From mboxrd@z Thu Jan  1 00:00:00 1970
From: Greg McGary <greg@mcgary.org>
To: law@cygnus.com
Cc: gcc@gcc.gnu.org
Subject: Re: MIPS div_trap vs. general conditional traps
Date: Thu, 07 Sep 2000 16:53:00 -0000
Message-id: <msn1hjoj3d.fsf@mcgary.org>
References: <8419.968364901@upchuck>
X-SW-Source: 2000-09/msg00170.html

Jeffrey A Law <law@cygnus.com> writes:

>   In message < 200009062017.NAA06786@kayak.mcgary.org >you write:
>   > I implemented conditional traps for MIPS using the MIPS
>   > conditional-trap machine instructions for ISA>=2 and using the MIPS
>   > `break' instruction for ISA==1.  I posted the patch last night.
> Sounds like a good thing.

Care to go all the way and review it?  8^)

Here's a newer mips.md that places the general conditional traps
before the div_traps for reasons explained in the comments:

Greg

Index: gcc/config/mips/mips.md
===================================================================
RCS file: /cvs/gcc/egcs/gcc/config/mips/mips.md,v
retrieving revision 1.84
retrieving revision 1.81.4.5
diff -u -p -r1.84 -r1.81.4.5
--- mips.md	2000/08/08 22:40:49	1.84
+++ mips.md	2000/09/07 17:12:08	1.81.4.5
@@ -495,7 +495,48 @@
 ;; 
 ;; (define_function_unit "sqrt"     1 1 (and (eq_attr "type" "fsqrt") (eq_attr "mode" "SF"))  54 0)
 ;; (define_function_unit "sqrt"     1 1 (and (eq_attr "type" "fsqrt") (eq_attr "mode" "DF")) 112 0)
+
+;;
+;;  ....................
+;;
+;;	CONDITIONAL TRAPS
+;;
+;;  ....................
+;;
 
+(define_insn "trap"
+  [(trap_if (const_int 1) (const_int 0))]
+  ""
+  "*
+{
+  if (ISA_HAS_COND_TRAP)
+    return \"teq\\t$0,$0\";
+  else
+    return \"break\";
+}")
+
+(define_expand "conditional_trap"
+  [(trap_if (match_operator 0 "cmp_op"
+			    [(match_dup 2) (match_dup 3)])
+	    (match_operand 1 "const_int_operand" ""))]
+  "ISA_HAS_COND_TRAP"
+  "
+{
+  mips_gen_conditional_trap (operands);
+  DONE;
+}")
+
+;; Match a TRAP_IF with 2nd arg of 0.  The div_trap_* insns match a
+;; 2nd arg of any CONST_INT, so this insn must appear first.
+;; gen_div_trap always generates TRAP_IF with 2nd arg of 6 or 7.
+
+(define_insn ""
+  [(trap_if (match_operator 0 "trap_cmp_op"
+                            [(match_operand:SI 1 "reg_or_0_operand" "d")
+                             (match_operand:SI 2 "nonmemory_operand" "dI")])
+	    (const_int 0))]
+  "ISA_HAS_COND_TRAP"
+  "t%C0\\t%z1,%z2")
 
 ;;
 ;;  ....................