We currently always store absolute filenames in coverage mapping. This
is problematic for several reasons. It poses a problem for distributed
compilation as source location might vary across machines. We are also
duplicating the path prefix potentially wasting space.
This change modifies how we store filenames in coverage mapping. Rather
than absolute paths, it stores the compilation directory and file paths
as given to the compiler, either relative or absolute. Later when
reading the coverage mapping information, we recombine relative paths
with the working directory. This approach is similar to handling
ofDW_AT_comp_dir in DWARF.
Finally, we also provide a new option, -fprofile-compilation-dir akin
to -fdebug-compilation-dir which can be used to manually override the
compilation directory which is useful in distributed compilation cases.
Differential Revision: https://reviews.llvm.org/D95753
We can always look through single-argument (LCSSA) phi nodes when
performing alias analysis. getUnderlyingObject() already does this,
but stripPointerCastsAndInvariantGroups() does not. We still look
through these phi nodes with the usual aliasPhi() logic, but
sometimes get sub-optimal results due to the restrictions on value
equivalence when looking through arbitrary phi nodes. I think it's
generally beneficial to keep the underlying object logic and the
pointer cast stripping logic in sync, insofar as it is possible.
With this patch we get marginally better results:
aa.NumMayAlias | 5010069 | 5009861
aa.NumMustAlias | 347518 | 347674
aa.NumNoAlias | 27201336 | 27201528
...
licm.NumPromoted | 1293 | 1296
I've renamed the relevant strip method to stripPointerCastsForAliasAnalysis(),
as we're past the point where we can explicitly spell out everything
that's getting stripped.
Differential Revision: https://reviews.llvm.org/D96668
We currently always store absolute filenames in coverage mapping. This
is problematic for several reasons. It poses a problem for distributed
compilation as source location might vary across machines. We are also
duplicating the path prefix potentially wasting space.
This change modifies how we store filenames in coverage mapping. Rather
than absolute paths, it stores the compilation directory and file paths
as given to the compiler, either relative or absolute. Later when
reading the coverage mapping information, we recombine relative paths
with the working directory. This approach is similar to handling
ofDW_AT_comp_dir in DWARF.
Finally, we also provide a new option, -fprofile-compilation-dir akin
to -fdebug-compilation-dir which can be used to manually override the
compilation directory which is useful in distributed compilation cases.
Differential Revision: https://reviews.llvm.org/D95753
This patch adds functionality to compare for the equality between `InterfaceFile`s based on attributes specific to linking.
Reviewed By: cishida, steven_wu
Differential Revision: https://reviews.llvm.org/D96629
This fixes https://bugs.llvm.org/show_bug.cgi?id=49185
When `NDEBUG` is not set, `LPMUpdater` checks if the added loops have the same parent loop as the current one in `addSiblingLoops`.
If multiple loop passes are executed through `LoopPassManager`, `U.ParentL` will be the same across all passes.
However, the parent loop might change after running a loop pass, resulting in assertion failures in subsequent passes.
This patch resets `U.ParentL` after running individual loop passes in `LoopPassManager`.
Reviewed By: asbirlea, ychen
Differential Revision: https://reviews.llvm.org/D96727
Adjust generateFMAsInMachineCombiner to return false if SVE is present
in order to combine fmul+fadd into fma. Also add new pseudo instructions
so as to select the most appropriate of FMLA/FMAD depending on register
allocation.
Depends on D96599
Differential Revision: https://reviews.llvm.org/D96424
Rework template argument checking so that all arguments are type-checked
and cast if necessary.
Add a test.
Differential Revision: https://reviews.llvm.org/D96416
As discussed on the RFC [0], I am sharing the set of patches that
enables checking of original Debug Info metadata preservation in
optimizations. The proof-of-concept/proposal can be found at [1].
The implementation from the [1] was full of duplicated code,
so this set of patches tries to merge this approach into the existing
debugify utility.
For example, the utility pass in the original-debuginfo-check
mode could be invoked as follows:
$ opt -verify-debuginfo-preserve -pass-to-test sample.ll
Since this is very initial stage of the implementation,
there is a space for improvements such as:
- Add support for the new pass manager
- Add support for metadata other than DILocations and DISubprograms
[0] https://groups.google.com/forum/#!msg/llvm-dev/QOyF-38YPlE/G213uiuwCAAJ
[1] https://github.com/djolertrk/llvm-di-checker
Differential Revision: https://reviews.llvm.org/D82545
This patch makes StorageMappingClass/SymbolType member optional in
class MCSectionXCOFF.
Non-csect sections like debug sections have no such properties.
Reviewed By: hubert.reinterpretcast
Differential Revision: https://reviews.llvm.org/D96641
ST_Data is used to model BFD `BFD_OBJECT`.
A STT_TLS symbol does not have the `BFD_OBJECT` flag in BFD.
This makes sense because a STT_TLS symbol is like in a different address space,
normal data/object properties do not apply on them.
With this change, a STT_TLS symbol will not be displayed as 'O'.
This new behavior matches objdump.
Differential Revision: https://reviews.llvm.org/D96735
We are going to support debug sections for XCOFF. So the csect
properties are not necessary. This patch makes these properties
optional.
Reviewed By: hubert.reinterpretcast
Differential Revision: https://reviews.llvm.org/D95931
As discussed in D95511, this allows us to encode invalid BBAddrMap
sections to be used in more rigorous testing.
Reviewed By: jhenderson
Differential Revision: https://reviews.llvm.org/D96831
Apply the patch for the third time after fixing buildbot failures.
Refactor SampleProfile.cpp to use the core code in CodeGen.
The main changes are:
(1) Move SampleProfileLoaderBaseImpl class to a header file.
(2) Split SampleCoverageTracker to a head file and a cpp file.
(3) Move the common codes (common options and callsiteIsHot())
to the common cpp file.
(4) Add inline keyword to avoid duplicated symbols -- they will
be removed later when the class is changed to a template.
Differential Revision: https://reviews.llvm.org/D96455
This adds a G_ASSERT_SEXT opcode, similar to G_ASSERT_ZEXT. This instruction
signifies that an operation was already sign extended from a smaller type.
This is useful for functions with sign-extended parameters.
E.g.
```
define void @foo(i16 signext %x) {
...
}
```
This adds verifier, regbankselect, and instruction selection support for
G_ASSERT_SEXT equivalent to G_ASSERT_ZEXT.
Differential Revision: https://reviews.llvm.org/D96890
Revert "[SampleFDO] Add missing #includes to unbreak modules build after D96455"
This reverts commit c73cbf218a289029cc0b54183c3cf79454ecc76f.
Revert "[SampleFDO] Fix MSVC "namespace uses itself" warning (NFC)"
This reverts commit a23e6b321ca623b83252f8b1e06a2ad4fc441f89.
Revert "[SampleFDO] Reapply: Refactor SampleProfile.cpp"
This reverts commit 6fd5ccff72eeaffcb3b3ba2696282015aab755bc.
Still seeing link failures when building llc (or other tools), due to
the new SampleProfileLoaderBaseImpl.h containing definitions that get
duplicated across multiple TU's.
```
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::findEquivalenceClasses(llvm::Function&)' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::buildEdges(llvm::Function&)' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::computeDominanceAndLoopInfo(llvm::Function&)' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::getFunctionLoc(llvm::Function&)' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::getBlockWeight(llvm::BasicBlock const*)' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::printBlockWeight(llvm::raw_ostream&, llvm::BasicBlock const*) const' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::printBlockEquivalence(llvm::raw_ostream&, llvm::BasicBlock const*)' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
duplicate symbol 'llvm::SampleProfileLoaderBaseImpl::printEdgeWeight(llvm::raw_ostream&, std::__1::pair<llvm::BasicBlock const*, llvm::BasicBlock const*>)' in:
tools/llc/CMakeFiles/llc.dir/llc.cpp.o
lib/libLLVMInstCombine.a(InstCombineVectorOps.cpp.o)
```
Bot: http://green.lab.llvm.org/green/view/LLDB/job/lldb-cmake/28999
```
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h:124:19: error: missing '#include "llvm/Analysis/PostDominators.h"'; 'PostDominatorTree' must be declared before it is used
std::unique_ptr<PostDominatorTree> PDT;
^
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/include/llvm/Analysis/PostDominators.h:28:7: note: declaration here is not visible
class PostDominatorTree : public PostDomTreeBase<BasicBlock> {
^
While building module 'LLVM_Transforms' imported from /Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/lib/Transforms/CFGuard/CFGuard.cpp:15:
In file included from <module-includes>:191:
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h:125:19: error: missing '#include "llvm/Analysis/LoopInfo.h"'; 'LoopInfo' must be declared before it is used
std::unique_ptr<LoopInfo> LI;
^
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/include/llvm/Analysis/LoopInfo.h:1079:7: note: declaration here is not visible
class LoopInfo : public LoopInfoBase<BasicBlock, Loop> {
^
While building module 'LLVM_Transforms' imported from /Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/lib/Transforms/CFGuard/CFGuard.cpp:15:
In file included from <module-includes>:191:
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h:149:3: error: missing '#include "llvm/Analysis/OptimizationRemarkEmitter.h"'; 'OptimizationRemarkEmitter' must be declared before it is used
OptimizationRemarkEmitter *ORE = nullptr;
^
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/include/llvm/Analysis/OptimizationRemarkEmitter.h:33:7: note: declaration here is not visible
class OptimizationRemarkEmitter {
^
/Users/buildslave/jenkins/workspace/lldb-cmake/llvm-project/llvm/lib/Transforms/CFGuard/CFGuard.cpp:15:10: fatal error: could not build module 'LLVM_Transforms'
```
Interval value
The II value was incremented before exiting the loop, and therefor when
used in the optimization remarks and debug dumps it did not reflect the
initiation interval actually used in Schedule.
Differential Revision: https://reviews.llvm.org/D95692
SROA does not correctly account for offsets in TBAA/TBAA struct metadata.
This patch creates functionality for generating new MD with the corresponding
offset and updates SROA to use this functionality.
Differential Revision: https://reviews.llvm.org/D95826
This is the preliminary patch of converting `LoopInterchange` pass to a loop-nest pass and has no intended functional change.
Changes that are not loop-nest related are split to D96650.
Reviewed By: Whitney
Differential Revision: https://reviews.llvm.org/D96644
Otherwise they are not allocated as a single bit field and take 4
bytes instead of 2.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D95954
This allows the option to affect the LTO output. Module::Max helps to
generate debug info for all modules in the same format.
Differential Revision: https://reviews.llvm.org/D96597
We can't construct a working unique_function from an object that's not callable
with the right types, so don't allow deduction to succeed.
This avoids some ambiguous conversion cases, e.g. allowing to overload
on different unique_function types, and to conversion operators to
unique_function.
std::function and the any_invocable proposal have these.
This was added to llvm::function_ref in D88901 and followups
Differential Revision: https://reviews.llvm.org/D96794
Reapply patch after fixing buildbot failure.
Refactor SampleProfile.cpp to use the core code in CodeGen.
The main changes are:
(1) Move SampleProfileLoaderBaseImpl class to a header file.
(2) Split SampleCoverageTracker to a head file and a cpp file.
(3) Move the common codes (common options and callsiteIsHot())
to the common cpp file.
Differential Revision: https://reviews.llvm.org/D96455
Basic block sections enables function sections implicitly, this is not needed
and is inefficient with "=list" option.
We had basic block sections enable function sections implicitly in clang. This
is particularly inefficient with "=list" option as it places functions that do
not have any basic block sections in separate sections. This causes unnecessary
object file overhead for large applications.
This patch disables this implicit behavior. It only creates function sections
for those functions that require basic block sections.
Further, there was an inconistent behavior with llc as llc was not turning on
function sections by default. This patch makes llc and clang consistent and
tests are added to check the new behavior.
This is the first of two patches and this adds functionality in LLVM to
create a new section for the entry block if function sections is not
enabled.
Differential Revision: https://reviews.llvm.org/D93876
This change introduces support for zero flag ELF section groups to LLVM.
LLVM already supports COMDAT sections, which in ELF are a special type
of ELF section groups. These are generally useful to enable linker GC
where you want a group of sections to always travel together, that is to
be either retained or discarded as a whole, but without the COMDAT
semantics. Other ELF assemblers already support zero flag ELF section
groups and this change helps us reach feature parity.
Differential Revision: https://reviews.llvm.org/D95851
This reverts commit 310b35304cdf5a230c042904655583c5532d3e91.
The build is broken with -DBUILD_SHARED_LIBS=ON :
lib/ProfileData/CMakeFiles/LLVMProfileData.dir/SampleProfileLoaderBaseUtil.cpp.o: In function `llvm::sampleprofutil::callsiteIsHot(llvm::sampleprof::FunctionSamples const*, llvm::ProfileSummaryInfo*, bool)':
SampleProfileLoaderBaseUtil.cpp:(.text._ZN4llvm14sampleprofutil13callsiteIsHotEPKNS_10sampleprof15FunctionSamplesEPNS_18ProfileSummaryInfoEb+0x1a): undefined reference to `llvm::ProfileSummaryInfo::isColdCount(unsigned long) const'
SampleProfileLoaderBaseUtil.cpp:(.text._ZN4llvm14sampleprofutil13callsiteIsHotEPKNS_10sampleprof15FunctionSamplesEPNS_18ProfileSummaryInfoEb+0x28): undefined reference to `llvm::ProfileSummaryInfo::isHotCount(unsigned long) const'
...
This patch fixes a warning:
llvm-project/llvm/include/llvm/ProfileData/SampleProfileLoaderBaseImpl.h:69:7:
error: 'llvm::SampleProfileLoaderBaseImpl' has virtual functions but
non-virtual destructor [-Werror,-Wnon-virtual-dtor]
Differential Revision: https://reviews.llvm.org/D96810
Refactor SampleProfile.cpp to use the core code in CodeGen.
The main changes are:
(1) Move SampleProfileLoaderBaseImpl class to a header file.
(2) Split SampleCoverageTracker to a head file and a cpp file.
(3) Move the common codes (common options and callsiteIsHot())
to the common cpp file.
Differential Revision: https://reviews.llvm.org/D96455
The tile directive is in OpenMP's Technical Report 8 and foreseeably will be part of the upcoming OpenMP 5.1 standard.
This implementation is based on an AST transformation providing a de-sugared loop nest. This makes it simple to forward the de-sugared transformation to loop associated directives taking the tiled loops. In contrast to other loop associated directives, the OMPTileDirective does not use CapturedStmts. Letting loop associated directives consume loops from different capture context would be difficult.
A significant amount of code generation logic is taking place in the Sema class. Eventually, I would prefer if these would move into the CodeGen component such that we could make use of the OpenMPIRBuilder, together with flang. Only expressions converting between the language's iteration variable and the logical iteration space need to take place in the semantic analyzer: Getting the of iterations (e.g. the overload resolution of `std::distance`) and converting the logical iteration number to the iteration variable (e.g. overload resolution of `iteration + .omp.iv`). In clang, only CXXForRangeStmt is also represented by its de-sugared components. However, OpenMP loop are not defined as syntatic sugar. Starting with an AST-based approach allows us to gradually move generated AST statements into CodeGen, instead all at once.
I would also like to refactor `checkOpenMPLoop` into its functionalities in a follow-up. In this patch it is used twice. Once for checking proper nesting and emitting diagnostics, and additionally for deriving the logical iteration space per-loop (instead of for the loop nest).
Differential Revision: https://reviews.llvm.org/D76342
This patch enables scalable vectorization of loops with integer/fast reductions, e.g:
```
unsigned sum = 0;
for (int i = 0; i < n; ++i) {
sum += a[i];
}
```
A new TTI interface, isLegalToVectorizeReduction, has been added to prevent
reductions which are not supported for scalable types from vectorizing.
If the reduction is not supported for a given scalable VF,
computeFeasibleMaxVF will fall back to using fixed-width vectorization.
Reviewed By: david-arm, fhahn, dmgreen
Differential Revision: https://reviews.llvm.org/D95245
This patch changes costAndCollectOperands to use InstructionCost for
accumulated cost values.
isHighCostExpansion will return true if the cost has exceeded the budget.
Reviewed By: CarolineConcatto, ctetreau
Differential Revision: https://reviews.llvm.org/D92238
The GPUDivergenceAnalysis is now renamed to just "DivergenceAnalysis"
since there is no conflict with LegacyDivergenceAnalysis. In the
legacy PM, this analysis can only be used through the legacy DA
serving as a wrapper. It is now made available as a pass in the new
PM, and has no relation with the legacy DA.
The new DA currently cannot handle irreducible control flow; its
presence can cause the analysis to run indefinitely. The analysis is
now modified to detect this and report all instructions in the
function as divergent. This is super conservative, but allows the
analysis to be used without hanging the compiler.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D96615
The API is a bit awkward since you need to index into an array in the
passed struct. I guess an alternative would be to pass all of the
individual fields.
Return the best covering index, and additional needed to complete the
mask. This logically belongs in TargetRegisterInfo, although I ended
up not needing it for why I originally split this out.
If we're going to end up expanding anyway, we should do it early
so we don't create extra operations to handle the bytes added by
promotion.
Simlilar was done for BSWAP previously.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D96681
This commit fixes how metadata is handled in CloneModule to be sound,
and improves how it's handled in CloneFunctionInto (although the latter
is still awkward when called within a module).
Ruiling Song pointed out in PR48841 that CloneModule was changed to
unsoundly use the RF_ReuseAndMutateDistinctMDs flag (renamed in
fa35c1f80f0ea080a7cbc581416929b0a654f25c for clarity). This flag papered
over a crash caused by other various changes made to CloneFunctionInto
over the past few years that made it unsound to use cloning between
different modules.
(This commit partially addresses PR48841, fixing the repro from
preprocessed source but not textual IR. MDNodeMapper::mapDistinctNode
became unsound in df763188c9a1ecb1e7e5c4d4ea53a99fbb755903 and this
commit does not address that regression.)
RF_ReuseAndMutateDistinctMDs is designed for the IRMover to use,
avoiding unnecessary clones of all referenced metadata when linking
between modules (with IRMover, the source module is discarded after
linking). It never makes sense to use when you're not discarding the
source. This commit drops its incorrect use in CloneModule.
Sadly, the right thing to do with metadata when cloning a function is
complicated, and this patch doesn't totally fix it.
The first problem is that there are two different types of referenceable
metadata and it's not obvious what to with one of them when remapping.
- `!0 = !{!1}` is metadata's version of a constant. Programatically it's
called "uniqued" (probably a better term would be "constant") because,
like `ConstantArray`, it's stored in uniquing tables. Once it's
constructed, it's illegal to change its arguments.
- `!0 = distinct !{!1}` is a bit closer to a global variable. It's legal
to change the operands after construction.
What should be done with distinct metadata when cloning functions within
the same module?
- Should new, cloned nodes be created?
- Should all references point to the same, old nodes?
The answer depends on whether that metadata is effectively owned by a
function.
And that's the second problem. Referenceable metadata's ownership model
is not clear or explicit. Technically, it's all stored on an
LLVMContext. However, any metadata that is `distinct`, that transitively
references a `distinct` node, or that transitively references a
GlobalValue is specific to a Module and is effectively owned by it. More
specifically, some metadata is effectively owned by a specific Function
within a module.
Effectively function-local metadata was introduced somewhere around
c10d0e5ccd12f049bddb24dcf8bbb7fbbc6c68f2, which made it illegal for two
functions to share a DISubprogram attachment.
When cloning a function within a module, you need to clone the
function-local debug info and suppress cloning of global debug info (the
status quo suppresses cloning some global debug info but not all). When
cloning a function to a new/different module, you need to clone all of
the debug info.
Here's what I think we should do (eventually? soon? not this patch
though):
- Distinguish explicitly (somehow) between pure constant metadata owned
by the LLVMContext, global metadata owned by the Module, and local
metadata owned by a GlobalValue (such as a function).
- Update CloneFunctionInto to trigger cloning of all "local" metadata
(only), perhaps by adding a bit to RemapFlag. Alternatively, split
out a separate function CloneFunctionMetadataInto to prime the
metadata map that callers are updated to call ahead of time as
appropriate.
Here's the somewhat more isolated fix in this patch:
- Converted the `ModuleLevelChanges` parameter to `CloneFunctionInto` to
an enum called `CloneFunctionChangeType` that is one of
LocalChangesOnly, GlobalChanges, DifferentModule, and ClonedModule.
- The code maintaining the "functions uniquely own subprograms"
invariant is now only active in the first two cases, where a function
is being cloned within a single module. That's necessary because this
code inhibits cloning of (some) "global" metadata that's effectively
owned by the module.
- The code maintaining the "all compile units must be explicitly
referenced by !llvm.dbg.cu" invariant is now only active in the
DifferentModule case, where a function is being cloned into a new
module in isolation.
- CoroSplit.cpp's call to CloneFunctionInto in CoroCloner::create
uses LocalChangeOnly, since fa635d730f74f3285b77cc1537f1692184b8bf5b
only set `ModuleLevelChanges` to trigger cloning of local metadata.
- CloneModule drops its unsound use of RF_ReuseAndMutateDistinctMDs
and special handling of !llvm.dbg.cu.
- Fixed some outdated header docs and left a couple of FIXMEs.
Differential Revision: https://reviews.llvm.org/D96531
This patch uses the function getShuffleCost with SK_Reverse to compute the cost
for experimental.vector.reverse.
For scalable vector type, it adds a table will the legal types on
AArch64TTIImpl::getShuffleCost to not assert in BasicTTIImpl::getShuffleCost,
and for fixed vector, it relies on the existing cost model in BasicTTIImpl.
Depends on D94883
Differential Revision: https://reviews.llvm.org/D95603
Currently, setting the `no-nans-fp-math` attribute to true will allow
loops with fmin/fmax to vectorize, though we should be requiring that
`no-signed-zeros-fp-math` is also set.
This patch adds the check for no-signed-zeros at the function level and includes
tests to make sure we don't vectorize functions with only one of the attributes
associated.
Reviewed By: spatel
Differential Revision: https://reviews.llvm.org/D96604
This patch adds a new intrinsic experimental.vector.reduce that takes a single
vector and returns a vector of matching type but with the original lane order
reversed. For example:
```
vector.reverse(<A,B,C,D>) ==> <D,C,B,A>
```
The new intrinsic supports fixed and scalable vectors types.
The fixed-width vector relies on shufflevector to maintain existing behaviour.
Scalable vector uses the new ISD node - VECTOR_REVERSE.
This new intrinsic is one of the named shufflevector intrinsics proposed on the
mailing-list in the RFC at [1].
Patch by Paul Walker (@paulwalker-arm).
[1] https://lists.llvm.org/pipermail/llvm-dev/2020-November/146864.html
Differential Revision: https://reviews.llvm.org/D94883
