How to turn any possible optimization during compilation?

[Peng Yu via Gcc-help <gcc-help@xxxxxxxxxxx>]

In the following example, printf() is converted to puts(). What are
the options to turn off any possible optimization during compilation
and just let gcc literally translate the C code to the assembly code?

Note that clang does not perform such an optimization. Should gcc do
the same to turn off any optimization by default? Thanks.

$ gcc -S -x c -o - - <<< '#include <stdio.h>'$'\n''int main() {
puts("Hello World1!"); printf("Hello World2!\n"); }'
    .file    ""
    .text
    .section    .rodata
.LC0:
    .string    "Hello World1!"
.LC1:
    .string    "Hello World2!"
    .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
    leaq    .LC0(%rip), %rdi
    call    puts@PLT
    leaq    .LC1(%rip), %rdi
    call    puts@PLT
    movl    $0, %eax
    popq    %rbp
    .cfi_def_cfa 7, 8
    ret
    .cfi_endproc
.LFE0:
    .size    main, .-main
    .ident    "GCC: (Debian 10.2.1-6) 10.2.1 20210110"
    .section    .note.GNU-stack,"",@progbits

$ clang -S -x c -o - - <<< '#include <stdio.h>'$'\n''int main() {
puts("Hello World1!"); printf("Hello World2!\n"); }'
    .text
    .file    "-"
    .globl    main                            # -- Begin function main
    .p2align    4, 0x90
    .type    main,@function
main:                                   # @main
    .cfi_startproc
# %bb.0:
    pushq    %rbp
    .cfi_def_cfa_offset 16
    .cfi_offset %rbp, -16
    movq    %rsp, %rbp
    .cfi_def_cfa_register %rbp
    subq    $16, %rsp
    movabsq    $.L.str, %rdi
    callq    puts
    movabsq    $.L.str.1, %rdi
    movl    %eax, -4(%rbp)                  # 4-byte Spill
    movb    $0, %al
    callq    printf
    xorl    %ecx, %ecx
    movl    %eax, -8(%rbp)                  # 4-byte Spill
    movl    %ecx, %eax
    addq    $16, %rsp
    popq    %rbp
    .cfi_def_cfa %rsp, 8
    retq
.Lfunc_end0:
    .size    main, .Lfunc_end0-main
    .cfi_endproc
                                        # -- End function
    .type    .L.str,@object                  # @.str
    .section    .rodata.str1.1,"aMS",@progbits,1
.L.str:
    .asciz    "Hello World1!"
    .size    .L.str, 14

    .type    .L.str.1,@object                # @.str.1
.L.str.1:
    .asciz    "Hello World2!\n"
    .size    .L.str.1, 15

    .ident    "Debian clang version 11.0.1-2"
    .section    ".note.GNU-stack","",@progbits
    .addrsig
    .addrsig_sym puts
    .addrsig_sym printf

-- 
Regards,
Peng