[antlr-interest] slowdown

[Terence Parr]

search for time out or Xwatchconversion 
T
On Dec 16, 2010, at 8:56 AM, Justin Murray wrote:

> Hello,
> 
> 
> 
> I have started adding {actions} to my grammar, and have noticed that the
> code generation started taking much longer than before. I used the
> -Xwatchconversion flag to try to get an idea of what is happening. What
> I found is that the generation gets to the following point:
> 
> 
> 
> attempting LL(1) DFA (d=627) for ()* loopback of 1409:3: (o= OR e2=
> exprAND )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=628) for ()* loopback of 1417:3: (o= AND e2=
> exprBOR )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=629) for ()* loopback of 1425:3: (o= BOR e2=
> exprBXOR | o= BNOR e2= exprBXOR )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=630) for ()* loopback of 1434:3: (o= BXOR e2=
> exprBAND )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=631) for ()* loopback of 1442:3: (o= BAND e2=
> exprEqual | o= BNAND e2= exprEqual )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=632) for ()* loopback of 1451:3: (o= ( EQ | '='
> ) e2= exprComp | o= NE e2= exprComp )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=633) for ()* loopback of 1460:3: (o= LT_ e2=
> exprShift | o= LE e2= exprShift | o= GT e2= exprShift | o= GE e2=
> exprShift )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=634) for ()* loopback of 1471:3: (o= '<<' e2=
> exprAdd | o= '>>' e2= exprAdd )*
> 
> --------------------
> 
> attempting LL(1) DFA (d=635) for ()* loopback of 1481:3: (o= '+' e2=
> exprMult | o= '-' e2= exprMult )*
> 
> decision 635 not suitable for LL(1)-optimized DFA analysis
> 
> --------------------
> 
> building lookahead DFA (d=635) for ()* loopback of 1481:3: (o= '+' e2=
> exprMult | o= '-' e2= exprMult )*
> 
> convert DFA state 0 (174414 nfa states)
> 
> convert DFA state 29 (106645 nfa states)
> 
> 
> 
> It then hangs on this last line for several minutes (3 or 4), before
> proceeding on with this output:
> 
> 
> 
> trying decision 635 again with k=1; reason: non-LL(*) && predicate
> visible
> 
> convert DFA state 0 (174414 nfa states)
> 
> convert DFA state 29 (106645 nfa states)
> 
> convert DFA state 30 (106645 nfa states)
> 
> cost: 173 states, 160260 ms
> 
> --------------------
> 
> attempting LL(1) DFA (d=636) for ()* loopback of 1490:3: (o= '*' e2=
> exprPow | o= '/' e2= exprPow | o= '%' e2= exprPow )*
> 
> 
> 
> While it is possible that I may have inadvertently changed the syntax,
> for the most part I was just adding in my action code. The first
> question is, should adding action code have any effect on the time it
> takes to generate the code? That aside, what would cause the lengthy
> hangup on that one decision? The rest of the decisions go by very
> quickly.
> 
> 
> 
> Thanks,
> 
> Justin Murray 
> Software Engineer 
> jmurray at aerotech.com
> 
> Aerotech, Inc. 
> 101 Zeta Drive 
> Pittsburgh, PA 15238 
> 412-963-7470
> 
> 
> 
> 
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