Commit Graph

10534 Commits

Author SHA1 Message Date
Chandler Carruth
477f28c48d [x86] Fix PR20540 where the x86 shuffle DAG combiner had completely
broken logic for merging shuffle masks in the face of SM_SentinelZero
mask operands.

While these are '-1' they don't mean 'undef' the way '-1' means in the
pre-legalized shuffle masks. Instead, they mean that the shuffle
operation is forcibly zeroing that lane. Reflect this and explicitly
handle it in a bunch of places. In one place the effect is equivalent
but much more clear. In the rest it was really weirdly broken.

Also, rewrite the entire merging thing to be a more directy operation
with a single loop and just doing math to map the indices through the
various masks.

Also add a bunch of asserts to try to make in extremely clear what the
different masks can possibly look like.

Finally, add some comments to clarify that we're merging shuffle masks
*up* here rather than *down* as we do everywhere else, and thus the
logic is quite confusing.

Thanks to several different people for sending test cases, and for
Robert Khasanov for an initial attempt at fixing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215687 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-15 02:43:18 +00:00
Juergen Ributzka
6398a7f5fd Revert several FastISel commits to track down a buildbot error.
This reverts:
r215595 "[FastISel][X86] Add large code model support for materializing floating-point constants."
r215594 "[FastISel][X86] Use XOR to materialize the "0" value."
r215593 "[FastISel][X86] Emit more efficient instructions for integer constant materialization."
r215591 "[FastISel][AArch64] Make use of the zero register when possible."
r215588 "[FastISel] Let the target decide first if it wants to materialize a constant."
r215582 "[FastISel][AArch64] Cleanup constant materialization code. NFCI."

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215673 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 19:56:28 +00:00
Duncan P. N. Exon Smith
3f8f30fcee Fix whitespace error from r215279, NFC
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215667 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 17:18:26 +00:00
Adam Nemet
90eb948fc9 [AVX512] Switch FMA intrinsics to the masking version
This does the renaming and updates the lowering logic.

Part of <rdar://problem/17688758>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215664 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 17:13:30 +00:00
Adam Nemet
b27f7ac2d7 [X86] Break out logic to map FMA Intrinsic number to Opcode
No functional change.  Will be used to lower AVX512 masking FMA intrinsics.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215663 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 17:13:27 +00:00
Adam Nemet
e9565b2d72 [AVX512] Add enum for the static rounding types
No functional change.  This will be used by the new FMA intrinsic lowering
code.

We can probably add NO_EXC here as well, I am just not too familiar with this
part of AVX512 yet.  We can add that later.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215662 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 17:13:26 +00:00
Adam Nemet
6360552890 [AVX512] Break out the logic to lower masking intrinsics
No functional change.  This will be used by the FMA intrinsic lowering as well
and hopefully many more.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215661 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 17:13:24 +00:00
Adam Nemet
265d201e19 [AVX512] Add masking variant for the FMA instructions
This change further evolves the base class AVX512_masking in order to make it
suitable for the masking variants of the FMA instructions.

Besides AVX512_masking there is now a new base class that instructions
including FMAs can use: AVX512_masking_3src.  With three-source (destructive)
instructions one of the sources is already tied to the destination.  This
difference from AVX512_masking is captured by this new class.  The common bits
between _masking and _masking_3src are broken out into a new super class
called AVX512_masking_common.

As with valign, there is some corresponding restructuring of the underlying
format classes.  The idea is the same we want to derive from two classes
essentially: one providing the format bits and another format-independent
multiclass supplying the various masking and non-masking instruction variants.

Existing fma tests in avx512-fma*.ll provide coverage here for the non-masking
variants.  For masking, the next patches in the series will add intrinsics and
intrinsic tests.

For AVX512_masking_3src to work, the (ins ...) dag has to be passed *without*
the leading source operand that is tied to dst ($src1).  This is necessary to
properly construct the (ins ...) for the different variants.  For the record,
I did check that if $src is mistakenly included, you do get a fairly intuitive
error message from the tablegen backend.

Part of <rdar://problem/17688758>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215660 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 17:13:19 +00:00
Chandler Carruth
cad1711154 [x86] Begin stubbing out the AVX support in the new vector shuffle
lowering scheme.

Currently, this just directly bails to the fallback path of splitting
the 256-bit vector into two 128-bit vectors, operating there, and then
joining the results back together. While the results are far from
perfect, they are *shockingly* good for what we're doing here. I'll be
layering the rest of the functionality on top of this piece by piece and
updating tests as I go.

Note that 256-bit vectors in this mode are still somewhat WIP. While
I think the code paths that I'm adding here are clean and good-to-go,
there are still a lot of 128-bit assumptions that I'll need to stomp out
as I march through the functional spread here.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215637 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-14 12:13:59 +00:00
Quentin Colombet
b2b79cd485 [X86] Fix the value of the low mask for the lowering of MUL_LOHI for v4i32.
Found by code inspection.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215604 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 23:49:24 +00:00
Juergen Ributzka
b677a877c8 [FastISel][X86] Add large code model support for materializing floating-point constants.
In the large code model for X86 floating-point constants are placed in the
constant pool and materialized by loading from it. Since the constant pool
could be far away, a PC relative load might not work. Therefore we first
materialize the address of the constant pool with a movabsq and then load
from there the floating-point value.

Fixes <rdar://problem/17674628>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215595 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:25:35 +00:00
Juergen Ributzka
0701e5d43b [FastISel][X86] Use XOR to materialize the "0" value.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215594 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:22:17 +00:00
Juergen Ributzka
f245d9aa77 [FastISel][X86] Emit more efficient instructions for integer constant materialization.
This mostly affects the i64 value type, which always resulted in an 15byte
mobavsq instruction to materialize any constant. The custom code checks the
value of the immediate and tries to use a different and smaller mov
instruction when possible.

This fixes <rdar://problem/17420988>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215593 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:18:11 +00:00
Juergen Ributzka
a0c81f0639 [FastISel][X86] Refactor constant materialization. NFCI.
Split the constant materialization code into three separate helper functions for
Integer-, Floating-Point-, and GlobalValue-Constants.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215586 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 22:01:55 +00:00
Benjamin Kramer
00e08fcaa0 Canonicalize header guards into a common format.
Add header guards to files that were missing guards. Remove #endif comments
as they don't seem common in LLVM (we can easily add them back if we decide
they're useful)

Changes made by clang-tidy with minor tweaks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215558 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 16:26:38 +00:00
Aaron Ballman
8b77c00bbf Silence a -Wparenthesis warning with these asserts. NFC.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215537 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 10:49:07 +00:00
Robert Khasanov
232202439a [SKX] Extended non-temporal load/store instructions for AVX512VL subsets.
Added avx512_movnt_vl multiclass for handling 256/128-bit forms of instruction.
Added encoding and lowering tests.

Reviewed by Elena Demikhovsky <elena.demikhovsky@intel.com>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215536 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 10:46:00 +00:00
Elena Demikhovsky
4c97c1420b AVX-512: Fixed a bug in shufflevector lowering.
PALIGNR instruction does not exist in AVX-512F set.
Added a test.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215526 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 07:58:43 +00:00
Chandler Carruth
6bb093bbe7 [x86] Rewrite a core part of the new vector shuffle lowering to handle
one pesky test case correctly.

This test case caused the old code to infloop occilating between solving
the low-half and the high-half. The 'side balancing' part of
single-input v8 shuffle lowering didn't handle the one pattern which can
cause it to occilate. Fortunately the fuzz testing found this case.
Unfortuately it was *terrible* to handle. I'm really sorry for the
amount and density of the code here, I'd love suggestions on how to
simplify it. I feel like there *must* be a simpler form here, but after
a lot of days I've not found it. This is the only one I've found that
even works. I've added the one pesky test case along with some nice
comments explaining the core problem that we have to solve here.

So far this has survived approximately 32k test cases. More strenuous
fuzzing commencing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215519 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-13 01:25:45 +00:00
Adam Nemet
6ea7f36872 [AVX512] Handle valign masking intrinsic via C++ lowering
I think that this will scale better in most cases than adding a Pat<> for each
mapping from the intrinsic DAG to the intruction (i.e. rri, rrik, rrikz).  We
can just lower to the SDNode and have the resulting DAG be matches by the DAG
patterns.

Alternatively (long term), we could keep the Pat<>s but generate them via the
new AVX512_masking multiclass.  The difficulty is that in order to formulate
that we would have to concatenate DAGs.  Currently this is only supported if
the operators of the input DAGs are identical.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215473 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-12 21:13:12 +00:00
Sanjay Patel
01c6ad07d2 fixed typos
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215451 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-12 16:00:06 +00:00
Elena Demikhovsky
e659e17483 AVX-512: added a missing bitcast from v16f32 to v16i32
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215351 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-11 09:59:08 +00:00
Hans Wennborg
edcf61a55c Increase the size of these SmallVectors in X86ISelLowering.cpp.
In a Clang bootstrap, their sizes were always 12, 16 and 16, respectively.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215336 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-11 02:21:22 +00:00
Sanjay Patel
21327ec3e9 fixed typos
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215299 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-09 22:23:02 +00:00
Eric Christopher
a617b53aa8 Initialize X86 DataLayout based on the Triple only.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215279 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-09 04:38:53 +00:00
Eric Christopher
d0ba0f6dd1 Move some X86 subtarget configuration onto the subtarget that's being
created.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215271 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-09 01:07:25 +00:00
Rui Ueyama
72260fe2b4 [FastISel][X86] Silence -Wenum-compare warning
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215253 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-08 22:47:49 +00:00
Juergen Ributzka
0980ef248e [FastISel][X86] Fix INC/DEC optimization (r215230)
I accidentally also used INC/DEC for unsigned arithmetic which doesn't work,
because INC/DEC don't set the required flag which is used for the overflow
check.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215237 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-08 18:47:04 +00:00
Juergen Ributzka
cbda4b32c6 [FastISel][X86] Use INC/DEC when possible for {sadd|ssub}.with.overflow intrinsics.
This is a small peephole optimization to emit INC/DEC when possible.

Fixes <rdar://problem/17952308>.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215230 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-08 17:21:37 +00:00
Patrik Hagglund
cf403861a3 [pr19635] Revert most of r170537, and add new testcase.
Patch provided by Andrey Kuharev.

Sorry, r170537 was obviously wrong.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215190 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-08 08:21:19 +00:00
Adam Nemet
a8e1cda622 [AVX512] Add zero-masking variant to AVX512_masking multiclass
This completes one item from the todo-list of r215125 "Generate masking
instruction variants with tablegen".

The AddedComplexity is needed just like for the k variant.

Added a codegen test based on valignq.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215173 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 23:53:38 +00:00
Adam Nemet
690499ed49 [AVX512] Add codegen test for the masking variant of valign
The AddedComplexity is needed just like in avx512_perm_3src.  There may be a
bug in the complexity computation...

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215168 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 23:18:18 +00:00
Eric Christopher
aa5b9c0f6f Temporarily Revert "Nuke the old JIT." as it's not quite ready to
be deleted. This will be reapplied as soon as possible and before
the 3.6 branch date at any rate.

Approved by Jim Grosbach, Lang Hames, Rafael Espindola.

This reverts commits r215111, 215115, 215116, 215117, 215136.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215154 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 22:02:54 +00:00
Adam Nemet
c10cecfe69 [AVX512] Generate masking instruction variants with tablegen
After adding the masking variants to several instructions, I have decided to
experiment with generating these from the non-masking/unconditional
variant. This will hopefully reduce the amount repetition that we currently
have in order to define an instruction with all its variants (for a reg/mem
instruction this would be 6 instruction defs and 2 Pat<> for the intrinsic).

The patch is the first cut that is currently only applied to valignd/q to make
the patch small.

A few notes on the approach:

  * In order to stitch together the dag for both the conditional and the
  unconditional patterns I pass the RHS of the set rather than the full
  pattern (set dest, RHS).
  * Rather than subclassing each instruction base class (e.g. AVX512AIi8),
  with a masking variant which wouldn't scale, I derived the masking
  instructions from a new base class AVX512 (this is just I<> with
  Requires<HasAVX512>).  The instructions derive from this now, plus a new set
  of classes that add the format bits and everything else that instruction
  base class provided (i.e. AVX512AIi8 vs. AVX512AIi8Base).

I hope we can go incrementally from here.  I expect that:

  * We will need different variants of the masking class.  One example is
  instructions requiring three vector sources.  In this case we tie one of the
  source operands to dest rather than a new implicit source operand ($src0)
  * Add the zero-masking variant
  * Add more AVX512*Base classes as new uses are added

I've looked at X86.td.expanded before and after to make sure that nothing got
lost for valignd/q.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215125 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 17:53:55 +00:00
Rafael Espindola
875710a2fd Nuke the old JIT.
I am sure we will be finding bits and pieces of dead code for years to
come, but this is a good start.

Thanks to Lang Hames for making MCJIT a good replacement!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215111 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 14:21:18 +00:00
Alexander Kornienko
2ca1dd1381 Insert parens to avoid a warning:
suggest parentheses around arithmetic in operand of '^' [-Wparentheses]


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215101 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 12:09:34 +00:00
Pavel Chupin
28e06347c9 Fix lld-x86_64-win7 Build #11969
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215097 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 11:09:59 +00:00
Chandler Carruth
0e89fbb120 [x86] Fix another miscompile found through fuzz testing the new vector
shuffle lowering.

This is closely related to the previous one. Here we failed to use the
source offset when swapping in the other case -- where we end up
swapping the *final* shuffle. The cause of this bug is a bit different:
I simply wasn't thinking about the fact that this mask is actually
a slice of a wide mask and thus has numbers that need SourceOffset
applied. Simple fix. Would be even more simple with an algorithm-y thing
to use here, but correctness first. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215095 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 10:37:35 +00:00
Chandler Carruth
0651861b7b [x86] Fix another miscompile in the new vector shuffle lowering found
via the fuzz tester.

Here I missed an offset when round-tripping a value through a shuffle
mask. I got it right 2 lines below. See a problem? I do. ;] I'll
probably be adding a little "swap" algorithm which accepts a range and
two values and swaps those values where they occur in the range. Don't
really have a name for it, let me know if you do.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215094 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 10:14:27 +00:00
Chandler Carruth
b3364512fc [x86] Fix another miscompile in the new vector shuffle lowering found
through the new fuzzer.

This one is great: bad operator precedence led the modulus to happen at
the wrong point. All the asserts didn't fire because there were usually
the right values past the end of the 4 element region we were looking
at. Probably could have gotten a crash here with ASan + fuzzing, but the
correctness tests pinpointed this really nicely.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215092 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 09:45:02 +00:00
Pavel Chupin
5d8c984e54 [x32] Use ebp/esp as frame and stack pointer
Summary:
Since pointers are 32-bit on x32 we can use ebp and esp as frame and stack
pointer. Some operations like PUSH/POP and CFI_INSTRUCTION still
require 64-bit register, so using 64-bit MachineFramePtr where required.

X86_64 NaCl uses 64-bit frame/stack pointers, however it's been found that
both isTarget64BitLP64 and isTarget64BitILP32 are true for NaCl. Addressing
this issue here as well by making isTarget64BitLP64 false.

Also mark hasReservedSpillSlot unreachable on X86. See inlined comments.

Test Plan: Add one new simple test and upgrade 2 existing with x32 target case.

Reviewers: nadav, dschuff

Subscribers: llvm-commits, zinovy.nis

Differential Revision: http://reviews.llvm.org/D4617

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215091 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 09:41:19 +00:00
Chandler Carruth
15d82b7d33 [x86] Fix a miscompile in the new shuffle lowering found through the new
fuzz testing.

The function which tested for adjacency did what it said on the tin, but
when I called it, I wanted it to do something more thorough: I wanted to
know if the *pairs* of shuffle elements were adjacent and started at
0 mod 2. In one place I had the decency to try to test for this, but in
the other it was completely skipped, miscompiling this test case. Fix
this by making the helper actually do what I wanted it to do everywhere
I called it (and removing the now redundant code in one place).

I *really* dislike the name "canWidenShuffleElements" for this
predicate. If anyone can come up with a better name, please let me know.
The other name I thought about was "canWidenShuffleMask" but is it
really widening the mask to reduce the number of lanes shuffled? I don't
know. Naming things is hard.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215089 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 08:11:31 +00:00
Saleem Abdulrasool
7cc1de1090 MC: split Win64EHUnwindEmitter into a shared streamer
This changes Win64EHEmitter into a utility WinEH UnwindEmitter that can be
shared across multiple architectures and a target specific bit which is
overridden (Win64::UnwindEmitter).  This enables sharing the section selection
code across X86 and the intended use in ARM for emitting unwind information for
Windows on ARM.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215050 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 02:59:41 +00:00
Quentin Colombet
15c8452584 [X86][SchedModel] Fixed missing/wrong scheduling model found by code inspection.
Source: Agner Fog's Instruction tables.

Related to <rdar://problem/15607571>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215045 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-07 00:20:44 +00:00
Reid Kleckner
41d6599bb1 MC X86: Accept ".att_syntax prefix" and diagnose noprefix
Fixes PR18916.  I don't think we need to implement support for either
hybrid syntax.  Nobody should write Intel assembly with '%' prefixes on
their registers or AT&T assembly without them.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215031 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 23:21:13 +00:00
Sanjay Patel
e15fd3d953 fix typo
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214995 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 21:08:38 +00:00
Eric Christopher
41612a9b85 Remove the target machine from CCState. Previously it was only used
to get the subtarget and that's accessible from the MachineFunction
now. This helps clear the way for smaller changes where we getting
a subtarget will require passing in a MachineFunction/Function as
well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214988 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 18:45:26 +00:00
Robert Khasanov
ec4188bad7 [AVX512] Added load/store instructions to Register2Memory opcode tables.
Added lowering tests for load/store.

Reviewed by Elena Demikhovsky <elena.demikhovsky@intel.com>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214972 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 15:40:34 +00:00
Chandler Carruth
a341a8070a [x86] Fix two independent miscompiles in the process of getting the same
test case to actually generate correct code.

The primary miscompile fixed here is that we weren't correctly handling
in-place elements in one half of a single-input v8i16 shuffle when
moving a dword of elements from that half to the other half. Some times,
we would clobber the in-place elements in forming the dword to move
across halves.

The fix to this involves forcibly marking the in-place inputs even when
there is no need to gather them into a dword, and to much more carefully
re-arrange the elements when grouping them into a dword to move across
halves. With these two changes we would generate correct shuffles for
the test case, but found another miscompile. There are also some random
perturbations of the generated shuffle pattern in SSE2. It looks like
a wash; more instructions in some cases fewer in others.

The second miscompile would corrupt the results into nonsense. This is
a buggy pattern in one of the added DAG combines. Mapping elements
through a PSHUFD when pairing redundant half-shuffles is *much* harder
than this code makes it out to be -- it requires reasoning about *all*
of where the input is used in the PSHUFD, not just one part of where it
is used. Plus, we can't combine a half shuffle *into* a PSHUFD but the
code didn't guard against it. I think this was just a bad idea and I've
just removed that aspect of the combine. No tests regress as
a consequence so seems OK.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214954 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 10:16:36 +00:00
Chandler Carruth
346b68772b [x86] Switch to a formulation of a for loop that is much more obviously
not corrupting the mask by mutating it more times than intended. No
functionality changed (the results were non-overlapping so the old
version "worked" but was non-obvious).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@214953 91177308-0d34-0410-b5e6-96231b3b80d8
2014-08-06 10:16:33 +00:00