Commit Graph

48529 Commits

Author SHA1 Message Date
Craig Topper f014ec9b3b [X86] Fix typo in comment. NFC
llvm-svn: 338274
2018-07-30 17:34:31 +00:00
Craig Topper dd0ef801f8 Recommit r338204 "[X86] Correct the immediate cost for 'add/sub i64 %x, 0x80000000'."
This checks in a more direct way without triggering a UBSAN error.

llvm-svn: 338273
2018-07-30 17:29:57 +00:00
Thomas Preud'homme 6c1b075299 Fix uninitialized read in ARM's PrintAsmOperand
Summary:
Fix read of uninitialized RC variable in ARM's PrintAsmOperand when
hasRegClassConstraint returns false. This was causing
inline-asm-operand-implicit-cast test to fail in r338206.

Reviewers: t.p.northover, weimingz, javed.absar, chill

Reviewed By: chill

Subscribers: chill, eraman, kristof.beyls, chrib, llvm-commits

Differential Revision: https://reviews.llvm.org/D49984

llvm-svn: 338268
2018-07-30 16:45:40 +00:00
Sander de Smalen e64206a02c [AArch64][SVE] Asm: Enable instructions to be prefixed.
This patch enables instructions that are destructive on their
destination- and first source operand, to be prefixed with a
MOVPRFX instruction.

This patch also adds a variety of tests:

- positive tests for all instructions and forms that accept a
  movprfx for either or both predicated and unpredicated forms.

- negative tests for all instructions and forms that do not accept
  an unpredicated or predicated movprfx.

- negative tests for the diagnostics that get emitted when a MOVPRFX
  instruction is used incorrectly.

This is patch [2/2] in a series to add MOVPRFX instructions:
- Patch [1/2]: https://reviews.llvm.org/D49592
- Patch [2/2]: https://reviews.llvm.org/D49593

Reviewers: rengolin, SjoerdMeijer, samparker, fhahn, javed.absar

Reviewed By: SjoerdMeijer

Differential Revision: https://reviews.llvm.org/D49593

llvm-svn: 338261
2018-07-30 16:05:45 +00:00
Sander de Smalen 9b33309c87 [AArch64][SVE] Asm: Add MOVPRFX instructions.
This patch adds predicated and unpredicated MOVPRFX instructions, which
can be prepended to SVE instructions that are destructive on their first
source operand, to make them a constructive operation, e.g.

  add z1.s, p0/m, z1.s, z2.s        <=> z1 = z1 + z2

can be made constructive:

  movprfx z0, z1
  add z0.s, p0/m, z0.s, z2.s        <=> z0 = z1 + z2

The predicated MOVPRFX instruction can additionally be used to zero
inactive elements, e.g.

  movprfx z0.s, p0/z, z1.s
  add z0.s, p0/m, z0.s, z2.s

Not all instructions can be prefixed with the MOVPRFX instruction
which is why this patch also adds a mechanism to validate prefixed
instructions. The exact rules when a MOVPRFX applies is detailed in
the SVE supplement of the Architectural Reference Manual.

This is patch [1/2] in a series to add MOVPRFX instructions:
- Patch [1/2]: https://reviews.llvm.org/D49592
- Patch [2/2]: https://reviews.llvm.org/D49593

Reviewers: rengolin, SjoerdMeijer, samparker, fhahn, javed.absar

Reviewed By: SjoerdMeijer

Differential Revision: https://reviews.llvm.org/D49592

llvm-svn: 338258
2018-07-30 15:42:46 +00:00
Krzysztof Parzyszek 24fae50905 [Hexagon] Simplify A4_rcmp[n]eqi R, 0
Consider cases when register R is known to be zero/non-zero, or when it
is defined by a C2_muxii instruction.

llvm-svn: 338251
2018-07-30 14:28:02 +00:00
Matt Arsenault de496c32a4 AMDGPU: Reduce code size with fcanonicalize (fneg x)
When fcanonicalize is lowered to a mul, we can
use -1.0 for free and avoid the cost of the bigger
encoding for source modifers.

llvm-svn: 338244
2018-07-30 12:16:58 +00:00
Matt Arsenault f3c9a34def AMDGPU: Make fneg combine handle fcanonicalize
llvm-svn: 338243
2018-07-30 12:16:47 +00:00
Francis Visoiu Mistrih 7d003657de [MachineOutliner][X86] Use TAILJMPd64 instead of JMP_1 for TailCall construction
The machine verifier asserts with:

Assertion failed: (isMBB() && "Wrong MachineOperand accessor"), function getMBB, file ../include/llvm/CodeGen/MachineOperand.h, line 542.

It calls analyzeBranch which tries to call getMBB if the opcode is
JMP_1, but in this case we do:

JMP_1 @OUTLINED_FUNCTION

I believe we have to use TAILJMPd64 instead of JMP_1 since JMP_1 is used
with brtarget8.

Differential Revision: https://reviews.llvm.org/D49299

llvm-svn: 338237
2018-07-30 09:59:33 +00:00
Dean Michael Berris 927b3da6c9 Revert "[X86] Correct the immediate cost for 'add/sub i64 %x, 0x80000000'."
This reverts commit r338204.

llvm-svn: 338236
2018-07-30 09:45:09 +00:00
Nicolai Haehnle 7f0d05d532 AMDGPU: Force skip over s_sendmsg and exp instructions
Summary:
These instructions interact with hardware blocks outside the shader core,
and they can have "scalar" side effects even when EXEC = 0. We don't
want these scalar side effects to occur when all lanes want to skip
these instructions, so always add the execz skip branch instruction
for basic blocks that contain them.

Also ensure that we skip scalar stores / atomics, though we don't
code-gen those yet.

Reviewers: arsenm, rampitec

Subscribers: kzhuravl, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits

Differential Revision: https://reviews.llvm.org/D48431

Change-Id: Ieaeb58352e2789ffd64745603c14970c60819d44
llvm-svn: 338235
2018-07-30 09:23:59 +00:00
Petr Pavlu 8b6eff4e77 [ARM] Fix over-alignment in arguments that are HA of 128-bit vectors
Code in `CC_ARM_AAPCS_Custom_Aggregate()` is responsible for handling
homogeneous aggregates for `CC_ARM_AAPCS_VFP`. When an aggregate ends up
fully on stack, the function tries to pack all resulting items of the
aggregate as tightly as possible according to AAPCS.

Once the first item was laid out, the alignment used for consecutive
items was the size of one item. This logic went wrong for 128-bit
vectors because their alignment is normally only 64 bits, and so could
result in inserting unexpected padding between the first and second
element.

The patch fixes the problem by updating the alignment with the item size
only if this results in reducing it.

Differential Revision: https://reviews.llvm.org/D49720

llvm-svn: 338233
2018-07-30 08:49:30 +00:00
Dylan McKay 6bc5d5c6db [AVR] Re-enable expansion of ADDE/ADDC/SUBE/SUBC in ISel
This was disabled in r333748, which broke four tests.

In the future, these need to be updated to UADDO/ADDCARRY or
USUBO/SUBCARRY.

llvm-svn: 338212
2018-07-29 11:38:36 +00:00
Sander de Smalen ad88a99956 [AArch64][SVE] Asm: Support for WHILE(LE|LO|LS|LT) instructions.
The WHILE instructions generate a predicate that is true while the 
comparison of the first scalar operand (incremented for each predicate
element) with the second scalar operand is true and false thereafter.

  WHILELE  While incrementing signed scalar less than or equal to scalar
  WHILELO  While incrementing unsigned scalar lower than scalar
  WHILELS  While incrementing unsigned scalar lower than or same as scalar
  WHILELT  While incrementing signed scalar less than scalar

e.g.

  whilele  p0.s, x0, x1

  generates predicate p0 (for 32bit elements) by incrementing
  (signed) x0 and comparing that vector to splat(x1).

llvm-svn: 338211
2018-07-29 08:51:08 +00:00
Sander de Smalen e70ed3187c [AArch64][SVE] Asm: Instructions to perform serialized operations.
The instructions added in this patch permit active elements within
a vector to be processed sequentially without unpacking the vector.

  PFIRST      Set the first active element to true.
  PNEXT       Find next active element in predicate.
  CTERMEQ     Compare and terminate loop when equal.
  CTERMNE     Compare and terminate loop when not equal.

llvm-svn: 338210
2018-07-29 08:00:16 +00:00
Craig Topper 5daa032546 [X86] Correct the immediate cost for 'add/sub i64 %x, 0x80000000'.
X86 normally requires immediates to be a signed 32-bit value which would exclude i64 0x80000000. But for add/sub we can negate the constant and use the opposite instruction.

llvm-svn: 338204
2018-07-28 18:21:46 +00:00
Craig Topper ba208b07b6 [X86] Use alignTo and divideCeil to make some code more readable. NFC
llvm-svn: 338203
2018-07-28 18:21:45 +00:00
Sander de Smalen 5b3a289424 [AArch64][SVE] Asm: Support for PFALSE and PTEST instructions.
This patch adds PFALSE (unconditionally sets all elements of
the predicate to false) and PTEST (set the status flags for the
predicate).

llvm-svn: 338198
2018-07-28 14:18:11 +00:00
Matt Arsenault 8f9dde94b7 AMDGPU: Stop wasting argument registers with v3i32/v3f32
SelectionDAGBuilder widens v3i32/v3f32 arguments to
to v4i32/v4f32 which consume an additional register.
In addition to wasting argument space, this produces extra
instructions since now it appears the 4th vector component has
a meaningful value to most combines.

llvm-svn: 338197
2018-07-28 14:11:34 +00:00
Sander de Smalen 3878bf83dd [AArch64][SVE] Asm: Data-dependent loop predicate partitioning instructions.
This patch adds support for instructions that partition a predicate
based on data-dependent termination conditions in a loop.

  BRKA      Break after the first true condition
  BRKAS     Break after the first true condition, setting condition flags
  BRKB      Break before the first true condition
  BRKBS     Break before the first true condition, setting condition flags

  BRKPA     Break after the first true condition, propagating from the 
            previous partition
  BRKPAS    Break after the first true condition, propagating from the 
            previous partition, setting condition flags
  BRKPB     Break before the first true condition, propagating from the 
            previous partition
  BRKPBS    Break before the first true condition, propagating from the 
            previous partition, setting condition flags

  BRKN      Propagate break to next partition
  BKRNS     Propagate break to next partition, setting condition flags

llvm-svn: 338196
2018-07-28 14:04:52 +00:00
Matt Arsenault 81920b0a25 DAG: Add calling convention argument to calling convention funcs
This seems like a pretty glaring omission, and AMDGPU
wants to treat kernels differently from other calling
conventions.

llvm-svn: 338194
2018-07-28 13:25:19 +00:00
Matt Arsenault 72b0e38b26 AMDGPU: Stop trying to extend arguments for clover
This was trying to replace i8/i16 arguments with i32, which
was broken and no longer necessary.

llvm-svn: 338193
2018-07-28 12:34:25 +00:00
Wouter van Oortmerssen a90d24da1c Revert "[WebAssembly] Added default stack-only instruction mode for MC."
This reverts commit d3c9af4179eae7793d1487d652e2d4e23844555f.
(SVN revision 338164)

llvm-svn: 338176
2018-07-27 23:19:51 +00:00
Craig Topper c3e11bf3f7 [X86] Add support expanding multiplies by constant where the constant is -3/-5/-9 multplied by a power of 2.
These can be replaced with an LEA, a shift, and a negate. This seems to match what gcc and icc would do.

llvm-svn: 338174
2018-07-27 23:04:59 +00:00
Wouter van Oortmerssen a67c4137c3 [WebAssembly] Added default stack-only instruction mode for MC.
Summary:
Moved Explicit Locals pass to last.
Made that pass obligatory.
Made it convert from register to stack based instructions, and removed the registers.
Fixes to related code that was expecting register based instructions.
Added the correct testing flag to all tests, depending on what the
format they were expecting so far.
Translated one test to stack format as example: reg-stackify-stack.ll

tested:
llvm-lit -v `find test -name WebAssembly`
unittests/MC/*

Reviewers: dschuff, sunfish

Subscribers: sbc100, jgravelle-google, eraman, aheejin, llvm-commits

Differential Revision: https://reviews.llvm.org/D49160

llvm-svn: 338164
2018-07-27 20:56:43 +00:00
Jessica Paquette f90edbe3d6 Recommit "Enable MachineOutliner by default under -Oz for AArch64"
Fixed the ASAN failure from before in r338148, so recommiting.

This patch enables the MachineOutliner by default in AArch64 under -Oz.

The MachineOutliner offers around a 4.5% improvement on the current -Oz code
size improvements.

We have done work into improving the debuggability of outlined code, so that
users of -Oz won't be surprised by the optimization. We have also been executing
the LLVM test suite and common external tests such as the SPEC suites
continuously with no issue. The outliner has a low compile-time overhead of
roughly 1%. At this point, the outliner would be a really good addition to the
-Oz pass pipeline!

llvm-svn: 338160
2018-07-27 20:18:27 +00:00
Jessica Paquette 9d93c6026a [MachineOutliner] Exit getOutliningCandidateInfo when we erase all candidates
There was a missing check for if a candidate list was entirely deleted. This
adds that check.

This fixes an asan failure caused by running test/CodeGen/AArch64/addsub_ext.ll
with the MachineOutliner enabled.

llvm-svn: 338148
2018-07-27 18:21:57 +00:00
Evandro Menezes fcca45f0dd [ARM] Add new target feature to fuse literal generation
This feature enables the fusion of such operations on Cortex A57 and Cortex
A72, as recommended in their Software Optimisation Guides, sections 4.14 and
4.11, respectively.

Differential revision: https://reviews.llvm.org/D49563

llvm-svn: 338147
2018-07-27 18:16:47 +00:00
Jessica Paquette faea2d3130 Revert "Enable MachineOutliner by default under -Oz for AArch64"
It failed an Asan test on a bot:

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/21543/steps/check-llvm%20asan/logs/stdio

Fixing that before recommitting.

llvm-svn: 338136
2018-07-27 17:25:38 +00:00
Yonghong Song 04ccfda075 bpf: add missing RegState to notify MachineInstr verifier necessary register usage
Errors like the following are reported by:

  https://urldefense.proofpoint.com/v2/url?u=http-3A__lab.llvm.org-3A8011_builders_llvm-2Dclang-2Dx86-5F64-2Dexpensive-2Dchecks-2Dwin_builds_11261&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=DA8e1B5r073vIqRrFz7MRA&m=929oWPCf7Bf2qQnir4GBtowB8ZAlIRWsAdTfRkDaK-g&s=9k-wbEUVpUm474hhzsmAO29VXVvbxJPWD9RTgCD71fQ&e=

  *** Bad machine code: Explicit definition marked as use ***
  - function:    cal_align1
  - basic block: %bb.0 entry (0x47edd98)
  - instruction: LDB $r3, $r2, 0
  - operand 0:   $r3

This is because RegState info was missing for ScratchReg inside
expandMEMCPY. This caused incomplete register usage information to
MachineInstr verifier which then would complain as there could be potential
code-gen issue if the complained MachineInstr is used in place where
register usage information matters even though the memcpy expanding is not
in such case as it happens at the last stage of IR optimization pipeline.

We should always specify those register usage information which compiler
couldn't deduct automatically whenever we add a hardware register manually.

Reported-by: Builder llvm-clang-x86_64-expensive-checks-win Build #11261
Signed-off-by: Jiong Wang <jiong.wang@netronome.com>
Reviewed-by: Yonghong Song <yhs@fb.com>
llvm-svn: 338134
2018-07-27 16:58:52 +00:00
Jessica Paquette d4229b985c Enable MachineOutliner by default under -Oz for AArch64
This patch enables the MachineOutliner by default in AArch64 under -Oz.

The MachineOutliner offers around a 4.5% improvement on the current -Oz code
size improvements.

We have done work into improving the debuggability of outlined code, so that
users of -Oz won't be surprised by the optimization. We have also been executing
the LLVM test suite and common external tests such as the SPEC suites
continuously with no issue. The outliner has a low compile-time overhead of
roughly 1%. At this point, the outliner would be a really good addition to the
-Oz pass pipeline!

llvm-svn: 338133
2018-07-27 16:44:42 +00:00
Jan Vesely 6ff58ed5ca AMDGPU/R600: Add MOV instructions to BFE patterns
R600 can't handle immediates for BFE, these will be eliminated later.
Fixes powr/pow regressions n r600 since r334817

Differential Revision: https://reviews.llvm.org/D49641

llvm-svn: 338127
2018-07-27 15:00:13 +00:00
Sander de Smalen a703b8dc71 [AArch64][SVE] Asm: Predicated integer reductions.
This patch adds support for various integer reduction operations:

  SADDV    signed add reduction to scalar
  UADDV    unsigned add reduction to scalar

  SMAXV    signed maximum reduction to scalar
  SMINV    signed minimum reduction to scalar
  UMAXV    unsigned maximum reduction to scalar
  UMINV    unsigned minimum reduction to scalar

  ANDV     logical AND reduction to scalar
  ORV      logical OR reduction to scalar
  EORV     logical EOR reduction to scalar

The reduction is predicated, e.g.
  smaxv s0, p0, z1.s

performs a signed maximum reduction on active elements in z1,
and stores the (signed max value) result in s0.

llvm-svn: 338126
2018-07-27 14:24:55 +00:00
Sander de Smalen fcb636d222 [AArch64][SVE] Asm: Predicated floating point reductions.
This patch adds support for various floating-point
reduction operations:

  FADDA    strictly-ordered add reduction, accumulating in scalar
  FADDV    recursive add reduction to scalar
  FMAXV    recursive max reduction to scalar
  FMINV    recursive min reduction to scalar
  FMAXNMV  recursive max number reduction to scalar
  FMINNMV  recursive min number reduction to scalar

The reduction is predicated, e.g.

  fadda d0, p0, d0, z1.d

performs the add-reduction in strict order on active elements
in z1, accumulating into d0.

  faddv d0, p0, z1.d

performs the add-reduction (not in strict order)
on active elements in z1, storing the result in d0.

llvm-svn: 338123
2018-07-27 13:58:48 +00:00
Sander de Smalen 88e154ff90 [AArch64][SVE] Asm: Support for FEXPA and FTSSEL.
This patch adds support for transcendental acceleration
instructions 'FEXPA' (exponential accelerator) and 'FTSSEL'
(trigonometric select coefficient).

llvm-svn: 338121
2018-07-27 12:40:09 +00:00
Sander de Smalen 71929e7cad [AArch64][SVE] Asm: Support for FRECPE and FRSQRTE.
Support for floating-point instructions for reciprocal
estimate (FRECPE) and reciprocal square root estimate (FRSQRTE).

llvm-svn: 338120
2018-07-27 12:26:24 +00:00
Matt Arsenault 0183c56c11 AMDGPU: Fix code size for return_to_epilog pseudo
llvm-svn: 338113
2018-07-27 09:15:03 +00:00
Tom Stellard e9bdc5f1d8 AMDGPU/GlobalISel: Fix crash in regbankselect on non-power-of-2 types
Reviewers: arsenm

Reviewed By: arsenm

Subscribers: kzhuravl, wdng, nhaehnle, yaxunl, rovka, kristof.beyls, dstuttard, tpr, llvm-commits, t-tye

Differential Revision: https://reviews.llvm.org/D49624

llvm-svn: 338102
2018-07-27 06:04:40 +00:00
Craig Topper 561e298e29 [X86] Remove an unnecessary 'if' that prevented treating INT64_MAX and -INT64_MAX as power of 2 minus 1 in the multiply expansion code.
Not sure why they were being explicitly excluded, but I believe all the math inside the if works. I changed the absolute value to be uint64_t instead of int64_t so INT64_MIN+1 wouldn't be signed wrap.

llvm-svn: 338101
2018-07-27 05:56:27 +00:00
Craig Topper e364baa88b [X86] Add matching for another pattern of PMADDWD.
Summary:
This is the pattern you get from the loop vectorizer for something like this

int16_t A[1024];
int16_t B[1024];
int32_t C[512];

void pmaddwd() {
  for (int i = 0; i != 512; ++i)
    C[i] = (A[2*i]*B[2*i]) + (A[2*i+1]*B[2*i+1]);
}

In this case we will have (add (mul (build_vector), (build_vector)), (mul (build_vector), (build_vector))). This is different than the pattern we currently match which has the build_vectors between an add and a single multiply. I'm not sure what C code would get you that pattern.

Reviewers: RKSimon, spatel, zvi

Reviewed By: zvi

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D49636

llvm-svn: 338097
2018-07-27 04:29:10 +00:00
Craig Topper f7bc550223 [X86] When removing sign extends from gather/scatter indices, make sure we handle UpdateNodeOperands finding an existing node to CSE with.
If this happens the operands aren't updated and the existing node is returned. Make sure we pass this existing node up to the DAG combiner so that a proper replacement happens. Otherwise we get stuck in an infinite loop with an unoptimized node.

llvm-svn: 338090
2018-07-27 00:00:30 +00:00
Scott Linder eb1f75d561 [AMDGPU] Fix VGPR spills where offset doesn't fit in 12 bits
Scale the offset of VGPR spills by the wave size when it cannot fit in the
12-bit offset immediate field and so is added to the soffset SGPR. This
accounts for hardware swizzling of scratch memory.

Differential Revision: https://reviews.llvm.org/D49448

llvm-svn: 338060
2018-07-26 19:47:51 +00:00
Ana Pazos 2e4106b73d [RISCV] Add support for _interrupt attribute
- Save/restore only registers that are used.
This includes Callee saved registers and Caller saved registers
(arguments and temporaries) for integer and FP registers.
- If there is a call in the interrupt handler, save/restore all
Caller saved registers (arguments and temporaries) and all FP registers.
- Emit special return instructions depending on "interrupt"
attribute type.
Based on initial patch by Zhaoshi Zheng.

Reviewers: asb

Reviewed By: asb

Subscribers: rkruppe, the_o, MartinMosbeck, brucehoult, rbar, johnrusso, simoncook, sabuasal, niosHD, kito-cheng, shiva0217, zzheng, edward-jones, mgrang, rogfer01, llvm-commits

Differential Revision: https://reviews.llvm.org/D48411

llvm-svn: 338047
2018-07-26 17:49:43 +00:00
Alexey Bataev 4dd7558fab [DEBUGINFO, NVPTX] Emit correct debug information for local variables.
Summary:
NVPTX target dos not use register-based frame information. Instead it
relies on the artificial local_depot that is used instead of the frame
and the data for variables must be emitted relatively to this
local_depot.

Reviewers: tra, jlebar, echristo

Subscribers: jholewinski, aprantl, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D45963

llvm-svn: 338039
2018-07-26 16:29:52 +00:00
Luke Cheeseman 66b5e7da4c Enable some pointer authentication instructions for aarch64 v8a targets
- Some of the v8.3 pointer authentication instruction inhabit the Hint space
- These instructions can be assembled to hint instructions which act as NOP instructions prior to v8.3
- This patch permits using the hint instructions for all v8a targets
- Also, correct the RETA{A,B} instructions to match the instruction attributes of RET (set isTerminator and isBarrier)

Differential Revision: https://reviews.llvm.org/D49786

llvm-svn: 338029
2018-07-26 14:00:50 +00:00
Stefan Maksimovic 4a612d4bf2 [mips] Sign extend i32 return values on MIPS64
Override getTypeForExtReturn so that functions returning
an i32 typed value have it sign extended on MIPS64.

Also provide patterns to get rid of unneeded sign extensions
for arithmetic instructions which implicitly sign extend
their results.

Differential Revision: https://reviews.llvm.org/D48374

llvm-svn: 338019
2018-07-26 10:59:35 +00:00
Chandler Carruth 1387159b93 [x86/SLH] Extract the logic to trace predicate state through calls to
a helper function with a nice overview comment. NFC.

This is a preperatory refactoring to implementing another component of
mitigation here that was descibed in the design document but hadn't been
implemented yet.

llvm-svn: 338016
2018-07-26 09:42:57 +00:00
Sjoerd Meijer dc198344ce [AArch64] Armv8.2-A: add the crypto extensions
This adds MC support for the crypto instructions that were made optional
extensions in Armv8.2-A (AArch64 only).

Differential Revision: https://reviews.llvm.org/D49370

llvm-svn: 338010
2018-07-26 07:13:59 +00:00
Craig Topper 4e687d5bb2 [X86] Don't use CombineTo to skip adding new nodes to the DAGCombiner worklist in combineMul.
I'm not sure if this was trying to avoid optimizing the new nodes further or what. Or maybe to prevent a cycle if something tried to reform the multiply? But I don't think its a reliable way to do that. If the user of the expanded multiply is visited by the DAGCombiner after this conversion happens, the DAGCombiner will check its operands, see that they haven't been visited by the DAGCombiner before and it will then add the first node to the worklist. This process will repeat until all the new nodes are visited.

So this seems like an unreliable prevention at best. So this patch just returns the new nodes like any other combine. If this starts causing problems we can try to add target specific nodes or something to more directly prevent optimizations.

Now that we handle the combine normally, we can combine any negates the mul expansion creates into their users since those will be visited now.

llvm-svn: 338007
2018-07-26 05:40:10 +00:00
Craig Topper 370bdd3a0f [X86] Remove some unnecessary explicit calls to DCI.AddToWorkList.
These calls were making sure some newly created nodes were added to worklist, but the DAGCombiner has internal support for ensuring it has visited all nodes. Any time it visits a node it ensures the operands have been queued to be visited as well. This means if we only need to return the last new node. The DAGCombiner will take care of adding its inputs thus walking backwards through all the new nodes.

llvm-svn: 337996
2018-07-26 03:20:27 +00:00