Question

我尝试修补gcc，以便在目标寄存器的fdivd之后存储到堆栈中，即：

fdivd％f0，％f2，％f4; =＆GT;变 fdivd％f0，％f2，％f4; std％f4，[％fp + ...]

我使用a中的（emit_insn，DONE）序列为divdf3生成rtl define_expand模式（见下文）。

在汇编程序输出阶段，我使用了define_insn和write 输出“fdivd \ t %% 1，%% 2，%% 0; std %% 0，%% 3”作为表达式字符串。

生成的代码似乎没问题。但是：

我的问题：

如何标记模式， 不会被标记为延迟槽 ？如何指定输出为2条指令并暗示调度程序有关它？是define_insn divdf3_store中的（set_attr“length”“2”）属性（下面）已经足够吗？

- 问候康拉德

-------------- changed sparc.md -------------------------
;;;;;;;;;;;;;;;;;; handle divdf3 ;;;;;;;;;;;;;;;;
(define_expand "divdf3"
  [(parallel [(set (match_operand:DF 0 "register_operand" "=e")
                      (div:DF (match_operand:DF 1 "register_operand" "e")
                (match_operand:DF 2 "register_operand" "e")))
          (clobber (match_scratch:SI 3 ""))])]
  "TARGET_FPU"
  "{
      output_divdf3_emit (operands[0], operands[1], operands[2], operands[3]);
      DONE;
    }")

(define_insn "divdf3_store"
  [(set (match_operand:DF 0 "register_operand" "=e")
                      (div:DF (match_operand:DF 1 "register_operand" "e")
                (match_operand:DF 2 "register_operand" "e")))
          (clobber (match_operand:DF 3 "memory_operand" ""  ))]
  "TARGET_FPU && TARGET_STORE_AFTER_DIVSQRT"
   {
       return output_divdf3 (operands[0], operands[1], operands[2], operands[3]);
   }
   [(set_attr "type" "fpdivd")
   (set_attr "fptype" "double")
   (set_attr "length" "2")])

(define_insn "divdf3_nostore"
  [(set (match_operand:DF 0 "register_operand" "=e")
    (div:DF (match_operand:DF 1 "register_operand" "e")
        (match_operand:DF 2 "register_operand" "e")))]
  "TARGET_FPU && (!TARGET_STORE_AFTER_DIVSQRT)"
  "fdivd\t%1, %2, %0"
  [(set_attr "type" "fpdivd")
   (set_attr "fptype" "double")])



-------------- changed sparc.c -------------------------

/**************************** handle fdivd ****************************/
char *
output_divdf3 (rtx op0, rtx op1, rtx dest, rtx scratch)
{
  static char string[128];
  if (debug_patch_divsqrt) {
    fprintf(stderr, "debug_patch_divsqrt:\n");
    debug_rtx(op0);
    debug_rtx(op1);
    debug_rtx(dest);
    fprintf(stderr, "scratch: 0x%x\n",(int)scratch);
  }
  sprintf(string,"fdivd\t%%1, %%2, %%0; std %%0, %%3 !!!");
  return string;
}

void
output_divdf3_emit (rtx dest, rtx op0, rtx op1, rtx scratch)
{
  rtx slot0, div, divsave;

  if (debug_patch_divsqrt) {
    fprintf(stderr, "output_divdf3_emit:\n");
    debug_rtx(op0);
    debug_rtx(op1);
    debug_rtx(dest);
    fprintf(stderr, "scratch: 0x%x\n",(int)scratch);
  }

  div = gen_rtx_SET (VOIDmode,
             dest,
             gen_rtx_DIV (DFmode,
                  op0,
                  op1));

  if (TARGET_STORE_AFTER_DIVSQRT) {
    slot0 = assign_stack_local (DFmode, 8, 8);
    divsave = gen_rtx_SET (VOIDmode, slot0, dest);
    emit_insn(divsave);
    emit_insn (gen_rtx_PARALLEL(VOIDmode,
                gen_rtvec (2,
                       div,
                       gen_rtx_CLOBBER (SImode,
                                slot0))));
  } else {
    emit_insn(div);
  }
}

Answer 1

我是第二个Laurynas。对于这样一个精确的问题，gcc @ gcc.gnu.org将非常有帮助。

如何避免计划进入延迟槽

1 个答案: