: Use foreach loops for inst and wait event types
Summary:
It hides the type casting ugliness, and I happened to have to add a new
such loop (in a later patch).

Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits, hakzsam

Differential Revision: https://reviews.llvm.org/D54227

llvm-svn: 347849
2018-11-29 11:06:11 +00:00
Nicolai Haehnle 1a94cbb3f5 AMDGPU/InsertWaitcnts: Untangle some semi-global state
Summary:
Reduce the statefulness of the algorithm in two ways:

1. More clearly split generateWaitcntInstBefore into two phases: the
   first one which determines the required wait, if any, without changing
   the ScoreBrackets, and the second one which actually inserts the wait
   and updates the brackets.

2. Communicate pre-existing s_waitcnt instructions using an argument to
   generateWaitcntInstBefore instead of through the ScoreBrackets.

To simplify these changes, a Waitcnt structure is introduced which carries
the counts of an s_waitcnt instruction in decoded form.

There are some functional changes:

1. The FIXME for the VCCZ bug workaround was implemented: we only wait for
   SMEM instructions as required instead of waiting on all counters.

2. We now properly track pre-existing waitcnt's in all cases, which leads
   to less conservative waitcnts being emitted in some cases.

     s_load_dword ...
     s_waitcnt lgkmcnt(0)    <-- pre-existing wait count
     ds_read_b32 v0, ...
     ds_read_b32 v1, ...
     s_waitcnt lgkmcnt(0)    <-- this is too conservative
     use(v0)
     more code
     use(v1)

   This increases code size a bit, but the reduced latency should still be a
   win in basically all cases. The worst code size regressions in my shader-db
   are:

 WORST REGRESSIONS - Code Size
 Before After     Delta Percentage
   1724  1736        12    0.70 %   shaders/private/f1-2015/1334.shader_test [0]
   2276  2284         8    0.35 %   shaders/private/f1-2015/1306.shader_test [0]
   4632  4640         8    0.17 %   shaders/private/ue4_elemental/62.shader_test [0]
   2376  2384         8    0.34 %   shaders/private/f1-2015/1308.shader_test [0]
   3284  3292         8    0.24 %   shaders/private/talos_principle/1955.shader_test [0]

Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits, hakzsam

Differential Revision: https://reviews.llvm.org/D54226

llvm-svn: 347848
2018-11-29 11:06:06 +00:00
Nicolai Haehnle c548d91419 AMDGPU/InsertWaitcnts: Some more const-correctness
Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits, hakzsam

Differential Revision: https://reviews.llvm.org/D54225

llvm-svn: 347192
2018-11-19 12:03:11 +00:00
Nicolai Haehnle 61396ff67c AMDGPU/InsertWaitcnts: Cleanup some old cruft (NFCI)
Summary: Remove redundant logic and simplify control flow.

Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits

Differential Revision: https://reviews.llvm.org/D54086

llvm-svn: 346363
2018-11-07 21:53:36 +00:00
Nicolai Haehnle 0ab31c9c44 AMDGPU/InsertWaitcnts: Remove kill-related logic
Summary:
This is not needed, because we don't actually insert relevant branches
for KILLs that late in the compilation flow.

Besides, this was always checking for the wrong kill opcode anyway...

Reviewers: msearles, rampitec, scott.linder, kanarayan

Subscribers: arsenm, kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits

Differential Revision: https://reviews.llvm.org/D54085

llvm-svn: 346362
2018-11-07 21:53:29 +00:00
Konstantin Zhuravlyov 71e43ee47d AMDGPU: Re-apply r341982 after fixing the layering issue
Move isa version determination into TargetParser.

Also switch away from target features to CPU string when
determining isa version. This fixes an issue when we
output wrong isa version in the object code when features
of a particular CPU are altered (i.e. gfx902 w/o xnack
used to result in gfx900).

llvm-svn: 342069
2018-09-12 18:50:47 +00:00
Ilya Biryukov 95066496d0 Revert "AMDGPU: Move isa version and EF_AMDGPU_MACH_* determination into TargetParser."
This reverts commit r341982.

The change introduced a layering violation. Reverting to unbreak
our integrate.

llvm-svn: 342023
2018-09-12 07:05:30 +00:00
Konstantin Zhuravlyov 941615e4c8 AMDGPU: Move isa version and EF_AMDGPU_MACH_* determination
into TargetParser.

Also switch away from target features to CPU string when
determining isa version. This fixes an issue when we
output wrong isa version in the object code when features
of a particular CPU are altered (i.e. gfx902 w/o xnack
used to result in gfx900).

Differential Revision: https://reviews.llvm.org/D51890

llvm-svn: 341982
2018-09-11 18:56:51 +00:00
Matt Arsenault 0da6350dc8 AMDGPU: Remove remnants of old address space mapping
llvm-svn: 341165
2018-08-31 05:49:54 +00:00
Mark Searles f4e7025299 [AMDGPU][Waitcnt] Re-apply fix "comparison of integers of different signs" build error"
Re-apply "[AMDGPU][Waitcnt] fix "comparison of integers of different signs" build error""
( fe0a456510131f268e388c4a18a92f575c0db183 ), which was inadvertantly reverted via
2b2ee080f0164485562593b1b87291a48cea4a9a .

llvm-svn: 337156
2018-07-16 10:21:36 +00:00
Mark Searles c2d5d9adb5 Revert "[AMDGPU][Waitcnt] fix "comparison of integers of different signs" build error"
This reverts commit fe0a456510131f268e388c4a18a92f575c0db183.

llvm-svn: 337153
2018-07-16 10:02:40 +00:00
Tom Stellard 5bfbae5cb1 AMDGPU: Refactor Subtarget classes
Summary:
This is a follow-up to r335942.
- Merge SISubtarget into AMDGPUSubtarget and rename to GCNSubtarget
- Rename AMDGPUCommonSubtarget to AMDGPUSubtarget
- Merge R600Subtarget::Generation and GCNSubtarget::Generation into
  AMDGPUSubtarget::Generation.

Reviewers: arsenm, jvesely

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D49037

llvm-svn: 336851
2018-07-11 20:59:01 +00:00
Mark Searles 5bfd8d8991 [AMDGPU][Waitcnt] fix "comparison of integers of different signs" build error
Build error on Android; reported by and fix provided by (thanks) by Mauro Rossi <issor.oruam@gmail.com>

Fixes the following building error:

external/llvm/lib/Target/AMDGPU/SIInsertWaitcnts.cpp:1903:61:
error: comparison of integers of different signs:
'typename iterator_traits<__wrap_iter<MachineBasicBlock **> >::difference_type'
(aka 'int') and 'unsigned int' [-Werror,-Wsign-compare]
                      BlockWaitcntProcessedSet.end(), &MBB) < Count)) {
                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~
1 error generated.

Differential Revision: https://reviews.llvm.org/D49089

llvm-svn: 336588
2018-07-09 19:28:14 +00:00
Tom Stellard c5a154db48 AMDGPU: Separate R600 and GCN TableGen files
Summary:
We now have two sets of generated TableGen files, one for R600 and one
for GCN, so each sub-target now has its own tables of instructions,
registers, ISel patterns, etc.  This should help reduce compile time
since each sub-target now only has to consider information that
is specific to itself.  This will also help prevent the R600
sub-target from slowing down new features for GCN, like disassembler
support, GlobalISel, etc.

Reviewers: arsenm, nhaehnle, jvesely

Reviewed By: arsenm

Subscribers: MatzeB, kzhuravl, wdng, mgorny, yaxunl, dstuttard, tpr, t-tye, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D46365

llvm-svn: 335942
2018-06-28 23:47:12 +00:00
Konstantin Zhuravlyov 777477705a AMDGPU: Silence unused warnings in waitcnt insertion pass in release build
Differential Revision: https://reviews.llvm.org/D48607

llvm-svn: 335669
2018-06-26 21:33:38 +00:00
Scott Linder 5792dd0f39 [AMDGPU] Fix bug with tracking processed blocks in SIInsertWaitcnts
BlockWaitcntProcessedSet was not being cleared between calls, so it was
producing incorrect counts in cases where MBB addresses happened to coincide
across multiple calls.

Differential Revision: https://reviews.llvm.org/D48391

llvm-svn: 335268
2018-06-21 18:48:48 +00:00
Mark Searles f0b93f1e9e [AMDGPU][Waitcnt] Fix handling of flat instrs
On GFX9 and earlier, flat memory ops may decrement VMCNT out-of-order as well as LGKMCNT out-of-order.

Differential Revision: https://reviews.llvm.org/D46616

llvm-svn: 333926
2018-06-04 16:51:59 +00:00
Mark Searles ed54ff1d51 [AMDGPU][Waitcnt] Fix build error: unused variable 'SWaitInst'
https://reviews.llvm.org/rL333556 caused a buildbot failure.

See http://lab.llvm.org:8011/builders/lld-x86_64-darwin13/builds/21876/steps/build_Lld/logs/stdio

/Users/buildslave/as-bldslv9/lld-x86_64-darwin13/llvm.src/lib/Target/AMDGPU/SIInsertWaitcnts.cpp:2007:10: error: unused variable 'SWaitInst' [-Werror,-Wunused-variable]
    auto SWaitInst = BuildMI(EntryBB, EntryBB.getFirstNonPHI(),

The unused variable was for debugging purposes; removing that piece of code
to fix the build.

llvm-svn: 333559
2018-05-30 16:27:57 +00:00
Mark Searles 1054541490 [AMDGPU][Waitcnt] Fix handling of loops with many bottom blocks
In terms of waitcnt insertion/if necessary, the waitcnt pass forces convergence
for a loop. Previously, that kicked if greater than 2 passes over a loop, which
doesn't account for loop with many bottom blocks. So, increase the threshold to
(n+1), where n is the number of bottom blocks. This gives the pass an
opportunity to consider the contribution of each bottom block, to the overall
loop, before the forced convergence potentially kicks in.

Differential Revision: https://reviews.llvm.org/D47488

llvm-svn: 333556
2018-05-30 15:47:45 +00:00
Nicola Zaghen d34e60ca85 Rename DEBUG macro to LLVM_DEBUG.
The DEBUG() macro is very generic so it might clash with other projects.
The renaming was done as follows:
- git grep -l 'DEBUG' | xargs sed -i 's/\bDEBUG\s\?(/LLVM_DEBUG(/g'
- git diff -U0 master | ../clang/tools/clang-format/clang-format-diff.py -i -p1 -style LLVM
- Manual change to APInt
- Manually chage DOCS as regex doesn't match it.

In the transition period the DEBUG() macro is still present and aliased
to the LLVM_DEBUG() one.

Differential Revision: https://reviews.llvm.org/D43624

llvm-svn: 332240
2018-05-14 12:53:11 +00:00
Shiva Chen 801bf7ebbe [DebugInfo] Examine all uses of isDebugValue() for debug instructions.
Because we create a new kind of debug instruction, DBG_LABEL, we need to
check all passes which use isDebugValue() to check MachineInstr is debug
instruction or not. When expelling debug instructions, we should expel
both DBG_VALUE and DBG_LABEL. So, I create a new function,
isDebugInstr(), in MachineInstr to check whether the MachineInstr is
debug instruction or not.

This patch has no new test case. I have run regression test and there is
no difference in regression test.

Differential Revision: https://reviews.llvm.org/D45342

Patch by Hsiangkai Wang.

llvm-svn: 331844
2018-05-09 02:42:00 +00:00
Mark Searles 4a0f2c5047 [AMDGPU][Waitcnt] Remove the old waitcnt pass
Remove the old waitcnt pass ( si-insert-waits ), which is no longer maintained
and getting crufty

Differential Revision: https://reviews.llvm.org/D46448

llvm-svn: 331641
2018-05-07 14:43:28 +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
Mark Searles 2a19af6e17 [AMDGPU][Waitcnt] As of gfx7, VMEM operations do not increment the export counter and the input registers are available in the next instruction; update the waitcnt pass to take this into account.
Differential Revision: https://reviews.llvm.org/D46067

llvm-svn: 330954
2018-04-26 16:11:19 +00:00
Mark Searles ec58183e1b [AMDGPU] Waitcnt pass: add debug options
- Add "amdgpu-waitcnt-forcezero" to force all waitcnt instrs to be emitted as s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)

- Add debug counters to control force emit of s_waitcnt instrs; debug counters:
si-insert-waitcnts-forceexp: force emit s_waitcnt expcnt(0) instrs
si-insert-waitcnts-forcevm: force emit s_waitcnt lgkmcnt(0) instrs
si-insert-waitcnts-forcelgkm: force emit s_waitcnt vmcnt(0) instrs

- Add some debug statements

Note that a variant of this patch was previously committed/reverted.

Differential Revision: https://reviews.llvm.org/D45888

llvm-svn: 330862
2018-04-25 19:21:26 +00:00
Mark Searles 70901b9047 [AMDGPU][Waitcnt] NFC. Cleanup some code/naming consistency:
- s/SWaitcnt/Waitcnt s/WaitCnt/Waitcnt

llvm-svn: 330730
2018-04-24 15:59:59 +00:00
Mark Searles 1bc6e71f32 [AMDGPU] Do not only rely on BB number when finding bottom loop
We should also check that the "bottom" basic block of a loopis a successor of the "header" basic block, otherwise we don't propagate the information correctly when the CFG is complex. This fixes an important rendering problem with Wolfsentein 2, because of one vector-memory wait was missing.

Differential Revision: https://reviews.llvm.org/D43831

llvm-svn: 330337
2018-04-19 15:42:30 +00:00
Mark Searles c3c02bde73 [AMDGPU] Waitcnt pass: Modify the waitcnt pass to propagate info in the case of a single basic block loop. mergeInputScoreBrackets() does this for us; update it so that it processes the single bb's score bracket when processing the single bb's preds. It is, after all, a pred of itself, so it's score bracket is needed.
Differential Revision: https://reviews.llvm.org/D44434

llvm-svn: 327583
2018-03-14 22:04:32 +00:00
Mark Searles 65207923f6 [AMDGPU] Make note of existing waitcnt instrs; this is add-on work related to suppression of redundant waitcnt instrs. It is necessary to make note of these existing waitcnt instrs so that we do not fall into an infinite loop when handling loops. Also, [NFC] some minor code clean-up.
llvm-svn: 325524
2018-02-19 19:19:59 +00:00
Stanislav Mekhanoshin ff2763a658 [AMDGPU] Combine adjacent waitcounts in a single strongest wait
Differential Revision: https://reviews.llvm.org/D43350

llvm-svn: 325299
2018-02-15 22:03:55 +00:00
Stanislav Mekhanoshin db39b4b0b4 [AMDGPU] Fixed wait count reuse
The code reusing existing wait counts is incorrect since it keeps
adding new operands to an old instruction instead of replacing
the immediate. It was also effectively switched off by the condition
that wait count is not an AMDGPU::S_WAITCNT.

Also switched to BuildMI instead of creating instructions directly.

Differential Revision: https://reviews.llvm.org/D42997

llvm-svn: 324547
2018-02-08 00:18:35 +00:00