procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

cfg.texi (Edges): Update.

Browse source 
* doc/cfg.texi (Edges): Update. Document the edge_iterator data
	type and its methods.

From-SVN: r91671
This commit is contained in:
Ben Elliston 2004-12-03 02:01:35 +00:00 • committed by Ben Elliston
parent dda7d95b7d
commit 9208393247
2 changed files with 69 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
gcc/ChangeLog
View file

@ -1,3 +1,8 @@
2004-12-03 Ben Elliston <bje@au.ibm.com>
* doc/cfg.texi (Edges): Update. Document the edge_iterator data
type and its methods.
2004-12-02 Richard Henderson <rth@redhat.com>
* expr.c (write_complex_part): Use simplify_gen_subreg when the

69
gcc/doc/cfg.texi
View file

@ -145,11 +145,70 @@ a predecessor of B, and B is a successor of A@. Edges are represented
in GCC with the @code{edge} data type. Each @code{edge} acts as a
link between two basic blocks: the @code{src} member of an edge
points to the predecessor basic block of the @code{dest} basic block.
The members @code{pred} and @code{succ} of the @code{basic_block} data
type point to singly linked lists of edges to the predecessors and
successors of the block. The edges are linked via the
@code{succ_next} and @code{pred_next} members of the @code{edge} data
type.
The members @code{preds} and @code{succs} of the @code{basic_block} data
type point to type-safe vectors of edges to the predecessors and
successors of the block.
@cindex edge iterators
When walking the edges in an edge vector, @dfn{edge iterators} should
be used. Edge iterators are constructed using the
@code{edge_iterator} data structure and several methods are available
to operate on them:
@ftable @code
@item ei_start
This function initializes an @code{edge_iterator} that points to the
first edge in a vector of edges.
@item ei_last
This function initializes an @code{edge_iterator} that points to the
last edge in a vector of edges.
@item ei_end_p
This predicate is @code{true} if an @code{edge_iterator} represents
the last edge in an edge vector.
@item ei_one_before_end_p
This predicate is @code{true} if an @code{edge_iterator} represents
the second last edge in an edge vector.
@item ei_next
This function takes a pointer to an @code{edge_iterator} and makes it
point to the next edge in the sequence.
@item ei_prev
This function takes a pointer to an @code{edge_iterator} and makes it
point to the previous edge in the sequence.
@item ei_edge
This function returns the @code{edge} currently pointed to by an
@code{edge_iterator}.
@item ei_safe_safe
This function returns the @code{edge} currently pointed to by an
@code{edge_iterator}, but returns @code{NULL} if the iterator is
pointing at the end of the sequence. This function has been provided
for existing code makes the assumption that a @code{NULL} edge
indicates the end of the sequence.
@end ftable
The convenience macro @code{FOR_EACH_EDGE} can be used to visit all of
the edges in a sequence of predecessor or successor edges. It must
not be used when an element might be removed during the traversal,
otherwise elements will be missed. Here is an example of how to use
the macro:
@smallexample
edge e;
edge_iterator ei;
FOR_EACH_EDGE (e, ei, bb->succs)
@{
if (e->flags & EDGE_FALLTHRU)
break;
@}
@end smallexample
@findex fall-thru
There are various reasons why control flow may transfer from one block