Question

I am searching for a compiler or better IDE for C which could generate completely linked program, including functions from CRT, in assembler form. Is there any? I tried Visual C Express 2008. It has a disassembler, but its somewhat strange. I mean for some reason it shows many “strange” lines of code, such as mov a,#3 in about 100 lines…. It for study purposes. Thanks for tips.

Answer 1

gcc will generate ASM files. If you use gcc -Wa,-adhln -g [source.c] gcc and as will interleave the C source lines with the generated assembly code.

clang with LLVM will generate high quality ASM files.

Example:

This C function:

long Fibonacci(long x) {
  if (x == 0) return 0;  
  if (x == 1) return 1;
  return Fibonacci(x - 1) + Fibonacci(x - 2);
}

Becomes this ASM file:

_Fibonacci:
Leh_func_begin1:
    pushq   %rbp
Ltmp0:
    movq    %rsp, %rbp
Ltmp1:
    subq    $32, %rsp
Ltmp2:
    movq    %rdi, -16(%rbp)
    movq    -16(%rbp), %rax
    cmpq    $0, %rax
    jne LBB1_2
    movq    $0, -8(%rbp)
    jmp LBB1_5
LBB1_2:
    movq    -16(%rbp), %rax
    cmpq    $1, %rax
    jne LBB1_4
    movq    $1, -8(%rbp)
    jmp LBB1_5
LBB1_4:
    movq    -16(%rbp), %rax
    movabsq $1, %rcx
    subq    %rcx, %rax
    movq    %rax, %rdi
    callq   _Fibonacci
    movq    -16(%rbp), %rcx
    movabsq $2, %rdx
    subq    %rdx, %rcx
    movq    %rcx, %rdi
    movq    %rax, -24(%rbp)
    callq   _Fibonacci
    movq    -24(%rbp), %rcx
    addq    %rax, %rcx
    movq    %rcx, -8(%rbp)
LBB1_5:
    movq    -8(%rbp), %rax
    addq    $32, %rsp
    popq    %rbp
    ret
Leh_func_end1:

When you do this, you will want optimizations OFF.

It is also possible to interleave the generated ASM code with the higher level source, such as the writer has done HERE.