# COMPILER DESIGN

242 views
what is backpatching?????????????/

plz explain with an example.
1
Backpaching is the process of leaving blank entries for the goto instruction where the target address is unkonown in the forward transfer in the first pass and filling these unknown in the second pass.

Kindly visit the link mentioned below. It contains wonderful description of back patching. Yeah. :)

http://www.csd.uwo.ca/~moreno//CS447/Lectures/IntermediateCode.html/node7.html

## Related questions

1
107 views
Implement Algorithm $3.23$, which converts a regular expression into a nondeterministic finite automaton, by an L-attributed SDD on a top-down parsable grammar. Assume that there is a token char representing any character, and that char.$lexval$ is the character it ... that is, a state never before returned by this function. Use any convenient notation to specify the transitions of the $NFA$.
1 vote
In Fig. $4.56$ is a grammar for certain statements, similar to that discussed in Question $4.4.12$. Again, $e$ and $s$ are terminals standing for conditional expressions and "other statements," respectively. Build an LR parsing table for this grammar, resolving conflicts in the usual way ... your parser on the following inputs: if e then s ; if e then s end while e do begin s ; if e then s ; end
The following is an ambiguous grammar for expressions with $n$ binary, infix operators, at $n$ different levels of precedence: $E\rightarrow E\theta_{1}E\mid E\theta_{2}E\mid \cdot\cdot\cdot E\theta_{n}E\mid(E)\mid id$ ... of the tables for the two (ambiguous and unambiguous) grammars compare? What does that comparison tell you about the use of ambiguous expression grammars?
Show that the following grammar $S\rightarrow Aa\mid bAc\mid Bc\mid bBa$ $A\rightarrow d$ $B\rightarrow d$ is LR(1) but not LALR(1).