前提と質問内容

(前提)3x3の正方行列の掛け算を行うプログラムをC言語で書き、
compiler explorerというC言語のアセンブラ出力を確認できるページで
x86-64 icc 19.0.1とMIPS gcc 5.4のアセンブリ言語に出力しました。

(質問)内側のループにおける代入文とフロー制御の命令回数と、プログラム全体の計算複雑度はC言語からアセンブリ言語に変換すると変わるのでしょうか。

現在の見解

C言語のプログラムでは、内側のループにおける代入文とフロー制御(C言語はプログラム上でプログラマーが行う必要がないのかもしれませんが)の命令数は

C[i][j] += A[i][k]*B[k][j];

の1回だと考えています。

またプログラム全体の計算複雑度はO(N^3)だと思います。

(現在の見解)内側のループにおける代入文とフロー制御は、アセンブリ言語の方が明確にアドレスなどを指定しないといけないので、命令数が増えると考えています。一方、プログラム全体の計算複雑度はどのように考えればいいのかアセンブリ言語を見てもわからず困っています。

内側のループにおける代入文とフロー制御について、
例えばMIPSの場合、compiler explorerで

C[i][j] += A[i][k]*B[k][j];

と対応する以下の部分の命令数を数えれば「内側のループにおける代入文とフロー制御の命令回数」と言えるのでしょうか。

lw $3,32($fp)
nop
move $2,$3
sll $2,$2,1
addu $2,$2,$3
lw $3,36($fp)
nop
addu $2,$2,$3
sll $2,$2,3
addiu $3,$fp,32
addu $2,$3,$2
lwc1 $f2,164($2)
nop
lwc1 $f3,160($2)
lw $3,32($fp)
nop
move $2,$3
sll $2,$2,1
addu $2,$2,$3
lw $3,40($fp)
nop
addu $2,$2,$3
sll $2,$2,3
addiu $3,$fp,32
addu $2,$3,$2
lwc1 $f4,20($2)
nop
lwc1 $f5,16($2)
lw $3,40($fp)
nop
move $2,$3
sll $2,$2,1
addu $2,$2,$3
lw $3,36($fp)
nop
addu $2,$2,$3
sll $2,$2,3
addiu $3,$fp,32
addu $2,$3,$2
lwc1 $f0,92($2)
nop
lwc1 $f1,88($2)
nop
mul.d $f0,$f4,$f0
add.d $f0,$f2,$f0
lw $3,32($fp)
nop
move $2,$3
sll $2,$2,1
addu $2,$2,$3
lw $3,36($fp)
nop
addu $2,$2,$3
sll $2,$2,3
addiu $3,$fp,32
addu $2,$3,$2
swc1 $f0,164($2)
swc1 $f1,160($2)

実行中のプログラム

x86-64 icc 19.0.1とMIPS gcc 5.4のアセンブリ言語に出力したプログラムも掲載しましたが、C言語と対応する部分を確認するには、以下のC言語のプログラムをcompiler explorerに貼り付けて変換いただく方がわかりやすいと思います。

C言語のプログラム

#include<stdio.h>

#define N 3
int 
main(int argc, char *argv[])
{
    double A[N][N] = {
        {1.0, 3.0, 1.0},
        {3.0, 1.0, 3.0},
        {1.0, 1.0, 1.0}
    };

    double B[N][N] = {
        {6.0, 1.0, 0.0},
        {0.0, 1.0, 6.0},
        {0.0, 1.0, 1.0}
    };

    double C[N][N] = {
        {0.0, 0.0, 0.0},
        {0.0, 0.0, 0.0},
        {0.0, 0.0, 0.0}
    };
    int i, j, k;

    for(i=0; i<N; i++)
        for(j=0; j<N; j++)
            for(k=0; k<N; k++)
                C[i][j] += A[i][k]*B[k][j];

    for(i=0; i<N; i++)
        for(j=0; j<N; j++)
            printf("C[%d][%d] = %f\n", i, j, C[i][j]);
}

MIPSのプログラム

$LC2:
        .ascii  "C[%d][%d] = %f\012\000"
$LC0:
        .word   1072693248
        .word   0
        .word   1074266112
        .word   0
        .word   1072693248
        .word   0
        .word   1074266112
        .word   0
        .word   1072693248
        .word   0
        .word   1074266112
        .word   0
        .word   1072693248
        .word   0
        .word   1072693248
        .word   0
        .word   1072693248
        .word   0
$LC1:
        .word   1075314688
        .word   0
        .word   1072693248
        .word   0
        .word   0
        .word   0
        .word   0
        .word   0
        .word   1072693248
        .word   0
        .word   1075314688
        .word   0
        .word   0
        .word   0
        .word   1072693248
        .word   0
        .word   1072693248
        .word   0
main:
        addiu   $sp,$sp,-272
        sw      $31,268($sp)
        sw      $fp,264($sp)
        move    $fp,$sp
        sw      $4,272($fp)
        sw      $5,276($fp)
        lui     $2,%hi($LC0)
        addiu   $3,$fp,48
        addiu   $2,$2,%lo($LC0)
        li      $4,72                 # 0x48
        move    $6,$4
        move    $5,$2
        move    $4,$3
        jal     memcpy
        nop

        lui     $2,%hi($LC1)
        addiu   $3,$fp,120
        addiu   $2,$2,%lo($LC1)
        li      $4,72                 # 0x48
        move    $6,$4
        move    $5,$2
        move    $4,$3
        jal     memcpy
        nop

        sw      $0,196($fp)
        sw      $0,192($fp)
        sw      $0,204($fp)
        sw      $0,200($fp)
        sw      $0,212($fp)
        sw      $0,208($fp)
        sw      $0,220($fp)
        sw      $0,216($fp)
        sw      $0,228($fp)
        sw      $0,224($fp)
        sw      $0,236($fp)
        sw      $0,232($fp)
        sw      $0,244($fp)
        sw      $0,240($fp)
        sw      $0,252($fp)
        sw      $0,248($fp)
        sw      $0,260($fp)
        sw      $0,256($fp)
        sw      $0,32($fp)
$L7:
        lw      $2,32($fp)
        nop
        slt     $2,$2,3
        beq     $2,$0,$L2
        nop

        sw      $0,36($fp)
$L6:
        lw      $2,36($fp)
        nop
        slt     $2,$2,3
        beq     $2,$0,$L3
        nop

        sw      $0,40($fp)
$L5:
        lw      $2,40($fp)
        nop
        slt     $2,$2,3
        beq     $2,$0,$L4
        nop

        lw      $3,32($fp)
        nop
        move    $2,$3
        sll     $2,$2,1
        addu    $2,$2,$3
        lw      $3,36($fp)
        nop
        addu    $2,$2,$3
        sll     $2,$2,3
        addiu   $3,$fp,32
        addu    $2,$3,$2
        lwc1    $f2,164($2)
        nop
        lwc1    $f3,160($2)
        lw      $3,32($fp)
        nop
        move    $2,$3
        sll     $2,$2,1
        addu    $2,$2,$3
        lw      $3,40($fp)
        nop
        addu    $2,$2,$3
        sll     $2,$2,3
        addiu   $3,$fp,32
        addu    $2,$3,$2
        lwc1    $f4,20($2)
        nop
        lwc1    $f5,16($2)
        lw      $3,40($fp)
        nop
        move    $2,$3
        sll     $2,$2,1
        addu    $2,$2,$3
        lw      $3,36($fp)
        nop
        addu    $2,$2,$3
        sll     $2,$2,3
        addiu   $3,$fp,32
        addu    $2,$3,$2
        lwc1    $f0,92($2)
        nop
        lwc1    $f1,88($2)
        nop
        mul.d   $f0,$f4,$f0
        add.d   $f0,$f2,$f0
        lw      $3,32($fp)
        nop
        move    $2,$3
        sll     $2,$2,1
        addu    $2,$2,$3
        lw      $3,36($fp)
        nop
        addu    $2,$2,$3
        sll     $2,$2,3
        addiu   $3,$fp,32
        addu    $2,$3,$2
        swc1    $f0,164($2)
        swc1    $f1,160($2)
        lw      $2,40($fp)
        nop
        addiu   $2,$2,1
        sw      $2,40($fp)
        b       $L5
        nop

$L4:
        lw      $2,36($fp)
        nop
        addiu   $2,$2,1
        sw      $2,36($fp)
        b       $L6
        nop

$L3:
        lw      $2,32($fp)
        nop
        addiu   $2,$2,1
        sw      $2,32($fp)
        b       $L7
        nop

$L2:
        sw      $0,32($fp)
$L11:
        lw      $2,32($fp)
        nop
        slt     $2,$2,3
        beq     $2,$0,$L8
        nop

        sw      $0,36($fp)
$L10:
        lw      $2,36($fp)
        nop
        slt     $2,$2,3
        beq     $2,$0,$L9
        nop

        lw      $3,32($fp)
        nop
        move    $2,$3
        sll     $2,$2,1
        addu    $2,$2,$3
        lw      $3,36($fp)
        nop
        addu    $2,$2,$3
        sll     $2,$2,3
        addiu   $3,$fp,32
        addu    $2,$3,$2
        lwc1    $f0,164($2)
        nop
        lwc1    $f1,160($2)
        nop
        swc1    $f0,20($sp)
        swc1    $f1,16($sp)
        lw      $6,36($fp)
        lw      $5,32($fp)
        lui     $2,%hi($LC2)
        addiu   $4,$2,%lo($LC2)
        jal     printf
        nop

        lw      $2,36($fp)
        nop
        addiu   $2,$2,1
        sw      $2,36($fp)
        b       $L10
        nop

$L9:
        lw      $2,32($fp)
        nop
        addiu   $2,$2,1
        sw      $2,32($fp)
        b       $L11
        nop

$L8:
        move    $2,$0
        move    $sp,$fp
        lw      $31,268($sp)
        lw      $fp,264($sp)
        addiu   $sp,$sp,272
        j       $31
        nop

x86-64 のプログラム

.L_2__STRING.0:
        .long   1680169795
        .long   1680169821
        .long   540876893
        .long   681509

main:
        push      rbp                                           #7.1
        mov       rbp, rsp                                      #7.1
        sub       rsp, 256                                      #7.1
        mov       QWORD PTR [-8+rbp], rbx                       #7.1[spill]
        mov       DWORD PTR [-240+rbp], edi                     #7.1
        mov       QWORD PTR [-232+rbp], rsi                     #7.1
        lea       rax, QWORD PTR [-224+rbp]                     #8.17
        mov       edx, offset flat: A.136.0                     #8.17
        mov       ecx, 72                                       #8.17
        mov       rdi, rax                                      #8.17
        mov       rsi, rdx                                      #8.17
        mov       eax, ecx                                      #8.17
        shr       rcx, 2                                        #8.17
        rep   movsd                                             #8.17
        mov       ecx, eax                                      #8.17
        and       ecx, 3                                        #8.17
        rep   movsb                                             #8.17
        lea       rax, QWORD PTR [-152+rbp]                     #14.17
        mov       edx, offset flat: B.136.0                     #14.17
        mov       ecx, 72                                       #14.17
        mov       rdi, rax                                      #14.17
        mov       rsi, rdx                                      #14.17
        mov       eax, ecx                                      #14.17
        shr       rcx, 2                                        #14.17
        rep   movsd                                             #14.17
        mov       ecx, eax                                      #14.17
        and       ecx, 3                                        #14.17
        rep   movsb                                             #14.17
        lea       rax, QWORD PTR [-80+rbp]                      #20.17
        mov       edx, 0                                        #20.17
        mov       ecx, 72                                       #20.17
        mov       rdi, rax                                      #20.17
        mov       eax, edx                                      #20.17
        and       eax, 65535                                    #20.17
        mov       ah, al                                        #20.17
        mov       edx, eax                                      #20.17
        shl       eax, 16                                       #20.17
        or        eax, edx                                      #20.17
        mov       esi, ecx                                      #20.17
        shr       rcx, 2                                        #20.17
        rep   stosd                                             #20.17
        mov       ecx, esi                                      #20.17
        and       ecx, 3                                        #20.17
        rep   stosb                                             #20.17
        mov       DWORD PTR [-256+rbp], 0                       #27.6
..B1.5:                         # Preds ..B1.6 ..B1.4
        mov       eax, DWORD PTR [-256+rbp]                     #27.11
        cmp       eax, 3                                        #27.13
        jl        ..B1.7        # Prob 50%                      #27.13
        jmp       ..B1.13       # Prob 100%                     #27.13
..B1.6:                         # Preds ..B1.8
        mov       eax, 1                                        #27.16
        add       eax, DWORD PTR [-256+rbp]                     #27.16
        mov       DWORD PTR [-256+rbp], eax                     #27.16
        jmp       ..B1.5        # Prob 100%                     #27.16
..B1.7:                         # Preds ..B1.5
        mov       DWORD PTR [-252+rbp], 0                       #28.7
..B1.8:                         # Preds ..B1.9 ..B1.7
        mov       eax, DWORD PTR [-252+rbp]                     #28.12
        cmp       eax, 3                                        #28.14
        jl        ..B1.10       # Prob 50%                      #28.14
        jmp       ..B1.6        # Prob 100%                     #28.14
..B1.9:                         # Preds ..B1.11
        mov       eax, 1                                        #28.17
        add       eax, DWORD PTR [-252+rbp]                     #28.17
        mov       DWORD PTR [-252+rbp], eax                     #28.17
        jmp       ..B1.8        # Prob 100%                     #28.17
..B1.10:                        # Preds ..B1.8
        mov       DWORD PTR [-248+rbp], 0                       #29.8
..B1.11:                        # Preds ..B1.12 ..B1.10
        mov       eax, DWORD PTR [-248+rbp]                     #29.13
        cmp       eax, 3                                        #29.15
        jge       ..B1.9        # Prob 50%                      #29.15
        lea       rax, QWORD PTR [-80+rbp]                      #30.5
        mov       edx, DWORD PTR [-256+rbp]                     #30.7
        movsxd    rdx, edx                                      #30.5
        imul      rdx, rdx, 24                                  #30.5
        add       rax, rdx                                      #30.5
        mov       edx, DWORD PTR [-252+rbp]                     #30.10
        movsxd    rdx, edx                                      #30.5
        imul      rdx, rdx, 8                                   #30.5
        add       rax, rdx                                      #30.5
        lea       rdx, QWORD PTR [-224+rbp]                     #30.16
        mov       ecx, DWORD PTR [-256+rbp]                     #30.18
        movsxd    rcx, ecx                                      #30.16
        imul      rcx, rcx, 24                                  #30.16
        add       rdx, rcx                                      #30.16
        mov       ecx, DWORD PTR [-248+rbp]                     #30.21
        movsxd    rcx, ecx                                      #30.16
        imul      rcx, rcx, 8                                   #30.16
        add       rdx, rcx                                      #30.16
        movsd     xmm0, QWORD PTR [rdx]                         #30.16
        lea       rdx, QWORD PTR [-152+rbp]                     #30.24
        mov       ecx, DWORD PTR [-248+rbp]                     #30.26
        movsxd    rcx, ecx                                      #30.24
        imul      rcx, rcx, 24                                  #30.24
        add       rdx, rcx                                      #30.24
        mov       ecx, DWORD PTR [-252+rbp]                     #30.29
        movsxd    rcx, ecx                                      #30.24
        imul      rcx, rcx, 8                                   #30.24
        add       rdx, rcx                                      #30.24
        movsd     xmm1, QWORD PTR [rdx]                         #30.24
        mulsd     xmm0, xmm1                                    #30.24
        movsd     xmm1, QWORD PTR [rax]                         #30.5
        addsd     xmm1, xmm0                                    #30.5
        lea       rax, QWORD PTR [-80+rbp]                      #30.5
        mov       edx, DWORD PTR [-256+rbp]                     #30.7
        movsxd    rdx, edx                                      #30.5
        imul      rdx, rdx, 24                                  #30.5
        add       rax, rdx                                      #30.5
        mov       edx, DWORD PTR [-252+rbp]                     #30.10
        movsxd    rdx, edx                                      #30.5
        imul      rdx, rdx, 8                                   #30.5
        add       rax, rdx                                      #30.5
        movsd     QWORD PTR [rax], xmm1                         #30.5
        mov       eax, 1                                        #29.18
        add       eax, DWORD PTR [-248+rbp]                     #29.18
        mov       DWORD PTR [-248+rbp], eax                     #29.18
        jmp       ..B1.11       # Prob 100%                     #29.18
..B1.13:                        # Preds ..B1.5
        mov       DWORD PTR [-256+rbp], 0                       #32.6
..B1.14:                        # Preds ..B1.15 ..B1.13
        mov       eax, DWORD PTR [-256+rbp]                     #32.11
        cmp       eax, 3                                        #32.13
        jl        ..B1.16       # Prob 50%                      #32.13
        jmp       ..B1.20       # Prob 100%                     #32.13
..B1.15:                        # Preds ..B1.17
        mov       eax, 1                                        #32.16
        add       eax, DWORD PTR [-256+rbp]                     #32.16
        mov       DWORD PTR [-256+rbp], eax                     #32.16
        jmp       ..B1.14       # Prob 100%                     #32.16
..B1.16:                        # Preds ..B1.14
        mov       DWORD PTR [-252+rbp], 0                       #33.7
..B1.17:                        # Preds ..B1.18 ..B1.16
        mov       eax, DWORD PTR [-252+rbp]                     #33.12
        cmp       eax, 3                                        #33.14
        jl        ..B1.19       # Prob 50%                      #33.14
        jmp       ..B1.15       # Prob 100%                     #33.14
..B1.18:                        # Preds ..B1.23
        mov       eax, 1                                        #33.17
        add       eax, DWORD PTR [-252+rbp]                     #33.17
        mov       DWORD PTR [-252+rbp], eax                     #33.17
        jmp       ..B1.17       # Prob 100%                     #33.17
..B1.19:                        # Preds ..B1.17
        mov       eax, offset flat: .L_2__STRING.0              #34.4
        mov       edx, DWORD PTR [-256+rbp]                     #34.4
        mov       ecx, DWORD PTR [-252+rbp]                     #34.4
        lea       rbx, QWORD PTR [-80+rbp]                      #34.4
        mov       esi, DWORD PTR [-256+rbp]                     #34.4
        movsxd    rsi, esi                                      #34.4
        imul      rsi, rsi, 24                                  #34.4
        add       rbx, rsi                                      #34.4
        mov       esi, DWORD PTR [-252+rbp]                     #34.4
        movsxd    rsi, esi                                      #34.4
        imul      rsi, rsi, 8                                   #34.4
        add       rbx, rsi                                      #34.4
        movsd     xmm0, QWORD PTR [rbx]                         #34.4
        mov       rdi, rax                                      #34.4
        mov       esi, edx                                      #34.4
        mov       edx, ecx                                      #34.4
        mov       eax, 1                                        #34.4
        call      printf                                        #34.4
        mov       DWORD PTR [-244+rbp], eax                     #34.4
        jmp       ..B1.18       # Prob 100%                     #34.4
..B1.20:                        # Preds ..B1.14
        mov       eax, 0                                        #35.1
        mov       rbx, QWORD PTR [-8+rbp]                       #35.1[spill]
        leave                                                   #35.1
        ret                                                     #35.1
A.136.0:
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x40080000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x40080000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x40080000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x3ff00000
B.136.0:
        .long   0x00000000,0x40180000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x40180000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x3ff00000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000
        .long   0x00000000,0x00000000