loop.texi: Document number_of_latch_executions and number_of_cond_exit_executions.

	* doc/loop.texi: Document number_of_latch_executions and
	number_of_cond_exit_executions.
	* tree-scalar-evolution.c (compute_overall_effect_of_inner_loop,
	chrec_is_positive, number_of_iterations_for_all_loops,
	scev_const_prop): Use number_of_latch_executions.
	(set_nb_iterations_in_loop): Do not increase the value of the
	number of iterations.
	(number_of_iterations_in_loop): Renamed to ...
	(number_of_latch_executions): ... this.
	(number_of_exit_cond_executions): New function.
	* tree-scalar-evolution.h (number_of_iterations_in_loop): Declaration
	removed.
	(number_of_latch_executions, number_of_exit_cond_executions): Declare.
	* tree-ssa-loop-ivcanon.c (canonicalize_loop_induction_variables): Use
	number_of_latch_executions.
	* tree-data-ref.c (get_number_of_iters_for_loop): Use
	number_of_exit_cond_executions.
	* tree-vect-analyze.c (vect_get_loop_niters): Ditto.
	* cfgloop.h (struct loop): Improve description of the nb_iterations
	field.

	* gcc.dg/tree-ssa/loop-17.c: Update outcome.

From-SVN: r119718

1 files changed, 15 insertions, 13 deletions

diff --git a/gcc/doc/loop.texi b/gcc/doc/loop.texi
index 354241f..1b189c7 100644
--- a/gcc/doc/loop.texi
+++ b/gcc/doc/loop.texi
@@ -397,13 +397,15 @@ calculations.
 @cindex Number of iterations analysis
 
 Both on GIMPLE and on RTL, there are functions available to determine
-the number of iterations of a loop, with a similar interface.  In many
-cases, it is not possible to determine number of iterations
-unconditionally -- the determined number is correct only if some
-assumptions are satisfied.  The analysis tries to verify these
-conditions using the information contained in the program; if it fails,
-the conditions are returned together with the result.  The following
-information and conditions are provided by the analysis:
+the number of iterations of a loop, with a similar interface.  The
+number of iterations of a loop in GCC is defined as the number of
+executions of the loop latch.  In many cases, it is not possible to
+determine the number of iterations unconditionally -- the determined
+number is correct only if some assumptions are satisfied.  The analysis
+tries to verify these conditions using the information contained in the
+program; if it fails, the conditions are returned together with the
+result.  The following information and conditions are provided by the
+analysis:
 
 @itemize
 @item @code{assumptions}: If this condition is false, the rest of
@@ -431,16 +433,16 @@ number of iterations -- @code{find_loop_niter} on GIMPLE and
 @code{find_simple_exit} on RTL.  Finally, there are functions that
 provide the same information, but additionally cache it, so that
 repeated calls to number of iterations are not so costly --
-@code{number_of_iterations_in_loop} on GIMPLE and
-@code{get_simple_loop_desc} on RTL.
+@code{number_of_latch_executions} on GIMPLE and @code{get_simple_loop_desc}
+on RTL.
 
 Note that some of these functions may behave slightly differently than
 others -- some of them return only the expression for the number of
 iterations, and fail if there are some assumptions.  The function
-@code{number_of_iterations_in_loop} works only for single-exit loops,
-and it returns the value for number of iterations higher by one with
-respect to all other functions (i.e., it returns number of executions of
-the exit statement, not of the loop latch).
+@code{number_of_latch_executions} works only for single-exit loops.
+The function @code{number_of_cond_exit_executions} can be used to
+determine number of executions of the exit condition of a single-exit
+loop (i.e., the @code{number_of_latch_executions} increased by one).
 
 @node Dependency analysis
 @section Data Dependency Analysis