> 
> > Hi,
> > 
> > I am looking into your bug report
> > 
> > http://www.cygnus.com/ml/egcs-bugs/1998-Nov/0476.html
> > 
> > I don't have a real fix yet. But I did find a bug in reg-stack.c which
> > would silently generate incorrect code. This patch is a sanity check
> > and it will cause compiler to abort on your testcase instead of
> > generating buggy asm code. I will work on a real fix when I find more
> > time.
> > 
> > Thanks.
> 
> 

Hi,

This is a patch for egcs 1.1.1 which fixes the bug

http://www.cygnus.com/ml/egcs-bugs/1998-Nov/0476.html

The detailed analysises can be found at

http://www.cygnus.com/ml/egcs-bugs/1998-Dec/0475.html
http://www.cygnus.com/ml/egcs-bugs/1998-Dec/0481.html

If you are using floating point with Pentium Pro optimization, I
strongly encourage you to give this patch a try.

Thanks.


-- 
H.J. Lu ([EMAIL PROTECTED])
---
Fri Dec 18 06:57:12 1998  H.J. Lu  ([EMAIL PROTECTED])

        * reg-stack.c (subst_stack_regs_pat): Abort if the destination
        of a FP conditional move is not on the FP register stack.

        * config/i386/i386.md (movsfcc, movdfcc, movxfcc): Make sure the
        target is among the sources.
        (movsfcc+1, movsfcc+2, movsfcc+3, movsfcc+4, movsfcc+5, movdfcc+1,
        movdfcc+2, movdfcc+3, movdfcc+4, movdfcc+5, movxfcc+1, movxfcc+2,
        movxfcc+3, movxfcc+4, movxfcc+5): Disallow patterns where the target
        is not among the sources.

        * config/i386/i386.c (output_fp_conditional_move): Remove the
        third alternative.

diff -x CVS -x c-gperf.h -upr /home/work/misc/gnu/import/egcs/gcc/config/i386/i386.c 
./config/i386/i386.c
--- /home/work/misc/gnu/import/egcs/gcc/config/i386/i386.c      Wed Jul 29 07:35:38 
1998
+++ ./config/i386/i386.c        Fri Dec 18 09:06:53 1998
@@ -5208,12 +5208,6 @@ output_fp_conditional_move (which_altern
       output_asm_insn (AS2 (fcmov%f1,%3,%0), operands);
       break;
 
-    case 2:
-      /* r <- cond ? r : arg */
-      output_asm_insn (AS2 (fcmov%F1,%2,%0), operands);
-      output_asm_insn (AS2 (fcmov%f1,%3,%0), operands);
-      break;
-
     default:
       abort ();
     }
diff -x CVS -x c-gperf.h -upr /home/work/misc/gnu/import/egcs/gcc/config/i386/i386.md 
./config/i386/i386.md
--- /home/work/misc/gnu/import/egcs/gcc/config/i386/i386.md     Thu Jul 30 08:11:16 
1998
+++ ./config/i386/i386.md       Fri Dec 18 08:47:30 1998
@@ -7383,6 +7383,15 @@ byte_xor_operation:
   if (GET_MODE_CLASS (GET_MODE (i386_compare_op0)) != MODE_INT)
     FAIL;
 
+  /* We have to make sure that the target is among the sources so
+     that it is on the register stack. */
+  if (!rtx_equal_p (operands[0], operands[2])
+      && !rtx_equal_p (operands[0], operands[3]))
+    {
+      emit_insn (gen_movsf (operands[0], operands[2]));
+      operands[2] = operands[0];
+    }
+
   /* The floating point conditional move instructions don't directly
      support conditions resulting from a signed integer comparison. */
 
@@ -7411,36 +7420,36 @@ byte_xor_operation:
 }")
 
 (define_insn ""
-  [(set (match_operand:SF 0 "register_operand" "=f,f,f,f,f,f")
+  [(set (match_operand:SF 0 "register_operand" "=f,f,f,f")
        (if_then_else:SF (match_operator 1 "comparison_operator" 
-             [(match_operand:QI 2 "nonimmediate_operand" "q,m,q,m,q,m")
-               (match_operand:QI 3 "general_operand" "qmn,qn,qmn,qn,qmn,qn")])
-             (match_operand:SF 4 "register_operand" "f,f,0,0,f,f")
-             (match_operand:SF 5 "register_operand" "0,0,f,f,f,f")))]
+             [(match_operand:QI 2 "nonimmediate_operand" "q,m,q,m")
+               (match_operand:QI 3 "general_operand" "qmn,qn,qmn,qn")])
+             (match_operand:SF 4 "register_operand" "f,f,0,0")
+             (match_operand:SF 5 "register_operand" "0,0,f,f")))]
   "TARGET_CMOVE
     && GET_CODE (operands[1]) != LT && GET_CODE (operands[1]) != LE
     && GET_CODE (operands[1]) != GE && GET_CODE (operands[1]) != GT"
   "#")
 
 (define_insn ""
-  [(set (match_operand:SF 0 "register_operand" "=f,f,f,f,f,f")
+  [(set (match_operand:SF 0 "register_operand" "=f,f,f,f")
        (if_then_else:SF (match_operator 1 "comparison_operator" 
-               [(match_operand 2 "nonimmediate_operand" "r,m,r,m,r,m")
-                (match_operand 3 "general_operand" "rmi,ri,rmi,ri,rmi,ri")])
-             (match_operand:SF 4 "register_operand" "f,f,0,0,f,f")
-             (match_operand:SF 5 "register_operand" "0,0,f,f,f,f")))]
+               [(match_operand 2 "nonimmediate_operand" "r,m,r,m")
+                (match_operand 3 "general_operand" "rmi,ri,rmi,ri")])
+             (match_operand:SF 4 "register_operand" "f,f,0,0")
+             (match_operand:SF 5 "register_operand" "0,0,f,f")))]
   "TARGET_CMOVE && GET_MODE_CLASS (GET_MODE (operands[2])) == MODE_INT
     && GET_CODE (operands[1]) != LT && GET_CODE (operands[1]) != LE
     && GET_CODE (operands[1]) != GE && GET_CODE (operands[1]) != GT"
   "#")
 
 (define_split
-  [(set (match_operand:SF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:SF 0 "register_operand" "=f,f")
        (if_then_else:SF (match_operator 1 "comparison_operator" 
                                [(match_operand 2 "nonimmediate_operand" "")
                                 (const_int 0)])
-                     (match_operand:SF 3 "register_operand" "f,0,f")
-                     (match_operand:SF 4 "register_operand" "0,f,f")))]
+                     (match_operand:SF 3 "register_operand" "f,0")
+                     (match_operand:SF 4 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   [(set (cc0)
        (match_dup 2))
@@ -7450,12 +7459,12 @@ byte_xor_operation:
   "")
 
 (define_split
-  [(set (match_operand:SF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:SF 0 "register_operand" "=f,f")
        (if_then_else:SF (match_operator 1 "comparison_operator" 
                                [(match_operand 2 "nonimmediate_operand" "")
                                 (match_operand 3 "general_operand" "")])
-                     (match_operand:SF 4 "register_operand" "f,0,f")
-                     (match_operand:SF 5 "register_operand" "0,f,f")))]
+                     (match_operand:SF 4 "register_operand" "f,0")
+                     (match_operand:SF 5 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   [(set (cc0) (compare (match_dup 2) (match_dup 3)))
    (set (match_dup 0)
@@ -7464,11 +7473,11 @@ byte_xor_operation:
   "")
 
 (define_insn ""
-  [(set (match_operand:SF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:SF 0 "register_operand" "=f,f")
        (if_then_else:SF (match_operator 1 "comparison_operator" 
                                [(cc0) (const_int 0)])
-                     (match_operand:SF 2 "register_operand" "f,0,f")
-                     (match_operand:SF 3 "register_operand" "0,f,f")))]
+                     (match_operand:SF 2 "register_operand" "f,0")
+                     (match_operand:SF 3 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   "* return output_fp_conditional_move (which_alternative, operands);")
 
@@ -7485,6 +7494,15 @@ byte_xor_operation:
   if (GET_MODE_CLASS (GET_MODE (i386_compare_op0)) != MODE_INT)
     FAIL;
 
+  /* We have to make sure that the target is among the sources so
+     that it is on the register stack. */
+  if (!rtx_equal_p (operands[0], operands[2])
+      && !rtx_equal_p (operands[0], operands[3]))
+    {
+      emit_insn (gen_movdf (operands[0], operands[2]));
+      operands[2] = operands[0];
+    }
+
   /* The floating point conditional move instructions don't directly
      support conditions resulting from a signed integer comparison. */
 
@@ -7513,36 +7531,36 @@ byte_xor_operation:
 }")
 
 (define_insn ""
-  [(set (match_operand:DF 0 "register_operand" "=f,f,f,f,f,f")
+  [(set (match_operand:DF 0 "register_operand" "=f,f,f,f")
        (if_then_else:DF (match_operator 1 "comparison_operator" 
-             [(match_operand:QI 2 "nonimmediate_operand" "q,m,q,m,q,m")
-               (match_operand:QI 3 "general_operand" "qmn,qn,qmn,qn,qmn,qn")])
-             (match_operand:DF 4 "register_operand" "f,f,0,0,f,f")
-             (match_operand:DF 5 "register_operand" "0,0,f,f,f,f")))]
+             [(match_operand:QI 2 "nonimmediate_operand" "q,m,q,m")
+               (match_operand:QI 3 "general_operand" "qmn,qn,qmn,qn")])
+             (match_operand:DF 4 "register_operand" "f,f,0,0")
+             (match_operand:DF 5 "register_operand" "0,0,f,f")))]
   "TARGET_CMOVE
     && GET_CODE (operands[1]) != LT && GET_CODE (operands[1]) != LE
     && GET_CODE (operands[1]) != GE && GET_CODE (operands[1]) != GT"
   "#")
 
 (define_insn ""
-  [(set (match_operand:DF 0 "register_operand" "=f,f,f,f,f,f")
+  [(set (match_operand:DF 0 "register_operand" "=f,f,f,f")
        (if_then_else:DF (match_operator 1 "comparison_operator" 
-             [(match_operand 2 "nonimmediate_operand" "r,m,r,m,r,m")
-               (match_operand 3 "general_operand" "rmi,ri,rmi,ri,rmi,ri")])
-             (match_operand:DF 4 "register_operand" "f,f,0,0,f,f")
-             (match_operand:DF 5 "register_operand" "0,0,f,f,f,f")))]
+             [(match_operand 2 "nonimmediate_operand" "r,m,r,m")
+               (match_operand 3 "general_operand" "rmi,ri,rmi,ri")])
+             (match_operand:DF 4 "register_operand" "f,f,0,0")
+             (match_operand:DF 5 "register_operand" "0,0,f,f")))]
   "TARGET_CMOVE && GET_MODE_CLASS (GET_MODE (operands[2])) == MODE_INT
     && GET_CODE (operands[1]) != LT && GET_CODE (operands[1]) != LE
     && GET_CODE (operands[1]) != GE && GET_CODE (operands[1]) != GT"
   "#")
 
 (define_split
-  [(set (match_operand:DF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:DF 0 "register_operand" "=f,f")
        (if_then_else:DF (match_operator 1 "comparison_operator" 
                                [(match_operand 2 "nonimmediate_operand" "")
                                 (const_int 0)])
-                     (match_operand:DF 3 "register_operand" "f,0,f")
-                     (match_operand:DF 4 "register_operand" "0,f,f")))]
+                     (match_operand:DF 3 "register_operand" "f,0")
+                     (match_operand:DF 4 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   [(set (cc0)
        (match_dup 2))
@@ -7552,12 +7570,12 @@ byte_xor_operation:
   "")
 
 (define_split
-  [(set (match_operand:DF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:DF 0 "register_operand" "=f,f")
        (if_then_else:DF (match_operator 1 "comparison_operator" 
                                [(match_operand 2 "nonimmediate_operand" "")
                                 (match_operand 3 "general_operand" "")])
-                     (match_operand:DF 4 "register_operand" "f,0,f")
-                     (match_operand:DF 5 "register_operand" "0,f,f")))]
+                     (match_operand:DF 4 "register_operand" "f,0")
+                     (match_operand:DF 5 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   [(set (cc0) (compare (match_dup 2) (match_dup 3)))
    (set (match_dup 0)
@@ -7566,11 +7584,11 @@ byte_xor_operation:
   "")
 
 (define_insn ""
-  [(set (match_operand:DF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:DF 0 "register_operand" "=f,f")
        (if_then_else:DF (match_operator 1 "comparison_operator" 
                                [(cc0) (const_int 0)])
-                     (match_operand:DF 2 "register_operand" "f,0,f")
-                     (match_operand:DF 3 "register_operand" "0,f,f")))]
+                     (match_operand:DF 2 "register_operand" "f,0")
+                     (match_operand:DF 3 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   "* return output_fp_conditional_move (which_alternative, operands);")
 
@@ -7587,6 +7605,15 @@ byte_xor_operation:
   if (GET_MODE_CLASS (GET_MODE (i386_compare_op0)) != MODE_INT)
     FAIL;
 
+  /* We have to make sure that the target is among the sources so
+     that it is on the register stack. */
+  if (!rtx_equal_p (operands[0], operands[2])
+      && !rtx_equal_p (operands[0], operands[3]))
+    {
+      emit_insn (gen_movxf (operands[0], operands[2]));
+      operands[2] = operands[0];
+    }
+
   /* The floating point conditional move instructions don't directly
      support conditions resulting from a signed integer comparison. */
 
@@ -7615,36 +7642,36 @@ byte_xor_operation:
 }")
 
 (define_insn ""
-  [(set (match_operand:XF 0 "register_operand" "=f,f,f,f,f,f")
+  [(set (match_operand:XF 0 "register_operand" "=f,f,f,f")
        (if_then_else:XF (match_operator 1 "comparison_operator" 
-             [(match_operand:QI 2 "nonimmediate_operand" "q,m,q,m,q,m")
-               (match_operand:QI 3 "general_operand" "qmn,qn,qmn,qn,qmn,qn")])
-             (match_operand:XF 4 "register_operand" "f,f,0,0,f,f")
-             (match_operand:XF 5 "register_operand" "0,0,f,f,f,f")))]
+             [(match_operand:QI 2 "nonimmediate_operand" "q,m,q,m")
+               (match_operand:QI 3 "general_operand" "qmn,qn,qmn,qn")])
+             (match_operand:XF 4 "register_operand" "f,f,0,0")
+             (match_operand:XF 5 "register_operand" "0,0,f,f")))]
   "TARGET_CMOVE
     && GET_CODE (operands[1]) != LT && GET_CODE (operands[1]) != LE
     && GET_CODE (operands[1]) != GE && GET_CODE (operands[1]) != GT"
   "#")
 
 (define_insn ""
-  [(set (match_operand:XF 0 "register_operand" "=f,f,f,f,f,f")
+  [(set (match_operand:XF 0 "register_operand" "=f,f,f,f")
        (if_then_else:XF (match_operator 1 "comparison_operator" 
-             [(match_operand 2 "nonimmediate_operand" "r,m,r,m,r,m")
-               (match_operand 3 "general_operand" "rmi,ri,rmi,ri,rmi,ri")])
-             (match_operand:XF 4 "register_operand" "f,f,0,0,f,f")
-             (match_operand:XF 5 "register_operand" "0,0,f,f,f,f")))]
+             [(match_operand 2 "nonimmediate_operand" "r,m,r,m")
+               (match_operand 3 "general_operand" "rmi,ri,rmi,ri")])
+             (match_operand:XF 4 "register_operand" "f,f,0,0")
+             (match_operand:XF 5 "register_operand" "0,0,f,f")))]
   "TARGET_CMOVE && GET_MODE_CLASS (GET_MODE (operands[2])) == MODE_INT
     && GET_CODE (operands[1]) != LT && GET_CODE (operands[1]) != LE
     && GET_CODE (operands[1]) != GE && GET_CODE (operands[1]) != GT"
   "#")
 
 (define_split
-  [(set (match_operand:XF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:XF 0 "register_operand" "=f,f")
        (if_then_else:XF (match_operator 1 "comparison_operator" 
                                [(match_operand 2 "nonimmediate_operand" "")
                                 (const_int 0)])
-                     (match_operand:XF 3 "register_operand" "f,0,f")
-                     (match_operand:XF 4 "register_operand" "0,f,f")))]
+                     (match_operand:XF 3 "register_operand" "f,0")
+                     (match_operand:XF 4 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   [(set (cc0)
        (match_dup 2))
@@ -7654,12 +7681,12 @@ byte_xor_operation:
   "")
 
 (define_split
-  [(set (match_operand:XF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:XF 0 "register_operand" "=f,f")
        (if_then_else:XF (match_operator 1 "comparison_operator" 
                                [(match_operand 2 "nonimmediate_operand" "")
                                 (match_operand 3 "general_operand" "")])
-                     (match_operand:XF 4 "register_operand" "f,0,f")
-                     (match_operand:XF 5 "register_operand" "0,f,f")))]
+                     (match_operand:XF 4 "register_operand" "f,0")
+                     (match_operand:XF 5 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   [(set (cc0) (compare (match_dup 2) (match_dup 3)))
    (set (match_dup 0)
@@ -7668,11 +7695,11 @@ byte_xor_operation:
   "")
 
 (define_insn ""
-  [(set (match_operand:XF 0 "register_operand" "=f,f,f")
+  [(set (match_operand:XF 0 "register_operand" "=f,f")
        (if_then_else:XF (match_operator 1 "comparison_operator" 
                                [(cc0) (const_int 0)])
-                     (match_operand:XF 2 "register_operand" "f,0,f")
-                     (match_operand:XF 3 "register_operand" "0,f,f")))]
+                     (match_operand:XF 2 "register_operand" "f,0")
+                     (match_operand:XF 3 "register_operand" "0,f")))]
   "TARGET_CMOVE && reload_completed"
   "* return output_fp_conditional_move (which_alternative, operands);")
 
diff -x CVS -x c-gperf.h -upr /home/work/misc/gnu/import/egcs/gcc/reg-stack.c 
./reg-stack.c
--- /home/work/misc/gnu/import/egcs/gcc/reg-stack.c     Thu Oct  8 12:10:13 1998
+++ ./reg-stack.c       Wed Dec 16 14:45:00 1998
@@ -2349,6 +2349,10 @@ subst_stack_regs_pat (insn, regstack, pa
        break;
 
       case IF_THEN_ELSE:
+       /* dest has to be on stack. */
+       if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
+         abort ();
+
        /* This insn requires the top of stack to be the destination. */
 
        /* If the comparison operator is an FP comparison operator,
@@ -2402,9 +2406,7 @@ subst_stack_regs_pat (insn, regstack, pa
              }
        }
 
-       /* Make dest the top of stack.  Add dest to regstack if not present. */
-       if (get_hard_regnum (regstack, *dest) < FIRST_STACK_REG)
-         regstack->reg[++regstack->top] = REGNO (*dest);       
+       /* Make dest the top of stack. */
        SET_HARD_REG_BIT (regstack->reg_set, REGNO (*dest));
        replace_reg (dest, FIRST_STACK_REG);
 

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