diff mbox

Re-apply fix to realistic loop estimates

Message ID 20160520125728.GA86577@kam.mff.cuni.cz
State New
Headers show

Commit Message

Jan Hubicka May 20, 2016, 12:57 p.m. UTC 
Hi,
this patch re-applies the idx_infer_loop_bounds. With fix to the tree-vect-loop.c
change there should be no performance regressions. Prefetch-5.c testcase still changes
and I will send patch adding likely upper bounds shortly to handle this one.

Bootstrapped/regtested x86_64-linux, comitted.

Honza

	* gcc.dg/tree-ssa/prefetch-5.c: xfail.
	* tree-ssa-loop-niter.c (idx_infer_loop_bounds): We can not produce
	realistic upper bounds here.
diff mbox

Patch

Index: testsuite/gcc.dg/tree-ssa/prefetch-5.c
===================================================================
--- testsuite/gcc.dg/tree-ssa/prefetch-5.c	(revision 236478)
+++ testsuite/gcc.dg/tree-ssa/prefetch-5.c	(working copy)
@@ -54,5 +54,7 @@  int loop5 (int n, struct tail5 *x)
   return s;
 }
 
-/* { dg-final { scan-tree-dump-times "Issued prefetch" 2 "aprefetch" } } */
-/* { dg-final { scan-tree-dump-times "Not prefetching" 1 "aprefetch" } } */
+/* Until we are able to track likely upper bounds, we can't really work out that
+   small trailing arrays should not be prefetched.  */
+/* { dg-final { scan-tree-dump-times "Issued prefetch" 2 "aprefetch" { xfail *-*-* } } } */
+/* { dg-final { scan-tree-dump-times "Not prefetching" 1 "aprefetch" { xfail *-*-* } } } */
Index: tree-ssa-loop-niter.c
===================================================================
--- tree-ssa-loop-niter.c	(revision 236478)
+++ tree-ssa-loop-niter.c	(working copy)
@@ -3115,7 +3115,6 @@  idx_infer_loop_bounds (tree base, tree *
   tree low, high, type, next;
   bool sign, upper = true, at_end = false;
   struct loop *loop = data->loop;
-  bool reliable = true;
 
   if (TREE_CODE (base) != ARRAY_REF)
     return true;
@@ -3187,14 +3186,14 @@  idx_infer_loop_bounds (tree base, tree *
       && tree_int_cst_compare (next, high) <= 0)
     return true;
 
-  /* If access is not executed on every iteration, we must ensure that overlow may
-     not make the access valid later.  */
+  /* If access is not executed on every iteration, we must ensure that overlow
+     may not make the access valid later.  */
   if (!dominated_by_p (CDI_DOMINATORS, loop->latch, gimple_bb (data->stmt))
       && scev_probably_wraps_p (initial_condition_in_loop_num (ev, loop->num),
 				step, data->stmt, loop, true))
-    reliable = false;
+    upper = false;
 
-  record_nonwrapping_iv (loop, init, step, data->stmt, low, high, reliable, upper);
+  record_nonwrapping_iv (loop, init, step, data->stmt, low, high, false, upper);
   return true;
 }