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> > It's definitely dangerous to use array indexes outside the bounds
> > of the array, particularly on the PA.  There can be problems with
> > space register selection, although I wouldn't expect this to be a in
> > the linux kernel.  You can avoid index insns with "-mdisable-indexing".
> > Let me know if you see anything strange in the assembler output.
> > 
> > Dave

The following is the output using gcc 3.0.4.

--- unwind-orig.c       Fri Jun  7 11:01:22 2002
+++ unwind.c    Fri Jun  7 09:23:17 2002
@@ -106,7 +106,7 @@
        table->base_addr = base_addr;
        table->gp = gp;
        table->start = base_addr + start[0].region_start;
-       table->end = base_addr + end[-1].region_end;
+       table->end = base_addr + (--end)->region_end;
        table->table = (struct unwind_table_entry *)table_start;
        table->length = end - start;
        table->next = NULL;

--- unwind-orig.s       Fri Jun  7 11:01:33 2002
+++ unwind.s    Fri Jun  7 09:24:55 2002
@@ -7,22 +7,23 @@
        .CALLINFO FRAME=0,NO_CALLS
        .ENTRY
        stw %r24,12(%r26)
-       ldw -52(%r30),%r21
+       ldw -52(%r30),%r22
        stw %r25,4(%r26)
        stw %r23,8(%r26)
-       ldw 0(%r21),%r19
-       ldw -56(%r30),%r22
+       ldw 0(%r22),%r19
+       ldw -56(%r30),%r20
        addl %r24,%r19,%r19
        stw %r19,16(%r26)
-       sub %r22,%r21,%r20
-       ldw -12(%r22),%r19
-       extrs %r20,27,28,%r20
+       ldo -16(%r20),%r20
+       ldw 4(%r20),%r19
+       sub %r20,%r22,%r21
+       extrs %r21,27,28,%r21
        addl %r24,%r19,%r24
-       stw %r20,28(%r26)
        stw %r24,20(%r26)
+       stw %r21,28(%r26)
        stw %r0,0(%r26)
        bv %r0(%r2)
-       stw %r21,24(%r26)
+       stw %r22,24(%r26)
        .EXIT
        .PROCEND
 .Lfe1:

Aside from some register juggling, the only difference is
that we now use 'ldo,ldw,sub,extrs' instead of 'sub,ldw,extrs'.
The question is: Can this do bad things?

I'll have time on Monday to go through it thoroughly.

c.