Summary:
Only instantiate anonymous records once all variable references in template
arguments have been resolved. This allows patterns like the new test case,
which in practice can appear in expressions like:
class IntrinsicTypeProfile<list<LLVMType> ty, int shift> {
list<LLVMType> types =
!listconcat(ty, [llvm_any_ty, LLVMMatchType<shift>]);
}
class FooIntrinsic<IntrinsicTypeProfile P, ...>
: Intrinsic<..., P.types, ...>;
Without this change, the anonymous LLVMMatchType instantiation would
never get resolved.
Another consequence of this change is that anonymous inline
instantiations are uniqued via the folding set of the newly introduced
VarDefInit.
Change-Id: I7a7041a20e297cf98c9109b28d85e64e176c932a
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43756
llvm-svn: 326788
Summary:
So that we will be able to generate new anonymous names more easily
outside the parser as well.
Change-Id: I28f396a7bdbc3ff0c665d466abbd3d31376e21b4
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43755
llvm-svn: 326787
Summary:
There are various places where resolving and constant folds can
get stuck, especially around casts. We don't always signal an
error for those, because in many cases they can legitimately
occur without being an error in the "untaken branch" of an !if.
Change-Id: I3befc0e4234c8e6cc61190504702918c9f29ce5c
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43754
llvm-svn: 326786
Summary:
Distinguish two relationships between types: is-a and convertible-to.
For example, a bit is not an int or vice versa, but they can be
converted into each other (with range checks that you can think of
as "dynamic": unlike other type checks, those range checks do not
happen during parsing, but only once the final values have been
established).
Actually converting initializers between types is subtle: even
when values of type A can be converted to type B (e.g. int into
string), it may not be possible to do so with a concrete initializer
(e.g., a VarInit that refers to a variable of type int cannot
be immediately converted to a string).
For this reason, distinguish between getCastTo and convertInitializerTo:
the latter implements the actual conversion when appropriate, while
the former will first try to do the actual conversion and fall back
to introducing a !cast operation so that the conversion will be
delayed until variable references have been resolved.
To make the approach of adding !cast operations to work, !cast needs
to fallback to convertInitializerTo when the special string <-> record
logic does not apply.
This enables casting records to a subclass, although that new
functionality is only truly useful together with !isa, which will be
added in a later change.
The test is removed because it uses !srl on a bit sequence,
which cannot really be supported consistently, but luckily
isn't used anywhere either.
Change-Id: I98168bf52649176654ed2ec61a29bdb29970cfe7
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43753
llvm-svn: 326785
Summary:
No functional change intended. The removed code has a loop for
recursive resolving, which is superseded by the recursive
resolving done by the Resolver implementations.
Add a test case which was broken by an earlier version of this
change.
Change-Id: Ib208d037b77a8bbb725977f1388601fc984723d8
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43655
llvm-svn: 326784
Summary:
Allow RecordRecTy to represent the type "subclass of N superclasses",
where N may be zero. Furthermore, generate RecordRecTy instances only
with actual classes in the list.
Keeping track of multiple superclasses is required to resolve the type
of a list correctly in some cases. The old code relied on the incorrect
behavior of typeIsConvertibleTo, and an earlier version of this change
relied on a modified ordering of superclasses (it was committed in
r325884 and then reverted because unfortunately some of clang-tblgen's
backends depend on the ordering).
Previously, the DefInit for each Record would have a RecordRecTy of
that Record as its type. Now, all defs with the same superclasses will
share the same type.
This allows us to be more consistent about type checks involving records:
- typeIsConvertibleTo actually requires the LHS to be a subtype of the
RHS
- resolveTypes will return the least supertype of given record types in
all cases
- different record types in the two branches of an !if are handled
correctly
Add a test that used to be accepted without flagging the obvious type
error.
Change-Id: Ib366db1a4e6a079f1a0851e469b402cddae76714
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43680
llvm-svn: 326783
I obviously messed up arguments to MachineOperand::CreateReg
in rL326769. This should make it work as intended.
Thanks to RKSimon for spotting this.
llvm-svn: 326780
In case PredBB == BB and StopAt == BB's terminator, StopAt != &*BI will
fail, because BB's terminator instruction gets replaced.
By using BB.getTerminator() we get the current terminator which we can use
to compare.
Reviewers: sanjoy, anna, reames
Reviewed By: anna
Differential Revision: https://reviews.llvm.org/D43822
llvm-svn: 326779
Before I started maintaining the AVR backend, this instruction
never originally used to have an earlyclobber flag.
Some time afterwards (years ago), I must've added it back in, not realising that it
was left out for a reason.
This pseudo instrction exists solely to work around a long standing bug
in the register allocator.
Before this commit, the LDDWRdYQ pseudo was not actually working around
any bug. With the earlyclobber flag removed again, the LDDWRdYQ pseudo
now correctly works around PR13375 again.
llvm-svn: 326774
Summary:
This is a workaround for pr36417
https://bugs.llvm.org/show_bug.cgi?id=36417
LiveDebugVariables will now verify that the DBG_VALUE instructions
are sane (prior to register allocation) by asking LIS if a virtual
register used in the DBG_VALUE is live (or dead def) in the slot
index before the DBG_VALUE. If it isn't sane the DBG_VALUE is
discarded.
One pass that was identified as introducing non-sane DBG_VALUE
instructtons, when analysing pr36417, was the DAG->DAG Instruction
Selection. It sometimes inserts DBG_VALUE instructions referring to
a virtual register that is defined later in the same basic block.
So it is a use before def kind of problem. The DBG_VALUE is
typically inserted in the beginning of a basic block when this
happens. The problem can be seen in the test case
test/DebugInfo/X86/dbg-value-inlined-parameter.ll
Reviewers: aprantl, rnk, probinson
Reviewed By: aprantl
Subscribers: vsk, davide, alexcrichton, Ka-Ka, eraman, llvm-commits, JDevlieghere
Differential Revision: https://reviews.llvm.org/D43956
llvm-svn: 326769
The MC layer doesn't currently emit relocations in offset
order for the entire code section so this check was causing
failures on the wasm waterfall.
Perhaps we can re-instate this check if we divide the relocations
per-function, or add extra ordering the MC object writer.
Differential Revision: https://reviews.llvm.org/D44136
llvm-svn: 326765
EAX can turn out to be alive here, when shrink wrapping is done
(which is allowed when using dwarf exceptions, contrary to the
normal case with WinCFI).
This fixes PR36487.
Differential Revision: https://reviews.llvm.org/D43968
llvm-svn: 326764
DWARF v5 specifies that the root file (also given in the DW_AT_name
attribute of the compilation unit DIE) should be emitted explicitly to
the line table's list of files. This makes the line table more
independent of the .debug_info section.
Differential Revision: https://reviews.llvm.org/D44054
llvm-svn: 326758
The 'hasOneUse' check is a giveaway that something's not right.
We never need to check that in InstSimplify because we don't
create new instructions here.
These are all handled as icmp simplifies which then trigger
existing select simplifies, so there's no need to duplicate
a composite fold of the two.
llvm-svn: 326750
Summary:
Fabs is a common floating-point operation, especially for some expansions. This patch adds
a new generic opcode for llvm.fabs.* intrinsic in order to avoid building/matching this intrinsic.
Reviewers: qcolombet, aditya_nandakumar, dsanders, rovka
Reviewed By: aditya_nandakumar
Subscribers: kristof.beyls, javed.absar, llvm-commits
Differential Revision: https://reviews.llvm.org/D43864
llvm-svn: 326749
Summary:
RewriteStatepointsForGC collects parse points for further processing.
During the collection if a callsite is found in an unreachable block
(DominatorTree::isReachableFromEntry()) then all unreachable blocks are
removed by removeUnreachableBlocks(). Some of the removed blocks could
have been reachable according to DominatorTree::isReachableFromEntry().
In this case the collected parse points became stale and resulted in a
crash when accessed.
The fix is to unconditionally canonicalize the IR to
removeUnreachableBlocks and then collect the parse points.
The added test crashes with the old version and passes with this patch.
Patch by Yevgeny Rouban!
Reviewed by: Anna
Differential Revision: https://reviews.llvm.org/D43929
llvm-svn: 326748
Summary:
It can be useful for tools to be able to retrieve the values of variables
declared via STATISTIC() directly without having to emit them and parse
them back. Use cases include:
* Needing to report specific statistics to a test harness
* Wanting to post-process statistics. For example, to produce a percentage of
functions that were fully selected by GlobalISel
Make this possible by adding llvm::GetStatistics() which returns an
iterator_range that can be used to inspect the statistics that have been
touched during execution. When statistics are disabled (NDEBUG and not
LLVM_ENABLE_STATISTICS) this method will return an empty range.
This patch doesn't address the effect of multiple compilations within the same
process. In such situations, the statistics will be cumulative for all
compilations up to the GetStatistics() call.
Reviewers: qcolombet, rtereshin, aditya_nandakumar, bogner
Reviewed By: rtereshin, bogner
Subscribers: llvm-commits, mgorny
Differential Revision: https://reviews.llvm.org/D43901
This re-commit fixes a missing include of <vector> which it seems clang didn't
mind but G++ and MSVC objected to. It seems that, clang was ok with std::vector
only being forward declared at the point of use since it was fully defined
eventually but G++/MSVC both rejected it at the point of use.
llvm-svn: 326738
Up until Power9, the performance profile for rlwinm., rldicl. and andi. looked
more or less equivalent. However with Power9, the rotates are still 2-way
cracked whereas the and-immediate is not.
This patch just ensures that we don't emit record-form rotates when an andi.
is adequate.
As first pointed out by Carrot in https://bugs.llvm.org/show_bug.cgi?id=30833
(this patch is a fix for that PR).
Differential Revision: https://reviews.llvm.org/D43977
llvm-svn: 326736
Summary:
Presently, InstCombiner::foldICmpWithCastAndCast() implicitly assumes that it is
only invoked with icmp instructions of integer type. If that assumption is broken,
and it is called with an icmp of vector type, then it fails (asserts/crashes).
This patch addresses the deficiency. It allows it to simplify
icmp (ptrtoint x), (ptrtoint/c) of vector type into a compare of the inputs,
much as is done when the type is integer.
Reviewers: apilipenko, fedor.sergeev, mkazantsev, anna
Reviewed By: anna
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D44063
llvm-svn: 326730
This patch teaches getMinimumFPType to support shrinking a vector of ConstantFPs. This should improve our ability to combine vector fptrunc with fp binops.
Differential Revision: https://reviews.llvm.org/D43774
llvm-svn: 326729
Despite building cleanly on my machine in three separate configs, it's failing on pretty much all bots due to missing includes among other things. Investigating.
llvm-svn: 326726
Summary:
It can be useful for tools to be able to retrieve the values of variables
declared via STATISTIC() directly without having to emit them and parse
them back. Use cases include:
* Needing to report specific statistics to a test harness
* Wanting to post-process statistics. For example, to produce a percentage of
functions that were fully selected by GlobalISel
Make this possible by adding llvm::GetStatistics() which returns an
iterator_range that can be used to inspect the statistics that have been
touched during execution. When statistics are disabled (NDEBUG and not
LLVM_ENABLE_STATISTICS) this method will return an empty range.
This patch doesn't address the effect of multiple compilations within the same
process. In such situations, the statistics will be cumulative for all
compilations up to the GetStatistics() call.
Reviewers: qcolombet, rtereshin, aditya_nandakumar, bogner
Reviewed By: rtereshin, bogner
Subscribers: llvm-commits, mgorny
Differential Revision: https://reviews.llvm.org/D43901
llvm-svn: 326723
The error occurs when reading i16 elements (as in the testcase) from a v8i8
with a pattern of <0,2,4,6>. As all the data in the vector is accessed, the
operation is not a VUZP. The patch stops the pattern recognition of VUZP when
EXTRACT_VECTOR_ELT has a different element type than BUILD_VECTOR.
llvm-svn: 326722
getCompare returns true, false or undef constants if the comparison can
be evaluated, or nullptr if it cannot. This is in line with what
ConstantExpr::getCompare returns. It also allows us to use
ConstantExpr::getCompare for comparing constants.
Reviewers: davide, mssimpso, dberlin, anna
Reviewed By: davide
Differential Revision: https://reviews.llvm.org/D43761
llvm-svn: 326720
Use the whole gammut of constant immediates available to set up a vector.
Instead of using, for example, `mov w0, #0xffff; dup v0.4s, w0`, which
transfers between register files, use the more efficient `movi v0.4s, #-1`
instead. Not limited to just a few values, but any immediate value that can
be encoded by all the variants of `FMOV`, `MOVI`, `MVNI`, thus eliminating
the need to there be patterns to optimize special cases.
Differential revision: https://reviews.llvm.org/D42133
llvm-svn: 326718
This is a NFC simple patch that changes the DEBUG dumping in the
MachineScheduler so that the dumping of the built SUnits is done before the
SchedImpl->initialize() is called.
This is better on SystemZ, since it has a strategy that does some dumping at
the start of the region, and it is not possible to easily read it if it is
output above a long list of SU.
Review: Javed Absar
https://reviews.llvm.org/D44089
llvm-svn: 326716
These were just copies of the relevant fuzzer binary with (presumably)
meaningful suffixes, but accounted for more than 10% of my build
directory (> 8GB). Hard drive space is cheap, but not that cheap.
llvm-svn: 326710
Summary:
Use the new resolver interface more explicitly, and avoid traversing
all the initializers multiple times.
Change-Id: I679e86988b309d19f25e6cca8b0b14ea150198a6
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43654
llvm-svn: 326708
Summary:
Use the new resolver interface more explicitly, and avoid traversing
all the initializers multiple times.
Change-Id: Ia4dcc6d42dd8b65e6079d318c6a202f36f320fee
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43653
llvm-svn: 326707
Summary:
Use the new resolver interface more explicitly, and avoid traversing
all the initializers multiple times.
Add a test case for a pattern that was broken by an earlier version
of this change.
An additional change is that we now remove *all* template arguments
after resolving them.
Change-Id: I86c828c8cc84c18b052dfe0f64c0d5cbf3c4e13c
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43652
llvm-svn: 326706
Summary:
This changes the syntax of !foreach so that the first "parameter" is
a new syntactic variable: !foreach(x, lst, expr) will define the
variable x within the scope of expr, and evaluation of the !foreach
will substitute elements of the given list (or dag) for x in expr.
Aside from leading to a nicer syntax, this allows more complex
expressions where x is deeply nested, or even constant expressions
in which x does not occur at all.
!foreach is currently not actually used anywhere in trunk, but I
plan to use it in the AMDGPU backend. If out-of-tree targets are
using it, they can adjust to the new syntax very easily.
Change-Id: Ib966694d8ab6542279d6bc358b6f4d767945a805
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits, tpr
Differential Revision: https://reviews.llvm.org/D43651
llvm-svn: 326705
Summary:
The intention is to allow us to more easily restructure how resolving is
done, e.g. resolving multiple variables simultaneously, or using the
resolving mechanism to implement !foreach.
Change-Id: I4b976b54a32e240ad4f562f7eb86a4d663a20ea8
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43564
llvm-svn: 326704
Summary:
NAME has already worked for def in a multiclass, since the (protoype)
record including its NAME variable is created before parsing the
superclasses. Since defm's do not have an associated single record,
support for NAME has to be implemented differently here.
Original test cases provided by Artem Belevich (tra)
Change-Id: I933b74f328c0ff202e7dc23a35b78f3505760cc9
Reviewers: arsenm, craig.topper, tra, MartinO
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D43656
llvm-svn: 326700
The former simply makes more sense: we want to access the data here in
the backend, not information about the type.
More importantly, removing users of RecordRecTy::getRecord() allows us
more freedom to refactor the frontend.
Change-Id: Iee8905fd22cdb9b11c42ca03246c03d8fe4dd77f
llvm-svn: 326699
Summary:
We can discard initial blocks that do other work
We do not need to limit ourselves to just the first block in the chain.
Reviewers: courbet, davide
Reviewed By: courbet
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D44029
llvm-svn: 326698
We now check relocations offsets are within range, and the relocation
index is valid.
Also updated tests which contained invalid Wasm files that were
previously not checked.
Differential Revision: https://reviews.llvm.org/D43684
llvm-svn: 326697
These instructions require that the two S registers are adjacent (but not the R
registers), because only the first register is included in the encoding, but we
were not checking this in the assembler.
Differential revision: https://reviews.llvm.org/D44084
llvm-svn: 326696
This is required in order to enable relocs to be validated
as they are read in.
Also update tests with new section ordering.
Differential Revision: https://reviews.llvm.org/D43940
llvm-svn: 326694
This allows LLD to print the name for an InputGlobal when encountering
an error.
Differential Revision: https://reviews.llvm.org/D44033
llvm-svn: 326691
Previously, we passed "#" to --autocomplete to indicate to enable cc1
flags. For example, when -cc1 or -Xclang was passed to bash, bash
executed `clang --autocomplete=#-<flag they want to complete>`.
However, this was not a good implementation because it depends -Xclang
and -cc1 parsing to shell. So I changed this to pass all flags shell
has, so that Clang can handle them internally.
I had to change many testcases because API spec changed quite a lot.
Reviewers: teemperor, v.g.vassilev
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D39342
llvm-svn: 326684
Almost none of these usages were FP specific. And we had no clear guideliness on when to use hasAVX vs hasFP256.
I might also remove hasInt256 too since its an alias for hasAVX2.
llvm-svn: 326682
Loading a constant into a k-register in AVX512 requires a bitcast from a scalar constant. In the test case here we have a k-register store that gets split into multiple parts of KNL. MergeConsecutiveStores sees each of these pieces as a consecutive store and looks through the bitcast to find the underly scalar constant. But when we went to create the combined store we didn't look through the same bitcast.
llvm-svn: 326677
Add tests for FIADD/FISUB/FISUBR/FIMUL/FIDIV/FIDIVR
Shows we have more FILD stack usage than necessary (arg load, spill, reload to x87)
llvm-svn: 326674
rL322525 - mmx zero constant support
rL322553 - mmx i32 zero extended value
rL326497 - mmx i64 general constant handling
Not all constants are folded, we generate some on the GPRs (similar to SSE build vector) where appropriate
llvm-svn: 326673
We were previously doing this with isel patterns. Moving it to op legalization gives us chance to see the required bitcast earlier. And it lets us remove some isel patterns.
llvm-svn: 326669
Iterating through predecessors of `TailBB` while removing their
terminators leads to use after-free, because the predecessor list is
changing on each removal.
llvm-svn: 326668
Summary:
`musttail` calls can't be naively splitted. The split blocks must
include not only the call instruction itself, but also (optional)
`bitcast` and `return` instructions that follow it.
Clone `bitcast` and `ret`, place them into the split blocks, and
remove the tail block when done.
Reviewers: junbuml, mcrosier, davidxl, davide, fhahn
Reviewed By: fhahn
Subscribers: JDevlieghere, llvm-commits
Differential Revision: https://reviews.llvm.org/D43729
llvm-svn: 326666
This caused some links to fail with ThinLTO due to missing symbols as
well as causing some binaries to have failures at runtime. We're working
with the author to get a test case, but want to get the tree green
again.
Further, it appears to introduce a data race. While the test usage of
threads was disabled in r325361 & r325362, that isn't an acceptable fix.
I've reverted both of these as well. This code needs to be thread safe.
Test cases for this are already on the original commit thread.
llvm-svn: 326638
X86 considers v1i1 a legal type under AVX512 and as such a truncate from a v1iX type to v1i1 can be turned into a scalar truncate plus a conversion to v1i1. We would much prefer a v1i1 SCALAR_TO_VECTOR over a one element BUILD_VECTOR.
During lowering we were detecting the v1i1 BUILD_VECTOR as a splat BUILD_VECTOR like we try to do for v2i1/v4i1/etc. In this case we create (select i1 splat_elt, v1i1 all-ones, v1i1 all-zeroes). That goes through some more legalization and we end up with a CMOV choosing between 0 and 1 in scalar and a scalar_to_vector.
Arguably we could detect the v1i1 BUILD_VECTOR and do this better in X86 target code. But just using a SCALAR_TO_VECTOR in legalization is much easier.
llvm-svn: 326637
The fast/linear DAG scheduler doesn't lower DBG_VALUEs except for
function entry nodes.
Patch by Joshua Cranmer!
Differential Revision: https://reviews.llvm.org/D43028
llvm-svn: 326631
Summary:
The symbolizer was checking for .debug as a subdirectory of the
binary file itself, not of the directory containing the binary. This led to
a failure to find split debug info when it was contained in a .debug directory.
Reviewers: rnk, glider, zturner
Subscribers: llvm-commits, aprantl
Differential Revision: https://reviews.llvm.org/D44025
llvm-svn: 326630
In stage2 -O3 builds of llc, this results in small but measurable
increases in the number of variables with locations, and in the number
of unique source variables overall.
(According to llvm-dwarfdump --statistics, there are 123 additional
variables with locations, which is just a 0.006% improvement).
The size of the .debug_loc section of the llc dsym increases by 0.004%.
llvm-svn: 326629
Summary:
This patch implements relaxation for RISCV in the MC layer.
The following relaxations are currently handled:
1) Relax C_BEQZ to BEQ and C_BNEZ to BNEZ in RISCV.
2) Relax and C_J $imm to JAL x0, $imm and CJAL to JAL ra, $imm.
Reviewers: asb, llvm-commits, efriedma
Reviewed By: asb
Subscribers: shiva0217
Differential Revision: https://reviews.llvm.org/D43055
llvm-svn: 326626
In stage2 -O3 builds of llc, this results in a 0.3% increase in the
number of variables with locations, and a 0.2% increase in the number of
unique source variables overall.
The size of the .debug_loc section of the llc dsym increases by 0.5%.
llvm-svn: 326621
This cast was causing invalid signatures to be written
for libcall functions.
Add an MC test which includes a call to builtin memcpy.
Differential Revision: https://reviews.llvm.org/D44037
llvm-svn: 326618
Instead of returning the smaller FP constant we now return the minimal Type the constant can fit into. We also return the Type of the input to any fp extends. The legality checks are then done on just the size of these Types. If we find something profitable we then emit FPTruncs in front of the smaller binop and assume those FPTruncs will be constant folded or combined with any ConstantFPs or fpextends.
Differential Revision: https://reviews.llvm.org/D44038
llvm-svn: 326617
Summary:
Original change was D43991 (rL326541) and was reverted by rL326571 and
rL326572. This adds also the necessary MCCodeEmitter patch.
Reviewers: sbc100
Subscribers: jfb, dschuff, sbc100, jgravelle-google, sunfish, llvm-commits, ncw
Differential Revision: https://reviews.llvm.org/D44034
llvm-svn: 326614
The byte-swapping loads and stores do not actually perform multiple
accesses to their memory operand, so they are OK to use with volatile
memory operands as well. Remove overly cautious check.
llvm-svn: 326613
This adds back-end support for the anyregcc calling convention
for use with patchpoints.
Since all registers are considered call-saved with anyregcc
(except for 0 and 1 which may still be clobbered by PLT stubs
and the like), this required adding support for saving and
restoring vector registers in prologue/epilogue code for the
first time. This is not used by any other calling convention.
llvm-svn: 326612
Nicolai Haehnle