Commit Graph

1033 Commits

Author SHA1 Message Date
Hal Finkel e6702ca0e2 [PowerPC] Try harder to find a base+offset when looking for consecutive accesses
When forming permutation-based unaligned vector loads, we need to know whether
it is valid to read ahead of the requested address by a full vector length.
Doing so is more efficient (and allows for more CSE with later loads), but
could trigger a page fault if invalid. To determine validity, we look for other
loads in the same block that access the relevant address range.

The relevant point here is that we need to do this as part of the process of
forming permutation-based vector loads, and this happens quite early in the
SDAG pipeline - specifically before many of the address calculations are fully
canonicalized. As a result, we need to try harder to recognize base+offset
address computations, because they still might appear as chain of adds
(base+offset+offset, for example). To account for this, we'll look through
chains of adds, accumulating the constant offsets.

llvm-svn: 246813
2015-09-03 22:37:44 +00:00
Hal Finkel 99d95328d6 [PowerPC] Compute the MMO offset for an unaligned load with signed arithmetic
If you compute the MMO offset using unsigned arithmetic, you end up with a
large positive offset instead of a small negative one. In theory, this could
cause bad instruction-scheduling decisions later.

I noticed this by inspection from the debug output, and using that for the
regression test is the best I can do right now.

llvm-svn: 246805
2015-09-03 21:12:15 +00:00
Hal Finkel 77c8b7ffd3 [PowerPC] Don't always consider P8Altivec-only masks in LowerVECTOR_SHUFFLE
LowerVECTOR_SHUFFLE needs to decide whether to pass a vector shuffle off to the
TableGen-generated matching code, and it does this by testing the same
predicates used by the TableGen files. Unfortunately, when we added new
P8Altivec-only predicates, we started universally testing them in
LowerVECTOR_SHUFFLE, and if then matched when targeting a system prior to a P8,
we'd end up with a selection failure.

llvm-svn: 246675
2015-09-02 16:52:37 +00:00
Hal Finkel a2cdbce661 [PowerPC] Fixup SELECT_CC (and SETCC) patterns with i1 comparison operands
There were really two problems here. The first was that we had the truth tables
for signed i1 comparisons backward. I imagine these are not very common, but if
you have:
  setcc i1 x, y, LT
this has the '0 1' and the '1 0' results flipped compared to:
  setcc i1 x, y, ULT
because, in the signed case, '1 0' is really '-1 0', and the answer is not the
same as in the unsigned case.

The second problem was that we did not have patterns (at all) for the unsigned
comparisons select_cc nodes for i1 comparison operands. This was the specific
cause of PR24552. These had to be added (and a missing Altivec promotion added
as well) to make sure these function for all types. I've added a bunch more
test cases for these patterns, and there are a few FIXMEs in the test case
regarding code-quality.

Fixes PR24552.

llvm-svn: 246400
2015-08-30 22:12:50 +00:00
Hal Finkel be78c25acb [PowerPC] Fix the int2fp(fp2int(x)) DAGCombine to ignore ppc_fp128
This DAGCombine was creating custom SDAG nodes with an illegal ppc_fp128
operand type because it was triggering on f64/f32 int2fp(fp2int(ppc_fp128 x)),
but shouldn't (it should only apply to f32/f64 types). The result was a crash.

llvm-svn: 245530
2015-08-20 01:18:20 +00:00
Nemanja Ivanovic 5f1cea4141 Temporary fix for the self-host failures introduced by rL244921.
This revision has introduced an issue that only affects bootstrapped compiler
when it is printing the ASM. I am working on resolving the issue, but in the
meantime, I'm disabling the legalization of scalar_to_vector operation for v2i64
and the associated testing until I can get this fixed.

llvm-svn: 245481
2015-08-19 19:04:47 +00:00
Nemanja Ivanovic 1c39ca6501 Scalar to vector conversions using direct moves
This patch corresponds to review:
http://reviews.llvm.org/D11471

It improves the code generated for converting a scalar to a vector value. With
direct moves from GPRs to VSRs, we no longer require expensive stack operations
for this. Subsequent patches will handle the reverse case and more general
operations between vectors and their scalar elements.

llvm-svn: 244921
2015-08-13 17:40:44 +00:00
Alex Lorenz e40c8a2b26 PseudoSourceValue: Replace global manager with a manager in a machine function.
This commit removes the global manager variable which is responsible for
storing and allocating pseudo source values and instead it introduces a new
manager class named 'PseudoSourceValueManager'. Machine functions now own an
instance of the pseudo source value manager class.

This commit also modifies the 'get...' methods in the 'MachinePointerInfo'
class to construct pseudo source values using the instance of the pseudo
source value manager object from the machine function.

This commit updates calls to the 'get...' methods from the 'MachinePointerInfo'
class in a lot of different files because those calls now need to pass in a
reference to a machine function to those methods.

This change will make it easier to serialize pseudo source values as it will
enable me to transform the mips specific MipsCallEntry PseudoSourceValue
subclass into two target independent subclasses.

Reviewers: Akira Hatanaka
llvm-svn: 244693
2015-08-11 23:09:45 +00:00
Bill Schmidt 42ddd71120 [PPC] Fix PR24216: Don't generate splat for misaligned shuffle mask
Given certain shuffle-vector masks, LLVM emits splat instructions
which splat the wrong bytes from the source register.  The issue is
that the function PPC::isSplatShuffleMask() in PPCISelLowering.cpp
does not ensure that the splat pattern found is requesting bytes that
are aligned on an EltSize boundary.  This patch detects this situation
as not a valid splat mask, resulting in a permute being generated
instead of a splat.

Patch and test case by Tyler Kenney, cleaned up a bit by me.

This is a simple bug fix that would be good to incorporate into 3.7.

llvm-svn: 243519
2015-07-29 14:31:57 +00:00
Sanjay Patel 1dd15598cf fix TLI's combineRepeatedFPDivisors interface to return the minimum user threshold
This fix was suggested as part of D11345 and is part of fixing PR24141.

With this change, we can avoid walking the uses of a divisor node if the target
doesn't want the combineRepeatedFPDivisors transform in the first place.

There is no NFC-intended other than that.

Differential Revision: http://reviews.llvm.org/D11531

llvm-svn: 243498
2015-07-28 23:05:48 +00:00
Chih-Hung Hsieh 1e859582d6 Implement target independent TLS compatible with glibc's emutls.c.
The 'common' section TLS is not implemented.
Current C/C++ TLS variables are not placed in common section.
DWARF debug info to get the address of TLS variables is not generated yet.

clang and driver changes in http://reviews.llvm.org/D10524

  Added -femulated-tls flag to select the emulated TLS model,
  which will be used for old targets like Android that do not
  support ELF TLS models.

Added TargetLowering::LowerToTLSEmulatedModel as a target-independent
function to convert a SDNode of TLS variable address to a function call
to __emutls_get_address.

Added into lib/Target/*/*ISelLowering.cpp to call LowerToTLSEmulatedModel
for TLSModel::Emulated. Although all targets supporting ELF TLS models are
enhanced, emulated TLS model has been tested only for Android ELF targets.
Modified AsmPrinter.cpp to print the emutls_v.* and emutls_t.* variables for
emulated TLS variables.
Modified DwarfCompileUnit.cpp to skip some DIE for emulated TLS variabls.

TODO: Add proper DIE for emulated TLS variables.
      Added new unit tests with emulated TLS.

Differential Revision: http://reviews.llvm.org/D10522

llvm-svn: 243438
2015-07-28 16:24:05 +00:00
Pete Cooper 2e20147403 Revert "Add const to some Type* parameters which didn't need to be mutable. NFC."
This reverts commit r243146.

Feedback from Craig Topper and David Blaikie was that we don't put const on Type as it has no mutable state.

llvm-svn: 243282
2015-07-27 17:15:24 +00:00
Pete Cooper 098f7c1fcb Add const to some Type* parameters which didn't need to be mutable. NFC.
We were only getting the size of the type which doesn't need to modify
the type.

llvm-svn: 243146
2015-07-24 19:19:26 +00:00
Pete Cooper 0debbdc872 Use foreach loops for StructType::elements(). NFC.
We had a few places where we did

for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {

but those could instead do

for (auto *EltTy : STy->elements()) {

llvm-svn: 243136
2015-07-24 18:55:49 +00:00
Bill Schmidt 54cced54a6 [PowerPC] v4i32 is a VSRCRegClass
I was looking at some vector code generation and kept seeing
unnecessary vector copies into the Altivec half of the VSX registers.
I discovered that we overlooked v4i32 when adding the register classes
for VSX; we only added v4f32 and v2f64.  This means that anything that
canonicalizes into v4i32 (which is a LOT of stuff) ends up being
forced into VRRC on its way to VSRC.

The fix is one line.  The rest of the patch is fixing up some test
cases whose code generation has changed as a result.

This seems like it would be a good candidate for backport to 3.7.

llvm-svn: 242442
2015-07-16 21:14:07 +00:00
Bill Schmidt 1e77bb12b4 [PPC64LE] Fix vec_sld semantics for little endian
The vec_sld interface provides access to the vsldoi instruction.
Unlike most of the vec_* interfaces, we do not attempt to change the
generated code for vec_sld based on the endian mode.  It is too
difficult to correctly infer the desired semantics because of
different element types, and the corrected instruction sequence is
expensive, involving loading a permute control vector and performing a
generalized permute.

For GCC, this was implemented as "Don't touch the vec_sld"
implementation.  When it came time for the LLVM implementation, I did
the same thing.  However, this was hasty and incorrect.  In LLVM's
version of altivec.h, vec_sld was previously defined in terms of the
vec_perm interface.  Because vec_perm semantics are adjusted for
little endian, this means that leaving vec_sld untouched causes it to
generate something different for LE than for BE.  Not good.

This back-end patch accompanies the changes to altivec.h that change
vec_sld's behavior for little endian.  Those changes mean that we see
slightly different code in the back end when trying to recognize a
VSLDOI instruction in isVSLDOIShuffleMask.  In particular, a
ShuffleKind of 1 (where the two inputs are identical) must now be
treated the same way as a ShuffleKind of 2 (little endian with
different inputs) when little endian mode is in force.  This is
because ShuffleKind of 1 is defined using big-endian numbering.

This has a ripple effect on LowerBUILD_VECTOR, where we create our own
internal VSLDOI instructions.  Because these are a ShuffleKind of 1,
they will now have their shift amounts subtracted from 16 when
recognizing the shuffle mask.  To avoid problems we have to subtract
them from 16 again before creating the VSLDOI instructions.

There are a couple of other uses of BuildVSLDOI, but these do not need
to be modified because the shift amount is 8, which is unchanged when
subtracted from 16.

llvm-svn: 242296
2015-07-15 15:45:30 +00:00
Hal Finkel cbf08925ef [PowerPC] Make use of the TargetRecip system
r238842 added the TargetRecip system for controlling use of reciprocal
estimates for sqrt and division using a set of parameters that can be set by
the frontend. Clang now supports a sophisticated -mrecip option, and this will
allow that option to effectively control the relevant code-generation
functionality of the PPC backend.

llvm-svn: 241985
2015-07-12 02:33:57 +00:00
Hal Finkel 965cea5670 [PowerPC] Support the nest parameter attribute
This adds support for the 'nest' attribute, which allows the static chain
register to be set for functions calls under non-Darwin PPC/PPC64 targets. r11
is the chain register (which the PPC64 ELF ABI calls the "environment
pointer"). For indirect calls under PPC64 ELFv1, this would normally be loaded
from the function descriptor, but providing an explicit 'nest' parameter will
override that process and use the value provided.

This allows __builtin_call_with_static_chain to work as expected on PowerPC.

llvm-svn: 241984
2015-07-12 00:37:44 +00:00
Pat Gavlin a717f255b6 Allow {e,r}bp as the target of {read,write}_register.
This patch allows the read_register and write_register intrinsics to
read/write the RBP/EBP registers on X86 iff the targeted register is
the frame pointer for the containing function.

Differential Revision: http://reviews.llvm.org/D10977

llvm-svn: 241827
2015-07-09 17:40:29 +00:00
Mehdi Amini a749f2ad47 Remove getDataLayout() from TargetLowering
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: yaron.keren, rafael, llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D11042

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241779
2015-07-09 02:09:52 +00:00
Mehdi Amini 0cdec1e2ab Make isLegalAddressingMode() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, llvm-commits, rafael, yaron.keren

Differential Revision: http://reviews.llvm.org/D11040

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241778
2015-07-09 02:09:40 +00:00
Mehdi Amini 5c183d5239 Make getByValTypeAlignment() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: yaron.keren, rafael, llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D11038

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241777
2015-07-09 02:09:28 +00:00
Mehdi Amini 9639d650bb Make TargetLowering::getShiftAmountTy() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, llvm-commits, rafael, yaron.keren

Differential Revision: http://reviews.llvm.org/D11037

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241776
2015-07-09 02:09:20 +00:00
Mehdi Amini 44ede33a69 Make TargetLowering::getPointerTy() taking DataLayout as an argument
Summary:
This change is part of a series of commits dedicated to have a single
DataLayout during compilation by using always the one owned by the
module.

Reviewers: echristo

Subscribers: jholewinski, ted, yaron.keren, rafael, llvm-commits

Differential Revision: http://reviews.llvm.org/D11028

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 241775
2015-07-09 02:09:04 +00:00
Peter Collingbourne 6a9d1774d0 IR: Do not consider available_externally linkage to be linker-weak.
From the linker's perspective, an available_externally global is equivalent
to an external declaration (per isDeclarationForLinker()), so it is incorrect
to consider it to be a weak definition.

Also clean up some logic in the dead argument elimination pass and clarify
its comments to better explain how its behavior depends on linkage,
introduce GlobalValue::isStrongDefinitionForLinker() and start using
it throughout the optimizers and backend.

Differential Revision: http://reviews.llvm.org/D10941

llvm-svn: 241413
2015-07-05 20:52:35 +00:00
Benjamin Kramer 9bfb627a0e [TargetLowering] StringRefize asm constraint getters.
There is some functional change here because it changes target code from
atoi(3) to StringRef::getAsInteger which has error checking. For valid
constraints there should be no difference.

llvm-svn: 241411
2015-07-05 19:29:18 +00:00
Nemanja Ivanovic 7df26c9b6f Modified a comment about the reason for the patch (removed commented code).
llvm-svn: 241110
2015-06-30 20:01:16 +00:00
Nemanja Ivanovic 9c8d4cf272 Fixes a bug with __builtin_vsx_lxvdw4x on Little Endian systems
llvm-svn: 241108
2015-06-30 19:45:45 +00:00
NAKAMURA Takumi 520b45df84 PPCISelLowering.cpp: Appease PR23956. [-Wdocumentation]
llvm-svn: 240727
2015-06-25 23:38:44 +00:00
Kit Barton 13894c7f35 [PPC] Implement vmrgew and vmrgow instructions
This patch adds support for the vector merge even word and vector merge odd word
instructions introduced in POWER8.

Phabricator review: http://reviews.llvm.org/D10704

llvm-svn: 240650
2015-06-25 15:17:40 +00:00
Alexander Kornienko f00654e31b Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC)
Apparently, the style needs to be agreed upon first.

llvm-svn: 240390
2015-06-23 09:49:53 +00:00
Alexander Kornienko 70bc5f1398 Fixed/added namespace ending comments using clang-tidy. NFC
The patch is generated using this command:

tools/clang/tools/extra/clang-tidy/tool/run-clang-tidy.py -fix \
  -checks=-*,llvm-namespace-comment -header-filter='llvm/.*|clang/.*' \
  llvm/lib/


Thanks to Eugene Kosov for the original patch!

llvm-svn: 240137
2015-06-19 15:57:42 +00:00
Matt Arsenault bd7d80a4a6 Add address space argument to isLegalAddressingMode
This is important because of different addressing modes
depending on the address space for GPU targets.

This only adds the argument, and does not update
any of the uses to provide the correct address space.

llvm-svn: 238723
2015-06-01 05:31:59 +00:00
Kit Barton 6646033e6e This patch adds support for the vector quadword add/sub instructions introduced
in POWER8:

vadduqm
vaddeuqm
vaddcuq
vaddecuq
vsubuqm
vsubeuqm
vsubcuq
vsubecuq
In addition to adding the instructions themselves, it also adds support for the
v1i128 type for intrinsics (Intrinsics.td, Function.cpp, and
IntrinsicEmitter.cpp).

http://reviews.llvm.org/D9081

llvm-svn: 238144
2015-05-25 15:49:26 +00:00
Bill Schmidt e26236eed9 [PPC64] Add support for clrbhrb, mfbhrbe, rfebb.
This patch adds support for the ISA 2.07 additions involving the
branch history rolling buffer and event-based branching.  These will
not be used by typical applications, so built-in support is not
required.  They will only be available via inline assembly.

Assembly/disassembly tests are included in the patch.

llvm-svn: 238032
2015-05-22 16:44:10 +00:00
Bill Schmidt e13ac91c5d [PPC64] Handle vpkudum mask pattern correctly when vpkudum isn't available
My recent patch to add support for ISA 2.07 vector pack/unpack
instructions didn't properly check for availability of the vpkudum
instruction when recognizing it as a special vector shuffle case.
This causes us to leave the vector shuffle in place (rather than
converting it to a vector permute) so that it can be recognized later
as a vpkudum, but that pattern is invalid for processors prior to
POWER8.  Thus LLVM crashes with an "unable to select" message.  We
observed this since one of our buildbots is configured to generate
code for a POWER7.

This patch fixes the problem by checking for availability of the
vpkudum instruction during custom lowering of vector shuffles.

I've added a test case variant for the vpkudum pattern when the
instruction isn't available.

llvm-svn: 237952
2015-05-21 20:48:49 +00:00
David Blaikie ff6409d096 Simplify IRBuilder::CreateCall* by using ArrayRef+initializer_list/braced init only
llvm-svn: 237624
2015-05-18 22:13:54 +00:00
Bill Schmidt 5ed84cdba8 [PPC64] Add vector pack/unpack support from ISA 2.07
This patch adds support for the following new instructions in the
Power ISA 2.07:

  vpksdss
  vpksdus
  vpkudus
  vpkudum
  vupkhsw
  vupklsw

These instructions are available through the vec_packs, vec_packsu,
vec_unpackh, and vec_unpackl built-in interfaces.  These are
lane-sensitive instructions, so the built-ins have different
implementations for big- and little-endian, and the instructions must
be marked as killing the vector swap optimization for now.

The first three instructions perform saturating pack operations.  The
fourth performs a modulo pack operation, which means it can be
represented with a vector shuffle, and conversely the appropriate
vector shuffles may cause this instruction to be generated.  The other
instructions are only generated via built-in support for now.

Appropriate tests have been added.

There is a companion patch to clang for the rest of this support.

llvm-svn: 237499
2015-05-16 01:02:12 +00:00
Arnold Schwaighofer dc2711446e Fix compile error
llvm-svn: 236921
2015-05-09 00:10:25 +00:00
Arnold Schwaighofer f54b73d681 ScheduleDAGInstrs: In functions with tail calls PseudoSourceValues are not non-aliasing distinct objects
The code that builds the dependence graph assumes that two PseudoSourceValues
don't alias. In a tail calling function two FixedStackObjects might refer to the
same location. Worse 'immutable' fixed stack objects like function arguments are
not immutable and will be clobbered.

Change this so that a load from a FixedStackObject is not invariant in a tail
calling function and don't return a PseudoSourceValue for an instruction in tail
calling functions when building the dependence graph so that we handle function
arguments conservatively.

Fix for PR23459.

rdar://20740035

llvm-svn: 236916
2015-05-08 23:52:00 +00:00
Matthias Braun d04893fa36 Change getTargetNodeName() to produce compiler warnings for missing cases, fix them
llvm-svn: 236775
2015-05-07 21:33:59 +00:00
Nemanja Ivanovic f3c94b1e3c Add VSX Scalar loads and stores to the PPC back end
This patch corresponds to review:
http://reviews.llvm.org/D9440

It adds a new register class to the PPC back end to contain single precision
values in VSX registers. Additionally, it adds scalar loads and stores for
VSX registers.

llvm-svn: 236755
2015-05-07 18:24:05 +00:00
Kit Barton d4eb73c00e This patch adds ABI support for v1i128 data type.
It adds v1i128 to the appropriate register classes and checks parameter passing
and return values.

This is related to http://reviews.llvm.org/D9081, which will add instructions
that exploit the v1i128 datatype.

Phabricator review: http://reviews.llvm.org/D9475

llvm-svn: 236503
2015-05-05 16:10:44 +00:00
Sergey Dmitrouk 842a51bad8 Reapply r235977 "[DebugInfo] Add debug locations to constant SD nodes"
[DebugInfo] Add debug locations to constant SD nodes

This adds debug location to constant nodes of Selection DAG and updates
all places that create constants to pass debug locations
(see PR13269).

Can't guarantee that all locations are correct, but in a lot of cases choice
is obvious, so most of them should be. At least all tests pass.

Tests for these changes do not cover everything, instead just check it for
SDNodes, ARM and AArch64 where it's easy to get incorrect locations on
constants.

This is not complete fix as FastISel contains workaround for wrong debug
locations, which drops locations from instructions on processing constants,
but there isn't currently a way to use debug locations from constants there
as llvm::Constant doesn't cache it (yet). Although this is a bit different
issue, not directly related to these changes.

Differential Revision: http://reviews.llvm.org/D9084

llvm-svn: 235989
2015-04-28 14:05:47 +00:00
Daniel Jasper 48e93f7181 Revert "[DebugInfo] Add debug locations to constant SD nodes"
This breaks a test:
http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/23870

llvm-svn: 235987
2015-04-28 13:38:35 +00:00
Sergey Dmitrouk adb4c69d5c [DebugInfo] Add debug locations to constant SD nodes
This adds debug location to constant nodes of Selection DAG and updates
all places that create constants to pass debug locations
(see PR13269).

Can't guarantee that all locations are correct, but in a lot of cases choice
is obvious, so most of them should be. At least all tests pass.

Tests for these changes do not cover everything, instead just check it for
SDNodes, ARM and AArch64 where it's easy to get incorrect locations on
constants.

This is not complete fix as FastISel contains workaround for wrong debug
locations, which drops locations from instructions on processing constants,
but there isn't currently a way to use debug locations from constants there
as llvm::Constant doesn't cache it (yet). Although this is a bit different
issue, not directly related to these changes.

Differential Revision: http://reviews.llvm.org/D9084

llvm-svn: 235977
2015-04-28 11:56:37 +00:00
Krzysztof Parzyszek a46c36b8f4 Allow memory intrinsics to be tail calls
llvm-svn: 234764
2015-04-13 17:16:45 +00:00
Nemanja Ivanovic c38b5311cb Add direct moves to/from VSR and exploit them for FP/INT conversions
This patch corresponds to review:
http://reviews.llvm.org/D8928

It adds direct move instructions to/from VSX registers to GPR's. These are
exploited for FP <-> INT conversions.

llvm-svn: 234682
2015-04-11 10:40:42 +00:00
Hal Finkel 93138503ae [PowerPC] Don't crash on PPC32 i64 fp_to_uint on modern cores
When we have an instruction for this (and, thus, don't generate a runtime
call), we need to custom type legalize this (in a trivial way, just as we do
for fp_to_sint).

Fixes PR23173.

llvm-svn: 234561
2015-04-10 03:39:00 +00:00
Bill Schmidt 91dd765a04 [PowerPC] Enable splat generation for BUILD_VECTOR with little endian
When enabling PPC64LE, I disabled some optimizations of BUILD_VECTOR
nodes for little endian because wrong results were produced.  I've
subsequently investigated and found this is due to a call to
BuildVectorSDNode::isConstantSplat that was always specifying
big-endian.  With this changed to correctly identify the target
endianness, the optimizations work as expected.

I found another case of a call to the same method with big-endian
hardcoded, in PPC::isAllNegativeZeroVector().  I discovered this was
an orphaned method with no callers, so I've just removed it.

The existing test/CodeGen/PowerPC/vec_constants.ll checks these
optimizations, so for testing I've just added a variant for little
endian.

llvm-svn: 234011
2015-04-03 13:48:24 +00:00