[Bug c++/17596] New: expression parser is too slow, should be rewritten

[giovannibajo at libero dot it]

The expression parser is currently too slow due to its recursive nature. It 
could be speed up by rewriting it so that it manually tracks precedences.

Bug 14179 is an example of a machine-generated testcase which exposes our 
limits. I proposed a hack to help the testcase in that bug:
http://gcc.gnu.org/ml/gcc-patches/2004-09/msg01839.html

but the patch was rejected. Mark said:
"""
I would like to hold off on this patch. Like Nathan says, this is the first 
good evidence I've seen that implementing operator-precedence parsing might be 
a measureable win on real code. If you, or Nathan, or I, or Zack, or somebody 
gets to implementing that, then that's probably the best way to go. If not, 
then we should consider your patch, as it really does make a big difference. 
Would you mind reminding me about this patch when we get ready to make the 
release branch, assuming we've not yet implemented the operator-precedence 
thing?
"""
http://gcc.gnu.org/ml/gcc-patches/2004-09/msg01960.html


This bug was opened to track this.

-- 
           Summary: expression parser is too slow, should be rewritten
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Keywords: compile-time-hog
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: giovannibajo at libero dot it
                CC: gcc-bugs at gcc dot gnu dot org
OtherBugsDependingO 14179
             nThis:


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17596