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1 Optimization: time (Optimization flag comparison (.file "main…

1 Optimization: time

Optimization flag comparison

    .file    "main.c"
    .text
    .section    .rodata
.LC0:
    .string    "%lld\n"
.LC2:
    .string    "Elapsed time: %f"
    .text
    .globl    main
    .type    main, @function
main:
.LFB0:
    .cfi_startproc
    pushq    %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset 6, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register 6
    subq    $64, %rsp
    leaq    -48(%rbp), %rax
    movl    $1, %esi
    movq    %rax, %rdi
    call    timespec_get
    movq    $0, -8(%rbp)
    movq    $0, -16(%rbp)
    jmp    .L2
.L3:
    movq    -16(%rbp), %rax
    addq    %rax, -8(%rbp)
    addq    $1, -16(%rbp)
.L2:
    cmpq    $999999999, -16(%rbp)
    jle    .L3
    movq    -8(%rbp), %rax
    movq    %rax, %rsi
    movl    $.LC0, %edi
    movl    $0, %eax
    call    printf
    leaq    -64(%rbp), %rax
    movl    $1, %esi
    movq    %rax, %rdi
    call    timespec_get
    movq    -64(%rbp), %rdx
    movq    -48(%rbp), %rax
    subq    %rax, %rdx
    movq    %rdx, %rax
    cvtsi2ssq    %rax, %xmm0
    cvtss2sd    %xmm0, %xmm1
    movq    -56(%rbp), %rdx
    movq    -40(%rbp), %rax
    subq    %rax, %rdx
    movq    %rdx, %rax
    cvtsi2ssq    %rax, %xmm0
    cvtss2sd    %xmm0, %xmm0
    movsd    .LC1(%rip), %xmm2
    divsd    %xmm2, %xmm0
    addsd    %xmm1, %xmm0
    cvtsd2ss    %xmm0, %xmm3
    movss    %xmm3, -20(%rbp)
    cvtss2sd    -20(%rbp), %xmm0
    movl    $.LC2, %edi
    movl    $1, %eax
    call    pri

    .file    "main.c"
    .text
    .section    .rodata.str1.1,"aMS",@progbits,1
.LC0:
    .string    "%lld\n"
.LC2:
    .string    "Elapsed time: %f"
    .text
    .globl    main
    .type    main, @function
main:
.LFB11:
    .cfi_startproc
    subq    $40, %rsp
    .cfi_def_cfa_offset 48
    movl    $1, %esi
    leaq    16(%rsp), %rdi
    call    timespec_get
    movl    $1000000000, %eax
.L2:
    subq    $1, %rax
    jne    .L2
    movabsq    $499999999500000000, %rsi
    movl    $.LC0, %edi
    movl    $0, %eax
    call    printf
    movl    $1, %esi
    movq    %rsp, %rdi
    call    timespec_get
    movq    8(%rsp), %rax
    subq    24(%rsp), %rax
    pxor    %xmm0, %xmm0
    cvtsi2ssq    %rax, %xmm0
    cvtss2sd    %xmm0, %xmm0
    divsd    .LC1(%rip), %xmm0
    movq    (%rsp), %rax
    subq    16(%rsp), %rax
    pxor    %xmm1, %xmm1
    cvtsi2ssq    %rax, %xmm1
    cvtss2sd    %xmm1, %xmm1
    addsd    %xmm1, %xmm0
    cvtsd2ss    %xmm0, %xmm0
    cvtss2sd    %xmm0, %xmm0
    movl    $.LC2, %edi
    movl    $1, %eax
    call    printf
    movl    $0, %eax
    addq    $40, %rsp
    .cfi_def_cfa_offset 8
    ret
    .cfi_endproc
.LFE11:
    .size    main, .-main
    .section    .rodata.cst8,"aM",@progbits,8
    .align 8
.LC1:
    .long    0
    .long    1104006501
    .ident    "GCC: (GNU) 8.1.1 20180712 (Red Hat 8.1.1-5)"
    .section    .note.GNU-stack,"",@progbits

    .file    "main.c"
    .text
    .section    .rodata.str1.1,"aMS",@progbits,1
.LC0:
    .string    "%lld\n"
.LC2:
    .string    "Elapsed time: %f"
    .section    .text.startup,"ax",@progbits
    .p2align 4,,15
    .globl    main
    .type    main, @function
main:
.LFB11:
    .cfi_startproc
    subq    $40, %rsp
    .cfi_def_cfa_offset 48
    movl    $1, %esi
    movq    %rsp, %rdi
    call    timespec_get
    movl    $.LC0, %edi
    xorl    %eax, %eax
    movabsq    $499999999500000000, %rsi
    call    printf
    leaq    16(%rsp), %rdi
    movl    $1, %esi
    call    timespec_get
    movq    24(%rsp), %rax
    pxor    %xmm0, %xmm0
    subq    8(%rsp), %rax
    cvtsi2ssq    %rax, %xmm0
    pxor    %xmm1, %xmm1
    movq    16(%rsp), %rax
    subq    (%rsp), %rax
    cvtsi2ssq    %rax, %xmm1
    movl    $.LC2, %edi
    movl    $1, %eax
    cvtss2sd    %xmm0, %xmm0
    divsd    .LC1(%rip), %xmm0
    cvtss2sd    %xmm1, %xmm1
    addsd    %xmm1, %xmm0
    cvtsd2ss    %xmm0, %xmm0
    cvtss2sd    %xmm0, %xmm0
    call    printf
    xorl    %eax, %eax
    addq    $40, %rsp
    .cfi_def_cfa_offset 8
    ret
    .cfi_endproc
.LFE11:
    .size    main, .-main
    .section    .rodata.cst8,"aM",@progbits,8
    .align 8
.LC1:
    .long    0
    .long    1104006501
    .ident    "GCC: (GNU) 8.1.1 20180712 (Red Hat 8.1.1-5)"
    .section    .note.GNU-stack,"",@progbits

    .file    "main.c"
    .text
    .section    .rodata.str1.1,"aMS",@progbits,1
.LC0:
    .string    "%lld\n"
.LC2:
    .string    "Elapsed time: %f"
    .section    .text.startup,"ax",@progbits
    .p2align 4,,15
    .globl    main
    .type    main, @function
main:
.LFB11:
    .cfi_startproc
    subq    $40, %rsp
    .cfi_def_cfa_offset 48
    movl    $1, %esi
    movq    %rsp, %rdi
    call    timespec_get
    movl    $.LC0, %edi
    xorl    %eax, %eax
    movabsq    $499999999500000000, %rsi
    call    printf
    leaq    16(%rsp), %rdi
    movl    $1, %esi
    call    timespec_get
    movq    24(%rsp), %rax
    pxor    %xmm0, %xmm0
    subq    8(%rsp), %rax
    cvtsi2ssq    %rax, %xmm0
    pxor    %xmm1, %xmm1
    movq    16(%rsp), %rax
    subq    (%rsp), %rax
    cvtsi2ssq    %rax, %xmm1
    movl    $.LC2, %edi
    movl    $1, %eax
    cvtss2sd    %xmm0, %xmm0
    divsd    .LC1(%rip), %xmm0
    cvtss2sd    %xmm1, %xmm1
    addsd    %xmm1, %xmm0
    cvtsd2ss    %xmm0, %xmm0
    cvtss2sd    %xmm0, %xmm0
    call    printf
    xorl    %eax, %eax
    addq    $40, %rsp
    .cfi_def_cfa_offset 8
    ret
    .cfi_endproc
.LFE11:
    .size    main, .-main
    .section    .rodata.cst8,"aM",@progbits,8
    .align 8
.LC1:
    .long    0
    .long    1104006501
    .ident    "GCC: (GNU) 8.1.1 20180712 (Red Hat 8.1.1-5)"
    .section    .note.GNU-stack,"",@progbits

    .file    "main.c"
    .text
    .section    .rodata.str1.1,"aMS",@progbits,1
.LC0:
    .string    "%lld\n"
.LC2:
    .string    "Elapsed time: %f"
    .section    .text.startup,"ax",@progbits
    .globl    main
    .type    main, @function
main:
.LFB0:
    .cfi_startproc
    subq    $40, %rsp
    .cfi_def_cfa_offset 48
    movl    $1, %esi
    movq    %rsp, %rdi
    call    timespec_get
    movl    $.LC0, %edi
    xorl    %eax, %eax
    movabsq    $499999999500000000, %rsi
    call    printf
    leaq    16(%rsp), %rdi
    movl    $1, %esi
    call    timespec_get
    movq    24(%rsp), %rax
    subq    8(%rsp), %rax
    movl    $.LC2, %edi
    cvtsi2ssq    %rax, %xmm0
    movq    16(%rsp), %rax
    subq    (%rsp), %rax
    cvtsi2ssq    %rax, %xmm1
    movb    $1, %al
    cvtss2sd    %xmm0, %xmm0
    divsd    .LC1(%rip), %xmm0
    cvtss2sd    %xmm1, %xmm1
    addsd    %xmm1, %xmm0
    cvtsd2ss    %xmm0, %xmm0
    cvtss2sd    %xmm0, %xmm0
    call    printf
    xorl    %eax, %eax
    addq    $40, %rsp
    .cfi_def_cfa_offset 8
    ret
    .cfi_endproc
.LFE0:
    .size    main, .-main
    .section    .rodata.cst8,"aM",@progbits,8
    .align 8
.LC1:
    .long    0
    .long    1104006501
    .ident    "GCC: (GNU) 8.1.1 20180712 (Red Hat 8.1.1-5)"
    .section    .note.GNU-stack,"",@progbits

    .file    "main.c"
    .text
    .section    .rodata.str1.1,"aMS",@progbits,1
.LC0:
    .string    "%lld\n"
.LC2:
    .string    "Elapsed time: %f"
    .text
    .globl    main
    .type    main, @function
main:
.LFB11:
    .cfi_startproc
    subq    $40, %rsp
    .cfi_def_cfa_offset 48
    movl    $1, %esi
    leaq    16(%rsp), %rdi
    call    timespec_get
    movl    $0, %eax
    movl    $0, %esi
.L2:
    cmpq    $999999999, %rax
    jg    .L5
    addq    %rax, %rsi
    addq    $1, %rax
    jmp    .L2
.L5:
    movl    $.LC0, %edi
    movl    $0, %eax
    call    printf
    movl    $1, %esi
    movq    %rsp, %rdi
    call    timespec_get
    movq    (%rsp), %rax
    subq    16(%rsp), %rax
    pxor    %xmm0, %xmm0
    cvtsi2ssq    %rax, %xmm0
    cvtss2sd    %xmm0, %xmm0
    movq    8(%rsp), %rax
    subq    24(%rsp), %rax
    pxor    %xmm1, %xmm1
    cvtsi2ssq    %rax, %xmm1
    cvtss2sd    %xmm1, %xmm1
    divsd    .LC1(%rip), %xmm1
    addsd    %xmm1, %xmm0
    cvtsd2ss    %xmm0, %xmm0
    cvtss2sd    %xmm0, %xmm0
    movl    $.LC2, %edi
    movl    $1, %eax
    call    printf
    movl    $0, %eax
    addq    $40, %rsp
    .cfi_def_cfa_offset 8
    ret
    .cfi_endproc
.LFE11:
    .size    main, .-main
    .section    .rodata.cst8,"aM",@progbits,8
    .align 8
.LC1:
    .long    0
    .long    1104006501
    .ident    "GCC: (GNU) 8.1.1 20180712 (Red Hat 8.1.1-5)"
    .section    .note.GNU-stack,"",@progbits

    .file    "main.c"
    .text
    .section    .rodata.str1.1,"aMS",@progbits,1
.LC0:
    .string    "%lld\n"
.LC2:
    .string    "Elapsed time: %f"
    .section    .text.startup,"ax",@progbits
    .p2align 4,,15
    .globl    main
    .type    main, @function
main:
.LFB11:
    .cfi_startproc
    subq    $40, %rsp
    .cfi_def_cfa_offset 48
    movl    $1, %esi
    movq    %rsp, %rdi
    call    timespec_get
    movl    $.LC0, %edi
    xorl    %eax, %eax
    movabsq    $499999999500000000, %rsi
    call    printf
    leaq    16(%rsp), %rdi
    movl    $1, %esi
    call    timespec_get
    movq    24(%rsp), %rax
    pxor    %xmm0, %xmm0
    subq    8(%rsp), %rax
    cvtsi2ssq    %rax, %xmm0
    pxor    %xmm1, %xmm1
    movq    16(%rsp), %rax
    subq    (%rsp), %rax
    cvtsi2ssq    %rax, %xmm1
    movl    $.LC2, %edi
    movl    $1, %eax
    cvtss2sd    %xmm0, %xmm0
    mulsd    .LC1(%rip), %xmm0
    cvtss2sd    %xmm1, %xmm1
    addsd    %xmm1, %xmm0
    cvtsd2ss    %xmm0, %xmm0
    cvtss2sd    %xmm0, %xmm0
    call    printf
    xorl    %eax, %eax
    addq    $40, %rsp
    .cfi_def_cfa_offset 8
    ret
    .cfi_endproc
.LFE11:
    .size    main, .-main
    .section    .rodata.cst8,"aM",@progbits,8
    .align 8
.LC1:
    .long    3894859413
    .long    1041313291
    .ident    "GCC: (GNU) 8.1.1 20180712 (Red Hat 8.1.1-5)"
    .section    .note.GNU-stack,"",@progbits

#include "stdio.h"
#include "time.h"
#include "stdint.h"

int main(void) {
    struct timespec t0;
    struct timespec t;
    timespec_get(&t0, TIME_UTC);

    int64_t sum = 0;
    for (int64_t i = 0; i < 1000000000; i++) {
        sum += i;
    }
    printf("%lld\n",sum);

    timespec_get(&t, TIME_UTC);
    float seconds = (float)(t.tv_sec - t0.tv_sec) + (float)(int64_t)(t.tv_nsec - t0.tv_nsec)/1000000000.0;
    printf("Elapsed time: %f", seconds);
}