Commit Graph

3077 Commits

Author SHA1 Message Date
Reid Kleckner
0a17ddc991 [IR] Add llvm.dbg.addr, a control-dependent version of llvm.dbg.declare
Summary:
This implements the design discussed on llvm-dev for better tracking of
variables that live in memory through optimizations:
  http://lists.llvm.org/pipermail/llvm-dev/2017-September/117222.html

This is tracked as PR34136

llvm.dbg.addr is intended to be produced and used in almost precisely
the same way as llvm.dbg.declare is today, with the exception that it is
control-dependent. That means that dbg.addr should always have a
position in the instruction stream, and it will allow passes that
optimize memory operations on local variables to insert llvm.dbg.value
calls to reflect deleted stores. See SourceLevelDebugging.rst for more
details.

The main drawback to generating DBG_VALUE machine instrs is that they
usually cause LLVM to emit a location list for DW_AT_location. The next
step will be to teach DwarfDebug.cpp how to recognize more DBG_VALUE
ranges as not needing a location list, and possibly start setting
DW_AT_start_offset for variables whose lifetimes begin mid-scope.

Reviewers: aprantl, dblaikie, probinson

Subscribers: eraman, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D37768

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313825 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-20 21:52:33 +00:00
Artem Belevich
34fb94caca [NVPTX] Implemented shfl.sync instruction and supporting intrinsics/builtins.
Differential Revision: https://reviews.llvm.org/D38090

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313820 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-20 21:23:07 +00:00
Adam Nemet
093624c347 Allow ORE.emit to take a closure to delay building the remark object
In the lambda we are now returning the remark by value so we need to preserve
its type in the insertion operator.  This requires making the insertion
operator generic.

I've also converted a few cases to use the new API.  It seems to work pretty
well.  See the LoopUnroller for a slightly more interesting case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313691 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-19 23:00:55 +00:00
Reid Kleckner
3796a45d29 Re-land "Fix Bug 30978 by emitting cv file checksums."
This reverts r313431 and brings back r313374 with a fix to write
checksums as binary data and not ASCII hex strings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313657 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-19 18:14:45 +00:00
Jina Nahias
eef725fc85 [x86] Lowering Mask Set1 intrinsics to LLVM IR
This patch, together with a matching clang patch (https://reviews.llvm.org/D37668), implements the lowering of X86 mask set1 intrinsics to IR.

Differential Revision: https://reviews.llvm.org/D37669

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313625 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-19 11:03:06 +00:00
Benjamin Kramer
85bf7f5f6c Remove uses of deprecated std::pointer_to_unary_function.
It's removed in C++17. No functionality change intended.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313481 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-17 11:12:57 +00:00
NAKAMURA Takumi
5bf6db9da8 Reformat.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313457 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-16 12:13:03 +00:00
NAKAMURA Takumi
2ec96ad71f llvm/IR/DiagnosticHandler.h: Add include guard, or -fmodules would be confused.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313456 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-16 12:13:00 +00:00
Craig Topper
20d3306cef [X86] Remove VPERM2F128/VPERM2I128 intrinsics and autoupgrade to native shuffles.
I've moved the test cases from the InstCombine optimizations to the backend to keep the coverage we had there. It covered every possible immediate so I've preserved the resulting shuffle mask for each of those immediates.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313450 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-16 07:36:14 +00:00
Eric Beckmann
c41978fa1d Revert "Fix Bug 30978 by emitting cv file checksums."
This reverts commit 6389e7aa724ea7671d096f4770f016c3d86b0d54.

There is a bug in this implementation where the string value of the
checksum is outputted, instead of the actual hex bytes.  Therefore the
checksum is incorrect, and this prevent pdbs from being loaded by visual
studio.  Revert this until the checksum is emitted correctly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313431 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-16 01:14:36 +00:00
Craig Topper
e41f18bacd [X86] Remove GCCBuiltin names from perm2f128/perm2i128 intrinsics so we can provide a custom implementation in clang.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313420 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-15 23:05:51 +00:00
Vivek Pandya
18b4c37d1e This patch fixes https://bugs.llvm.org/show_bug.cgi?id=32352
It enables OptimizationRemarkEmitter::allowExtraAnalysis and MachineOptimizationRemarkEmitter::allowExtraAnalysis to return true not only for -fsave-optimization-record but when specific remarks are requested with
command line options.
The diagnostic handler used to be callback now this patch adds a class
DiagnosticHandler. It has virtual method to provide custom diagnostic handler
and methods to control which particular remarks are enabled. 
However LLVM-C API users can still provide callback function for diagnostic handler.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313390 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-15 20:10:09 +00:00
Vivek Pandya
4abccff981 This reverts r313381
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313387 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-15 19:53:54 +00:00
Vivek Pandya
bb8204f26f This patch fixes https://bugs.llvm.org/show_bug.cgi?id=32352
It enables OptimizationRemarkEmitter::allowExtraAnalysis and MachineOptimizationRemarkEmitter::allowExtraAnalysis to return true not only for -fsave-optimization-record but when specific remarks are requested with
command line options.
The diagnostic handler used to be callback now this patch adds a class
DiagnosticHandler. It has virtual method to provide custom diagnostic handler
and methods to control which particular remarks are enabled. 
However LLVM-C API users can still provide callback function for diagnostic handler.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313382 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-15 19:30:59 +00:00
Eric Beckmann
de72ac6394 Fix Bug 30978 by emitting cv file checksums.
Summary:
The checksums had already been placed in the IR, this patch allows
MCCodeView to actually write it out to an MCStreamer.

Subscribers: llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D37157

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313374 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-15 18:20:28 +00:00
Peter Collingbourne
a28eeed1b0 Reland r313157, "ThinLTO: Correctly follow aliasee references when dead stripping." which was reverted in r313222.
This reland includes a fix for the LowerTypeTests pass so that it
looks past aliases when determining which type identifiers are live.

Differential Revision: https://reviews.llvm.org/D37842

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313229 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-14 05:02:59 +00:00
Hiroshi Yamauchi
cca65fd2ed Add optional profile counts to block frequency dump.
Summary:
Print profile counts as the third value in addition to the existing 'float' and
the 'int' values in the textual block frequency dump, if available.

Reviewers: davidxl

Reviewed By: davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D37835

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313220 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-14 00:20:25 +00:00
Teresa Johnson
bca2a430d9 [ThinLTO] AliasSummary should not have any references
Summary: References should only be on the aliasee.

Reviewers: pcc

Subscribers: llvm-commits, inglorion

Differential Revision: https://reviews.llvm.org/D37814

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313158 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-13 17:10:24 +00:00
Uriel Korach
a01e7680ad [X86] [PATCH] [intrinsics] Lowering X86 ABS intrinsics to IR. (llvm)
This patch, together with a matching clang patch (https://reviews.llvm.org/D37694), implements the lowering of X86 ABS intrinsics to IR.

differential revision: https://reviews.llvm.org/D37693.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313134 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-13 09:02:36 +00:00
Peter Collingbourne
76221cbae0 IR: Represent -ggnu-pubnames with a flag on the DICompileUnit.
This allows the flag to be persisted through to LTO.

Differential Revision: https://reviews.llvm.org/D37655

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313078 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-12 21:50:41 +00:00
Yael Tsafrir
5c7706bd7c [X86] Lower _mm[256|512]_[mask[z]]_avg_epu[8|16] intrinsics to native llvm IR
Differential Revision: https://reviews.llvm.org/D37560

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@313013 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-12 07:50:35 +00:00
Vlad Tsyrklevich
30b473826c Fix broken links to the Itanium CXX ABI
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312985 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-12 00:19:11 +00:00
Peter Collingbourne
1a8b825606 LowerTypeTests: Add import/export support for targets without absolute symbol constants.
The rationale is the same as for r312967.

Differential Revision: https://reviews.llvm.org/D37408

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312968 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-11 22:49:10 +00:00
Peter Collingbourne
37911b93a0 WholeProgramDevirt: Add import/export support for targets without absolute symbol constants.
Not all targets support the use of absolute symbols to export
constants. In particular, ARM has a wide variety of constant encodings
that cannot currently be relocated by linkers. So instead of exporting
the constants using symbols, export them directly in the summary.
The values of the constants are left as zeroes on targets that support
symbolic exports.

This may result in more cache misses when targeting those architectures
as a result of arbitrary changes in constant values, but this seems
somewhat unavoidable for now.

Differential Revision: https://reviews.llvm.org/D37407

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312967 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-11 22:34:42 +00:00
Uriel Korach
73e68366a4 Revert "adding autoUpgrade support to broadcast[f|i]32x2 intrinsics"
This reverts commit r312879 - An accidental partial commit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312880 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-10 09:07:21 +00:00
Uriel Korach
986634ba4e adding autoUpgrade support to broadcast[f|i]32x2 intrinsics
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312879 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-10 08:40:13 +00:00
Reid Kleckner
6619121492 Sink some IntrinsicInst.h and Intrinsics.h out of llvm/include
Many of these uses can get by with forward declarations. Hopefully this
speeds up compilation after adding a single intrinsic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312759 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-07 23:27:44 +00:00
Reid Kleckner
ccd20ac14d Move duplicate helpers from DbgValueInst / DbgDeclareInst to DbgInfoIntrinsic
NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312754 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-07 22:46:24 +00:00
Reid Kleckner
c86178ea37 Add llvm.codeview.annotation to implement MSVC __annotation
Summary:
This intrinsic represents a label with a list of associated metadata
strings. It is modelled as reading and writing inaccessible memory so
that it won't be removed as dead code. I think the intention is that the
annotation strings should appear at most once in the debug info, so I
marked it noduplicate. We are allowed to inline code with annotations as
long as we strip the annotation, but that can be done later.

Reviewers: majnemer

Subscribers: eraman, llvm-commits, hiraditya

Differential Revision: https://reviews.llvm.org/D36904

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312569 91177308-0d34-0410-b5e6-96231b3b80d8
2017-09-05 20:14:58 +00:00
Eugene Zelenko
3df2f4a7e2 [IR] Missing changes for r312289 (NFC).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312290 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-31 22:06:09 +00:00
Jessica Paquette
70b69dcc75 [NFC] Change Key in Argument to a std::string
Before, Key was a StringRef to avoid unnecessary copies. This commit changes
that to a std::string.

This was okay previously because when people called emit for remarks before,
they would create the remark *within* the call to emit. However, if you build
the remark up and call emit *afterward*, it's possible to end up freeing the
memory assigned to the StringRef before the call to emit.

This caused a test failure with https://reviews.llvm.org/D37085 on Linux.
Since building remarks before a call to emit is a valid use-case, it makes
sense to replace this with a std::string.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312277 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-31 20:47:37 +00:00
Adrian Prantl
5c6206ffb7 Refactor DIBuilder::createFragmentExpression into a static DIExpression member
NFC

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312165 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-30 20:04:17 +00:00
Adrian Prantl
69e607f200 Canonicalize the representation of empty an expression in DIGlobalVariableExpression
This change simplifies code that has to deal with
DIGlobalVariableExpression and mirrors how we treat DIExpressions in
debug info intrinsics. Before this change there were two ways of
representing empty expressions on globals, a nullptr and an empty
!DIExpression().

If someone needs to upgrade out-of-tree testcases:
  perl -pi -e 's/(!DIGlobalVariableExpression\(var: ![0-9]*)\)/\1, expr: !DIExpression())/g' <MYTEST.ll>
will catch 95%.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312144 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-30 18:06:51 +00:00
Craig Topper
4c877efda7 [X86] Remove GCCBuiltin for some intrinsics that aren't used by clang. Add TODO to remove them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312136 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-30 16:28:09 +00:00
Sanjay Patel
1bf0915d7a [Instruction] add moveAfter() convenience function; NFCI
As suggested in D37121, here's a wrapper for removeFromParent() + insertAfter(),
but implemented using moveBefore() for symmetry/efficiency.

Differential Revision: https://reviews.llvm.org/D37239


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312001 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-29 14:07:48 +00:00
NAKAMURA Takumi
d60caed503 Prune whitespaces in blank lines.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311876 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-28 07:48:37 +00:00
Dehao Chen
d38687abb5 Move accurate-sample-profile into the function attribute.
Summary: We need to have accurate-sample-profile in function attribute so that it works with LTO.

Reviewers: davidxl, rsmith

Reviewed By: davidxl

Subscribers: sanjoy, mehdi_amini, javed.absar, llvm-commits, eraman

Differential Revision: https://reviews.llvm.org/D37113

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311706 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-24 21:37:04 +00:00
Wei Ding
75acc65cb3 Add ‘llvm.experimental.constrained.fma‘ Intrinsic.
Differential Revision: http://reviews.llvm.org/D36335

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311629 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-24 04:18:24 +00:00
Adam Nemet
05f89d64f5 Support all integer types in DiagnosticInfoOptimizationBase::Argument
We were missing size_t (unsigned long) on macOS.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311628 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-24 04:04:49 +00:00
Sam Elliott
4467dc73bd [ORE] Remove Old Optimization Remark API
Summary: https://bugs.llvm.org/show_bug.cgi?id=33789

Reviewers: anemet

Reviewed By: anemet

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D36972

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311380 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-21 20:30:44 +00:00
Jakub Kuderski
f39b8ab08c [Dominators] Introduce batch updates
Summary:
This patch introduces a way of informing the (Post)DominatorTree about multiple CFG updates that happened since the last tree update. This makes performing tree updates much easier, as it internally takes care of applying the updates in lockstep with the (virtual) updates to the CFG, which is done by reverse-applying future CFG updates.

The batch updater is able to remove redundant updates that cancel each other out. In the future, it should be also possible to reorder updates to reduce the amount of work needed to perform the updates.

Reviewers: dberlin, sanjoy, grosser, davide, brzycki

Reviewed By: brzycki

Subscribers: mgorny, llvm-commits

Differential Revision: https://reviews.llvm.org/D36167

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311015 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-16 16:12:52 +00:00
Charles Saternos
417caf5c7c [ThinLTO] Fix ThinLTO crash while destroying context
Fix for PR32763

An assert that checks if a Ref was untracked fails during ThinLTO context cleanup. The issue is because lazy loading temporary nodes didn't properly track ValueAsMetadata nodes. This patch ensures that the temporary nodes are properly tracked when they're replaced with the value.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310967 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-15 22:23:44 +00:00
Andrew Kaylor
68d0bd1ed4 Add strictfp attribute to prevent unwanted optimizations of libm calls
Differential Revision: https://reviews.llvm.org/D34163



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310885 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-14 21:15:13 +00:00
Eli Friedman
f524386039 [OptDiag] Updating Remarks in SampleProfile
Updating remark API to newer OptimizationDiagnosticInfo API. This
allows remarks to show up in diagnostic yaml file, and enables use
of opt-viewer tool.

Hotness information for remarks (L505 and L751) do not display hotness
information, most likely due to profile information not being
propagated yet. Unsure if this is the desired outcome.

Patch by Tarun Rajendran.

Differential Revision: https://reviews.llvm.org/D36127



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310763 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-11 21:12:04 +00:00
Craig Topper
09c4df1c6d [AVX512] Remove and autoupgrade many of the broadcast intrinsics
Summary:
This autoupgrades most of the broadcast intrinsics. They've been unused in clang for some time.

This leaves the 32x2 intrinsics because they are still used in clang.

Reviewers: RKSimon, zvi, igorb

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D36606

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310725 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-11 16:22:45 +00:00
Mandeep Singh Grang
4e3dcfc420 [COFF, ARM64] Add MS builtins __dmb, __dsb, __isb
Reviewers: mstorsjo, rnk, ruiu, compnerd, efriedma

Reviewed By: efriedma

Subscribers: efriedma, aemerson, javed.absar, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D36110

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310502 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-09 17:58:39 +00:00
Connor Abbott
8e92b2817e [AMDGPU] Add llvm.amdgpu.update.dpp intrinsic
Summary:
Now that we've made all the necessary backend changes, we can add a new
intrinsic which exposes the new capabilities to IR producers. Since
llvm.amdgpu.update.dpp is a strict superset of llvm.amdgpu.mov.dpp, we
should deprecate the former. We also add tests for all the functionality
that was added in previous changes, now that we can access it via an IR
construct.

Reviewers: tstellar, arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye

Differential Revision: https://reviews.llvm.org/D34718

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310399 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-08 18:52:22 +00:00
Adrian Prantl
645c1ad429 Remove unused include directive and un-break the module build.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310124 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-04 20:41:37 +00:00
Connor Abbott
c300b1a6d3 [AMDGPU] Implement llvm.amdgcn.set.inactive intrinsic
Summary:
This intrinsic lets us set inactive lanes to an identity value when
implementing wavefront reductions. In combination with Whole Wavefront
Mode, it lets inactive lanes be skipped over as required by GLSL/Vulkan.
Lowering the intrinsic needs to happen post-RA so that RA knows that the
destination isn't completely overwritten due to the EXEC shenanigans, so
we need another pseudo-instruction to represent the un-lowered
intrinsic.

Reviewers: tstellar, arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, dstuttard, tpr, t-tye

Differential Revision: https://reviews.llvm.org/D34719

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310088 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-04 18:36:54 +00:00
Connor Abbott
ecf573917a [AMDGPU] Add support for Whole Wavefront Mode
Summary:
Whole Wavefront Wode (WWM) is similar to WQM, except that all of the
lanes are always enabled, regardless of control flow. This is required
for implementing wavefront reductions in non-uniform control flow, where
we need to use the inactive lanes to propagate intermediate results, so
they need to be enabled. We need to propagate WWM to uses (unless
they're explicitly marked as exact) so that they also propagate
intermediate results correctly. We do the analysis and exec mask munging
during the WQM pass, since there are interactions with WQM for things
that require both WQM and WWM. For simplicity, WWM is entirely
block-local -- blocks are never WWM on entry or exit of a block, and WWM
is not propagated to the block level.  This means that computations
involving WWM cannot involve control flow, but we only ever plan to use
WWM for a few limited purposes (none of which involve control flow)
anyways.

Shaders can ask for WWM using the @llvm.amdgcn.wwm intrinsic. There
isn't yet a way to turn WWM off -- that will be added in a future
change.

Finally, it turns out that turning on inactive lanes causes a number of
problems with register allocation. While the best long-term solution
seems like teaching LLVM's register allocator about predication, for now
we need to add some hacks to prevent ourselves from getting into trouble
due to constraints that aren't currently expressed in LLVM. For the gory
details, see the comments at the top of SIFixWWMLiveness.cpp.

Reviewers: arsenm, nhaehnle, tpr

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

Differential Revision: https://reviews.llvm.org/D35524

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310087 91177308-0d34-0410-b5e6-96231b3b80d8
2017-08-04 18:36:52 +00:00