Slowdown with views in 0.12.119

[ffreyer]

I have a reimplementation of Linearlagebra.qr in my codebase which uses @turbo. In it there is

using LinearAlgebra, LoopVectorization, BenchmarkTools

function reflectorApply!(x::AbstractVector{<: Real}, τ::Real, A::StridedMatrix{<: Real})
    m, n = size(A)
    @inbounds for j = 1:n
        # dot
        vAj = A[1, j]
        @turbo for i = 2:m
            vAj += conj(x[i]) * A[i, j]
        end

        vAj = conj(τ)*vAj

        # ger
        A[1, j] -= vAj
        @turbo for i = 2:m
            A[i, j] -= x[i]*vAj
        end
    end
    return A
end

which is called with two views into the same array:

input = rand(64, 64)
n = 64
j = 17
τ = 1.7
x = LinearAlgebra.view(input, j:n, j)
y = LinearAlgebra.view(input, j:n, j+1:n)
@benchmark reflectorApply!($x, $τ, $y)

I've noticed that after triggering a package update things have been running more slowly and Identified that the problem is here. Trying some different version of LoopVectorization pointed showed that v0.12.119 had made this much slower:

# median times via @benchmark, after julia restart
# no turbo:  2.9µs
# 0.12.124: 48µs
# 0.12.120: 46µs
# 0.12.119: 46µs
# 0.12.118:  0.72µs
# 0.12.115:  0.74µs
# 0.12.110:  0.72µs
# 0.12.100:  0.71µs

Rewriting this to use no views restores the performance from before 0.12.119.

[chriselrod]

Hmm, I cannot reproduce...

julia> @benchmark reflectorApply!($x, $τ, $y)
BenchmarkTools.Trial: 10000 samples with 171 evaluations.
 Range (min … max):  630.281 ns … 855.865 ns  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     635.731 ns               ┊ GC (median):    0.00%
 Time  (mean ± σ):   637.356 ns ±   5.920 ns  ┊ GC (mean ± σ):  0.00% ± 0.00%

           ▃▃▂█▄▄▂▁
  ▂▂▃▃▃▄▄▅▇█████████▇▇▅▄▄▃▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▂▂▂▂▂▂▂▃▃▃▃▃▃▃▃▃▃▃▃▂ ▃
  630 ns           Histogram: frequency by time          654 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.

(lvdev) pkg> st -m LoopVectorization
Status `~/Documents/progwork/julia/env/lvdev/Manifest.toml`
  [bdcacae8] LoopVectorization v0.12.125 `~/.julia/dev/LoopVectorization`

julia> versioninfo()
Julia Version 1.9.0-DEV.1130
Commit c80316e125* (2022-08-15 13:05 UTC)
Platform Info:
  OS: Linux (x86_64-redhat-linux)
  CPU: 36 × Intel(R) Core(TM) i9-7980XE CPU @ 2.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-14.0.5 (ORCJIT, skylake-avx512)
  Threads: 18 on 36 virtual cores

[chriselrod]

Mind showing me the

@code_typed reflectorApply!(x, τ, y)

and

@code_native debuginfo = :none syntax = :intel reflectorApply!(x, τ, y)

        .text
        .file   "reflectorApply!"
        .globl  "julia_reflectorApply!_4509"    # -- Begin function julia_reflectorApply!_4509
        .p2align        4, 0x90
        .type   "julia_reflectorApply!_4509",@function
"julia_reflectorApply!_4509":           # @"julia_reflectorApply!_4509"
        .cfi_startproc
# %bb.0:                                # %top
        push    rbp
        .cfi_def_cfa_offset 16
        push    r15
        .cfi_def_cfa_offset 24
        push    r14
        .cfi_def_cfa_offset 32
        push    r13
        .cfi_def_cfa_offset 40
        push    r12
        .cfi_def_cfa_offset 48
        push    rbx
        .cfi_def_cfa_offset 56
        .cfi_offset rbx, -56
        .cfi_offset r12, -48
        .cfi_offset r13, -40
        .cfi_offset r14, -32
        .cfi_offset r15, -24
        .cfi_offset rbp, -16
        mov     qword ptr [rsp - 56], rsi       # 8-byte Spill
        mov     qword ptr [rsp - 48], rdi       # 8-byte Spill
        mov     r11, qword ptr [rcx + 32]
        mov     qword ptr [rsp - 80], rcx       # 8-byte Spill
        mov     rcx, qword ptr [rcx + 24]
        mov     rax, rcx
        mov     qword ptr [rsp - 64], rcx       # 8-byte Spill
        sub     r11, rcx
        movabs  rax, 9223372036854775806
        cmp     r11, rax
        jbe     .LBB0_1
.LBB0_26:                               # %L694
        mov     rcx, qword ptr [rsp - 80]       # 8-byte Reload
        mov     rax, qword ptr [rcx]
        mov     rdx, qword ptr [rsp - 56]       # 8-byte Reload
        mov     qword ptr [rdx], rax
        vmovups ymm0, ymmword ptr [rcx]
        vmovups ymm1, ymmword ptr [rcx + 24]
        mov     rax, qword ptr [rsp - 48]       # 8-byte Reload
        vmovups ymmword ptr [rax + 24], ymm1
        vmovups ymmword ptr [rax], ymm0
        pop     rbx
        .cfi_def_cfa_offset 48
        pop     r12
        .cfi_def_cfa_offset 40
        pop     r13
        .cfi_def_cfa_offset 32
        pop     r14
        .cfi_def_cfa_offset 24
        pop     r15
        .cfi_def_cfa_offset 16
        pop     rbp
        .cfi_def_cfa_offset 8
        vzeroupper
        ret
.LBB0_1:                                # %L34.preheader
        .cfi_def_cfa_offset 56
        mov     rdi, qword ptr [rsp - 80]       # 8-byte Reload
        mov     r9, qword ptr [rdi + 8]
        mov     rax, qword ptr [rdi + 16]
        sub     rax, r9
        inc     rax
        mov     rsi, rax
        sar     rsi, 63
        andn    rcx, rsi, rax
        inc     r11
        mov     rax, qword ptr [rdi]
        lea     rsi, [r9 - 1]
        mov     qword ptr [rsp - 8], rsi        # 8-byte Spill
        mov     r12, qword ptr [rax]
        mov     r13, qword ptr [rax + 24]
        mov     rax, qword ptr [rdx]
        mov     r8, qword ptr [rax]
        mov     r10, qword ptr [rdx + 8]
        mov     rsi, qword ptr [rdx + 24]
        dec     rsi
        imul    rsi, qword ptr [rax + 24]
        lea     rax, [r10 + rsi]
        lea     rdx, [r8 + 8*rax]
        mov     rax, qword ptr [rsp - 64]       # 8-byte Reload
        lea     rbp, [rax - 1]
        imul    rbp, r13
        lea     rax, [r9 + rbp]
        dec     rax
        lea     rax, [r12 + 8*rax + 8]
        mov     qword ptr [rsp - 16], rax       # 8-byte Spill
        lea     rax, [rcx - 1]
        mov     rdi, rax
        and     rdi, -32
        and     rax, -16
        lea     ebx, [rcx - 1]
        and     ebx, 7
        mov     r14d, 8
        cmovne  r14d, ebx
        lea     rbx, [rcx - 2]
        shl     r9, 3
        lea     r15, [r9 + 8*rbp]
        lea     rbp, [rcx - 10]
        mov     qword ptr [rsp - 72], rbp       # 8-byte Spill
        shl     r10, 3
        lea     rsi, [r10 + 8*rsi]
        lea     rbp, [rcx - 18]
        mov     qword ptr [rsp - 32], rbp       # 8-byte Spill
        add     rsi, r8
        add     rsi, 192
        mov     ebp, -1
        bzhi    ebp, ebp, r14d
        mov     dword ptr [rsp - 84], ebp       # 4-byte Spill
        mov     r9, rcx
        add     rcx, -26
        mov     qword ptr [rsp - 40], rcx       # 8-byte Spill
        lea     r10, [r12 + r15 + 192]
        lea     rcx, [8*r13]
        mov     qword ptr [rsp - 24], rcx       # 8-byte Spill
        mov     r14d, 1
        jmp     .LBB0_2
        .p2align        4, 0x90
.LBB0_19:                               # %L602
                                        #   in Loop: Header=BB0_2 Depth=1
        mov     ecx, dword ptr [rsp - 84]       # 4-byte Reload
        kmovd   k1, ecx
        vmovupd zmm2 {k1} {z}, zmmword ptr [rdx + 8*rdi]
        vmovupd zmm3 {k1} {z}, zmmword ptr [r8 + 8*rdi]
        vbroadcastsd    zmm1, xmm1
        vfnmadd213pd    zmm1, zmm2, zmm3        # zmm1 = -(zmm2 * zmm1) + zmm3
        vmovupd zmmword ptr [r8 + 8*rdi] {k1}, zmm1
.LBB0_25:                               # %L682
                                        #   in Loop: Header=BB0_2 Depth=1
        lea     rbp, [r14 + 1]
        add     r10, qword ptr [rsp - 24]       # 8-byte Folded Reload
        cmp     r14, r11
        mov     r14, rbp
        je      .LBB0_26
.LBB0_2:                                # %L34
                                        # =>This Loop Header: Depth=1
                                        #     Child Loop BB0_5 Depth 2
                                        #     Child Loop BB0_16 Depth 2
        lea     r8, [8*r14 - 8]
        imul    r8, r13
        cmp     r9, 33
        jae     .LBB0_4
# %bb.3:                                #   in Loop: Header=BB0_2 Depth=1
        vxorpd  xmm1, xmm1, xmm1
        xor     r15d, r15d
        vxorpd  xmm2, xmm2, xmm2
        jmp     .LBB0_7
        .p2align        4, 0x90
.LBB0_4:                                # %L194.preheader
                                        #   in Loop: Header=BB0_2 Depth=1
        vxorpd  xmm2, xmm2, xmm2
        vxorpd  xmm1, xmm1, xmm1
        vxorpd  xmm3, xmm3, xmm3
        vxorpd  xmm4, xmm4, xmm4
        xor     ebp, ebp
        .p2align        4, 0x90
.LBB0_5:                                # %L205
                                        #   Parent Loop BB0_2 Depth=1
                                        # =>  This Inner Loop Header: Depth=2
        vmovupd zmm5, zmmword ptr [rsi + 8*rbp - 192]
        vmovupd zmm6, zmmword ptr [rsi + 8*rbp - 128]
        vmovupd zmm7, zmmword ptr [rsi + 8*rbp - 64]
        vmovupd zmm8, zmmword ptr [rsi + 8*rbp]
        vfmadd231pd     zmm4, zmm5, zmmword ptr [r10 + 8*rbp - 192] # zmm4 = (zmm5 * mem) + zmm4
        vfmadd231pd     zmm3, zmm6, zmmword ptr [r10 + 8*rbp - 128] # zmm3 = (zmm6 * mem) + zmm3
        vfmadd231pd     zmm1, zmm7, zmmword ptr [r10 + 8*rbp - 64] # zmm1 = (zmm7 * mem) + zmm1
        vfmadd231pd     zmm2, zmm8, zmmword ptr [r10 + 8*rbp] # zmm2 = (zmm8 * mem) + zmm2
        add     rbp, 32
        cmp     rdi, rbp
        jne     .LBB0_5
# %bb.6:                                # %L232
                                        #   in Loop: Header=BB0_2 Depth=1
        vaddpd  zmm1, zmm4, zmm1
        vaddpd  zmm2, zmm3, zmm2
        mov     r15, rdi
.LBB0_7:                                # %L237
                                        #   in Loop: Header=BB0_2 Depth=1
        mov     rbp, qword ptr [rsp - 64]       # 8-byte Reload
        add     rbp, r14
        add     rbp, -2
        imul    rbp, r13
        add     r8, qword ptr [rsp - 16]        # 8-byte Folded Reload
        cmp     r15, rax
        jne     .LBB0_9
# %bb.8:                                #   in Loop: Header=BB0_2 Depth=1
        mov     r15, rax
        add     rbp, qword ptr [rsp - 8]        # 8-byte Folded Reload
        cmp     r15, rbx
        jg      .LBB0_14
        jmp     .LBB0_11
        .p2align        4, 0x90
.LBB0_9:                                # %L260
                                        #   in Loop: Header=BB0_2 Depth=1
        vmovupd zmm3, zmmword ptr [rdx + 8*r15]
        vmovupd zmm4, zmmword ptr [rdx + 8*r15 + 64]
        vfmadd231pd     zmm1, zmm3, zmmword ptr [r8 + 8*r15] # zmm1 = (zmm3 * mem) + zmm1
        vfmadd231pd     zmm2, zmm4, zmmword ptr [r8 + 8*r15 + 64] # zmm2 = (zmm4 * mem) + zmm2
        or      r15, 16
        add     rbp, qword ptr [rsp - 8]        # 8-byte Folded Reload
        cmp     r15, rbx
        jg      .LBB0_14
.LBB0_11:                               # %L280
                                        #   in Loop: Header=BB0_2 Depth=1
        cmp     qword ptr [rsp - 72], r15       # 8-byte Folded Reload
        jge     .LBB0_13
# %bb.12:                               # %L291
                                        #   in Loop: Header=BB0_2 Depth=1
        mov     ecx, dword ptr [rsp - 84]       # 4-byte Reload
        kmovd   k1, ecx
        vmovupd zmm3 {k1} {z}, zmmword ptr [rdx + 8*r15]
        vmovupd zmm4 {k1} {z}, zmmword ptr [r8 + 8*r15]
        vfmadd231pd     zmm1 {k1}, zmm3, zmm4   # zmm1 {%k1} = (zmm3 * zmm4) + zmm1
        jmp     .LBB0_14
        .p2align        4, 0x90
.LBB0_13:                               # %L299
                                        #   in Loop: Header=BB0_2 Depth=1
        vmovupd zmm3, zmmword ptr [rdx + 8*r15]
        mov     ecx, dword ptr [rsp - 84]       # 4-byte Reload
        kmovd   k1, ecx
        vmovupd zmm4 {k1} {z}, zmmword ptr [rdx + 8*r15 + 64]
        vmovupd zmm5 {k1} {z}, zmmword ptr [r8 + 8*r15 + 64]
        vfmadd231pd     zmm1, zmm3, zmmword ptr [r8 + 8*r15] # zmm1 = (zmm3 * mem) + zmm1
        vfmadd231pd     zmm2 {k1}, zmm4, zmm5   # zmm2 {%k1} = (zmm4 * zmm5) + zmm2
.LBB0_14:                               # %L309
                                        #   in Loop: Header=BB0_2 Depth=1
        vaddpd  zmm1, zmm1, zmm2
        vmovsd  xmm2, qword ptr [r12 + 8*rbp]   # xmm2 = mem[0],zero
        vextractf64x4   ymm3, zmm1, 1
        vaddpd  zmm1, zmm1, zmm3
        vextractf128    xmm3, ymm1, 1
        vaddpd  xmm1, xmm1, xmm3
        vpermilpd       xmm3, xmm1, 1           # xmm3 = xmm1[1,0]
        vaddsd  xmm1, xmm1, xmm3
        vaddsd  xmm1, xmm2, xmm1
        vmulsd  xmm1, xmm1, xmm0
        vsubsd  xmm2, xmm2, xmm1
        vmovsd  qword ptr [r12 + 8*rbp], xmm2
        test    rdi, rdi
        je      .LBB0_17
# %bb.15:                               # %L563.lr.ph
                                        #   in Loop: Header=BB0_2 Depth=1
        vbroadcastsd    zmm2, xmm1
        xor     ebp, ebp
        .p2align        4, 0x90
.LBB0_16:                               # %L563
                                        #   Parent Loop BB0_2 Depth=1
                                        # =>  This Inner Loop Header: Depth=2
        vmovupd zmm3, zmmword ptr [rsi + 8*rbp - 192]
        vmovupd zmm4, zmmword ptr [rsi + 8*rbp - 128]
        vmovupd zmm5, zmmword ptr [rsi + 8*rbp - 64]
        vmovupd zmm6, zmmword ptr [rsi + 8*rbp]
        vfnmadd213pd    zmm3, zmm2, zmmword ptr [r10 + 8*rbp - 192] # zmm3 = -(zmm2 * zmm3) + mem
        vfnmadd213pd    zmm4, zmm2, zmmword ptr [r10 + 8*rbp - 128] # zmm4 = -(zmm2 * zmm4) + mem
        vfnmadd213pd    zmm5, zmm2, zmmword ptr [r10 + 8*rbp - 64] # zmm5 = -(zmm2 * zmm5) + mem
        vfnmadd213pd    zmm6, zmm2, zmmword ptr [r10 + 8*rbp] # zmm6 = -(zmm2 * zmm6) + mem
        vmovupd zmmword ptr [r10 + 8*rbp - 192], zmm3
        vmovupd zmmword ptr [r10 + 8*rbp - 128], zmm4
        vmovupd zmmword ptr [r10 + 8*rbp - 64], zmm5
        vmovupd zmmword ptr [r10 + 8*rbp], zmm6
        add     rbp, 32
        cmp     rdi, rbp
        jne     .LBB0_16
.LBB0_17:                               # %L589
                                        #   in Loop: Header=BB0_2 Depth=1
        cmp     rdi, rbx
        jg      .LBB0_25
# %bb.18:                               # %L591
                                        #   in Loop: Header=BB0_2 Depth=1
        cmp     qword ptr [rsp - 72], rdi       # 8-byte Folded Reload
        jl      .LBB0_19
# %bb.20:                               # %L613
                                        #   in Loop: Header=BB0_2 Depth=1
        cmp     qword ptr [rsp - 32], rdi       # 8-byte Folded Reload
        jge     .LBB0_22
# %bb.21:                               # %L616
                                        #   in Loop: Header=BB0_2 Depth=1
        vmovupd zmm2, zmmword ptr [rdx + 8*rdi]
        mov     ecx, dword ptr [rsp - 84]       # 4-byte Reload
        kmovd   k1, ecx
        vmovupd zmm3 {k1} {z}, zmmword ptr [rdx + 8*rdi + 64]
        vmovupd zmm4 {k1} {z}, zmmword ptr [r8 + 8*rdi + 64]
        vbroadcastsd    zmm1, xmm1
        vfnmadd213pd    zmm2, zmm1, zmmword ptr [r8 + 8*rdi] # zmm2 = -(zmm1 * zmm2) + mem
        vfnmadd231pd    zmm4, zmm1, zmm3        # zmm4 = -(zmm1 * zmm3) + zmm4
        vmovupd zmmword ptr [r8 + 8*rdi], zmm2
        vmovupd zmmword ptr [r8 + 8*rdi + 64] {k1}, zmm4
        jmp     .LBB0_25
.LBB0_22:                               # %L632
                                        #   in Loop: Header=BB0_2 Depth=1
        vmovupd zmm3, zmmword ptr [rdx + 8*rdi]
        vmovupd zmm2, zmmword ptr [rdx + 8*rdi + 64]
        cmp     qword ptr [rsp - 40], rdi       # 8-byte Folded Reload
        jge     .LBB0_24
# %bb.23:                               # %L635
                                        #   in Loop: Header=BB0_2 Depth=1
        lea     rbp, [rdx + 8*rdi]
        add     rbp, 128
        mov     ecx, dword ptr [rsp - 84]       # 4-byte Reload
        kmovd   k1, ecx
        vmovupd zmm4 {k1} {z}, zmmword ptr [rbp]
        vmovupd zmm5 {k1} {z}, zmmword ptr [r8 + 8*rdi + 128]
        vbroadcastsd    zmm1, xmm1
        vfnmadd213pd    zmm3, zmm1, zmmword ptr [r8 + 8*rdi] # zmm3 = -(zmm1 * zmm3) + mem
        vfnmadd213pd    zmm2, zmm1, zmmword ptr [r8 + 8*rdi + 64] # zmm2 = -(zmm1 * zmm2) + mem
        vfnmadd231pd    zmm5, zmm1, zmm4        # zmm5 = -(zmm1 * zmm4) + zmm5
        vmovupd zmmword ptr [r8 + 8*rdi], zmm3
        vmovupd zmmword ptr [r8 + 8*rdi + 64], zmm2
        vmovupd zmmword ptr [r8 + 8*rdi + 128] {k1}, zmm5
        jmp     .LBB0_25
.LBB0_24:                               # %L656
                                        #   in Loop: Header=BB0_2 Depth=1
        lea     rbp, [rdx + 8*rdi]
        vmovupd zmm4, zmmword ptr [rbp + 128]
        mov     ecx, dword ptr [rsp - 84]       # 4-byte Reload
        kmovd   k1, ecx
        vmovupd zmm5 {k1} {z}, zmmword ptr [rbp + 192]
        vmovupd zmm6 {k1} {z}, zmmword ptr [r8 + 8*rdi + 192]
        vbroadcastsd    zmm1, xmm1
        vfnmadd213pd    zmm3, zmm1, zmmword ptr [r8 + 8*rdi] # zmm3 = -(zmm1 * zmm3) + mem
        vfnmadd213pd    zmm2, zmm1, zmmword ptr [r8 + 8*rdi + 64] # zmm2 = -(zmm1 * zmm2) + mem
        vfnmadd213pd    zmm4, zmm1, zmmword ptr [r8 + 8*rdi + 128] # zmm4 = -(zmm1 * zmm4) + mem
        vfnmadd231pd    zmm6, zmm1, zmm5        # zmm6 = -(zmm1 * zmm5) + zmm6
        vmovupd zmmword ptr [r8 + 8*rdi], zmm3
        vmovupd zmmword ptr [r8 + 8*rdi + 64], zmm2
        vmovupd zmmword ptr [r8 + 8*rdi + 128], zmm4
        vmovupd zmmword ptr [r8 + 8*rdi + 192] {k1}, zmm6
        jmp     .LBB0_25
.Lfunc_end0:
        .size   "julia_reflectorApply!_4509", .Lfunc_end0-"julia_reflectorApply!_4509"
        .cfi_endproc
                                        # -- End function
        .type   .L_j_const1,@object             # @_j_const1
        .section        .rodata.cst8,"aM",@progbits,8
        .p2align        3
.L_j_const1:
        .quad   1                               # 0x1
        .size   .L_j_const1, 8

        .section        ".note.GNU-stack","",@progbits

[chriselrod]

There's basically only one change between 0.12.118 and 0.12.119: https://github.com/JuliaSIMD/LoopVectorization.jl/compare/v0.12.118...v0.12.119 so if the change were in LoopVectorization.jl itself instead of a dependency, there is only one place I have to look.

However, I cannot reproduce a performance problem with either AVX512 or AVX2.

Additionally, that change should be irrelevant here. So, more likely there's a problem in a dependency somewhere that in LV itself, and switching versions changed the dependencies.

[ffreyer]

Versioninfo:

Julia Version 1.7.0
Commit 3bf9d17731 (2021-11-30 12:12 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i5-6600 CPU @ 3.30GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-12.0.1 (ORCJIT, skylake)

I put code_typed and native in a gist since they're quite long: https://gist.github.com/ffreyer/d8427ec1cf4215f69efed8a30f5ec04d

I checked this on the login node of a cluster now as well and I don't get a slow down there. So maybe it's specific to julia 1.7 or my cpu?

julia> versioninfo()
Julia Version 1.7.1
Commit ac5cc99908* (2021-12-22 19:35 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Xeon(R) Gold 6148 CPU @ 2.40GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-12.0.1 (ORCJIT, skylake-avx512)

# with LoopVectorization 0.12.125
julia> @benchmark reflectorApply!($x, $τ, $y)
BenchmarkTools.Trial: 10000 samples with 165 evaluations.
 Range (min … max):  651.345 ns …  2.410 μs  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     692.697 ns              ┊ GC (median):    0.00%
 Time  (mean ± σ):   703.326 ns ± 64.135 ns  ┊ GC (mean ± σ):  0.00% ± 0.00%

  ▅█  ▁▂▁ ▁▄▆   ▁    ▃▅▆  ▁▂   ▁                       ▃       ▁
  ██▃████▆████▆▇██▆▇████▆▇██▇▇███▇▇▇▇▇▆▅▆▄▆▆▅▄▄▂▄▃▂▃▂▃▄█▅▂▂▅▆▄ █
  651 ns        Histogram: log(frequency) by time       914 ns <

 Memory estimate: 0 bytes, allocs estimate: 0.

[chriselrod]

From your code:

        movabs  rax, offset StrideIndex
        vzeroupper
        call    rax
        mov     r13, qword ptr [r13]
        mov     rax, qword ptr [rsp + 96]
        add     rax, r13
        mov     qword ptr [rsp + 104], rax
        mov     rdi, r12
        mov     rsi, qword ptr [rsp + 32]
        movabs  rax, offset StrideIndex
        call    rax

or

│            invoke LayoutPointers.StrideIndex(x::SubArray{Float64, 1, Matrix{Float64}, Tuple{UnitRange{Int64}, Int64}, true})::ArrayInterface.StrideIndex{1, (1,), 1, Tuple{Static.StaticInt{1}}, Tuple{Static.StaticInt{1}}}
│     %136 = Base.getfield(A, :parent)::Matrix{Float64}
│     %137 = $(Expr(:foreigncall, :(:jl_array_ptr), Ptr{Float64}, svec(Any), 0, :(:ccall), :(%136)))::Ptr{Float64}
│     %138 = Base.getfield(A, :parent)::Matrix{Float64}
│     %139 = Base.getfield(A, :indices)::Tuple{UnitRange{Int64}, UnitRange{Int64}}
│     %140 = LayoutPointers.getfield(%139, 1, false)::UnitRange{Int64}
│     %141 = Base.getfield(%140, :start)::Int64
│     %142 = Base.sub_int(%141, 1)::Int64
│     %143 = Core.getfield(%139, 2)::UnitRange{Int64}
│     %144 = Base.getfield(%143, :start)::Int64
│     %145 = Base.sub_int(%144, 1)::Int64
│     %146 = Base.arraysize(%138, 1)::Int64
│            Base.arraysize(%138, 2)::Int64
│     %148 = Base.mul_int(1, %146)::Int64
│     %149 = Base.mul_int(%142, 1)::Int64
│     %150 = Base.mul_int(%145, %148)::Int64
│     %151 = Base.add_int(%149, %150)::Int64
│     %152 = Base.mul_int(8, %151)::Int64
│     %153 = Core.bitcast(Core.UInt, %137)::UInt64
│     %154 = Base.bitcast(UInt64, %152)::UInt64
│     %155 = Base.add_ptr(%153, %154)::UInt64
│     %156 = Core.bitcast(Ptr{Float64}, %155)::Ptr{Float64}
│     %157 = invoke LayoutPointers.StrideIndex(A::SubArray{Float64, 2, Matrix{Float64}, Tuple{UnitRange{Int64}, UnitRange{Int64}}, false})::ArrayInterface.StrideIndex{2, (1, 2), 1, Tuple{Static.StaticInt{1}, Int64}, Tuple{Static.StaticInt{1}, Static.StaticInt{1}}}

That is bad.

[chriselrod]

What do you get for ] st -m ArrayInterface?

[ffreyer]

(@v1.7) pkg> st -m ArrayInterface
      Status `~/.julia/environments/v1.7/Manifest.toml`
  [4fba245c] ArrayInterface v6.0.22

[ffreyer]

And no slowdown in 1.8.0

[chriselrod]

I'm guessing it is because StrideIndex is not inlining

[ffreyer]

I also tried

(@v1.7) pkg> activate .
  Activating new project at `~/Documents/julia source`
(julia source) pkg> add LoopVectorization BenchmarkTools

and I still get a slowdown in 1.7. The package version match, except for some packages getting version numbers in 1.8 while not having any in 1.7 (ArgTools, Downloads, ...)

[ffreyer]

With https://github.com/JuliaArrays/ArrayInterface.jl/pull/343:

https://gist.github.com/ffreyer/d63a95c21857678e8b76f40fff457a4a

I'm fine with switching to the view-less version/upgrading Julia too

[chriselrod]

Could you share the code typed? That looks really bad, but I don't know what functions are being called.

[ffreyer]

I updated the gist

[chriselrod]

@Tokazama do you want to make sure ArrayInterfaceCore.is_splat_index is elided?

[chriselrod]

I can confirm that I see the regression on 1.7.3:

julia> @benchmark reflectorApply!($x, $τ, $y)
BenchmarkTools.Trial: 10000 samples with 1 evaluation.
 Range (min … max):   77.337 μs … 142.382 μs  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     127.234 μs               ┊ GC (median):    0.00%
 Time  (mean ± σ):   127.364 μs ±   2.679 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

                                                          █▂
  ▂▂▂▁▂▁▂▂▂▂▂▂▂▂▁▂▂▂▁▂▂▂▂▂▂▂▂▂▁▂▂▂▂▁▁▂▂▂▂▂▂▁▂▂▂▁▁▂▂▁▂▁▂▂▂▄██▄▄▃ ▂
  77.3 μs          Histogram: frequency by time          131 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

julia> versioninfo()
Julia Version 1.7.3
Commit 742b9abb4d (2022-05-06 12:58 UTC)
Platform Info:
  OS: Linux (x86_64-redhat-linux)
  CPU: Intel(R) Core(TM) i9-7980XE CPU @ 2.60GHz

[chriselrod]

35 ──││││││ %87  = ArrayInterfaceCore.is_splat_index::Core.Const(ArrayInterfaceCore.is_splat_index)
│    ││││││┌ @ /home/chriselrod/.julia/dev/ArrayInterface/lib/ArrayInterfaceCore/src/ArrayInterfaceCore.jl:39 within `map_tuple_type`
│    │││││││ %88  = %new(ArrayInterfaceCore.var"#1#2"{typeof(ArrayInterfaceCore.is_splat_index), DataType}, %87, Tuple{UnitRange{Int64}, Int64})::Core.Const(ArrayInterfaceCore.var"#1#2"{typeof(ArrayInterfaceCore.is_splat_index), DataType}(ArrayInterfaceCore.is_splat_index, Tuple{UnitRange{Int64}, Int64}))
│    │││││││┌ @ ntuple.jl:49 within `ntuple`
│    ││││││││        invoke %88(1::Int64)
│    ││││││││        invoke %88(2::Int64)

and

   %89 = invoke #1(::Int64)::Core.Const(false)
   %90 = invoke #1(::Int64)::Core.Const(false)
   %96 = invoke #1(::Int64)::Core.Const(false)
   %97 = invoke #1(::Int64)::Core.Const(false)
   %101 = invoke #1(::Int64)::Core.Const(false)
   %102 = invoke #1(::Int64)::Core.Const(false)
   %132 = invoke #1(::Int64)::Core.Const(false)
   %133 = invoke #1(::Int64)::Core.Const(false)
   %139 = invoke #1(::Int64)::Core.Const(false)
   %140 = invoke #1(::Int64)::Core.Const(false)
   %144 = invoke #1(::Int64)::Core.Const(false)
   %145 = invoke #1(::Int64)::Core.Const(false)
   %378 = invoke #1(::Int64)::Core.Const(false)
   %379 = invoke #1(::Int64)::Core.Const(false)
   %385 = invoke #1(::Int64)::Core.Const(false)
   %386 = invoke #1(::Int64)::Core.Const(false)
   %390 = invoke #1(::Int64)::Core.Const(false)
   %391 = invoke #1(::Int64)::Core.Const(false)
   %431 = invoke #1(::Int64)::Core.Const(false)
   %432 = invoke #1(::Int64)::Core.Const(false)
   %438 = invoke #1(::Int64)::Core.Const(false)
   %439 = invoke #1(::Int64)::Core.Const(false)
   %443 = invoke #1(::Int64)::Core.Const(false)
   %444 = invoke #1(::Int64)::Core.Const(false)

Look at all these useless function calls known to return false.

[chriselrod]

@ffreyer Try the ArrayInterfaceCore version from that PR, with the map_tuple_type that specializes. It fixed the regression for me.

[ffreyer]

With that I get

julia> @benchmark reflectorApply!($x, $τj, $y)
BenchmarkTools.Trial: 10000 samples with 71 evaluations.
 Range (min … max):  847.521 ns …   3.534 μs  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     921.204 ns               ┊ GC (median):    0.00%
 Time  (mean ± σ):   972.610 ns ± 190.748 ns  ┊ GC (mean ± σ):  0.00% ± 0.00%

   █ ▇▃▂▁                                                        
  ▃█▇████▆▃▂▁▁▁▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁ ▂
  848 ns           Histogram: frequency by time         1.84 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

which is much better but still a bit slower than it used to be

[chriselrod]

Yeah. The @code_typed still shows a bunch of crap coming from @nospecializes

   35 ── %87  = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 1)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││╻╷╷╷╷╷╷╷      bytestrideindex
   │     %88  = (isa)(%87, Type{UnitRange{Int64}})::Bool                                                                                │││┃││││││       StrideIndex
   └────        goto #37 if not %88                                                                                                     ││││┃│││││        stride_rank
   36 ──        goto #40                                                                                                                │││││┃││││         to_parent_dims
   37 ── %91  = (isa)(%87, Type{Int64})::Bool                                                                                           ││││││┃│││          IndicesInfo
   └────        goto #39 if not %91                                                                                                     │││││││┃││           map_tuple_type
   38 ──        goto #40                                                                                                                ││││││││┃│            ntuple
   39 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       │││││││││┃             #36
   └────        unreachable                                                                                                             ││││││││││
   40 ┄─        goto #41                                                                                                                ││││││││││
   41 ── %97  = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 2)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││││││││││
   │     %98  = (isa)(%97, Type{UnitRange{Int64}})::Bool                                                                                ││││││││││
   └────        goto #43 if not %98                                                                                                     ││││││││││
   42 ──        goto #46                                                                                                                ││││││││││
   43 ── %101 = (isa)(%97, Type{Int64})::Bool                                                                                           ││││││││││
   └────        goto #45 if not %101                                                                                                    ││││││││││
   44 ──        goto #46                                                                                                                ││││││││││
   45 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       ││││││││││
   └────        unreachable                                                                                                             ││││││││││
   46 ┄─        goto #47                                                                                                                ││││││││││
   47 ──        goto #48                                                                                                                │││││││││
   48 ──        goto #49                                                                                                                ││││││││
   49 ── %109 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 1)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││││││││╻╷            ntuple
   │     %110 = (isa)(%109, Type{UnitRange{Int64}})::Bool                                                                               │││││││││┃             #36
   └────        goto #51 if not %110                                                                                                    ││││││││││
   50 ──        goto #54                                                                                                                ││││││││││
   51 ── %113 = (isa)(%109, Type{Int64})::Bool                                                                                          ││││││││││
   └────        goto #53 if not %113                                                                                                    ││││││││││
   52 ──        goto #54                                                                                                                ││││││││││
   53 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       ││││││││││
   └────        unreachable                                                                                                             ││││││││││
   54 ┄─        goto #55                                                                                                                ││││││││││
   55 ── %119 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 2)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││││││││││
   │     %120 = (isa)(%119, Type{UnitRange{Int64}})::Bool                                                                               ││││││││││
   └────        goto #57 if not %120                                                                                                    ││││││││││
   56 ──        goto #60                                                                                                                ││││││││││
   57 ── %123 = (isa)(%119, Type{Int64})::Bool                                                                                          ││││││││││
   └────        goto #59 if not %123                                                                                                    ││││││││││
   58 ──        goto #60                                                                                                                ││││││││││
   59 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       ││││││││││
   └────        unreachable                                                                                                             ││││││││││
   60 ┄─        goto #61                                                                                                                ││││││││││
   61 ──        goto #62                                                                                                                │││││││││
   62 ──        goto #63                                                                                                                ││││││││
   63 ──        goto #64                                                                                                                │││││││
   64 ──        goto #65                                                                                                                ││││││
   65 ──        goto #66                                                                                                                │││││
   66 ──        nothing::Nothing                                                                                                        │
   67 ──        nothing::Nothing                                                                                                        │
   68 ── %136 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 1)::Union{Type{UnitRange{Int64}}, Type{Int64}}             │││││╻╷╷╷╷         from_parent_dims
   │     %137 = (isa)(%136, Type{UnitRange{Int64}})::Bool                                                                               ││││││┃│││          IndicesInfo
   └────        goto #70 if not %137                                                                                                    │││││││┃││           map_tuple_type
   69 ──        goto #73                                                                                                                ││││││││┃│            ntuple
   70 ── %140 = (isa)(%136, Type{Int64})::Bool                                                                                          │││││││││┃             #36
   └────        goto #72 if not %140                                                                                                    ││││││││││
   71 ──        goto #73                                                                                                                ││││││││││
   72 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       ││││││││││
   └────        unreachable                                                                                                             ││││││││││
   73 ┄─        goto #74                                                                                                                ││││││││││
   74 ── %146 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 2)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││││││││││
   │     %147 = (isa)(%146, Type{UnitRange{Int64}})::Bool                                                                               ││││││││││
   └────        goto #76 if not %147                                                                                                    ││││││││││
   75 ──        goto #79                                                                                                                ││││││││││
   76 ── %150 = (isa)(%146, Type{Int64})::Bool                                                                                          ││││││││││
   └────        goto #78 if not %150                                                                                                    ││││││││││
   77 ──        goto #79                                                                                                                ││││││││││
   78 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       ││││││││││
   └────        unreachable                                                                                                             ││││││││││
   79 ┄─        goto #80                                                                                                                ││││││││││
   80 ──        goto #81                                                                                                                │││││││││
   81 ──        goto #82                                                                                                                ││││││││
   82 ── %158 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 1)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││││││││╻╷            ntuple
   │     %159 = (isa)(%158, Type{UnitRange{Int64}})::Bool                                                                               │││││││││┃             #36
   └────        goto #84 if not %159                                                                                                    ││││││││││
   83 ──        goto #87                                                                                                                ││││││││││
   84 ── %162 = (isa)(%158, Type{Int64})::Bool                                                                                          ││││││││││
   └────        goto #86 if not %162                                                                                                    ││││││││││
   85 ──        goto #87                                                                                                                ││││││││││
   86 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       ││││││││││
   └────        unreachable                                                                                                             ││││││││││
   87 ┄─        goto #88                                                                                                                ││││││││││
   88 ── %168 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 2)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││││││││││
   │     %169 = (isa)(%168, Type{UnitRange{Int64}})::Bool                                                                               ││││││││││
   └────        goto #90 if not %169                                                                                                    ││││││││││
   89 ──        goto #93                                                                                                                ││││││││││
   90 ── %172 = (isa)(%168, Type{Int64})::Bool                                                                                          ││││││││││
   └────        goto #92 if not %172                                                                                                    ││││││││││
   91 ──        goto #93                                                                                                                ││││││││││
   92 ──        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       ││││││││││
   └────        unreachable                                                                                                             ││││││││││
   93 ┄─        goto #94                                                                                                                ││││││││││
   94 ──        goto #95                                                                                                                │││││││││
   95 ──        goto #96                                                                                                                ││││││││
   96 ──        goto #97                                                                                                                │││││││
   97 ──        goto #98                                                                                                                ││││││
   98 ──        goto #99                                                                                                                │││││
   99 ── %183 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 1)::Union{Type{UnitRange{Int64}}, Type{Int64}}             │││││╻╷╷╷╷╷        strides
   │     %184 = (isa)(%183, Type{UnitRange{Int64}})::Bool                                                                               ││││││┃││││         to_parent_dims
   └────        goto #101 if not %184                                                                                                   │││││││┃│││          IndicesInfo
   100 ─        goto #104                                                                                                               ││││││││┃││           map_tuple_type
   101 ─ %187 = (isa)(%183, Type{Int64})::Bool                                                                                          │││││││││┃│            ntuple
   └────        goto #103 if not %187                                                                                                   ││││││││││┃             #36
   102 ─        goto #104                                                                                                               │││││││││││
   103 ─        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       │││││││││││
   └────        unreachable                                                                                                             │││││││││││
   104 ┄        goto #105                                                                                                               │││││││││││
   105 ─ %193 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 2)::Union{Type{UnitRange{Int64}}, Type{Int64}}             │││││││││││
   │     %194 = (isa)(%193, Type{UnitRange{Int64}})::Bool                                                                               │││││││││││
   └────        goto #107 if not %194                                                                                                   │││││││││││
   106 ─        goto #110                                                                                                               │││││││││││
   107 ─ %197 = (isa)(%193, Type{Int64})::Bool                                                                                          │││││││││││
   └────        goto #109 if not %197                                                                                                   │││││││││││
   108 ─        goto #110                                                                                                               │││││││││││
   109 ─        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       │││││││││││
   └────        unreachable                                                                                                             │││││││││││
   110 ┄        goto #111                                                                                                               │││││││││││
   111 ─        goto #112                                                                                                               ││││││││││
   112 ─        goto #113                                                                                                               │││││││││
   113 ─ %205 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 1)::Union{Type{UnitRange{Int64}}, Type{Int64}}             │││││││││╻╷            ntuple
   │     %206 = (isa)(%205, Type{UnitRange{Int64}})::Bool                                                                               ││││││││││┃             #36
   └────        goto #115 if not %206                                                                                                   │││││││││││
   114 ─        goto #118                                                                                                               │││││││││││
   115 ─ %209 = (isa)(%205, Type{Int64})::Bool                                                                                          │││││││││││
   └────        goto #117 if not %209                                                                                                   │││││││││││
   116 ─        goto #118                                                                                                               │││││││││││
   117 ─        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       │││││││││││
   └────        unreachable                                                                                                             │││││││││││
   118 ┄        goto #119                                                                                                               │││││││││││
   119 ─ %215 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 2)::Union{Type{UnitRange{Int64}}, Type{Int64}}             │││││││││││
   │     %216 = (isa)(%215, Type{UnitRange{Int64}})::Bool                                                                               │││││││││││
   └────        goto #121 if not %216                                                                                                   │││││││││││
   120 ─        goto #124                                                                                                               │││││││││││
   121 ─ %219 = (isa)(%215, Type{Int64})::Bool                                                                                          │││││││││││
   └────        goto #123 if not %219                                                                                                   │││││││││││
   122 ─        goto #124                                                                                                               │││││││││││
   123 ─        Core.throw(ErrorException("fatal error in type inference (type bound)"))::Union{}                                       │││││││││││
   └────        unreachable                                                                                                             │││││││││││
   124 ┄        goto #125                                                                                                               │││││││││││
   125 ─        goto #126                                                                                                               ││││││││││

and I suspect this makes it into the generated code, but I'm not sure. There aren't any calls.

[Tokazama]

We might need to revert the changes to flatten_tuples too

[Tokazama]

This is probably one of those instances where I should see what comes out of this when we use @assume_effects so we can still cut down on needless code generation.

[chriselrod]

FWIW, master seems fine. I haven't tried 1.8. But Julia 1.7 is not.

So we could have different versions for >= 1.8 vs not.

[Tokazama]

FWIW, master seems fine. I haven't tried 1.8. But Julia 1.7 is not.

So we could have different versions for >= 1.8 vs not.

I haven't tested this particular issue, but I know from experience that pre 1.8 inference requires a lot more explicitly defined types

[chriselrod]

This isn't even an inference failure. The compiler just isn't doing its job

   82 ── %158 = ArrayInterfaceCore.fieldtype(Tuple{UnitRange{Int64}, Int64}, 1)::Union{Type{UnitRange{Int64}}, Type{Int64}}             ││││││││╻╷            ntuple
   │     %159 = (isa)(%158, Type{UnitRange{Int64}})::Bool 

[ffreyer]

(1) With the new changes from the pr:

julia> @benchmark reflectorApply!($x, $τj, $y)
BenchmarkTools.Trial: 10000 samples with 156 evaluations.
 Range (min … max):  662.442 ns …  1.881 μs  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     739.295 ns              ┊ GC (median):    0.00%
 Time  (mean ± σ):   754.946 ns ± 87.526 ns  ┊ GC (mean ± σ):  0.00% ± 0.00%

    █      ▁                                                    
  ▄▁█▅▄█▄██████▆▅▅▄▃▃▃▃▃▃▂▂▂▂▂▂▃▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂ ▃
  662 ns          Histogram: frequency by time         1.14 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

vs (2) LoopVectorization@v0.12.18:

@benchmark reflectorApply!($x, $τ, $y)
BenchmarkTools.Trial: 10000 samples with 151 evaluations.
 Range (min … max):  677.364 ns …   1.560 μs  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     709.536 ns               ┊ GC (median):    0.00%
 Time  (mean ± σ):   742.538 ns ± 103.227 ns  ┊ GC (mean ± σ):  0.00% ± 0.00%

   █ ▆▇▂▂ ▁  ▁▂▂▁▁▁▁                                            ▁
  ▅█▆███████▆█████████▇▇███▇███▇▇▇▇▇▇▆█▆▇▇▇█▇▇▆▅▅▆▇▆▇▇▇▇▆▄▄▄▅▅▆ █
  677 ns        Histogram: log(frequency) by time       1.17 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

Across multiple benchmarks (1) usually has lower min times, but higher median, mean and max times than (2).

[chriselrod]

If you want to fix things, just @code_typed and look for any Julia function calls (like ArrayInterfaceCore.fieldtype above). If there are any, find out how to get rid of them (probably by encouraging the compiler to specialize, meaning deleting @nospecialize and replacing T::Type with ::Type{T}) where {T} in function signatures.