On Thu, Jan 05, 2017 at 05:13:24PM +0800, Michael W. Bombardieri wrote:
> Hi,
>
> Two loops in yacc/lalr.c can be converted into memcpy().
> I quickly tested this on i386 and amd64 against rcs/date.y
> and the output matched y.tab.c of unpatched yacc.
Some remarks:
1. use of magic nunber
2. You are assuming the layout of edge and nedge is the same. That is
the case , but I had to go look at the declaration and initialization
to decide that.
3. Is there an upstream we might want to be in-sync with?
Al in all I am not convinced this is worth it.
-Otto
>
> - Michael
>
>
> Index: lalr.c
> ===================================================================
> RCS file: /cvs/src/usr.bin/yacc/lalr.c,v
> retrieving revision 1.18
> diff -u -p -u -r1.18 lalr.c
> --- lalr.c 11 Dec 2015 20:25:47 -0000 1.18
> +++ lalr.c 5 Jan 2017 08:56:11 -0000
> @@ -324,8 +324,7 @@ initialize_F(void)
> if (nedges) {
> reads[i] = rp = NEW2(nedges + 1, short);
>
> - for (j = 0; j < nedges; j++)
> - rp[j] = edge[j];
> + memcpy(rp, edge, nedges * 2);
>
> rp[nedges] = -1;
> nedges = 0;
> @@ -403,8 +402,7 @@ build_relations(void)
>
> if (nedges) {
> includes[i] = shortp = NEW2(nedges + 1, short);
> - for (j = 0; j < nedges; j++)
> - shortp[j] = edge[j];
> + memcpy(shortp, edge, nedges * 2);
> shortp[nedges] = -1;
> }
> }
