127579 Commits

Author SHA1 Message Date
Artem Belevich
463904dd22 [NVPTX] Restructure shfl instrinsics and add variants that return a predicate.
Also, amend constraints for non-sync variants that are no longer
available on sm_70+ with PTX6.4+.

Differential Revision: https://reviews.llvm.org/D68892

llvm-svn: 374790
2019-10-14 16:53:34 +00:00
Simon Pilgrim
eba5934469 BitsInit::resolveReferences - silence static analyzer null dereference warning. NFCI.
The static analyzer is warning about a potential null dereference, assert to check that the loop has set the cached pointer.

llvm-svn: 374789
2019-10-14 16:46:21 +00:00
Simon Pilgrim
55a7bae051 XCOFFObjectWriter - silence static analyzer dyn_cast<> null dereference warning. NFCI.
The static analyzer is warning about a potential null dereference, but we should be able to use cast<> directly and if not assert will fire for us.

llvm-svn: 374788
2019-10-14 16:46:11 +00:00
Simon Pilgrim
80157bd480 [CostModel][X86] Add CTLZ scalar costs
Add specific scalar costs for CTLZ instructions, we can't discriminate between CTLZ and CTLZ_ZERO_UNDEF so we have to assume the worst. Given how BSR is often a microcoded nightmare on some older targets we might still be underestimating it.

For targets supporting LZCNT (Intel Haswell+ or AMD Fam10+), we provide overrides that assume 1cy costs.

llvm-svn: 374786
2019-10-14 16:30:17 +00:00
Joerg Sonnenberger
5200dee212 Reapply r374743 with a fix for the ocaml binding
Add a pass to lower is.constant and objectsize intrinsics

This pass lowers is.constant and objectsize intrinsics not simplified by
earlier constant folding, i.e. if the object given is not constant or if
not using the optimized pass chain. The result is recursively simplified
and constant conditionals are pruned, so that dead blocks are removed
even for -O0. This allows inline asm blocks with operand constraints to
work all the time.

The new pass replaces the existing lowering in the codegen-prepare pass
and fallbacks in SDAG/GlobalISEL and FastISel. The latter now assert
on the intrinsics.

Differential Revision: https://reviews.llvm.org/D65280

llvm-svn: 374784
2019-10-14 16:15:14 +00:00
David Green
6c8afa2a83 [ARM] Selection for MVE VMOVN
The adds both VMOVNt and VMOVNb instruction selection from the appropriate
shuffles. We detect shuffle masks of the form:
0, N, 2, N+2, 4, N+4, ...
or
0, N+1, 2, N+3, 4, N+5, ...
ISel will also try the opposite patterns, with inputs reversed. These are
selected to VMOVNt and VMOVNb respectively.

Differential Revision: https://reviews.llvm.org/D68283

llvm-svn: 374781
2019-10-14 15:19:33 +00:00
Simon Pilgrim
92f62b5161 [CostModel][X86] Add CTPOP scalar costs (PR43656)
Add specific scalar costs for ctpop instructions, these are based on the llvm-mca's SLM throughput numbers (the oldest model we have).

For targets supporting POPCNT, we provide overrides that assume 1cy costs.

llvm-svn: 374775
2019-10-14 14:07:43 +00:00
Guillaume Chatelet
4f6c7c9728 [Alignment][NFC] Move and type functions from MathExtras to Alignment
Summary:
This is patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68942

llvm-svn: 374773
2019-10-14 13:14:34 +00:00
Sander de Smalen
cb32afcabc [AArch64] Stackframe accesses to SVE objects.
Materialize accesses to SVE frame objects from SP or FP, whichever is
available and beneficial.

This patch still assumes the objects are pre-allocated. The automatic
layout of SVE objects within the stackframe will be added in a separate
patch.

Reviewers: greened, cameron.mcinally, efriedma, rengolin, thegameg, rovka

Reviewed By: cameron.mcinally

Differential Revision: https://reviews.llvm.org/D67749

llvm-svn: 374772
2019-10-14 13:11:34 +00:00
David Stenberg
b991d3f839 [DebugInfo] Fix truncation of call site immediates
Summary:
This addresses a bug in collectCallSiteParameters() where call site
immediates would be truncated from int64_t to unsigned.

This fixes PR43525.

Reviewers: djtodoro, NikolaPrica, aprantl, vsk

Reviewed By: aprantl

Subscribers: hiraditya, llvm-commits

Tags: #debug-info, #llvm

Differential Revision: https://reviews.llvm.org/D68869

llvm-svn: 374770
2019-10-14 12:49:58 +00:00
Dmitri Gribenko
d8ea0e7773 Revert "Add a pass to lower is.constant and objectsize intrinsics"
This reverts commit r374743. It broke the build with Ocaml enabled:
http://lab.llvm.org:8011/builders/clang-x86_64-debian-fast/builds/19218

llvm-svn: 374768
2019-10-14 12:22:48 +00:00
Alexander Timofeev
dd292a30dc [AMDGPU] Come back patch for the 'Assign register class for cross block values according to the divergence.'
Detailed description:

    After https://reviews.llvm.org/D59990 submit several issues were discovered.
    Changes in common code were preserved but AMDGPU specific part was reverted to keep the backend working correctly.

    Discovered issues were addressed in the following commits:

    https://reviews.llvm.org/D67662
    https://reviews.llvm.org/D67101
    https://reviews.llvm.org/D63953
    https://reviews.llvm.org/D63731

    This change brings back AMDGPU specific changes.

  Reviewed by: rampitec, arsenm

  Differential Revision: https://reviews.llvm.org/D68635

llvm-svn: 374767
2019-10-14 12:01:10 +00:00
Andrea Di Biagio
4a9308eaf8 [X86][BtVer2] Improved latency and throughput of float/vector loads and stores.
This patch introduces the following changes to the btver2 scheduling model:

- The number of micro opcodes for YMM loads and stores is now 2 (it was
  incorrectly set to 1 for both aligned and misaligned loads/stores).

- Increased the number of AGU resource cycles for YMM loads and stores
  to 2cy (instead of 1cy).

- Removed JFPU01 and JFPX from the list of resources consumed by pure
  float/vector loads (no MMX).

I verified with llvm-exegesis that pure XMM/YMM loads are no-pipe. Those
are dispatched to the FPU but not really issues on JFPU01.

Differential Revision: https://reviews.llvm.org/D68871

llvm-svn: 374765
2019-10-14 11:12:18 +00:00
Sam Parker
d863761b7a [NFC][TTI] Add Alignment for isLegalMasked[Load/Store]
Add an extra parameter so the backend can take the alignment into
consideration.

Differential Revision: https://reviews.llvm.org/D68400

llvm-svn: 374763
2019-10-14 10:00:21 +00:00
Craig Topper
ba34d0d84b [X86] Teach EmitTest to handle ISD::SSUBO/USUBO in order to use the Z flag from the subtract directly during isel.
This prevents isel from emitting a TEST instruction that
optimizeCompareInstr will need to remove later.

In some of the modified tests, the SUB gets duplicated due to
the flags being needed in two places and being clobbered in
between. optimizeCompareInstr was able to optimize away the TEST
that was using the result of one of them, but optimizeCompareInstr
doesn't know to turn SUB into CMP after removing the TEST. It
only knows how to turn SUB into CMP if the result was already
dead.

With this change the TEST never exists, so optimizeCompareInstr
doesn't have to remove it. Then it can just turn the SUB into
CMP immediately.

Fixes PR43649.

llvm-svn: 374755
2019-10-14 06:47:56 +00:00
Florian Hahn
78d40715b1 [NewGVN] Use m_Br to simplify code a bit. (NFC)
llvm-svn: 374744
2019-10-13 23:34:13 +00:00
Joerg Sonnenberger
ea06f385c5 Add a pass to lower is.constant and objectsize intrinsics
This pass lowers is.constant and objectsize intrinsics not simplified by
earlier constant folding, i.e. if the object given is not constant or if
not using the optimized pass chain. The result is recursively simplified
and constant conditionals are pruned, so that dead blocks are removed
even for -O0. This allows inline asm blocks with operand constraints to
work all the time.

The new pass replaces the existing lowering in the codegen-prepare pass
and fallbacks in SDAG/GlobalISEL and FastISel. The latter now assert
on the intrinsics.

Differential Revision: https://reviews.llvm.org/D65280

llvm-svn: 374743
2019-10-13 23:00:15 +00:00
Johannes Doerfert
82b7c96e47 [Attributor] Shortcut no-return through will-return
No-return and will-return are exclusive, assuming the latter is more
prominent we can avoid updates of the former unless will-return is not
known for sure.

llvm-svn: 374739
2019-10-13 21:25:53 +00:00
Johannes Doerfert
9a6e588316 [Attributor][FIX] NullPointerIsDefined needs the pointer AS (AANonNull)
Also includes a shortcut via AADereferenceable if possible.

llvm-svn: 374737
2019-10-13 20:48:26 +00:00
Johannes Doerfert
c49313343a [Attributor][MemBehavior] Fallback to the function state for arguments
Even if an argument is captured, we cannot have an effect the function
does not have. This is fine except for the special case of `inalloca` as
it does not behave by the rules.

TODO: Maybe the special rule for `inalloca` is wrong after all.
llvm-svn: 374736
2019-10-13 20:47:16 +00:00
Johannes Doerfert
fe8381ac47 [Attributor][FIX] Use check prefix that is actually tested
Summary:
This changes "CHECK" check lines to "ATTRIBUTOR" check lines where
necessary and also fixes the now exposed, mostly minor, problems.

Reviewers: sstefan1, uenoku

Subscribers: hiraditya, bollu, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68929

llvm-svn: 374735
2019-10-13 20:40:10 +00:00
Roman Lebedev
5739d56ede [NFC][InstCombine] Some preparatory cleanup in dropRedundantMaskingOfLeftShiftInput()
llvm-svn: 374734
2019-10-13 20:15:00 +00:00
Simon Pilgrim
d5a282cdbf [X86] getTargetShuffleInputs - Control KnownUndef mask element resolution as well as KnownZero.
We were already controlling whether the KnownZero elements were being written to the target mask, this extends it to the KnownUndef elements as well so we can prevent the target shuffle mask being manipulated at all.

llvm-svn: 374732
2019-10-13 19:35:35 +00:00
Craig Topper
73ce8d1bc9 [X86] Enable use of avx512 saturating truncate instructions in more cases.
This enables use of the saturating truncate instructions when the
result type is less than 128 bits. It also enables the use of
saturating truncate instructions on KNL when the input is less
than 512 bits. We can do this by widening the input and then
extracting the result.

llvm-svn: 374731
2019-10-13 19:07:28 +00:00
Sanjay Patel
072fec99fc [ConstantFold] fix inconsistent handling of extractelement with undef index (PR42689)
Any constant other than zero was already folded to undef if the index is undef.
https://bugs.llvm.org/show_bug.cgi?id=42689

llvm-svn: 374729
2019-10-13 17:34:08 +00:00
Sanjay Patel
048e400ca3 [InstCombine] don't assume 'inbounds' for bitcast deref or null pointer in non-default address space
Follow-up to D68244 to account for a corner case discussed in:
https://bugs.llvm.org/show_bug.cgi?id=43501

Add one more restriction: if the pointer is deref-or-null and in a non-default
(non-zero) address space, we can't assume inbounds.

Differential Revision: https://reviews.llvm.org/D68706

llvm-svn: 374728
2019-10-13 17:19:08 +00:00
Simon Pilgrim
8773c2f418 [X86] SimplifyMultipleUseDemandedBitsForTargetNode - use getTargetShuffleInputs with KnownUndef/Zero results.
llvm-svn: 374725
2019-10-13 17:03:11 +00:00
Simon Pilgrim
96a583c339 [X86] getTargetShuffleInputs - add KnownUndef/Zero output support
Adjust SimplifyDemandedVectorEltsForTargetNode to use the known elts masks instead of recomputing it locally.

llvm-svn: 374724
2019-10-13 17:03:02 +00:00
Simon Pilgrim
b9e25e757c IRTranslator - silence static analyzer null dereference warnings. NFCI.
The CmpInst::getType() calls can be replaced by just using User::getType() that it was dyn_cast from, and we then need to assert that any default predicate cases came from the CmpInst.

llvm-svn: 374716
2019-10-13 11:29:35 +00:00
Craig Topper
25aca9b88c [X86] Add a one use check on the setcc to the min/max canonicalization code in combineSelect.
This seems to improve std::midpoint code where we have a min and
a max with the same condition. If we split the setcc we can end
up with two compares if the one of the operands is a constant.
Since we aggressively canonicalize compares with constants.
For non-constants it can interfere with our ability to share
control flow if we need to expand cmovs into control flow.

I'm also not sure I understand this min/max canonicalization code.
The motivating case talks about comparing with 0. But we don't
check for 0 explicitly.

Removes one instruction from the codegen for PR43658.

llvm-svn: 374706
2019-10-13 06:48:05 +00:00
Craig Topper
890032afee [X86] Enable v4i32->v4i16 and v8i16->v8i8 saturating truncates to use pack instructions with avx512.
llvm-svn: 374705
2019-10-13 05:47:47 +00:00
Johannes Doerfert
1c4877f759 [Attributor][FIX] Avoid splitting blocks if possible
Before, we eagerly split blocks even if it was not necessary, e.g., they
had a single unreachable instruction and only a single predecessor.

llvm-svn: 374703
2019-10-13 05:27:09 +00:00
Johannes Doerfert
6b3ee37d3e [Attributor][FIX] Remove leftover, now unused, variable
llvm-svn: 374702
2019-10-13 05:19:17 +00:00
Johannes Doerfert
408a2116f8 [Attributor] Remove unused verification flag
We use the verify max iteration now which is more reliable.

llvm-svn: 374701
2019-10-13 05:07:00 +00:00
Johannes Doerfert
2388ee280b [Attributor][NFC] Expose call site traversal without QueryingAA
llvm-svn: 374700
2019-10-13 04:16:02 +00:00
Johannes Doerfert
807d9bd946 [Attributor][FIX] Ensure h2s doesn't trigger on escaped pointers
We do not yet perform h2s because we know something is free'ed but we do
it because we know the pointer does not escape. Storing the pointer
allows it to escape so we have to prevent that.

llvm-svn: 374699
2019-10-13 04:14:15 +00:00
Johannes Doerfert
7b069a879a [Attributor][FIX] Do not apply h2s for arbitrary mallocs
H2S did apply to mallocs of non-constant sizes if the uses were OK. This
is now forbidden through reording of the "good" and "bad" cases in the
conditional.

llvm-svn: 374698
2019-10-13 03:54:08 +00:00
Johannes Doerfert
a3ef980c25 [Attributor][FIX] Avoid modifying naked/optnone functions
The check for naked/optnone was insufficient for different reasons. We
now check before we initialize an abstract attribute and we do it for
all abstract attributes.

llvm-svn: 374694
2019-10-13 02:24:02 +00:00
Johannes Doerfert
67305cbcc3 [SROA] Reuse existing lifetime markers if possible
Summary:
If the underlying alloca did not change, we do not necessarily need new
lifetime markers. This patch adds a check and reuses the old ones if
possible.

Reviewers: reames, ssarda, t.p.northover, hfinkel

Subscribers: hiraditya, bollu, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68900

llvm-svn: 374692
2019-10-13 02:21:23 +00:00
Simon Pilgrim
cc8f5e36da [X86] scaleShuffleMask - use size_t Scale to avoid overflow warnings
llvm-svn: 374674
2019-10-12 18:33:47 +00:00
Roman Lebedev
ab2284f8a9 [NFC][LoopIdiom] Adjust FIXME to be self-explanatory
llvm-svn: 374670
2019-10-12 16:48:16 +00:00
Simon Pilgrim
4ce8f35c4d Replace for-loop of SmallVector::push_back with SmallVector::append. NFCI.
llvm-svn: 374669
2019-10-12 16:37:02 +00:00
Simon Pilgrim
846f09a144 Fix cppcheck shadow variable name warnings. NFCI.
llvm-svn: 374668
2019-10-12 16:36:52 +00:00
Simon Pilgrim
354303cc5c [X86] Use any_of/all_of patterns in shuffle mask pattern recognisers. NFCI.
llvm-svn: 374667
2019-10-12 16:36:44 +00:00
Roman Lebedev
0dff68630e [LoopIdiomRecognize] Recommit: BCmp loop idiom recognition
Summary:
This is a recommit, this originally landed in rL370454 but was
subsequently reverted in  rL370788 due to
https://bugs.llvm.org/show_bug.cgi?id=43206
The reduced testcase was added to bcmp-negative-tests.ll
as @pr43206_different_loops - we must ensure that the SCEV's
we got are both for the same loop we are currently investigating.

Original commit message:

@mclow.lists brought up this issue up in IRC.
It is a reasonably common problem to compare some two values for equality.
Those may be just some integers, strings or arrays of integers.

In C, there is `memcmp()`, `bcmp()` functions.
In C++, there exists `std::equal()` algorithm.
One can also write that function manually.

libstdc++'s `std::equal()` is specialized to directly call `memcmp()` for
various types, but not `std::byte` from C++2a. https://godbolt.org/z/mx2ejJ

libc++ does not do anything like that, it simply relies on simple C++'s
`operator==()`. https://godbolt.org/z/er0Zwf (GOOD!)

So likely, there exists a certain performance opportunities.
Let's compare performance of naive `std::equal()` (no `memcmp()`) with one that
is using `memcmp()` (in this case, compiled with modified compiler). {F8768213}

```
#include <algorithm>
#include <cmath>
#include <cstdint>
#include <iterator>
#include <limits>
#include <random>
#include <type_traits>
#include <utility>
#include <vector>

#include "benchmark/benchmark.h"

template <class T>
bool equal(T* a, T* a_end, T* b) noexcept {
  for (; a != a_end; ++a, ++b) {
    if (*a != *b) return false;
  }
  return true;
}

template <typename T>
std::vector<T> getVectorOfRandomNumbers(size_t count) {
  std::random_device rd;
  std::mt19937 gen(rd());
  std::uniform_int_distribution<T> dis(std::numeric_limits<T>::min(),
                                       std::numeric_limits<T>::max());
  std::vector<T> v;
  v.reserve(count);
  std::generate_n(std::back_inserter(v), count,
                  [&dis, &gen]() { return dis(gen); });
  assert(v.size() == count);
  return v;
}

struct Identical {
  template <typename T>
  static std::pair<std::vector<T>, std::vector<T>> Gen(size_t count) {
    auto Tmp = getVectorOfRandomNumbers<T>(count);
    return std::make_pair(Tmp, std::move(Tmp));
  }
};

struct InequalHalfway {
  template <typename T>
  static std::pair<std::vector<T>, std::vector<T>> Gen(size_t count) {
    auto V0 = getVectorOfRandomNumbers<T>(count);
    auto V1 = V0;
    V1[V1.size() / size_t(2)]++;  // just change the value.
    return std::make_pair(std::move(V0), std::move(V1));
  }
};

template <class T, class Gen>
void BM_bcmp(benchmark::State& state) {
  const size_t Length = state.range(0);

  const std::pair<std::vector<T>, std::vector<T>> Data =
      Gen::template Gen<T>(Length);
  const std::vector<T>& a = Data.first;
  const std::vector<T>& b = Data.second;
  assert(a.size() == Length && b.size() == a.size());

  benchmark::ClobberMemory();
  benchmark::DoNotOptimize(a);
  benchmark::DoNotOptimize(a.data());
  benchmark::DoNotOptimize(b);
  benchmark::DoNotOptimize(b.data());

  for (auto _ : state) {
    const bool is_equal = equal(a.data(), a.data() + a.size(), b.data());
    benchmark::DoNotOptimize(is_equal);
  }
  state.SetComplexityN(Length);
  state.counters["eltcnt"] =
      benchmark::Counter(Length, benchmark::Counter::kIsIterationInvariant);
  state.counters["eltcnt/sec"] =
      benchmark::Counter(Length, benchmark::Counter::kIsIterationInvariantRate);
  const size_t BytesRead = 2 * sizeof(T) * Length;
  state.counters["bytes_read/iteration"] =
      benchmark::Counter(BytesRead, benchmark::Counter::kDefaults,
                         benchmark::Counter::OneK::kIs1024);
  state.counters["bytes_read/sec"] = benchmark::Counter(
      BytesRead, benchmark::Counter::kIsIterationInvariantRate,
      benchmark::Counter::OneK::kIs1024);
}

template <typename T>
static void CustomArguments(benchmark::internal::Benchmark* b) {
  const size_t L2SizeBytes = []() {
    for (const benchmark::CPUInfo::CacheInfo& I :
         benchmark::CPUInfo::Get().caches) {
      if (I.level == 2) return I.size;
    }
    return 0;
  }();
  // What is the largest range we can check to always fit within given L2 cache?
  const size_t MaxLen = L2SizeBytes / /*total bufs*/ 2 /
                        /*maximal elt size*/ sizeof(T) / /*safety margin*/ 2;
  b->RangeMultiplier(2)->Range(1, MaxLen)->Complexity(benchmark::oN);
}

BENCHMARK_TEMPLATE(BM_bcmp, uint8_t, Identical)
    ->Apply(CustomArguments<uint8_t>);
BENCHMARK_TEMPLATE(BM_bcmp, uint16_t, Identical)
    ->Apply(CustomArguments<uint16_t>);
BENCHMARK_TEMPLATE(BM_bcmp, uint32_t, Identical)
    ->Apply(CustomArguments<uint32_t>);
BENCHMARK_TEMPLATE(BM_bcmp, uint64_t, Identical)
    ->Apply(CustomArguments<uint64_t>);

BENCHMARK_TEMPLATE(BM_bcmp, uint8_t, InequalHalfway)
    ->Apply(CustomArguments<uint8_t>);
BENCHMARK_TEMPLATE(BM_bcmp, uint16_t, InequalHalfway)
    ->Apply(CustomArguments<uint16_t>);
BENCHMARK_TEMPLATE(BM_bcmp, uint32_t, InequalHalfway)
    ->Apply(CustomArguments<uint32_t>);
BENCHMARK_TEMPLATE(BM_bcmp, uint64_t, InequalHalfway)
    ->Apply(CustomArguments<uint64_t>);
```
{F8768210}
```
$ ~/src/googlebenchmark/tools/compare.py --no-utest benchmarks build-{old,new}/test/llvm-bcmp-bench
RUNNING: build-old/test/llvm-bcmp-bench --benchmark_out=/tmp/tmpb6PEUx
2019-04-25 21:17:11
Running build-old/test/llvm-bcmp-bench
Run on (8 X 4000 MHz CPU s)
CPU Caches:
  L1 Data 16K (x8)
  L1 Instruction 64K (x4)
  L2 Unified 2048K (x4)
  L3 Unified 8192K (x1)
Load Average: 0.65, 3.90, 4.14
---------------------------------------------------------------------------------------------------
Benchmark                                         Time             CPU   Iterations UserCounters...
---------------------------------------------------------------------------------------------------
<...>
BM_bcmp<uint8_t, Identical>/512000           432131 ns       432101 ns         1613 bytes_read/iteration=1000k bytes_read/sec=2.20706G/s eltcnt=825.856M eltcnt/sec=1.18491G/s
BM_bcmp<uint8_t, Identical>_BigO               0.86 N          0.86 N
BM_bcmp<uint8_t, Identical>_RMS                   8 %             8 %
<...>
BM_bcmp<uint16_t, Identical>/256000          161408 ns       161409 ns         4027 bytes_read/iteration=1000k bytes_read/sec=5.90843G/s eltcnt=1030.91M eltcnt/sec=1.58603G/s
BM_bcmp<uint16_t, Identical>_BigO              0.67 N          0.67 N
BM_bcmp<uint16_t, Identical>_RMS                 25 %            25 %
<...>
BM_bcmp<uint32_t, Identical>/128000           81497 ns        81488 ns         8415 bytes_read/iteration=1000k bytes_read/sec=11.7032G/s eltcnt=1077.12M eltcnt/sec=1.57078G/s
BM_bcmp<uint32_t, Identical>_BigO              0.71 N          0.71 N
BM_bcmp<uint32_t, Identical>_RMS                 42 %            42 %
<...>
BM_bcmp<uint64_t, Identical>/64000            50138 ns        50138 ns        10909 bytes_read/iteration=1000k bytes_read/sec=19.0209G/s eltcnt=698.176M eltcnt/sec=1.27647G/s
BM_bcmp<uint64_t, Identical>_BigO              0.84 N          0.84 N
BM_bcmp<uint64_t, Identical>_RMS                 27 %            27 %
<...>
BM_bcmp<uint8_t, InequalHalfway>/512000      192405 ns       192392 ns         3638 bytes_read/iteration=1000k bytes_read/sec=4.95694G/s eltcnt=1.86266G eltcnt/sec=2.66124G/s
BM_bcmp<uint8_t, InequalHalfway>_BigO          0.38 N          0.38 N
BM_bcmp<uint8_t, InequalHalfway>_RMS              3 %             3 %
<...>
BM_bcmp<uint16_t, InequalHalfway>/256000     127858 ns       127860 ns         5477 bytes_read/iteration=1000k bytes_read/sec=7.45873G/s eltcnt=1.40211G eltcnt/sec=2.00219G/s
BM_bcmp<uint16_t, InequalHalfway>_BigO         0.50 N          0.50 N
BM_bcmp<uint16_t, InequalHalfway>_RMS             0 %             0 %
<...>
BM_bcmp<uint32_t, InequalHalfway>/128000      49140 ns        49140 ns        14281 bytes_read/iteration=1000k bytes_read/sec=19.4072G/s eltcnt=1.82797G eltcnt/sec=2.60478G/s
BM_bcmp<uint32_t, InequalHalfway>_BigO         0.40 N          0.40 N
BM_bcmp<uint32_t, InequalHalfway>_RMS            18 %            18 %
<...>
BM_bcmp<uint64_t, InequalHalfway>/64000       32101 ns        32099 ns        21786 bytes_read/iteration=1000k bytes_read/sec=29.7101G/s eltcnt=1.3943G eltcnt/sec=1.99381G/s
BM_bcmp<uint64_t, InequalHalfway>_BigO         0.50 N          0.50 N
BM_bcmp<uint64_t, InequalHalfway>_RMS             1 %             1 %
RUNNING: build-new/test/llvm-bcmp-bench --benchmark_out=/tmp/tmpQ46PP0
2019-04-25 21:19:29
Running build-new/test/llvm-bcmp-bench
Run on (8 X 4000 MHz CPU s)
CPU Caches:
  L1 Data 16K (x8)
  L1 Instruction 64K (x4)
  L2 Unified 2048K (x4)
  L3 Unified 8192K (x1)
Load Average: 1.01, 2.85, 3.71
---------------------------------------------------------------------------------------------------
Benchmark                                         Time             CPU   Iterations UserCounters...
---------------------------------------------------------------------------------------------------
<...>
BM_bcmp<uint8_t, Identical>/512000            18593 ns        18590 ns        37565 bytes_read/iteration=1000k bytes_read/sec=51.2991G/s eltcnt=19.2333G eltcnt/sec=27.541G/s
BM_bcmp<uint8_t, Identical>_BigO               0.04 N          0.04 N
BM_bcmp<uint8_t, Identical>_RMS                  37 %            37 %
<...>
BM_bcmp<uint16_t, Identical>/256000           18950 ns        18948 ns        37223 bytes_read/iteration=1000k bytes_read/sec=50.3324G/s eltcnt=9.52909G eltcnt/sec=13.511G/s
BM_bcmp<uint16_t, Identical>_BigO              0.08 N          0.08 N
BM_bcmp<uint16_t, Identical>_RMS                 34 %            34 %
<...>
BM_bcmp<uint32_t, Identical>/128000           18627 ns        18627 ns        37895 bytes_read/iteration=1000k bytes_read/sec=51.198G/s eltcnt=4.85056G eltcnt/sec=6.87168G/s
BM_bcmp<uint32_t, Identical>_BigO              0.16 N          0.16 N
BM_bcmp<uint32_t, Identical>_RMS                 35 %            35 %
<...>
BM_bcmp<uint64_t, Identical>/64000            18855 ns        18855 ns        37458 bytes_read/iteration=1000k bytes_read/sec=50.5791G/s eltcnt=2.39731G eltcnt/sec=3.3943G/s
BM_bcmp<uint64_t, Identical>_BigO              0.32 N          0.32 N
BM_bcmp<uint64_t, Identical>_RMS                 33 %            33 %
<...>
BM_bcmp<uint8_t, InequalHalfway>/512000        9570 ns         9569 ns        73500 bytes_read/iteration=1000k bytes_read/sec=99.6601G/s eltcnt=37.632G eltcnt/sec=53.5046G/s
BM_bcmp<uint8_t, InequalHalfway>_BigO          0.02 N          0.02 N
BM_bcmp<uint8_t, InequalHalfway>_RMS             29 %            29 %
<...>
BM_bcmp<uint16_t, InequalHalfway>/256000       9547 ns         9547 ns        74343 bytes_read/iteration=1000k bytes_read/sec=99.8971G/s eltcnt=19.0318G eltcnt/sec=26.8159G/s
BM_bcmp<uint16_t, InequalHalfway>_BigO         0.04 N          0.04 N
BM_bcmp<uint16_t, InequalHalfway>_RMS            29 %            29 %
<...>
BM_bcmp<uint32_t, InequalHalfway>/128000       9396 ns         9394 ns        73521 bytes_read/iteration=1000k bytes_read/sec=101.518G/s eltcnt=9.41069G eltcnt/sec=13.6255G/s
BM_bcmp<uint32_t, InequalHalfway>_BigO         0.08 N          0.08 N
BM_bcmp<uint32_t, InequalHalfway>_RMS            30 %            30 %
<...>
BM_bcmp<uint64_t, InequalHalfway>/64000        9499 ns         9498 ns        73802 bytes_read/iteration=1000k bytes_read/sec=100.405G/s eltcnt=4.72333G eltcnt/sec=6.73808G/s
BM_bcmp<uint64_t, InequalHalfway>_BigO         0.16 N          0.16 N
BM_bcmp<uint64_t, InequalHalfway>_RMS            28 %            28 %
Comparing build-old/test/llvm-bcmp-bench to build-new/test/llvm-bcmp-bench
Benchmark                                                  Time             CPU      Time Old      Time New       CPU Old       CPU New
---------------------------------------------------------------------------------------------------------------------------------------
<...>
BM_bcmp<uint8_t, Identical>/512000                      -0.9570         -0.9570        432131         18593        432101         18590
<...>
BM_bcmp<uint16_t, Identical>/256000                     -0.8826         -0.8826        161408         18950        161409         18948
<...>
BM_bcmp<uint32_t, Identical>/128000                     -0.7714         -0.7714         81497         18627         81488         18627
<...>
BM_bcmp<uint64_t, Identical>/64000                      -0.6239         -0.6239         50138         18855         50138         18855
<...>
BM_bcmp<uint8_t, InequalHalfway>/512000                 -0.9503         -0.9503        192405          9570        192392          9569
<...>
BM_bcmp<uint16_t, InequalHalfway>/256000                -0.9253         -0.9253        127858          9547        127860          9547
<...>
BM_bcmp<uint32_t, InequalHalfway>/128000                -0.8088         -0.8088         49140          9396         49140          9394
<...>
BM_bcmp<uint64_t, InequalHalfway>/64000                 -0.7041         -0.7041         32101          9499         32099          9498
```

What can we tell from the benchmark?
* Performance of naive equality check somewhat improves with element size,
  maxing out at eltcnt/sec=1.58603G/s for uint16_t, or bytes_read/sec=19.0209G/s
  for uint64_t. I think, that instability implies performance problems.
* Performance of `memcmp()`-aware benchmark always maxes out at around
  bytes_read/sec=51.2991G/s for every type. That is 2.6x the throughput of the
  naive variant!
* eltcnt/sec metric for the `memcmp()`-aware benchmark maxes out at
  eltcnt/sec=27.541G/s for uint8_t (was: eltcnt/sec=1.18491G/s, so 24x) and
  linearly decreases with element size.
  For uint64_t, it's ~4x+ the elements/second.
* The call obvious is more pricey than the loop, with small element count.
  As it can be seen from the full output {F8768210}, the `memcmp()` is almost
  universally worse, independent of the element size (and thus buffer size) when
  element count is less than 8.

So all in all, bcmp idiom does indeed pose untapped performance headroom.
This diff does implement said idiom recognition. I think a reasonable test
coverage is present, but do tell if there is anything obvious missing.

Now, quality. This does succeed to build and pass the test-suite, at least
without any non-bundled elements. {F8768216} {F8768217}
This transform fires 91 times:
```
$ /build/test-suite/utils/compare.py -m loop-idiom.NumBCmp result-new.json
Tests: 1149
Metric: loop-idiom.NumBCmp

Program                                         result-new

MultiSourc...Benchmarks/7zip/7zip-benchmark    79.00
MultiSource/Applications/d/make_dparser         3.00
SingleSource/UnitTests/vla                      2.00
MultiSource/Applications/Burg/burg              1.00
MultiSourc.../Applications/JM/lencod/lencod     1.00
MultiSource/Applications/lemon/lemon            1.00
MultiSource/Benchmarks/Bullet/bullet            1.00
MultiSourc...e/Benchmarks/MallocBench/gs/gs     1.00
MultiSourc...gs-C/TimberWolfMC/timberwolfmc     1.00
MultiSourc...Prolangs-C/simulator/simulator     1.00
```
The size changes are:
I'm not sure what's going on with SingleSource/UnitTests/vla.test yet, did not look.
```
$ /build/test-suite/utils/compare.py -m size..text result-{old,new}.json --filter-hash
Tests: 1149
Same hash: 907 (filtered out)
Remaining: 242
Metric: size..text

Program                                        result-old result-new diff
test-suite...ingleSource/UnitTests/vla.test   753.00     833.00     10.6%
test-suite...marks/7zip/7zip-benchmark.test   1001697.00 966657.00  -3.5%
test-suite...ngs-C/simulator/simulator.test   32369.00   32321.00   -0.1%
test-suite...plications/d/make_dparser.test   89585.00   89505.00   -0.1%
test-suite...ce/Applications/Burg/burg.test   40817.00   40785.00   -0.1%
test-suite.../Applications/lemon/lemon.test   47281.00   47249.00   -0.1%
test-suite...TimberWolfMC/timberwolfmc.test   250065.00  250113.00   0.0%
test-suite...chmarks/MallocBench/gs/gs.test   149889.00  149873.00  -0.0%
test-suite...ications/JM/lencod/lencod.test   769585.00  769569.00  -0.0%
test-suite.../Benchmarks/Bullet/bullet.test   770049.00  770049.00   0.0%
test-suite...HMARK_ANISTROPIC_DIFFUSION/128    NaN        NaN        nan%
test-suite...HMARK_ANISTROPIC_DIFFUSION/256    NaN        NaN        nan%
test-suite...CHMARK_ANISTROPIC_DIFFUSION/64    NaN        NaN        nan%
test-suite...CHMARK_ANISTROPIC_DIFFUSION/32    NaN        NaN        nan%
test-suite...ENCHMARK_BILATERAL_FILTER/64/4    NaN        NaN        nan%
Geomean difference                                                   nan%
         result-old    result-new       diff
count  1.000000e+01  10.00000      10.000000
mean   3.152090e+05  311695.40000  0.006749
std    3.790398e+05  372091.42232  0.036605
min    7.530000e+02  833.00000    -0.034981
25%    4.243300e+04  42401.00000  -0.000866
50%    1.197370e+05  119689.00000 -0.000392
75%    6.397050e+05  639705.00000 -0.000005
max    1.001697e+06  966657.00000  0.106242
```

I don't have timings though.

And now to the code. The basic idea is to completely replace the whole loop.
If we can't fully kill it, don't transform.
I have left one or two comments in the code, so hopefully it can be understood.

Also, there is a few TODO's that i have left for follow-ups:
* widening of `memcmp()`/`bcmp()`
* step smaller than the comparison size
* Metadata propagation
* more than two blocks as long as there is still a single backedge?
* ???

Reviewers: reames, fhahn, mkazantsev, chandlerc, craig.topper, courbet

Reviewed By: courbet

Subscribers: miyuki, hiraditya, xbolva00, nikic, jfb, gchatelet, courbet, llvm-commits, mclow.lists

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61144

llvm-svn: 374662
2019-10-12 15:35:32 +00:00
Simon Pilgrim
3fd222dafb [X86][SSE] Avoid unnecessary PMOVZX in v4i8 sum reduction
This should go away once D66004 has landed and we can simplify shuffle chains using demanded elts.

llvm-svn: 374658
2019-10-12 15:19:13 +00:00
Simon Pilgrim
a95636568c [CostModel][X86] Improve sum reduction costs.
I can't see any notable differences in costs between SSE2 and SSE42 arches for FADD/ADD reduction, so I've lowered the target to just SSE2.

I've also added vXi8 sum reduction costs in line with the PSADBW codegen and discussions on PR42674.

llvm-svn: 374655
2019-10-12 13:21:50 +00:00
Benjamin Kramer
8ac85c7928 [Attributor] Extend anonymous namespace. NFC.
llvm-svn: 374647
2019-10-12 11:01:52 +00:00
Benjamin Kramer
2d3816bb5d [LV] Merge LLVM_DEBUG blocks.
Avoids unused variable warnings about the range-based for loops in
there. NFCI.

llvm-svn: 374646
2019-10-12 10:57:22 +00:00
Craig Topper
1be8c5bd99 [X86] Use pack instructions for packus/ssat truncate patterns when 256-bit is the largest legal vector and the result type is at least 256 bits.
Since the input type is larger than 256-bits we'll need to some
concatenating to reassemble the results. The pack instructions
ability to concatenate while packing make this a shorter/faster
sequence.

llvm-svn: 374643
2019-10-12 07:59:29 +00:00