Commit Graph

2570 Commits

Author SHA1 Message Date
Simon Pilgrim 5f337149fa Use for-range loop. NFCI.
llvm-svn: 362897
2019-06-09 09:07:30 +00:00
Simon Pilgrim 6bae6d5a5d [DAGCombine] visitAND - merge (zext_inreg ((s)extload x)) -> (zextload x) combines. NFCI.
Same codegen, only differ by the oneuse limit for the sextload case.

llvm-svn: 362880
2019-06-08 17:02:00 +00:00
Simon Pilgrim f0240ee76d [DAGCombine] visitAND - fix local shadow variable warnings. NFCI.
llvm-svn: 362825
2019-06-07 18:36:43 +00:00
Simon Pilgrim 4c9db2045a [DAGCombine] Use APInt::extractBits in "sub-splat" constant mask detection. NFCI.
llvm-svn: 362820
2019-06-07 18:07:06 +00:00
Simon Pilgrim 842c7792aa [DAGCombine] MergeConsecutiveStores - improve non-temporal load\store handling (PR42123)
This patch is the first step towards ensuring MergeConsecutiveStores correctly handles non-temporal loads\stores:

1 - When merging load\stores we must ensure that they all have the same non-temporal flag. This is unlikely to occur, but can in strange cases where we're storing at the end of one page and the beginning of another.

2 - The merged load\store node must retain the non-temporal flag.

Differential Revision: https://reviews.llvm.org/D62910

llvm-svn: 362723
2019-06-06 17:04:13 +00:00
Simon Pilgrim da993d08c8 [DAGCombine] Cleanup isNegatibleForFree/GetNegatedExpression. NFCI.
Prep work for PR42105 - clang-format, use auto for cast and merge nested if()s

llvm-svn: 362695
2019-06-06 10:21:18 +00:00
Simon Pilgrim 77d6adc491 Fix shadow local variable warning. NFCI.
llvm-svn: 362622
2019-06-05 17:26:29 +00:00
Nemanja Ivanovic aed7227b71 Revert r362472 as it is breaking PPC build bots
The patch https://reviews.llvm.org/rL362472 broke PPC LNT buildbots.
Reverting it to bring the bots back to green.

llvm-svn: 362539
2019-06-04 18:48:43 +00:00
Craig Topper 09a4415803 [DAGCombiner][X86] Fold (not (neg X)) -> (add X, -1)
This is a special case of a more general transform (not (sub Y, X)) -> (add X, ~Y). InstCombine knows the general form. I've restricted to the special case to fix the motivating case PR42118. I tried handling any case where Y was constant, but got some changes on some Mips tests that I couldn't quickly prove where beneficial.

Fixes PR42118

Differential Revision: https://reviews.llvm.org/D62828

llvm-svn: 362533
2019-06-04 17:44:18 +00:00
Sanjay Patel 1e63dd0b44 [SelectionDAG][x86] limit post-legalization store merging by type
The proposal in D62498 showed that x86 would benefit from vector
store splitting, but that may conflict with the generic DAG
combiner's store merging transforms.

Add memory type to the existing TLI hook that enables the merging
transforms, so we can limit those changes to scalars only for x86.

llvm-svn: 362507
2019-06-04 15:15:59 +00:00
Roman Lebedev 3dce0326fe [DAGCombine][X86][AArch64][MIPS][LANAI] (C - x) - y -> C - (x + y) fold (PR41952)
Summary:
This *might* be the last fold for `sink-addsub-of-const.ll`, but i'm not sure yet.

As far as i can tell, there are no regressions here (ignoring x86-32),
all changes are either good or neutral.

This, almost surprisingly to me, fixes the motivational tests (in `shift-amount-mod.ll`)
`@reg32_lshr_by_sub_from_negated` from [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/vMd3

Reviewers: RKSimon, t.p.northover, craig.topper, spatel, efriedma

Reviewed By: RKSimon

Subscribers: sdardis, javed.absar, arichardson, kristof.beyls, jrtc27, atanasyan, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62774

llvm-svn: 362488
2019-06-04 11:06:21 +00:00
Roman Lebedev be6ce7b3f2 [DAGCombine][X86][AArch64][ARM] (C - x) + y -> (y - x) + C fold
Summary:
All changes except ARM look **great**.
https://rise4fun.com/Alive/R2M

The regression `test/CodeGen/ARM/addsubcarry-promotion.ll`
is recovered fully by D62392 + D62450.

Reviewers: RKSimon, craig.topper, spatel, rogfer01, efriedma

Reviewed By: efriedma

Subscribers: dmgreen, javed.absar, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62266

llvm-svn: 362487
2019-06-04 11:06:08 +00:00
Simon Pilgrim 3018d505a3 [SelectionDAG] Add fpto[us]i(undef) --> undef constant fold
Follow up to D62807.

Differential Revision: https://reviews.llvm.org/D62811

llvm-svn: 362483
2019-06-04 10:04:55 +00:00
QingShan Zhang 11de0e71b0 [DAGCombine] Match a pattern where a wide type scalar value is stored by several narrow stores
This opportunity is found from spec 2017 557.xz_r. And it is used by the sha encrypt/decrypt. See sha-2/sha512.c

static void store64(u64 x, unsigned char* y)
{
    for(int i = 0; i != 8; ++i)
        y[i] = (x >> ((7-i) * 8)) & 255;
}

static u64 load64(const unsigned char* y)
{
    u64 res = 0;
    for(int i = 0; i != 8; ++i)
        res |= (u64)(y[i]) << ((7-i) * 8);
    return res;
}
The load64 has been implemented by https://reviews.llvm.org/D26149
This patch is trying to implement the store pattern.

Match a pattern where a wide type scalar value is stored by several narrow
stores. Fold it into a single store or a BSWAP and a store if the targets
supports it.

Assuming little endian target:
i8 *p = ...
i32 val = ...
p[0] = (val >> 0) & 0xFF;
p[1] = (val >> 8) & 0xFF;
p[2] = (val >> 16) & 0xFF;
p[3] = (val >> 24) & 0xFF;

>
*((i32)p) = val;

i8 *p = ...
i32 val = ...
p[0] = (val >> 24) & 0xFF;
p[1] = (val >> 16) & 0xFF;
p[2] = (val >> 8) & 0xFF;
p[3] = (val >> 0) & 0xFF;

>
*((i32)p) = BSWAP(val);

Differential Revision: https://reviews.llvm.org/D61843

llvm-svn: 362472
2019-06-04 08:53:53 +00:00
Michael Berg 0b7f98da65 Propagate fmf for setcc/select folds
Summary: This change facilitates propagating fmf which was placed on setcc from fcmp through folds with selects so that back ends can model this path for arithmetic folds on selects in SDAG.

Reviewers: qcolombet, spatel

Reviewed By: qcolombet

Subscribers: nemanjai, jsji

Differential Revision: https://reviews.llvm.org/D62552

llvm-svn: 362439
2019-06-03 19:12:15 +00:00
Simon Pilgrim cb7e4e8193 [SelectionDAG] Add [us]itofp(undef) --> 0 constant fold (PR39205)
We were missing this fold in the DAG, which I've copied directly from llvm::ConstantFoldCastInstruction

Differential Revision: https://reviews.llvm.org/D62807

llvm-svn: 362397
2019-06-03 13:02:07 +00:00
Florian Hahn e71963c850 Recommit r360171: [DAGCombiner] Avoid creating large tokenfactors in visitTokenFactor.
If we hit the limit, we do expand the outstanding tokenfactors.
Otherwise, we might drop nodes with users in the unexpanded
tokenfactors. This fixes the crashes reported by Jordan Rupprecht.

Reviewers: niravd, spatel, craig.topper, rupprecht

Reviewed By: niravd

Differential Revision: https://reviews.llvm.org/D62633

llvm-svn: 362350
2019-06-03 01:30:19 +00:00
Craig Topper 50b35caf30 [DAGCombiner][X86] Fold away masked store and scatter with all zeroes mask.
Similar to what was done for masked load and gather.

llvm-svn: 362342
2019-06-02 22:52:38 +00:00
Craig Topper a7bc31ebc6 [DAGCombiner] Replace masked loads with a zero mask with the passthru value
Similar to what was recently done for gathers in r362015.

llvm-svn: 362337
2019-06-02 18:58:46 +00:00
Simon Pilgrim 7a869e7036 [DAGCombine] Fold insert_subvector(bitcast(x),bitcast(y),c1) -> bitcast(insert_subvector(x,y),c2)
Move this combine from x86 into generic DAGCombine, which currently only manages cases where the bitcast is between types of the same scalarsize.

Differential Revision: https://reviews.llvm.org/D59188

llvm-svn: 362324
2019-06-02 14:42:11 +00:00
Craig Topper f58ef87bb7 [DAGCombiner] Replace two unchecked dyn_casts with casts.
The results of the dyn_casts were immediately dereferenced on the next line
so they had better not be null.

I don't think there's any way for these dyn_casts to fail, so use a cast
of adding null check.

llvm-svn: 362315
2019-06-02 03:31:01 +00:00
Roman Lebedev 46511d75b5 [DAGCombine] Limit 'hoist add/sub binop w/ constant op' to non-opaque consts
I don't have a test case for these, but there is a test case for D62266
where, even after all the constant-folding patches, we still end up
with endless combine loop. Which makes sense, since we don't constant
fold for opaque constants.

llvm-svn: 362156
2019-05-30 21:10:37 +00:00
Roman Lebedev a4e3b50e26 [DAGCombiner][X86][AArch64] (x - C) + y -> (x + y) - C fold. Try 2
Summary:
Only vector tests are being affected here,
since subtraction by scalar constant is rewritten
as addition by negated constant.

No surprising test changes.

https://rise4fun.com/Alive/pbT

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs.

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62257

llvm-svn: 362146
2019-05-30 20:37:49 +00:00
Roman Lebedev 57aa36ff91 [DAGCombine] (x - C) - y -> (x - y) - C fold. Try 3
Summary:
Again only vectors affected. Frustrating. Let me take a look into that..

https://rise4fun.com/Alive/AAq

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs, and then reverted in
rL362109 to fix missing constant folds that were causing
endless combine loops.

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, JDevlieghere, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62294

llvm-svn: 362145
2019-05-30 20:37:39 +00:00
Roman Lebedev 63b4741534 [DAGCombine][X86][AArch64][AMDGPU] (x - y) + -1 -> add (xor y, -1), x fold. Try 3
Summary:
This prevents regressions in next patch,
and somewhat recovers from the regression to AMDGPU test in D62223.

It is indeed not great that we leave vector decrement,
don't transform it into vector add all-ones..

https://rise4fun.com/Alive/ZRl

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs, and then reverted in
rL362109 to fix missing constant folds that were causing
endless combine loops.

Reviewers: RKSimon, craig.topper, spatel, arsenm

Reviewed By: RKSimon, arsenm

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62263

llvm-svn: 362144
2019-05-30 20:37:29 +00:00
Roman Lebedev 05ad5fd213 [DAGCombiner][X86][AArch64][SPARC][SystemZ] y - (x + C) -> (y - x) - C fold. Try 3
Summary:
Direct sibling of D62223 patch.
While i don't have a direct motivational pattern for this,
it would seem to make sense to handle both patterns (or none),
for symmetry?

The aarch64 changes look neutral;
sparc and systemz look like improvement (one less instruction each);
x86 changes - 32bit case improves, 64bit case shows that LEA no longer
gets constructed, which may be because that whole test is `-mattr=+slow-lea,+slow-3ops-lea`

https://rise4fun.com/Alive/ffh

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs, and then reverted in
rL362109 to fix missing constant folds that were causing
endless combine loops.

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, jyknight, javed.absar, kristof.beyls, fedor.sergeev, jrtc27, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62252

llvm-svn: 362143
2019-05-30 20:37:18 +00:00
Roman Lebedev 1d9ec7a81b [DAGCombiner][X86][AArch64][AMDGPU] (x + C) - y -> (x - y) + C fold. Try 3
Summary:
The main motivation is shown by all these `neg` instructions that are now created.
In particular, the `@reg32_lshr_by_negated_unfolded_sub_b` test.

AArch64 test changes all look good (`neg` created), or neutral.

X86 changes look neutral (vectors), or good (`neg` / `xor eax, eax` created).

I'm not sure about `X86/ragreedy-hoist-spill.ll`, it looks like the spill
is now hoisted into preheader (which should still be good?),
2 4-byte reloads become 1 8-byte reload, and are elsewhere,
but i'm not sure how that affects that loop.

I'm unable to interpret AMDGPU change, looks neutral-ish?

This is hopefully a step towards solving [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/pkdq (we are missing more patterns, i'll submit them later)

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs, and then reverted in
rL362109 to fix missing constant folds that were causing
endless combine loops.

Reviewers: craig.topper, RKSimon, spatel, arsenm

Reviewed By: RKSimon

Subscribers: bjope, qcolombet, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, javed.absar, dstuttard, tpr, t-tye, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62223

llvm-svn: 362142
2019-05-30 20:36:54 +00:00
Roman Lebedev 7eb8b5b5dd [DAGCombine] ((c1-A)-c2) -> ((c1-c2)-A) constant-fold
Summary: https://rise4fun.com/Alive/B0A

Reviewers: t.p.northover, RKSimon, spatel, craig.topper

Reviewed By: RKSimon

Subscribers: javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62691

llvm-svn: 362135
2019-05-30 19:27:51 +00:00
Roman Lebedev 691b5e2ecc [DAGCombine] (A-C1)-C2 -> A-(C1+C2) constant-fold
Summary: https://rise4fun.com/Alive/Mb1M

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62689

llvm-svn: 362134
2019-05-30 19:27:42 +00:00
Roman Lebedev 0a3dbbcdfb [DAGCombine] (A+C1)-C2 -> A+(C1-C2) constant-fold
Summary:
Direct sibling of D62662, the root cause of the endless combine loop in D62257

https://rise4fun.com/Alive/d3W

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62664

llvm-svn: 362133
2019-05-30 19:27:32 +00:00
Roman Lebedev 9ff3159b4a [DAGCombine] Use FoldConstantArithmetic() to perform C2-(A+C1) -> (C2-C1)-A fold
Summary:
No tests change, and i'm not sure how to test this, but it's better safe than sorry.

Reviewers: spatel, RKSimon, craig.topper, t.p.northover

Reviewed By: craig.topper

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62663

llvm-svn: 362132
2019-05-30 19:27:26 +00:00
Roman Lebedev cc9a9cf237 [DAGCombine] ((A-c1)+c2) -> (A+(c2-c1)) constant-fold
Summary:
This was the root cause of the endless combine loop in D62257

https://rise4fun.com/Alive/d3W

Reviewers: RKSimon, spatel, craig.topper, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62662

llvm-svn: 362131
2019-05-30 19:27:19 +00:00
Roman Lebedev ef95679741 [DAGCombine] Use FoldConstantArithmetic() to perform ((c1-A)+c2) -> (c1+c2)-A fold
Summary: No tests change, and i'm not sure how to test this, but it's better safe than sorry.

Reviewers: spatel, RKSimon, craig.topper, t.p.northover

Reviewed By: craig.topper

Subscribers: llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62661

llvm-svn: 362130
2019-05-30 19:27:10 +00:00
Roman Lebedev 019d270e43 [DAGCombine] Revert of recommit of "binop-with-const hoisting" patches
I was looking into an endless combine loop the uncommitted follow-up patch
was causing, and it appears even these patches can exibit such an
endless loop. The root cause is that we try to hoist one binop (add/sub) with
constant operand, and if we get two such binops both of which are
eligible for this hoisting, we get stuck.

Some cases may highlight missing constant-folds.

Reverts r361871,r361872,r361873,r361874.

llvm-svn: 362109
2019-05-30 16:07:11 +00:00
Benjamin Kramer 107f8d9873 [DAGCombiner] Replace gathers with a zero mask with the passthru value
These can be created by the legalizer when splitting a larger gather.

See https://llvm.org/PR42055 for a motivating example.

Differential Revision: https://reviews.llvm.org/D62613

llvm-svn: 362015
2019-05-29 19:24:19 +00:00
Roman Lebedev dfc34f0211 [DAGCombine] (x - C) - y -> (x - y) - C fold. Try 2
Summary:
Again only vectors affected. Frustrating. Let me take a look into that..

https://rise4fun.com/Alive/AAq

This is a recommit, originally committed in rL361856, but reverted
to investigate test-suite compile-time hangs.

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, JDevlieghere, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62294

llvm-svn: 361874
2019-05-28 20:40:10 +00:00
Roman Lebedev d485c6bc9f [DAGCombine][X86][AArch64][AMDGPU] (x - y) + -1 -> add (xor y, -1), x fold. Try 2
Summary:
This prevents regressions in next patch,
and somewhat recovers from the regression to AMDGPU test in D62223.

It is indeed not great that we leave vector decrement,
don't transform it into vector add all-ones..

https://rise4fun.com/Alive/ZRl

This is a recommit, originally committed in rL361855, but reverted
to investigate test-suite compile-time hangs.

Reviewers: RKSimon, craig.topper, spatel, arsenm

Reviewed By: RKSimon, arsenm

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62263

llvm-svn: 361873
2019-05-28 20:40:03 +00:00
Roman Lebedev 96c9986199 [DAGCombiner][X86][AArch64][SPARC][SystemZ] y - (x + C) -> (y - x) - C fold. Try 2
Summary:
Direct sibling of D62223 patch.
While i don't have a direct motivational pattern for this,
it would seem to make sense to handle both patterns (or none),
for symmetry?

The aarch64 changes look neutral;
sparc and systemz look like improvement (one less instruction each);
x86 changes - 32bit case improves, 64bit case shows that LEA no longer
gets constructed, which may be because that whole test is `-mattr=+slow-lea,+slow-3ops-lea`

https://rise4fun.com/Alive/ffh

This is a recommit, originally committed in rL361853, but reverted
to investigate test-suite compile-time hangs.

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, jyknight, javed.absar, kristof.beyls, fedor.sergeev, jrtc27, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62252

llvm-svn: 361872
2019-05-28 20:39:55 +00:00
Roman Lebedev 2feb7e56e2 [DAGCombiner][X86][AArch64][AMDGPU] (x + C) - y -> (x - y) + C fold. Try 2
Summary:
The main motivation is shown by all these `neg` instructions that are now created.
In particular, the `@reg32_lshr_by_negated_unfolded_sub_b` test.

AArch64 test changes all look good (`neg` created), or neutral.

X86 changes look neutral (vectors), or good (`neg` / `xor eax, eax` created).

I'm not sure about `X86/ragreedy-hoist-spill.ll`, it looks like the spill
is now hoisted into preheader (which should still be good?),
2 4-byte reloads become 1 8-byte reload, and are elsewhere,
but i'm not sure how that affects that loop.

I'm unable to interpret AMDGPU change, looks neutral-ish?

This is hopefully a step towards solving [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/pkdq (we are missing more patterns, i'll submit them later)

This is a recommit, originally committed in rL361852, but reverted
to investigate test-suite compile-time hangs.

Reviewers: craig.topper, RKSimon, spatel, arsenm

Reviewed By: RKSimon

Subscribers: bjope, qcolombet, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, javed.absar, dstuttard, tpr, t-tye, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62223

llvm-svn: 361871
2019-05-28 20:39:39 +00:00
Roman Lebedev 272d70c366 Revert DAGCombine "hoist binop with const" folds
Appear to introduce test-suite compile-time hang.

http://lab.llvm.org:8011/builders/clang-cmake-x86_64-sde-avx512-linux/builds/22825

This reverts r361852,r361853,r361854,r361855,r361856

llvm-svn: 361865
2019-05-28 19:04:21 +00:00
Roman Lebedev 7669665432 [DAGCombine] (x - C) - y -> (x - y) - C fold
Summary:
Again only vectors affected. Frustrating. Let me take a look into that..

https://rise4fun.com/Alive/AAq

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, JDevlieghere, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62294

llvm-svn: 361856
2019-05-28 17:54:21 +00:00
Roman Lebedev 8c9b3e4e4a [DAGCombine][X86][AArch64][AMDGPU] (x - y) + -1 -> add (xor y, -1), x fold
Summary:
This prevents regressions in next patch,
and somewhat recovers from the regression to AMDGPU test in D62223.

It is indeed not great that we leave vector decrement,
don't transform it into vector add all-ones..

https://rise4fun.com/Alive/ZRl

Reviewers: RKSimon, craig.topper, spatel, arsenm

Reviewed By: RKSimon, arsenm

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

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62263

llvm-svn: 361855
2019-05-28 17:54:13 +00:00
Roman Lebedev 6a24c9b9ab [DAGCombiner][X86][AArch64] (x - C) + y -> (x + y) - C fold
Summary:
Only vector tests are being affected here,
since subtraction by scalar constant is rewritten
as addition by negated constant.

No surprising test changes.

https://rise4fun.com/Alive/pbT

Reviewers: RKSimon, craig.topper, spatel

Reviewed By: RKSimon

Subscribers: javed.absar, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62257

llvm-svn: 361854
2019-05-28 17:54:04 +00:00
Roman Lebedev 1499f65ac1 [DAGCombiner][X86][AArch64][SPARC][SystemZ] y - (x + C) -> (y - x) - C fold
Summary:
Direct sibling of D62223 patch.
While i don't have a direct motivational pattern for this,
it would seem to make sense to handle both patterns (or none),
for symmetry?

The aarch64 changes look neutral;
sparc and systemz look like improvement (one less instruction each);
x86 changes - 32bit case improves, 64bit case shows that LEA no longer
gets constructed, which may be because that whole test is `-mattr=+slow-lea,+slow-3ops-lea`

https://rise4fun.com/Alive/ffh

Reviewers: RKSimon, craig.topper, spatel, t.p.northover

Reviewed By: t.p.northover

Subscribers: t.p.northover, jyknight, javed.absar, kristof.beyls, fedor.sergeev, jrtc27, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62252

llvm-svn: 361853
2019-05-28 17:53:54 +00:00
Roman Lebedev 19f51ec04a [DAGCombiner][X86][AArch64][AMDGPU] (x + C) - y -> (x - y) + C fold
Summary:
The main motivation is shown by all these `neg` instructions that are now created.
In particular, the `@reg32_lshr_by_negated_unfolded_sub_b` test.

AArch64 test changes all look good (`neg` created), or neutral.

X86 changes look neutral (vectors), or good (`neg` / `xor eax, eax` created).

I'm not sure about `X86/ragreedy-hoist-spill.ll`, it looks like the spill
is now hoisted into preheader (which should still be good?),
2 4-byte reloads become 1 8-byte reload, and are elsewhere,
but i'm not sure how that affects that loop.

I'm unable to interpret AMDGPU change, looks neutral-ish?

This is hopefully a step towards solving [[ https://bugs.llvm.org/show_bug.cgi?id=41952 | PR41952 ]].

https://rise4fun.com/Alive/pkdq (we are missing more patterns, i'll submit them later)

Reviewers: craig.topper, RKSimon, spatel, arsenm

Reviewed By: RKSimon

Subscribers: bjope, qcolombet, kzhuravl, jvesely, wdng, nhaehnle, yaxunl, javed.absar, dstuttard, tpr, t-tye, kristof.beyls, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D62223

llvm-svn: 361852
2019-05-28 17:53:43 +00:00
Alexander Timofeev ba447bae74 [AMDGPU] Divergence driven ISel. Assign register class for cross block values according to the divergence.
Details: To make instruction selection really divergence driven it is necessary to assign
             the correct register classes to the cross block values beforehand. For the divergent targets
             same value type requires different register classes dependent on the value divergence.

    Reviewers: rampitec, nhaehnle

    Differential Revision: https://reviews.llvm.org/D59990

    This commit was reverted because of the build failure.
    The reason was mlformed patch.
    Build failure fixed.

llvm-svn: 361741
2019-05-26 20:33:26 +00:00
Peter Collingbourne 3b93737446 Revert r361644, "[AMDGPU] Divergence driven ISel. Assign register class for cross block values according to the divergence."
Broke sanitizer bots:
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/21694/steps/bootstrap%20clang/logs/stdio
http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-fast/builds/32478/steps/check-llvm%20asan/logs/stdio

llvm-svn: 361688
2019-05-25 01:52:38 +00:00
Alexander Timofeev dffedea014 [AMDGPU] Divergence driven ISel. Assign register class for cross block values according to the divergence.
Details: To make instruction selection really divergence driven it is necessary to assign
         the correct register classes to the cross block values beforehand. For the divergent targets
         same value type requires different register classes dependent on the value divergence.

Reviewers: rampitec, nhaehnle

Differential Revision: https://reviews.llvm.org/D59990

llvm-svn: 361644
2019-05-24 15:32:18 +00:00
Simon Pilgrim 95b8d9bbf8 [SelectionDAG] computeKnownBits - support constant pool values from target
This patch adds the overridable TargetLowering::getTargetConstantFromLoad function which allows targets to return any constant value loaded by a LoadSDNode node - only X86 makes use of this so far but everything should be in place for other targets.

computeKnownBits then uses this function to improve codegen, notably vector code after legalization.

A future commit will do the same for ComputeNumSignBits but computeKnownBits sees the bigger benefit.

This required a couple of fixes:
* SimplifyDemandedBits must early-out for getTargetConstantFromLoad cases to prevent infinite loops of constant regeneration (similar to what we already do for BUILD_VECTOR).
* Fix a DAGCombiner::visitTRUNCATE issue as we had trunc(shl(v8i32),v8i16) <-> shl(trunc(v8i16),v8i32) infinite loops after legalization on AVX512 targets.

Differential Revision: https://reviews.llvm.org/D61887

llvm-svn: 361620
2019-05-24 10:03:11 +00:00
Sanjay Patel 7d6c0bce50 [DAGCombiner] make folds of binops safe for opcodes that produce >1 value
This is no-functional-change-intended currently because the definition
of isBinOp() only includes opcodes that produce 1 value. But if we
share that implementation with isCommutativeBinOp() as proposed in
D62191, then we need to make sure that the callers bail out for
opcodes that they are not prepared to handle correctly.

llvm-svn: 361547
2019-05-23 20:17:25 +00:00