gas really slow on long lines

[Anders Waldenborg]

Assembling large files seemed a bit slow, so I did some
investigations. It turned out that long lines was making it slow.

There is a huge difference with a file with 1000000*"\t.long 0\n"
and a file with "\t.long 0" + (999999*",0")

Numbers talk, so here is a little table. First column is number of
lines, second is expressions per line.

1000000       1    1.30s
 100000      10    0.66s
  10000     100    0.80s
   1000    1000    2.50s
    100   10000   18.01s
     50   20000   35.12s
     10  100000 3m02.42s

So I fired up oprofile and did some profiling. lex_got in tc-i386.c
turned up as the main offender.

Without any deeper knowledge of the code it seems really stupid that
lex_got checks until end of line when it is called on each expression
on a line. I modified it to only check to ',' or end of line. With my
modified version the table looks like this:

1000000       1    1.34s
 100000      10    0.61s
  10000     100    0.50s
   1000    1000    0.50s
    100   10000    0.50s
     50   20000    0.36s
     10  100000    0.37s

Looks much better IMHO.

Here is the patch:

--- binutils-2.17.orig/gas/config/tc-i386.c	2006-04-07 
08:40:57.000000000 +0200
+++ binutils-2.17/gas/config/tc-i386.c  2007-08-23 16:56:42.795755012 +0200
@@ -3929,7 +3929,7 @@
     return NULL;

   for (cp = input_line_pointer; *cp != '@'; cp++)
-    if (is_end_of_line[(unsigned char) *cp])
+    if (is_end_of_line[(unsigned char) *cp] || *cp == ',')
       return NULL;

   for (j = 0; j < sizeof (gotrel) / sizeof (gotrel[0]); j++)