[LLVMdev] how to annotate assembler

[Konstantin Vladimirov]

Hi,

 Thank you, it is just what I need. But... it doesn't work for me:

 $ clang -S -O0 test.c -mllvm -show-mc-inst
error: unknown argument: '-show-mc-inst'

 $ clang --version
 clang version 1.1 (branches/release_27)
 Target: x86_64-pc-linux-gnu
 Thread model: posix

 May be I need LLVM with higher version, or mention something in
 configure options?

On Fri, Mar 2, 2012 at 4:32 PM, Benjamin Kramer
<benny.kra at googlemail.com> wrote:
>
> On 02.03.2012, at 09:20, Konstantin Vladimirov wrote:
>
>> Hi,
>>
>> In GCC there is one useful option -dp (or -dP for more verbose output)
>> to annotate assembler with instruction patterns, that was used when
>> assembler was generated. For example:
>
> The internal "-mllvm -show-mc-inst" option is probably as close as you can get.
>
> $ clang -S -O0 test.c -mllvm -show-mc-inst -o -
> _test:                                  ## @test
>        .cfi_startproc
> ## BB#0:                                ## %entry
>        pushq   %rbp                    ## <MCInst #2120 PUSH64r
>                                        ##  <MCOperand Reg:106>>
> Ltmp2:
>        .cfi_def_cfa_offset 16
> Ltmp3:
>        .cfi_offset %rbp, -16
>        movq    %rsp, %rbp              ## <MCInst #1491 MOV64rr
>                                        ##  <MCOperand Reg:106>
>                                        ##  <MCOperand Reg:114>>
> Ltmp4:
>        .cfi_def_cfa_register %rbp
>        movq    %rdi, -8(%rbp)          ## <MCInst #1482 MOV64mr
>                                        ##  <MCOperand Reg:106>
>                                        ##  <MCOperand Imm:1>
>                                        ##  <MCOperand Reg:0>
>                                        ##  <MCOperand Imm:-8>
>                                        ##  <MCOperand Reg:0>
>                                        ##  <MCOperand Reg:109>>
>        cvtsi2sdq       -8(%rbp), %xmm0 ## <MCInst #607 CVTSI2SD64rm
>                                        ##  <MCOperand Reg:128>
>                                        ##  <MCOperand Reg:106>
>                                        ##  <MCOperand Imm:1>
>                                        ##  <MCOperand Reg:0>
>                                        ##  <MCOperand Imm:-8>
>                                        ##  <MCOperand Reg:0>>
>        popq    %rbp                    ## <MCInst #2000 POP64r
>                                        ##  <MCOperand Reg:106>>
>        ret                             ## <MCInst #2227 RET>
>        .cfi_endproc
>
> - Ben
>
>>
>> double
>> test(long long s)
>> {
>>  return s;
>> }
>>
>> gcc -S -dp -O0 test.c
>>
>> test:
>> .LFB0:
>>  .cfi_startproc
>>  pushq %rbp  # 18  *pushdi2_rex64/1  [length = 1]
>>  .cfi_def_cfa_offset 16
>>  movq  %rsp, %rbp  # 19  *movdi_1_rex64/2  [length = 3]
>>  .cfi_offset 6, -16
>>  .cfi_def_cfa_register 6
>>  movq  %rdi, -8(%rbp)  # 2 *movdi_1_rex64/4  [length = 4]
>>  cvtsi2sdq -8(%rbp), %xmm0 # 6 *floatdidf2_sse_interunit/2 [length = 6]
>>  leave # 24  leave_rex64 [length = 1]
>>  .cfi_def_cfa 7, 8
>>  ret # 25  return_internal [length = 1]
>>  .cfi_endproc
>>
>> Now I may look into config/i386/i386.md, and look for mentioned
>> *pushdi2_rex64, movdi_1_rex64, floatdidf2_sse_interunit and other
>> patterns and study how they work.
>>
>> How to make the same annotation for clang output assembler code?
>>
>> test:
>> .Leh_func_begin1:
>>  pushq %rbp          # ??? what insn in X86InstrInfo.td?
>> .Llabel1:
>>  movq  %rsp, %rbp  # ??? what insn in X86InstrInfo.td?
>> .Llabel2:
>>  movq  %rdi, -16(%rbp)  # ??? what insn in X86InstrInfo.td?
>>  movq  -16(%rbp), %rax  # ??? what insn in X86InstrInfo.td?
>>  cvtsi2sdq %rax, %xmm0  # ??? what insn in X86InstrInfo.td?
>>  movsd %xmm0, -8(%rbp)  # ??? what insn in X86InstrInfo.td?
>>  movsd -8(%rbp), %xmm0  # ??? what insn in X86InstrInfo.td?
>>  popq  %rbp  # ??? what insn in X86InstrInfo.td?
>>  ret
>>
>>
>> ---
>> With best regards, Konstantin
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>