59 Commits

Author SHA1 Message Date
Craig Topper
3c4e635593 [X86] Always emit an integer vbroadcast_load from lowerBuildVectorAsBroadcast regardless of AVX vs AVX2
If we go with D75412, we no longer depend on the scalar type directly. So we don't need to avoid using i64. We already have AVX1 fallback patterns with i32 and i64 scalar types so we don't need to avoid using integer types on AVX1.

Differential Revision: https://reviews.llvm.org/D75413
2020-03-03 10:39:11 -08:00
Simon Pilgrim
e3bd011890 [X86][SSE] Combine combineLogicBlendIntoConditionalNegate for VSELECT nodes (PR43660)
Attempt to use combineLogicBlendIntoConditionalNegate for (select M, (sub 0, X), X) -> (sub (xor X, M), M)

We limit this to cases that can't easily replace the VSELECT with a shuffle (non-constant masks) or where a BLENDV is likely to occur (which tends to result in slower codegen).
2020-01-05 18:50:44 +00:00
Craig Topper
8b5f2ab2a4 Recommit r367901 "[X86] Enable -x86-experimental-vector-widening-legalization by default."
The assert that caused this to be reverted should be fixed now.

Original commit message:

This patch changes our defualt legalization behavior for 16, 32, and
64 bit vectors with i8/i16/i32/i64 scalar types from promotion to
widening. For example, v8i8 will now be widened to v16i8 instead of
promoted to v8i16. This keeps the elements widths the same and pads
with undef elements. We believe this is a better legalization strategy.
But it carries some issues due to the fragmented vector ISA. For
example, i8 shifts and multiplies get widened and then later have
to be promoted/split into vXi16 vectors.

This has the potential to cause regressions so we wanted to get
it in early in the 10.0 cycle so we have plenty of time to
address them.

Next steps will be to merge tests that explicitly test the command
line option. And then we can remove the option and its associated
code.

llvm-svn: 368183
2019-08-07 16:24:26 +00:00
Mitch Phillips
bd0d97e1c4 Revert "[X86] Enable -x86-experimental-vector-widening-legalization by default."
This reverts commit 3de33245d2c992c9e0af60372043540b60f3a810.

This commit broke the MSan buildbots. See
https://reviews.llvm.org/rL367901 for more information.

llvm-svn: 368107
2019-08-06 23:00:43 +00:00
Craig Topper
3de33245d2 [X86] Enable -x86-experimental-vector-widening-legalization by default.
This patch changes our defualt legalization behavior for 16, 32, and
64 bit vectors with i8/i16/i32/i64 scalar types from promotion to
widening. For example, v8i8 will now be widened to v16i8 instead of
promoted to v8i16. This keeps the elements widths the same and pads
with undef elements. We believe this is a better legalization strategy.
But it carries some issues due to the fragmented vector ISA. For
example, i8 shifts and multiplies get widened and then later have
to be promoted/split into vXi16 vectors.

This has the potential to cause regressions so we wanted to get
it in early in the 10.0 cycle so we have plenty of time to
address them.

Next steps will be to merge tests that explicitly test the command
line option. And then we can remove the option and its associated
code.

llvm-svn: 367901
2019-08-05 18:25:36 +00:00
Craig Topper
1deca50ab1 [X86] Allow execution domain fixing to turn SHUFPD into SHUFPS.
This can help with code size on SSE targets where SHUFPD requires
a 0x66 prefix and SHUFPS doesn't.

llvm-svn: 365293
2019-07-08 06:52:49 +00:00
Craig Topper
d8261f0288 [X86] Make movsd commutable to shufpd with a 0x02 immediate on pre-SSE4.1 targets.
This can help avoid a copy or enable load folding.

On SSE4.1 targets we can commute it to blendi instead.

I had to make shufpd with a 0x02 immediate commutable as well
since we expect commuting to be reversible.

llvm-svn: 365292
2019-07-08 06:52:43 +00:00
Craig Topper
06aea1720a [X86] Move promotion of vector and/or/xor from legalization to DAG combine
Summary:
I've noticed that the bitcasts we introduce for these make computeKnownBits and computeNumSignBits not work well in LegalizeVectorOps. LegalizeVectorOps legalizes bottom up while LegalizeDAG legalizes top down. The bottom up strategy for LegalizeVectorOps means operands are legalized before their uses. So we promote and/or/xor before we legalize the operands that use them making computeKnownBits/computeNumSignBits in places like LowerTruncate suboptimal. I looked at changing LegalizeVectorOps to be top down as well, but that was more disruptive and caused some regressions. I also looked at just moving promotion of binops to LegalizeDAG, but that had a few issues one around matching AND,ANDN,OR into VSELECT because I had to create ANDN as vXi64, but the other nodes hadn't legalized yet, I didn't look too hard at fixing that.

This patch seems to produce better results overall than my other attempts. We now form broadcasts of constants better in some cases. For at least some of them the AND was being introduced in LegalizeDAG, promoted to vXi64, and the BUILD_VECTOR was also legalized there. I think we got bad ordering of that. Now the promotion is out of the legalizer so we handle this better.

In the longer term I think we really should evaluate whether we should be doing this promotion at all. It's really there to reduce isel pattern count, but I'm wondering if we'd be better served just eating the pattern cost or doing C++ based isel for vector and/or/xor in X86ISelDAGToDAG. The masked and/or/xor will definitely be difficult in patterns if a bitcast gets between the vselect and the and/or/xor node. That becomes a lot of permutations to cover.

Reviewers: RKSimon, spatel

Reviewed By: RKSimon

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D53107

llvm-svn: 344487
2018-10-15 01:51:58 +00:00
Simon Pilgrim
2d0f20cc04 [X86] Handle COPYs of physregs better (regalloc hints)
Enable enableMultipleCopyHints() on X86.

Original Patch by @jonpa:

While enabling the mischeduler for SystemZ, it was discovered that for some reason a test needed one extra seemingly needless COPY (test/CodeGen/SystemZ/call-03.ll). The handling for that is resulted in this patch, which improves the register coalescing by providing not just one copy hint, but a sorted list of copy hints. On SystemZ, this gives ~12500 less register moves on SPEC, as well as marginally less spilling.

Instead of improving just the SystemZ backend, the improvement has been implemented in common-code (calculateSpillWeightAndHint(). This gives a lot of test failures, but since this should be a general improvement I hope that the involved targets will help and review the test updates.

Differential Revision: https://reviews.llvm.org/D38128

llvm-svn: 342578
2018-09-19 18:59:08 +00:00
Geoff Berry
a2b9011290 Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"
Re-enable commit r323991 now that r325931 has been committed to make
MachineOperand::isRenamable() check more conservative w.r.t. code
changes and opt-in on a per-target basis.

llvm-svn: 326208
2018-02-27 16:59:10 +00:00
Quentin Colombet
48abac82b8 Revert "[MachineCopyPropagation] Extend pass to do COPY source forwarding"
This reverts commit r323991.

This commit breaks target that don't model all the register constraints
in TableGen. So far the workaround was to set the
hasExtraXXXRegAllocReq, but it proves that it doesn't cover all the
cases.
For instance, when mutating an instruction (like in the lowering of
COPYs) the isRenamable flag is not properly updated. The same problem
will happen when attaching machine operand from one instruction to
another.

Geoff Berry is working on a fix in https://reviews.llvm.org/D43042.

llvm-svn: 325421
2018-02-17 03:05:33 +00:00
Craig Topper
0bcdd399e7 [X86] Turn selects with constant condition into vector shuffles during DAG combine
Summary:
Currently we convert to shuffles during lowering. This moves it to DAG combine so hopefully we can get it done before type legalization has to extend the condition.

I believe in some cases we're creating SHRUNKBLENDs that end up with constant conditions because we see the extended on the condition and think its a dynamic selelect before DAG combine gets a chance to constant fold the extend. We could add combines to turn SHRUNKBLENDs with constant condition back to vselect. But it seemed like it might be better to just send them to shuffles as early as possible so they never get a chance to become SHRUNKBLENDs. This the reason some tests went from blends controlled by a constant pool load to just move.

Some of the constant pool entries changed because the sign_extend introduced by type legalization turned undef elements in select condition into 0s. While the select->shuffle used -1 in the shuffle mask. So now the shuffle lowering can do what it wants with them.

I'll remove the lowering code as a follow up. We might be able to simplify some of the pre-checks for SHRUNKBLEND as the FIXME there says.

Reviewers: spatel, RKSimon, efriedma, zvi, andreadb

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D43367

llvm-svn: 325417
2018-02-17 00:30:30 +00:00
Geoff Berry
94503c7bc3 [MachineCopyPropagation] Extend pass to do COPY source forwarding
Summary:
This change extends MachineCopyPropagation to do COPY source forwarding
and adds an additional run of the pass to the default pass pipeline just
after register allocation.

This version of this patch uses the newly added
MachineOperand::isRenamable bit to avoid forwarding registers is such a
way as to violate constraints that aren't captured in the
Machine IR (e.g. ABI or ISA constraints).

This change is a continuation of the work started in D30751.

Reviewers: qcolombet, javed.absar, MatzeB, jonpa, tstellar

Subscribers: tpr, mgorny, mcrosier, nhaehnle, nemanjai, jyknight, hfinkel, arsenm, inouehrs, eraman, sdardis, guyblank, fedor.sergeev, aheejin, dschuff, jfb, myatsina, llvm-commits

Differential Revision: https://reviews.llvm.org/D41835

llvm-svn: 323991
2018-02-01 18:54:01 +00:00
Simon Pilgrim
940eae3cc1 [X86][SSE] Add custom execution domain fixing for BLENDPD/BLENDPS/PBLENDD/PBLENDW (PR34873)
Add support for custom execution domain fixing and implement support for BLENDPD/BLENDPS/PBLENDD/PBLENDW.

Differential Revision: https://reviews.llvm.org/D42042

llvm-svn: 322524
2018-01-15 22:18:45 +00:00
Francis Visoiu Mistrih
25528d6de7 [CodeGen] Unify MBB reference format in both MIR and debug output
As part of the unification of the debug format and the MIR format, print
MBB references as '%bb.5'.

The MIR printer prints the IR name of a MBB only for block definitions.

* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)->getNumber\(\)/" << printMBBReference(*\1)/g'
* find . \( -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#" << ([a-zA-Z0-9_]+)\.getNumber\(\)/" << printMBBReference(\1)/g'
* find . \( -name "*.txt" -o -name "*.s" -o -name "*.mir" -o -name "*.cpp" -o -name "*.h" -o -name "*.ll" \) -type f -print0 | xargs -0 sed -i '' -E 's/BB#([0-9]+)/%bb.\1/g'
* grep -nr 'BB#' and fix

Differential Revision: https://reviews.llvm.org/D40422

llvm-svn: 319665
2017-12-04 17:18:51 +00:00
Craig Topper
6fb55716e9 [X86] Redefine MOVSS/MOVSD instructions to take VR128 regclass as input instead of FR32/FR64
This patch redefines the MOVSS/MOVSD instructions to take VR128 as its second input. This allows the MOVSS/SD->BLEND commute to work without requiring a COPY to be inserted.

This should fix PR33079

Overall this looks to be an improvement in the generated code. I haven't checked the EXPENSIVE_CHECKS build but I'll do that and update with results.

Differential Revision: https://reviews.llvm.org/D38449

llvm-svn: 314914
2017-10-04 17:20:12 +00:00
Geoff Berry
fabedbad11 Revert "Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding""
This reverts commit r314729.

Another bug has been encountered in an out-of-tree target reported by Quentin.

llvm-svn: 314814
2017-10-03 16:59:13 +00:00
Geoff Berry
bfc5fb4571 Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"
Issues addressed since original review:
- Avoid bug in regalloc greedy/machine verifier when forwarding to use
  in an instruction that re-defines the same virtual register.
- Fixed bug when forwarding to use in EarlyClobber instruction slot.
- Fixed incorrect forwarding to register definitions that showed up in
  explicit_uses() iterator (e.g. in INLINEASM).
- Moved removal of dead instructions found by
  LiveIntervals::shrinkToUses() outside of loop iterating over
  instructions to avoid instructions being deleted while pointed to by
  iterator.
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
  doing so can break code that implicitly relies on the physical
  register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
  can break the machine verifier by creating LiveRanges that don't
  end on a use (since the undef operand is not considered a use).

  [MachineCopyPropagation] Extend pass to do COPY source forwarding

  This change extends MachineCopyPropagation to do COPY source forwarding.

  This change also extends the MachineCopyPropagation pass to be able to
  be run during register allocation, after physical registers have been
  assigned, but before the virtual registers have been re-written, which
  allows it to remove virtual register COPY LiveIntervals that become dead
  through the forwarding of all of their uses.

llvm-svn: 314729
2017-10-02 22:01:37 +00:00
Craig Topper
5bc10ede53 [SelectionDAG] Teach simplifyDemandedBits to handle shifts by constant splat vectors
This teach simplifyDemandedBits to handle constant splat vector shifts.

This required changing some uses of getZExtValue to getLimitedValue since we can't rely on legalization using getShiftAmountTy for the shift amount.

I believe there may have been a bug in the ((X << C1) >>u ShAmt) handling where we didn't check if the inner shift was too large. I've fixed that here.

I had to add new patterns to ARM because the zext/sext the patterns were trying to look for got turned into an any_extend with this patch. Happy to split that out too, but not sure how to test without this change.

Differential Revision: https://reviews.llvm.org/D37665

llvm-svn: 314139
2017-09-25 19:26:08 +00:00
Sam McCall
f71bb198ed Revert "Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding""
This crashes on boringSSL on PPC (will send reduced testcase)

This reverts commit r312328.

llvm-svn: 312490
2017-09-04 15:47:00 +00:00
Craig Topper
fa82efb50a [X86] Add VBLENDPS/VPBLENDD to the execution domain fixing tables.
llvm-svn: 312449
2017-09-03 17:52:23 +00:00
Geoff Berry
65528f2991 Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"
Issues addressed since original review:
- Moved removal of dead instructions found by
  LiveIntervals::shrinkToUses() outside of loop iterating over
  instructions to avoid instructions being deleted while pointed to by
  iterator.
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
  doing so can break code that implicitly relies on the physical
  register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
  can break the machine verifier by creating LiveRanges that don't
  end on a use (since the undef operand is not considered a use).

  [MachineCopyPropagation] Extend pass to do COPY source forwarding

  This change extends MachineCopyPropagation to do COPY source forwarding.

  This change also extends the MachineCopyPropagation pass to be able to
  be run during register allocation, after physical registers have been
  assigned, but before the virtual registers have been re-written, which
  allows it to remove virtual register COPY LiveIntervals that become dead
  through the forwarding of all of their uses.

llvm-svn: 312328
2017-09-01 14:27:20 +00:00
Hans Wennborg
24775a0a6c Revert r312154 "Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding""
It caused PR34387: Assertion failed: (RegNo < NumRegs && "Attempting to access record for invalid register number!")

> Issues identified by buildbots addressed since original review:
> - Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
> - The pass no longer forwards COPYs to physical register uses, since
>   doing so can break code that implicitly relies on the physical
>   register number of the use.
> - The pass no longer forwards COPYs to undef uses, since doing so
>   can break the machine verifier by creating LiveRanges that don't
>   end on a use (since the undef operand is not considered a use).
>
>   [MachineCopyPropagation] Extend pass to do COPY source forwarding
>
>   This change extends MachineCopyPropagation to do COPY source forwarding.
>
>   This change also extends the MachineCopyPropagation pass to be able to
>   be run during register allocation, after physical registers have been
>   assigned, but before the virtual registers have been re-written, which
>   allows it to remove virtual register COPY LiveIntervals that become dead
>   through the forwarding of all of their uses.

llvm-svn: 312178
2017-08-30 22:11:37 +00:00
Geoff Berry
feffb0c8af Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"
Issues identified by buildbots addressed since original review:
- Fixed ARMLoadStoreOptimizer bug exposed by this change in r311907.
- The pass no longer forwards COPYs to physical register uses, since
  doing so can break code that implicitly relies on the physical
  register number of the use.
- The pass no longer forwards COPYs to undef uses, since doing so
  can break the machine verifier by creating LiveRanges that don't
  end on a use (since the undef operand is not considered a use).

  [MachineCopyPropagation] Extend pass to do COPY source forwarding

  This change extends MachineCopyPropagation to do COPY source forwarding.

  This change also extends the MachineCopyPropagation pass to be able to
  be run during register allocation, after physical registers have been
  assigned, but before the virtual registers have been re-written, which
  allows it to remove virtual register COPY LiveIntervals that become dead
  through the forwarding of all of their uses.

llvm-svn: 312154
2017-08-30 18:41:07 +00:00
Geoff Berry
bd47e8a4f7 Revert "[MachineCopyPropagation] Extend pass to do COPY source forwarding" round 2
This reverts commit r311135.

sanitizer-x86_64-linux-android buildbot is timing out with just this
patch applied.

llvm-svn: 311142
2017-08-18 01:43:11 +00:00
Geoff Berry
51f52c4fca Re-enable "[MachineCopyPropagation] Extend pass to do COPY source forwarding"
Two issues identified by buildbots were addressed:
    - The pass no longer forwards COPYs to physical register uses, since
      doing so can break code that implicitly relies on the physical
      register number of the use.
    - The pass no longer forwards COPYs to undef uses, since doing so
      can break the machine verifier by creating LiveRanges that don't
      end on a use (since the undef operand is not considered a use).

    [MachineCopyPropagation] Extend pass to do COPY source forwarding

    This change extends MachineCopyPropagation to do COPY source forwarding.

    This change also extends the MachineCopyPropagation pass to be able to
    be run during register allocation, after physical registers have been
    assigned, but before the virtual registers have been re-written, which
    allows it to remove virtual register COPY LiveIntervals that become dead
    through the forwarding of all of their uses.

    Reviewers: qcolombet, javed.absar, MatzeB, jonpa

    Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny

    Differential Revision: https://reviews.llvm.org/D30751

llvm-svn: 311135
2017-08-17 23:06:55 +00:00
Geoff Berry
4e38e02e6f Revert "[MachineCopyPropagation] Extend pass to do COPY source forwarding"
This reverts commit r311038.

Several buildbots are breaking, and at least one appears to be due to
the forwarding of physical regs enabled by this change.  Reverting while
I investigate further.

llvm-svn: 311062
2017-08-17 04:04:11 +00:00
Geoff Berry
87f8d25150 [MachineCopyPropagation] Extend pass to do COPY source forwarding
This change extends MachineCopyPropagation to do COPY source forwarding.

This change also extends the MachineCopyPropagation pass to be able to
be run during register allocation, after physical registers have been
assigned, but before the virtual registers have been re-written, which
allows it to remove virtual register COPY LiveIntervals that become dead
through the forwarding of all of their uses.

Reviewers: qcolombet, javed.absar, MatzeB, jonpa

Subscribers: jyknight, nemanjai, llvm-commits, nhaehnle, mcrosier, mgorny

Differential Revision: https://reviews.llvm.org/D30751

llvm-svn: 311038
2017-08-16 20:50:01 +00:00
Simon Pilgrim
e74e08fe61 [X86][SSE] Dropped -mcpu from vector blend shuffle tests and regenerate
Use triple and attribute only for consistency 

llvm-svn: 305909
2017-06-21 13:45:33 +00:00
Dehao Chen
6b737ddce7 Add LiveRangeShrink pass to shrink live range within BB.
Summary: LiveRangeShrink pass moves instruction right after the definition with the same BB if the instruction and its operands all have more than one use. This pass is inexpensive and guarantees optimal live-range within BB.

Reviewers: davidxl, wmi, hfinkel, MatzeB, andreadb

Reviewed By: MatzeB, andreadb

Subscribers: hiraditya, jyknight, sanjoy, skatkov, gberry, jholewinski, qcolombet, javed.absar, krytarowski, atrick, spatel, RKSimon, andreadb, MatzeB, mehdi_amini, mgorny, efriedma, davide, dberlin, llvm-commits

Differential Revision: https://reviews.llvm.org/D32563

llvm-svn: 304371
2017-05-31 23:25:25 +00:00
Hans Wennborg
b00ffd8cb7 Revert r302938 "Add LiveRangeShrink pass to shrink live range within BB."
This also reverts follow-ups r303292 and r303298.

It broke some Chromium tests under MSan, and apparently also internal
tests at Google.

llvm-svn: 303369
2017-05-18 18:50:05 +00:00
Dehao Chen
65dd23e273 Add LiveRangeShrink pass to shrink live range within BB.
Summary: LiveRangeShrink pass moves instruction right after the definition with the same BB if the instruction and its operands all have more than one use. This pass is inexpensive and guarantees optimal live-range within BB.

Reviewers: davidxl, wmi, hfinkel, MatzeB, andreadb

Reviewed By: MatzeB, andreadb

Subscribers: hiraditya, jyknight, sanjoy, skatkov, gberry, jholewinski, qcolombet, javed.absar, krytarowski, atrick, spatel, RKSimon, andreadb, MatzeB, mehdi_amini, mgorny, efriedma, davide, dberlin, llvm-commits

Differential Revision: https://reviews.llvm.org/D32563

llvm-svn: 302938
2017-05-12 19:29:27 +00:00
Craig Topper
d7ae9ab1fa [X86] Fix printing of blendvpd/blendvps/pblendvb to include the implicit %xmm0 argument. This makes codegen output more obvious about the %xmm0 usage.
llvm-svn: 294131
2017-02-05 18:33:24 +00:00
Simon Pilgrim
e3e6585c2d [SelectionDAG] Update ComputeNumSignBits SRA/SHL handlers to accept scalar or vector splats
Use isConstOrConstSplat helper.

Also use APInt instead of getZExtValue directly to avoid out of range issues.

llvm-svn: 285033
2016-10-24 21:47:19 +00:00
Simon Pilgrim
ae17cf20ce [X86][SSE] Always combine target shuffles to MOVSD/MOVSS
Now we can commute to BLENDPD/BLENDPS on SSE41+ targets if necessary, so simplify the combine matching where we can.

This required me to add a couple of scalar math movsd/moss fold patterns that hadn't been needed in the past.

llvm-svn: 283038
2016-10-01 15:33:01 +00:00
Michael Kuperstein
ac2088d122 [X86] Remove transformVSELECTtoBlendVECTOR_SHUFFLE
The new X86 shuffle lowering can do just fine without transforming vselects
into vector_shuffles. It looks like the only thing this code does right now
is cause trouble - in particular, it can lead to combine/legalization infinite
loops.

Note that it's not completely NFC, since some of the shuffle masks get inverted,
which may cause slight differences further down the line. We may want to find
a way to invert those masks, but that's orthogonal to this commit.

This fixes the hang in PR27689.

llvm-svn: 269676
2016-05-16 18:27:00 +00:00
Kevin B. Smith
3802c4af59 [X86]: Fix for PR27251.
Differential Revision: http://reviews.llvm.org/D18850

llvm-svn: 265690
2016-04-07 16:15:34 +00:00
Simon Pilgrim
c5b5dcb985 [X86][AVX] Support bit-blend integer shuffles for 256-bit integer vectors
AVX1 doesn't support the shuffling of 256-bit integer vectors. For 32/64-bit elements we get around this by shuffling as float/double but for 8/16-bit elements (assuming they can't widen) we currently just split, shuffle as 128-bit vectors and concatenate the results back.

This patch adds the ability to lower using the bit-blend patterns before defaulting to the splitting behaviour.

Part 2 of 2

Differential Revision: http://reviews.llvm.org/D17292

llvm-svn: 261082
2016-02-17 10:50:06 +00:00
Ahmed Bougacha
af60a429c9 [X86] Generalize logic blend of (x, -x) combine to match (-x, x).
I suspect this is what let PR26110 lie dormant for so long.

llvm-svn: 261024
2016-02-16 22:14:07 +00:00
Ahmed Bougacha
132fbf5476 [X86] Don't turn (c?-v:v) into (c?-v:0) by blindly using PSIGN.
Currently, we sometimes miscompile this vector pattern:
    (c ? -v : v)
We lower it to (because "c" is <4 x i1>, lowered as a vector mask):
    (~c & v) | (c & -v)

When we have SSSE3, we incorrectly lower that to PSIGN, which does:
    (c < 0 ? -v : c > 0 ? v : 0)
in other words, when c is either all-ones or all-zero:
    (c ? -v : 0)
While this is an old bug, it rarely triggers because the PSIGN combine
is too sensitive to operand order. This will be improved separately.

Note that the PSIGN tests are also incorrect. Consider:
    %b.lobit = ashr <4 x i32> %b, <i32 31, i32 31, i32 31, i32 31>
    %sub = sub nsw <4 x i32> zeroinitializer, %a
    %0 = xor <4 x i32> %b.lobit, <i32 -1, i32 -1, i32 -1, i32 -1>
    %1 = and <4 x i32> %a, %0
    %2 = and <4 x i32> %b.lobit, %sub
    %cond = or <4 x i32> %1, %2
    ret <4 x i32> %cond
if %b is zero:
    %b.lobit = <4 x i32> zeroinitializer
    %sub = sub nsw <4 x i32> zeroinitializer, %a
    %0 = <4 x i32> <i32 -1, i32 -1, i32 -1, i32 -1>
    %1 = <4 x i32> %a
    %2 = <4 x i32> zeroinitializer
    %cond = or <4 x i32> %a, zeroinitializer
    ret <4 x i32> %a
whereas we currently generate:
    psignd %xmm1, %xmm0
    retq
which returns 0, as %xmm1 is 0.

Instead, use a pure logic sequence, as described in:
https://graphics.stanford.edu/~seander/bithacks.html#ConditionalNegate

Fixes PR26110.

Differential Revision: http://reviews.llvm.org/D17181

llvm-svn: 261023
2016-02-16 22:14:03 +00:00
Ahmed Bougacha
a87c3480b5 [X86] Extract PSIGN/BLENDVP tests into vector-blend.ll. NFC.
We're going to stop generating PSIGN, so calling a test "psign"
isn't ideal. Instead, call these tests what they really are:
variable blends using logic.
Also add a test to exhibit a case we're currently missing in
the PSIGN combine.

llvm-svn: 261022
2016-02-16 22:13:59 +00:00
Simon Pilgrim
f3c37cc87e Regenerate vector blend tests.
llvm-svn: 259406
2016-02-01 21:06:32 +00:00
Michael Kuperstein
04e79329d0 [X86] Fix wrong treatment of multi-lane blends in BUILD_VECTORtoBlendMask()
This fixes two separate bugs:
1) The mask for the high lane was not set correctly. That fixes PR24532.
2) The transformation should bail out if it believes it involves more than
2 lanes, as it does not currently do anything sensible in this case.

Differential Revision: http://reviews.llvm.org/D13505

llvm-svn: 249669
2015-10-08 08:13:02 +00:00
Chandler Carruth
d2b14b296c [x86] Make the new vector shuffle legality test on by default, which
reflects the fact that the x86 backend can in fact lower any shuffle you
want it to with reasonably high code quality.

My recent work on the new vector shuffle has made this regress *very*
little. The diff in the test cases makes me very, very happy.

llvm-svn: 229958
2015-02-20 03:05:47 +00:00
Chandler Carruth
8817e5e01b [x86] Remove the insanely over-aggressive unpack lowering strategy for
v16i8 shuffles, and replace it with new facilities.

This uses precise patterns to match exact unpacks, and the new
generalized unpack lowering only when we detect a case where we will
have to shuffle both inputs anyways and they terminate in exactly
a blend.

This fixes all of the blend horrors that I uncovered by always lowering
blends through the vector shuffle lowering. It also removes *sooooo*
much of the crazy instruction sequences required for v16i8 lowering
previously. Much cleaner now.

The only "meh" aspect is that we sometimes use pshufb+pshufb+unpck when
it would be marginally nicer to use pshufb+pshufb+por. However, the
difference there is *tiny*. In many cases its a win because we re-use
the pshufb mask. In others, we get to avoid the pshufb entirely. I've
left a FIXME, but I'm dubious we can really do better than this. I'm
actually pretty happy with this lowering now.

For SSE2 this exposes some horrors that were really already there. Those
will have to fixed by changing a different path through the v16i8
lowering.

llvm-svn: 229846
2015-02-19 12:10:37 +00:00
Chandler Carruth
bcb6c5f62d [x86] Add support for bit-wise blending and use it in the v8 and v16
lowering paths. I'm going to be leveraging this to simplify a lot of the
overly complex lowering of v8 and v16 shuffles in pre-SSSE3 modes.

Sadly, this isn't profitable on v4i32 and v2i64. There, the float and
double blending instructions for pre-SSE4.1 are actually pretty good,
and we can't beat them with bit math. And once SSE4.1 comes around we
have direct blending support and this ceases to be relevant.

Also, some of the test cases look odd because the domain fixer
canonicalizes these to floating point domain. That's OK, it'll use the
integer domain when it matters and some day I may be able to update
enough of LLVM to canonicalize the other way.

This restores almost all of the regressions from teaching x86's vselect
lowering to always use vector shuffle lowering for blends. The remaining
problems are because the v16 lowering path is still doing crazy things.
I'll be re-arranging that strategy in more detail in subsequent commits
to finish recovering the performance here.

llvm-svn: 229836
2015-02-19 10:46:52 +00:00
Chandler Carruth
b89464a9b6 [x86,sdag] Two interrelated changes to the x86 and sdag code.
First, don't combine bit masking into vector shuffles (even ones the
target can handle) once operation legalization has taken place. Custom
legalization of vector shuffles may exist for these patterns (making the
predicate return true) but that custom legalization may in some cases
produce the exact bit math this matches. We only really want to handle
this prior to operation legalization.

However, the x86 backend, in a fit of awesome, relied on this. What it
would do is mark VSELECTs as expand, which would turn them into
arithmetic, which this would then match back into vector shuffles, which
we would then lower properly. Amazing.

Instead, the second change is to teach the x86 backend to directly form
vector shuffles from VSELECT nodes with constant conditions, and to mark
all of the vector types we support lowering blends as shuffles as custom
VSELECT lowering. We still mark the forms which actually support
variable blends as *legal* so that the custom lowering is bypassed, and
the legal lowering can even be used by the vector shuffle legalization
(yes, i know, this is confusing. but that's how the patterns are
written).

This makes the VSELECT lowering much more sensible, and in fact should
fix a bunch of bugs with it. However, as you'll see in the test cases,
right now what it does is point out the *hilarious* deficiency of the
new vector shuffle lowering when it comes to blends. Fortunately, my
very next patch fixes that. I can't submit it yet, because that patch,
somewhat obviously, forms the exact and/or pattern that the DAG combine
is matching here! Without this patch, teaching the vector shuffle
lowering to produce the right code infloops in the DAG combiner. With
this patch alone, we produce terrible code but at least lower through
the right paths. With both patches, all the regressions here should be
fixed, and a bunch of the improvements (like using 2 shufps with no
memory loads instead of 2 andps with memory loads and an orps) will
stay. Win!

There is one other change worth noting here. We had hilariously wrong
vectorization cost estimates for vselect because we fell through to the
code path that assumed all "expand" vector operations are scalarized.
However, the "expand" lowering of VSELECT is vector bit math, most
definitely not scalarized. So now we go back to the correct if horribly
naive cost of "1" for "not scalarized". If anyone wants to add actual
modeling of shuffle costs, that would be cool, but this seems an
improvement on its own. Note the removal of 16 and 32 "costs" for doing
a blend. Even in SSE2 we can blend in fewer than 16 instructions. ;] Of
course, we don't right now because of OMG bad code, but I'm going to fix
that. Next patch. I promise.

llvm-svn: 229835
2015-02-19 10:36:19 +00:00
Michael Kuperstein
af9befa6b7 Fixes two issue in SimplifyDemandedBits of sext_in_reg:
1) We should not try to simplify if the sext has multiple uses
2) There is no need to simplify is the source value is already sign-extended.

Patch by Gil Rapaport <gil.rapaport@intel.com>

Differential Revision: http://reviews.llvm.org/D6949

llvm-svn: 229659
2015-02-18 09:43:40 +00:00
Chandler Carruth
4d31f58c88 [x86] Give movss and movsd execution domains in the x86 backend.
This associates movss and movsd with the packed single and packed double
execution domains (resp.). While this is largely cosmetic, as we now
don't have weird ping-pong-ing between single and double precision, it
is also useful because it avoids the domain fixing algorithm from seeing
domain breaks that don't actually exist. It will also be much more
important if we have an execution domain default other than packed
single, as that would cause us to mix movss and movsd with integer
vector code on a regular basis, a very bad mixture.

llvm-svn: 228135
2015-02-04 10:58:53 +00:00
Chandler Carruth
bb525e336b [x86] Mechanically update a bunch of tests' check lines using the latest
version of the script.

Changes include:
- Using the VEX prefix
- Skipping more detail when we have useful shuffle comments to match
- Matching more shuffle comments that have been added to the printer
  (yay!)
- Matching the destination registers of some AVX instructions
- Stripping trailing whitespace that crept in
- Fixing indentation issues

Nothing interesting going on here. I'm just trying really hard to ensure
these changes don't show up in the diffs with actual changes to the
backend.

llvm-svn: 228132
2015-02-04 10:46:53 +00:00