diff mbox series

Move VF based dependence check

Message ID 20231121143458.2CBF63858C53@sourceware.org
State Committed
Commit ae156936cf4f15d9cc2b7d4e39f2e6b8fe22a9c3
Headers
Series Move VF based dependence check |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gcc_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 warning Patch is already merged
linaro-tcwg-bot/tcwg_gcc_check--master-arm warning Patch is already merged

Commit Message

Richard Biener Nov. 21, 2023, 2:34 p.m. UTC 
  The following moves the check whether the maximum vectorization
factor determined by data dependence analysis is in conflict with
the chosen vectorization factor to after the point where we applied
both the SLP and the unrolling adjustment to the vectorization
factor.  We check the latter before applying unrolling, but the
SLP adjustment can result in both missed optimization and wrong-code.

Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.

	* tree-vect-loop.cc (vect_analyze_loop_2): Move check
	of VF against max_vf until VF is final.
---
 gcc/tree-vect-loop.cc | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
index 58679e91c0a..a73a533beb1 100644
--- a/gcc/tree-vect-loop.cc
+++ b/gcc/tree-vect-loop.cc
@@ -2817,9 +2817,6 @@  vect_analyze_loop_2 (loop_vec_info loop_vinfo, bool &fatal,
 			 "can't determine vectorization factor.\n");
       return ok;
     }
-  if (max_vf != MAX_VECTORIZATION_FACTOR
-      && maybe_lt (max_vf, LOOP_VINFO_VECT_FACTOR (loop_vinfo)))
-    return opt_result::failure_at (vect_location, "bad data dependence.\n");
 
   /* Compute the scalar iteration cost.  */
   vect_compute_single_scalar_iteration_cost (loop_vinfo);
@@ -2881,6 +2878,10 @@  start_over:
 		   LOOP_VINFO_INT_NITERS (loop_vinfo));
     }
 
+  if (max_vf != MAX_VECTORIZATION_FACTOR
+      && maybe_lt (max_vf, LOOP_VINFO_VECT_FACTOR (loop_vinfo)))
+    return opt_result::failure_at (vect_location, "bad data dependence.\n");
+
   loop_vinfo->vector_costs = init_cost (loop_vinfo, false);
 
   /* Analyze the alignment of the data-refs in the loop.