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Introduce new param: AVG_LOOP_NITER 

* params.def: Add avg-loop niter.
	* tree-ssa-loop-ivopts.c (avg_loop_niter): Use the param.
	* cfgloopanal.c (expected_loop_iterations_unbounded): Likewise.
	* doc/invoke.texi: Document the new parameter.

From-SVN: r238252
This commit is contained in:
Martin Liska 2016-07-12 17:27:36 +02:00 committed by Martin Liska
parent f507d20235
commit 4661839ee3
5 changed files with 22 additions and 9 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2016-07-12 Martin Liska <mliska@suse.cz>
* params.def: Add avg-loop niter.
* tree-ssa-loop-ivopts.c (avg_loop_niter): Use the param.
* cfgloopanal.c (expected_loop_iterations_unbounded): Likewise.
* doc/invoke.texi: Document the new parameter.
2016-07-12 Kyrylo Tkachov <kyrylo.tkachov@arm.com>
PR middle-end/71700

9
gcc/cfgloopanal.c
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@ -241,10 +241,9 @@ expected_loop_iterations_unbounded (const struct loop *loop,
if (read_profile_p)
*read_profile_p = false;
/* Average loop rolls about 3 times. If we have no profile at all, it is
best we can do. */
/* If we have no profile at all, use AVG_LOOP_NITER. */
if (profile_status_for_fn (cfun) == PROFILE_ABSENT)
expected = 3;
expected = PARAM_VALUE (PARAM_AVG_LOOP_NITER);
else if (loop->latch->count || loop->header->count)
{
gcov_type count_in, count_latch;
@ -282,9 +281,9 @@ expected_loop_iterations_unbounded (const struct loop *loop,
if (freq_in == 0)
{
/* If we have no profile at all, expect 3 iterations. */
/* If we have no profile at all, use AVG_LOOP_NITER iterations. */
if (!freq_latch)
expected = 3;
expected = PARAM_VALUE (PARAM_AVG_LOOP_NITER);
else
expected = freq_latch * 2;
}

3
gcc/doc/invoke.texi
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@ -9150,6 +9150,9 @@ If the number of candidates in the set is smaller than this value,
always try to remove unnecessary ivs from the set
when adding a new one.
@item avg-loop-niter
Average number of iterations of a loop.
@item scev-max-expr-size
Bound on size of expressions used in the scalar evolutions analyzer.
Large expressions slow the analyzer.

5
gcc/params.def
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@ -527,6 +527,11 @@ DEFPARAM(PARAM_IV_ALWAYS_PRUNE_CAND_SET_BOUND,
"If number of candidates in the set is smaller, we always try to remove unused ivs during its optimization.",
10, 0, 0)
DEFPARAM(PARAM_AVG_LOOP_NITER,
"avg-loop-niter",
"Average number of iterations of a loop.",
10, 1, 0)
DEFPARAM(PARAM_SCEV_MAX_EXPR_SIZE,
"scev-max-expr-size",
"Bound on size of expressions used in the scalar evolutions analyzer.",

7
gcc/tree-ssa-loop-ivopts.c
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@ -115,8 +115,6 @@ along with GCC; see the file COPYING3. If not see
/* The infinite cost. */
#define INFTY 10000000
#define AVG_LOOP_NITER(LOOP) 5
/* Returns the expected number of loop iterations for LOOP.
The average trip count is computed from profile data if it
exists. */
@ -128,8 +126,9 @@ avg_loop_niter (struct loop *loop)
if (niter == -1)
{
niter = likely_max_stmt_executions_int (loop);
if (niter == -1 || niter > AVG_LOOP_NITER (loop))
return AVG_LOOP_NITER (loop);
if (niter == -1 || niter > PARAM_VALUE (PARAM_AVG_LOOP_NITER))
return PARAM_VALUE (PARAM_AVG_LOOP_NITER);
}
return niter;