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• #48 P.H. senior tag

  2011-04-12 17:42:29 #48

  Összes hozzászólása itt Válaszok az összes hozzászólására itt Válaszok erre a hozzászólásra

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  P.H.

  senior tag

  Macro-op fusion

  The Sandy Bridge can fuse two instructions into one µop in more cases than previous processors can [...].

  The decoders will fuse an arithmetic or logic instruction and a subsequent conditional jump instruction into a single compute-and-branch µop in certain cases. The compute-and-branch µop is not split in two at the execution units but executed as a single µop by the branch unit at execution port 5.
  The CMP, ADD and SUB instructions can fuse with signed and unsigned branch instructions. INC and DEC can fuse with signed branch instructions, and TEST and AND instructions can fuse with all branch instructions (including useless combinations), [...]
  The first instruction can have an immediate operand or a memory source operand, but not both. It cannot have memory destination operand.

  Megcsillagoztam azokat az utasításpárokat, amelyek elméletileg egysíthetők, nem véve figyelembe a szükséges 3 utasításos teret köztük (egyrészt az elágazás-tévesztések miatt, másrészt nem nagyon lehet előre kiszámolni, mi tartozik decode-nál ugyanabba a 4-es utasításcsoportba):

  The programmer should keep fuseable arithmetic instructions together with a subsequent conditional jump rather than scheduling other instructions in-between; and there should preferably be at least three other instructions between one fuseable pair and the next fuseable pair in order to take advantage of macro-op fusion.

  Az ADD és SUB bevonása a Sandy Bridge-nél a macro-op fusion-be igen hatékony lépés volt az Intel-től.

  mov eax,edi
  pushad
  shl ebp,02h
  xor ecx,ecx
  lea edx,[ebp+ebp*02h]
  lea edi,[ebx+ebp]
  neg ebp
  @mark0:
  sub edx,04h
  mov [ebx+edx],ecx
  jg @mark0
  mov byte ptr [edi+00h],01h
  @@REDUCE_ROWS:
  mov ebx,ebp
  @rowmin:
  mov esi,02000000h
  mov ecx,ebp
  xor edx,edx
  @findrowmin:
  cmp esi,[eax]
  cmovz edx,ecx
  cmova esi,[eax]
  add eax,04h
  * add ecx,04h
  * jnz @findrowmin
  sub ecx,ebp
  * cmp esi,02000000h
  * jz @specific
  add eax,ebp
  @subrow:
  xor edx,edx
  cmp byte ptr [eax+03h],00h
  cmovz edx,esi
  sub [eax],edx
  add eax,04h
  * sub ecx,04h
  * jnz @subrow
  * add ebx,04h
  * jnz @rowmin
  jmp @columns
  @specific:
  cmp byte ptr [edi+edx],00h
  mov byte ptr [edi+edx],01h
  jnz @@ABNORMAL_EXIT
  add ecx,ebx
  sub dword ptr [esp+__SYS0],01h
  mov byte ptr [edi+ebx+02h],01h
  mov [edi+ecx*02h+__0STAR],edx
  jz @count_result_STACK
  * add ebx,04h
  * jnz @rowmin
  @columns:
  mov [edi+00h],bl
  @@RECUDE_COLUMNS:
  sub ebx,04h
  sub eax,04h
  * cmp ebx,ebp
  * jl @@2ND_STEP
  test byte ptr [edi+ebx],01h
  jnz @@RECUDE_COLUMNS
  mov esi,02000000h
  mov ecx,ebp
  @findcolmin:
  cmp esi,[eax]
  cmova esi,[eax]
  add eax,ebp
  * add ecx,04h
  * jnz @findcolmin
  cmp esi,02000000h
  lea ecx,[ebp-04h]
  jz @@ABNORMAL_EXIT
  @subcol:
  xor edx,edx
  * add ecx,04h
  * jz @@RECUDE_COLUMNS
  sub eax,ebp
  cmp [eax+03h],dl
  cmovz edx,esi
  * sub [eax],edx
  * jnz @subcol
  mov dl,[edi+ecx+02h]
  mov byte ptr [edi+ecx+02h],01h
  or dl,[edi+ebx]
  mov edx,ecx
  jnz @subcol
  mov byte ptr [edi+ebx],01h
  sub edx,ebp
  mov byte ptr [edi+ecx+02h],01h
  sub dword ptr [esp+__SYS0],01h
  mov [edi+edx*02h+__0STAR],ebx
  jnz @subcol
  jmp @count_result_STACK
  @@ABNORMAL_EXIT:
  add esp,20h
  xor eax,eax
  mov edx,7FFFFFFFh
  stc
  ret
  
  @@3RD_STEP:
  mov byte ptr [edi+ebx+03h],0FFh
  mov byte ptr [edi+edx],00h
  mov [edi+eax*02h+__COLON],ecx
  @@2ND_STEP:
  lea ecx,[ebp-04h]
  mov edx,00FFFFFFh
  jmp @c2col
  @zeroincol:
  cmp edx,[esi]
  mov bl,[edi+eax+03h]
  sbb bl,00h
  jz @@DECIDE_NEXT_STEP
  @nx2mtx:
  sub esi,ebp
  * add eax,04h
  * jnz @zeroincol
  @c2col:
  mov esi,ecx
  add esi,[esp+__MTX]
  sub esi,ebp
  @check2col:
  add esi,04h
  * add ecx,04h
  * jz @@5TH_STEP
  cmp byte ptr [edi+ecx],00h
  mov eax,ebp
  jnz @check2col
  jmp @zeroincol
  @@5TH_STEP:
  lea ebx,[ebp+03h]
  mov esi,[esp+__MTX]
  @nx5row:
  mov eax,[edi+ebx-03h]
  sub ecx,edx
  xor eax,edx
  cmovs edx,ecx
  mov ecx,ebp
  @decrease_row_free:
  bt dword ptr [edi+ecx],00h
  mov al,[esi+03h]
  adc al,[edi+ebx]
  mov eax,00000000h
  cmovz eax,edx
  sub [esi],eax
  add esi,04h
  * add ecx,04h
  * jnz @decrease_row_free
  * add ebx,04h
  * js @nx5row
  mov eax,[esp+__FREE0]
  xor edx,edx
  mov esi,eax
  sub eax,[esp+__MTX]
  idiv ebp
  neg eax
  lea ecx,[ebp+edx]
  lea eax,[ebp+eax*04h]
  @@DECIDE_NEXT_STEP:
  xor edx,edx
  mov [esp+__FREE0],esi
  * add edx,[esi]
  * jnz @nx2mtx
  mov ebx,eax
  sub eax,ebp
  * add edx,[edi+eax*02h+__0STAR]
  * jnz @@3RD_STEP
  @@4TH_STEP:
  sub edx,ebp
  jmp @newstar
  @0_star:
  mov [edi+ebx*02h+__0STAR],ecx
  mov ecx,[edi+eax*02h+__COLON]
  @newstar:
  mov ebx,eax
  lea eax,[edx-04h]
  @starincol:
  * cmp [edi+eax*02h+__0STAR],ecx
  * jz @0_star
  * sub eax,04h
  * jns @starincol
  mov [edi+ebx*02h+__0STAR],ecx
  @@1ST_STEP:
  sub dword ptr [esp+__SYS0],01h
  mov ebx,edi
  mov ecx,ebp
  jz @count_result_STACK
  mov edx,[edi]
  @restructure:
  mov esi,[ebx+__0STAR]
  mov byte ptr [edi+ecx+03h],00h
  add ebx,08h
  mov byte ptr [edi+esi],01h
  * add ecx,04h
  * jnz @restructure
  mov [edi],edx
  jmp @@2ND_STEP
  @count_result_STACK:
  xor ecx,ecx
  neg ebp
  xor eax,eax
  mov esi,[esp+__SAVE]
  mov ebx,[esp+__MARKS]
  add esp,20h
  @results:
  mov edx,[edi+ecx*02h+__0STAR]
  add ecx,04h
  add edx,ebp
  add eax,[esi+edx]
  shr edx,02h
  add esi,ebp
  cmp ecx,ebp
  mov [ebx],dl
  lea ebx,[ebx+01h]
  jnz @results

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