This removes --param vect-inner-loop-cost-factor in favor of looking
at the estimated number of iterations of the inner loop
when available and otherwise just assumes a single inner
iteration which is conservative on the side of not vectorizing.
The alternative is to retain the --param for exactly that case,
not sure if the result is better or not. The --param is new on
head, it was static '50' before.
Any strong opinions?
Richard.
2021-08-23 Richard Biener <rguent...@suse.de>
* doc/invoke.texi (vect-inner-loop-cost-factor): Remove
documentation.
* params.opt (--param vect-inner-loop-cost-factor): Remove.
* tree-vect-loop.c (_loop_vec_info::_loop_vec_info):
Initialize inner_loop_cost_factor to 1.
(vect_analyze_loop_form): Initialize inner_loop_cost_factor
from the estimated number of iterations of the inner loop.
---
gcc/doc/invoke.texi | 5 -----
gcc/params.opt | 4 ----
gcc/tree-vect-loop.c | 12 +++++++++++-
3 files changed, 11 insertions(+), 10 deletions(-)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index c057cc1e4ae..054950132f6 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -14385,11 +14385,6 @@ code to iterate. 2 allows partial vector loads and
stores in all loops.
The parameter only has an effect on targets that support partial
vector loads and stores.
-@item vect-inner-loop-cost-factor
-The factor which the loop vectorizer applies to the cost of statements
-in an inner loop relative to the loop being vectorized. The default
-value is 50.
-
@item avoid-fma-max-bits
Maximum number of bits for which we avoid creating FMAs.
diff --git a/gcc/params.opt b/gcc/params.opt
index f9264887b40..f7b19fa430d 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -1113,8 +1113,4 @@ Bound on number of runtime checks inserted by the
vectorizer's loop versioning f
Common Joined UInteger Var(param_vect_partial_vector_usage) Init(2)
IntegerRange(0, 2) Param Optimization
Controls how loop vectorizer uses partial vectors. 0 means never, 1 means
only for loops whose need to iterate can be removed, 2 means for all loops.
The default value is 2.
--param=vect-inner-loop-cost-factor=
-Common Joined UInteger Var(param_vect_inner_loop_cost_factor) Init(50)
IntegerRange(1, 999999) Param Optimization
-The factor which the loop vectorizer applies to the cost of statements in an
inner loop relative to the loop being vectorized.
-
; This comment is to ensure we retain the blank line above.
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index c521b43a47c..cb48717f20e 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -841,7 +841,7 @@ _loop_vec_info::_loop_vec_info (class loop *loop_in,
vec_info_shared *shared)
single_scalar_iteration_cost (0),
vec_outside_cost (0),
vec_inside_cost (0),
- inner_loop_cost_factor (param_vect_inner_loop_cost_factor),
+ inner_loop_cost_factor (1),
vectorizable (false),
can_use_partial_vectors_p (param_vect_partial_vector_usage != 0),
using_partial_vectors_p (false),
@@ -1519,6 +1519,16 @@ vect_analyze_loop_form (class loop *loop,
vec_info_shared *shared)
stmt_vec_info inner_loop_cond_info
= loop_vinfo->lookup_stmt (inner_loop_cond);
STMT_VINFO_TYPE (inner_loop_cond_info) = loop_exit_ctrl_vec_info_type;
+ /* If we have an estimate on the number of iterations of the inner
+ loop use that as the scale for costing, otherwise conservatively
+ assume a single inner iteration. */
+ widest_int nit;
+ if (get_estimated_loop_iterations (loop->inner, &nit))
+ LOOP_VINFO_INNER_LOOP_COST_FACTOR (loop_vinfo)
+ /* Since costing is done on unsigned int cap the scale on
+ some large number consistent with what we'd see in
+ CFG counts. */
+ = wi::smax (nit, REG_BR_PROB_BASE).to_uhwi ();
}
gcc_assert (!loop->aux);
--
2.31.1
