Better way than a terminal objdump to read assembly?-CodePudding

For example if I'm in perf report I can press enter to follow a branch. If a bin was using -g some source shows up too.

I don't really need the source but it'd be very convenient if I could follow the jumps. What can I do to make reading assembly easier? Since I'm on linux I ended up running perf and using report to read this

CodePudding user response：

objdump -d --visualize-jumps=color is interesting, although unusable on a large binary as it has so many columns of lines. In a random smaller binary I had lying around (from testing alignment of 64-bit _Atomic vars in 32-bit mode, in case anyone's curious; this binary was from clang):

objdump -drwC -Mintel --visualize-jumps=color

...
 726:                e8 a5 fd ff ff             call   4d0 <pthread_create@plt>
 72b:                83 c4 10                   add    esp,0x10
 72e:                85 c0                      test   eax,eax
 730:      /-------- 75 62                      jne    794 <main 0xb4>
 732:   /--|-------> c5 f8 57 c0                vxorps xmm0,xmm0,xmm0
 736:   |  |         c5 fb 10 8e 48 e8 ff ff    vmovsd xmm1,QWORD PTR [esi-0x17b8]
 73e:   |  |         66 90                      xchg   ax,ax
 740:   |  |  /----> 31 c0                      xor    eax,eax
 742:   |  |  |      31 d2                      xor    edx,edx
 744:   |  |  |      31 c9                      xor    ecx,ecx
 746:   |  |  |      31 db                      xor    ebx,ebx
 748:   |  |  |      f0 0f c7 8e c0 00 00 00    lock cmpxchg8b QWORD PTR [esi 0xc0]
 750:   |  |  |      c5 f9 6e d0                vmovd  xmm2,eax
 754:   |  |  |      c4 e3 69 22 d2 01          vpinsrd xmm2,xmm2,edx,0x1
 75a:   |  |  |      c5 f9 2e d0                vucomisd xmm2,xmm0
 75e:   |  |  |  /-- 75 02                      jne    762 <main 0x82>
 760:   |  |   --|-- 7b de                      jnp    740 <main 0x60>
 762:   |  |  |  \-> c5 f9 2e d1                vucomisd xmm2,xmm1
 766:   |  |  |  /-- 75 02                      jne    76a <main 0x8a>
 768:   |  |  \--|-- 7b d6                      jnp    740 <main 0x60>
 76a:   |  |     \-> 83 ec 04                   sub    esp,0x4

...

Agner Fog's objconv disassembler makes output that's ready to assemble, including labels on branch targets, making it easier to find the tops of loops. Example output in How to disassemble a binary executable in Linux to get the assembly code? Other answers show examples of objdump -d -S to mix source and asm.

Also related: How to remove "noise" from GCC/clang assembly output? I usually look at gcc -O3 ... -S output instead of assembling into a binary. Unless I already have a specific binary. The Godbolt compiler explorer has good tools for finding asm associated with a source line, like a loop body, which works most of the time depending on the the debug info generated by compilers.