diff mbox series

[rs6000] Improve suggested unroll factor in finish_cost

Message ID 0ea033e2-594e-4b25-b452-3df61f5f4825@linux.ibm.com
State New
Headers show
Series [rs6000] Improve suggested unroll factor in finish_cost | expand

Commit Message

Ajit Agarwal July 22, 2024, 12:48 p.m. UTC 
Hello All:

This patch improve determine_suggested_unroll_factor in finish_cost
with reduction factor of loads/stores/non_load_stores.

Return unroll factor calculated as per reduction factor
with number of loads/stores/non_load_stores (general_ops).

Bootstrapped and regtested on powerpc64-linux-gnu.

Expected gains with spec 2017 benchmarks.

Thanks & Regards
Ajit


rs6000: Improve suggested unroll factor in finish_cost

Improve determine_suggested_unroll_factor in finish_cost
with reduction factor of loads/stores/non_load_stores.

Return unroll factor calculated as per reduction factor
with number of loads/stores/non_load_stores (general_ops).

2024-07-22  Ajit Kumar Agarwal  <aagarwa1@linux.ibm.com>

gcc/ChangeLog:

	* config/rs6000/rs6000.cc: Improve
	determine_suggested_unroll_factor with reduction factor
	of load/stores/general_ops.
---
 gcc/config/rs6000/rs6000.cc | 60 ++++++++++---------------------------
 1 file changed, 16 insertions(+), 44 deletions(-)
diff mbox series

Patch

diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 5ed64b1e686..0d69ec4cfbe 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -5458,7 +5458,6 @@  rs6000_cost_data::adjust_vect_cost_per_loop (loop_vec_info loop_vinfo)
     - estimated iteration count when iteration count is unknown;
 */
 
-
 unsigned int
 rs6000_cost_data::determine_suggested_unroll_factor (loop_vec_info loop_vinfo)
 {
@@ -5483,53 +5482,26 @@  rs6000_cost_data::determine_suggested_unroll_factor (loop_vec_info loop_vinfo)
   unsigned int issue_width = rs6000_vect_unroll_issue;
   unsigned int uf = CEIL (reduc_factor * issue_width, nstmts_nonldst);
   uf = MIN ((unsigned int) rs6000_vect_unroll_limit, uf);
-  /* Make sure it is power of 2.  */
-  uf = 1 << ceil_log2 (uf);
+  unsigned int temp;
 
-  /* If the iteration count is known, the costing would be exact enough,
-     don't worry it could be worse.  */
-  if (LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo))
-    return uf;
-
-  /* Inspired by SPEC2017 parest_r, we want to aggressively unroll the
-     loop if either condition is satisfied:
-       - reduction factor exceeds the threshold;
-       - emulated gather load adopted.  */
-  if (reduc_factor > (unsigned int) rs6000_vect_unroll_reduc_threshold
-      || m_gather_load)
-    return uf;
-
-  /* Check if we can conclude it's good to unroll from the estimated
-     iteration count.  */
-  HOST_WIDE_INT est_niter = get_estimated_loop_iterations_int (loop);
-  unsigned int vf = vect_vf_for_cost (loop_vinfo);
-  unsigned int unrolled_vf = vf * uf;
-  if (est_niter == -1 || est_niter < unrolled_vf)
-    /* When the estimated iteration of this loop is unknown, it's possible
-       that we are able to vectorize this loop with the original VF but fail
-       to vectorize it with the unrolled VF any more if the actual iteration
-       count is in between.  */
-    return 1;
-  else
+  if (m_nstores > 0)
     {
-      unsigned int epil_niter_unr = est_niter % unrolled_vf;
-      unsigned int epil_niter = est_niter % vf;
-      /* Even if we have partial vector support, it can be still inefficent
-	 to calculate the length when the iteration count is unknown, so
-	 only expect it's good to unroll when the epilogue iteration count
-	 is not bigger than VF (only one time length calculation).  */
-      if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo)
-	  && epil_niter_unr <= vf)
-	return uf;
-      /* Without partial vector support, conservatively unroll this when
-	 the epilogue iteration count is less than the original one
-	 (epilogue execution time wouldn't be longer than before).  */
-      else if (!LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo)
-	       && epil_niter_unr <= epil_niter)
-	return uf;
+      temp = CEIL (reduc_factor * rs6000_vect_unroll_issue,
+		   m_nstores);
+      uf = MIN (uf, temp);
     }
 
-  return 1;
+  if (m_nloads > 0)
+    {
+      temp = CEIL (reduc_factor * rs6000_vect_unroll_issue,
+		   m_nloads + m_nstores);
+      uf = MIN (uf, temp);
+    }
+
+  /* Make sure it is power of 2.  */
+  uf = 1 << ceil_log2 (uf);
+
+  return uf;
 }
 
 void