Re: RFC: reloading sums

[Joern Rennecke <joern dot rennecke at superh dot com>]

Joern Rennecke wrote:
> 
> To make the problem better observable, I've created a synthetic
> testcase; ironically, it doesn't trigger for sh5-compact, where
> the problem was originally observed, but it does on sh5-media32,
> and my patch also cures the problem there.
> However, when I try the testcase on powerpc-eabi, it fails at -O2,
> with or without my patch.  It even fails when I change can_reload_into
> to return always 0.
> Unfortunalely, it's getting late here, and I don't have a powerpc-eabi
> debugger at hand.  Maybe one of you can find out what's going on here?

Well, it build overnight.  I've attached an untested patch that shows where
the problem was.
can_reload_into was actually called only with MEMs like this one for this
testcase on powerpc-eabi -O2:
Breakpoint 4, can_reload_into (in=0x4029e5b4, regno=19, mode=SImode)
    at ../../srcw/gcc/reload.c:857
857       int r = 0;
1: debug_rtx (in) = (mem:SI (plus:SI (reg/f:SI 1 r1)
        (reg:SI 19 r19 [572])) [3 a37+0 S4 A128])
	
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Index: config/rs6000/rs6000.md
===================================================================
RCS file: /cvs/gcc/gcc/gcc/config/rs6000/rs6000.md,v
retrieving revision 1.259
diff -p -u -r1.259 rs6000.md
--- config/rs6000/rs6000.md	9 Jun 2003 17:16:14 -0000	1.259
+++ config/rs6000/rs6000.md	20 Jun 2003 11:01:57 -0000
@@ -13989,15 +13989,15 @@
 
 (define_insn "*ctrsi_internal1"
   [(set (pc)
-	(if_then_else (ne (match_operand:SI 1 "register_operand" "c,*r,*r")
+	(if_then_else (ne (match_operand:SI 1 "register_operand" "c,*r,*r,*r")
 			  (const_int 1))
 		      (label_ref (match_operand 0 "" ""))
 		      (pc)))
-   (set (match_operand:SI 2 "register_operand" "=1,*r,m*q*c*l")
+   (set (match_operand:SI 2 "register_operand" "=1,*r,m,*q*c*l")
 	(plus:SI (match_dup 1)
 		 (const_int -1)))
-   (clobber (match_scratch:CC 3 "=X,&x,&x"))
-   (clobber (match_scratch:SI 4 "=X,X,r"))]
+   (clobber (match_scratch:CC 3 "=X,&x,&x,&x"))
+   (clobber (match_scratch:SI 4 "=X,X,&r,r"))]
   "! TARGET_POWERPC64"
   "*
 {
@@ -14009,7 +14009,7 @@
     return \"bdz $+8\;b %l0\";
 }"
   [(set_attr "type" "branch")
-   (set_attr "length" "4,12,16")])
+   (set_attr "length" "4,12,16,16")])
 
 (define_insn "*ctrsi_internal2"
   [(set (pc)