[gcc r12-939] vect: Replace hardcoded inner loop cost factor

[gcc r12-939] vect: Replace hardcoded inner loop cost factor

[Kewen Lin]

https://gcc.gnu.org/g:9c5bd1e9811babe255ddbbdcda1d00ea5997b826

commit r12-939-g9c5bd1e9811babe255ddbbdcda1d00ea5997b826
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Wed May 19 05:42:51 2021 -0500

    vect: Replace hardcoded inner loop cost factor
    
    This patch is to replace the current hardcoded weight factor
    50, which is applied by the loop vectorizer to the cost of
    statements in an inner loop relative to the loop being
    vectorized, with one newly added member inner_loop_cost_factor
    in loop vinfo.  It also introduces one parameter
    vect-inner-loop-cost-factor whose default value is 50, and
    is used to initialize the inner_loop_cost_factor member.
    
    The motivation here is that: if targets want to have one
    unique function to gather some information in each add_stmt_cost
    call, no matter that it's put before or after the cost tweaking
    part for inner loop, it may have the need to adjust (expand or
    shrink) the gathered data as the factor.  Now the factor is
    hardcoded, it's not easily maintained.
    
    Bootstrapped/regtested on powerpc64le-linux-gnu P9,
    x86_64-redhat-linux and aarch64-linux-gnu.
    
    gcc/ChangeLog:
    
            * doc/invoke.texi (vect-inner-loop-cost-factor): Document new
            parameter.
            * params.opt (vect-inner-loop-cost-factor): New.
            * targhooks.c (default_add_stmt_cost): Replace hardcoded factor
            50 with LOOP_VINFO_INNER_LOOP_COST_FACTOR, include head file
            tree-vectorizer.h and its required ones.
            * config/aarch64/aarch64.c (aarch64_add_stmt_cost): Replace
            hardcoded factor 50 with LOOP_VINFO_INNER_LOOP_COST_FACTOR.
            * config/arm/arm.c (arm_add_stmt_cost): Likewise.
            * config/i386/i386.c (ix86_add_stmt_cost): Likewise.
            * config/rs6000/rs6000.c (rs6000_add_stmt_cost): Likewise.
            * tree-vect-loop.c (vect_compute_single_scalar_iteration_cost):
            Likewise.
            (_loop_vec_info::_loop_vec_info): Init inner_loop_cost_factor.
            * tree-vectorizer.h (_loop_vec_info): Add inner_loop_cost_factor.
            (LOOP_VINFO_INNER_LOOP_COST_FACTOR): New macro.

Diff:
---
 gcc/config/aarch64/aarch64.c | 5 ++++-
 gcc/config/arm/arm.c         | 6 +++++-
 gcc/config/i386/i386.c       | 6 +++++-
 gcc/config/rs6000/rs6000.c   | 6 +++++-
 gcc/doc/invoke.texi          | 5 +++++
 gcc/params.opt               | 4 ++++
 gcc/targhooks.c              | 9 ++++++++-
 gcc/tree-vect-loop.c         | 3 ++-
 gcc/tree-vectorizer.h        | 5 +++++
 9 files changed, 43 insertions(+), 6 deletions(-)

diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 08356466e56..c1e451ec8dc 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -15435,7 +15435,10 @@ aarch64_add_stmt_cost (class vec_info *vinfo, void *data, int count,
 	 arbitrary and could potentially be improved with analysis.  */
       if (where == vect_body && stmt_info
 	  && stmt_in_inner_loop_p (vinfo, stmt_info))
-	count *= 50; /*  FIXME  */
+	{
+	  gcc_assert (loop_vinfo);
+	  count *= LOOP_VINFO_INNER_LOOP_COST_FACTOR (loop_vinfo); /*  FIXME  */
+	}
 
       retval = (unsigned) (count * stmt_cost);
       costs->region[where] += retval;
diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index 28cfd81cca7..caf4e56b9fe 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -12226,7 +12226,11 @@ arm_add_stmt_cost (vec_info *vinfo, void *data, int count,
 	 arbitrary and could potentially be improved with analysis.  */
       if (where == vect_body && stmt_info
 	  && stmt_in_inner_loop_p (vinfo, stmt_info))
-	count *= 50;  /* FIXME.  */
+	{
+	  loop_vec_info loop_vinfo = dyn_cast<loop_vec_info> (vinfo);
+	  gcc_assert (loop_vinfo);
+	  count *= LOOP_VINFO_INNER_LOOP_COST_FACTOR (loop_vinfo); /* FIXME.  */
+	}
 
       retval = (unsigned) (count * stmt_cost);
       cost[where] += retval;
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 743d8a25fe3..f3b451835da 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -22482,7 +22482,11 @@ ix86_add_stmt_cost (class vec_info *vinfo, void *data, int count,
      arbitrary and could potentially be improved with analysis.  */
   if (where == vect_body && stmt_info
       && stmt_in_inner_loop_p (vinfo, stmt_info))
-    count *= 50;  /* FIXME.  */
+    {
+      loop_vec_info loop_vinfo = dyn_cast<loop_vec_info> (vinfo);
+      gcc_assert (loop_vinfo);
+      count *= LOOP_VINFO_INNER_LOOP_COST_FACTOR (loop_vinfo); /* FIXME.  */
+    }
 
   retval = (unsigned) (count * stmt_cost);
 
diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 6db450ab954..dfa517bba6c 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -5364,7 +5364,11 @@ rs6000_add_stmt_cost (class vec_info *vinfo, void *data, int count,
 	 arbitrary and could potentially be improved with analysis.  */
       if (where == vect_body && stmt_info
 	  && stmt_in_inner_loop_p (vinfo, stmt_info))
-	count *= 50;  /* FIXME.  */
+	{
+	  loop_vec_info loop_vinfo = dyn_cast<loop_vec_info> (vinfo);
+	  gcc_assert (loop_vinfo);
+	  count *= LOOP_VINFO_INNER_LOOP_COST_FACTOR (loop_vinfo); /* FIXME.  */
+	}
 
       retval = (unsigned) (count * stmt_cost);
       cost_data->cost[where] += retval;
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 5e5fb169a25..49c74f37497 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -14226,6 +14226,11 @@ 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 2e4cbdd7a71..82600b930ba 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -1089,4 +1089,8 @@ 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/targhooks.c b/gcc/targhooks.c
index 1947ef26fd6..2d2de0431f3 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -90,6 +90,9 @@ along with GCC; see the file COPYING3.  If not see
 #include "attribs.h"
 #include "asan.h"
 #include "emit-rtl.h"
+#include "gimple.h"
+#include "cfgloop.h"
+#include "tree-vectorizer.h"
 
 bool
 default_legitimate_address_p (machine_mode mode ATTRIBUTE_UNUSED,
@@ -1480,7 +1483,11 @@ default_add_stmt_cost (class vec_info *vinfo, void *data, int count,
       arbitrary and could potentially be improved with analysis.  */
   if (where == vect_body && stmt_info
       && stmt_in_inner_loop_p (vinfo, stmt_info))
-    count *= 50;  /* FIXME.  */
+    {
+      loop_vec_info loop_vinfo = dyn_cast<loop_vec_info> (vinfo);
+      gcc_assert (loop_vinfo);
+      count *= LOOP_VINFO_INNER_LOOP_COST_FACTOR (loop_vinfo);
+    }
 
   retval = (unsigned) (count * stmt_cost);
   cost[where] += retval;
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index f10e66a2465..ff7673d7250 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -836,6 +836,7 @@ _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),
     vectorizable (false),
     can_use_partial_vectors_p (param_vect_partial_vector_usage != 0),
     using_partial_vectors_p (false),
@@ -1237,7 +1238,7 @@ vect_compute_single_scalar_iteration_cost (loop_vec_info loop_vinfo)
   /* FORNOW.  */
   innerloop_iters = 1;
   if (loop->inner)
-    innerloop_iters = 50; /* FIXME */
+    innerloop_iters = LOOP_VINFO_INNER_LOOP_COST_FACTOR (loop_vinfo);
 
   for (i = 0; i < nbbs; i++)
     {
diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
index 8d1ffafdbf0..7dcb4cd0b46 100644
--- a/gcc/tree-vectorizer.h
+++ b/gcc/tree-vectorizer.h
@@ -689,6 +689,10 @@ public:
   /* The cost of the vector loop body.  */
   int vec_inside_cost;
 
+  /* The factor used to over weight those statements in an inner loop
+     relative to the loop being vectorized.  */
+  unsigned int inner_loop_cost_factor;
+
   /* Is the loop vectorizable? */
   bool vectorizable;
 
@@ -807,6 +811,7 @@ public:
 #define LOOP_VINFO_SINGLE_SCALAR_ITERATION_COST(L) (L)->single_scalar_iteration_cost
 #define LOOP_VINFO_ORIG_LOOP_INFO(L)       (L)->orig_loop_info
 #define LOOP_VINFO_SIMD_IF_COND(L)         (L)->simd_if_cond
+#define LOOP_VINFO_INNER_LOOP_COST_FACTOR(L) (L)->inner_loop_cost_factor
 
 #define LOOP_VINFO_FULLY_MASKED_P(L)		\
   (LOOP_VINFO_USING_PARTIAL_VECTORS_P (L)	\