egcs 1.0.2 is broken on x86 and a patch for it.

[hjl@lucon.org (H.J. Lu)]

> 
> 
> Hello,
> 
> Richard - Could you please send the the correct patch for the fortran
> index problem from egcs 1.0.2 ? 
> 
> HJ and Richard: I have started to collect patches for 1.0.2. To date I
> have the libio patch and the optimization patch (to fix ImageMagick
> compile) from HJ. 
> 
> Other patches you might want in, I have to have them by the end of this
> week. Technically, by thursday, because I will need some time to rebuild
> the whole lot of packages...
> 

egcs 1.0.2 is broken on x86. The test case here is miscompiled by -O2.
Basically convert_regs () calls change_stack () with INSN to emit
some insn after INSN. But some insn has been added after INSN so
that change_stack () will emit some insn at the wrong place. As the
result, the floating point is broken on x86.

This patch seems to fix it. Could someone please take a look? Given
the bugs we have seen in egcs 1.0.2, I suggest egcs 1.0.3 be made.

Thanks.

H.J.
---
Wed Apr 15 08:01:56 1998  H.J. Lu  (hjl@gnu.org)

	* reg-stack.c (subst_asm_stack_regs): Change to return the last
	new insn generated by this function.
	(subst_stack_regs): Likewise.
	(convert_regs): Record the last newly generated insn and use
	it for change_stack () instead of INSN.

--- ../../../import/egcs/gcc/reg-stack.c	Wed Apr 15 07:30:26 1998
+++ ./reg-stack.c	Wed Apr 15 10:56:50 1998
@@ -262,9 +262,9 @@ static void move_for_stack_reg		PROTO((r
 static void swap_rtx_condition		PROTO((rtx));
 static void compare_for_stack_reg	PROTO((rtx, stack, rtx));
 static void subst_stack_regs_pat	PROTO((rtx, stack, rtx));
-static void subst_asm_stack_regs	PROTO((rtx, stack, rtx *, rtx **,
+static rtx subst_asm_stack_regs		PROTO((rtx, stack, rtx *, rtx **,
 					       char **, int, int));
-static void subst_stack_regs		PROTO((rtx, stack));
+static rtx subst_stack_regs		PROTO((rtx, stack));
 static void change_stack		PROTO((rtx, stack, stack, rtx (*) ()));
 
 static void goto_block_pat		PROTO((rtx, stack, rtx));
@@ -2407,9 +2407,11 @@ subst_stack_regs_pat (insn, regstack, pa
    stack-like regs in asm statements.  These rules are enforced by
    record_asm_stack_regs; see comments there for details.  Any
    asm_operands left in the RTL at this point may be assume to meet the
-   requirements, since record_asm_stack_regs removes any problem asm.  */
+   requirements, since record_asm_stack_regs removes any problem asm.
 
-static void
+   It returns the last new insn generated by this function. */
+
+static rtx
 subst_asm_stack_regs (insn, regstack, operands, operands_loc, constraints,
 		      n_inputs, n_outputs)
      rtx insn;
@@ -2688,14 +2690,18 @@ subst_asm_stack_regs (insn, regstack, op
 	      break;
 	    }
       }
+
+  return insn;
 }
 \f
 /* Substitute stack hard reg numbers for stack virtual registers in
    INSN.  Non-stack register numbers are not changed.  REGSTACK is the
    current stack content.  Insns may be emitted as needed to arrange the
-   stack for the 387 based on the contents of the insn.  */
+   stack for the 387 based on the contents of the insn.
 
-static void
+   It returns the last new insn generated by this function. */
+
+static rtx
 subst_stack_regs (insn, regstack)
      rtx insn;
      stack regstack;
@@ -2752,9 +2758,9 @@ subst_stack_regs (insn, regstack)
 	  decode_asm_operands (body, operands, operands_loc,
 			       constraints, NULL_PTR);
 	  get_asm_operand_lengths (body, n_operands, &n_inputs, &n_outputs);
-	  subst_asm_stack_regs (insn, regstack, operands, operands_loc,
-				constraints, n_inputs, n_outputs);
-	  return;
+	  return subst_asm_stack_regs (insn, regstack, operands,
+				       operands_loc, constraints,
+				       n_inputs, n_outputs);
 	}
 
       if (GET_CODE (PATTERN (insn)) == PARALLEL)
@@ -2772,7 +2778,7 @@ subst_stack_regs (insn, regstack)
      REG_UNUSED will already have been dealt with, so just return.  */
 
   if (GET_CODE (insn) == NOTE)
-    return;
+    return insn;
 
   /* If we are reached by a computed goto which sets this same stack register,
      then pop this stack register, but maintain regstack. */
@@ -2821,6 +2827,8 @@ subst_stack_regs (insn, regstack)
       }
     else
       note_link = &XEXP (note, 1);
+
+  return insn;
 }
 \f
 /* Change the organization of the stack so that it fits a new basic
@@ -3061,7 +3069,7 @@ static void
 convert_regs ()
 {
   register int block, reg;
-  register rtx insn, next;
+  register rtx insn, next, new;
   struct stack_def regstack;
 
   for (block = 0; block < blocks; block++)
@@ -3087,6 +3095,7 @@ convert_regs ()
       do
 	{
 	  insn = next;
+	  new = insn;
 	  next = NEXT_INSN (insn);
 
 	  /* Don't bother processing unless there is a stack reg
@@ -3094,7 +3103,8 @@ convert_regs ()
 	     floating point values).  */
 
 	  if (GET_MODE (insn) == QImode || GET_CODE (insn) == CALL_INSN)
-	    subst_stack_regs (insn, &regstack);
+	    /* We may have generated some new instructions here. */
+	    new = subst_stack_regs (insn, &regstack);
 
 	} while (insn != block_end[block]);
 
@@ -3117,7 +3127,7 @@ convert_regs ()
       /* Likewise handle the case where we fall into the next block.  */
 
       if ((block < blocks - 1) && block_drops_in[block+1])
-	change_stack (insn, &regstack, &block_stack_in[block+1],
+	change_stack (new, &regstack, &block_stack_in[block+1],
 		      emit_insn_after);
     }
 
--------
static __inline  double
mypow (double __x, double __y)
{
  register double __value;
  long __p = (long) __y;
  if (__y == (double) __p)
    {
      if (__p & 1)
	__x *= __x;
      if (__p == 0)
	return __x;
    }
  __asm __volatile__
    ("fmul %%st(1)"
     : "=t" (__value) :  "0" (__x), "u" (__y));
  return __value;
}

const double E1 = 2.71828182845904523536028747135;

double fact (double x)
{
  double corr;
  corr = 1.0;
  return corr * mypow(x/E1, x);
}

int main ()
{
  double y, z;

  y = fact (46.2);
  z = mypow (46.2/E1, 46.2);

  printf ("%26.19e, %26.19e\n", y, z);

  if (y > z)
    y -= z;
  else
    y = z - y;

  y /= z;
  if (y > 0.1)
    abort ();
 
  return 0;
}