On Mon, 7 Nov 2016, Richard Biener wrote:
>
> Currently we force peeling for gaps whenever element overrun can occur
> but for aligned accesses we know that the loads won't trap and thus
> we can avoid this.
>
> Bootstrap and regtest running on x86_64-unknown-linux-gnu (I expect
> some testsuite fallout here so didn't bother to invent a new testcase).
>
> Just in case somebody thinks the overrun is a bad idea in general
> (even when not trapping). Like for ASAN or valgrind.
This is what I applied.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
Richard.
2016-11-08 Richard Biener <rguent...@suse.de>
* tree-vect-stmts.c (get_group_load_store_type): If the
access is aligned do not trigger peeling for gaps.
* tree-vect-data-refs.c (vect_compute_data_ref_alignment): Do not
force alignment of vars with DECL_USER_ALIGN.
* gcc.dg/vect/vect-nb-iter-ub-2.c: Adjust.
diff --git a/gcc/testsuite/gcc.dg/vect/vect-nb-iter-ub-2.c
b/gcc/testsuite/gcc.dg/vect/vect-nb-iter-ub-2.c
index bc07b4b..4e13702 100644
--- a/gcc/testsuite/gcc.dg/vect/vect-nb-iter-ub-2.c
+++ b/gcc/testsuite/gcc.dg/vect/vect-nb-iter-ub-2.c
@@ -3,7 +3,7 @@
#include "tree-vect.h"
int ii[32];
-char cc[66] =
+char cc[66] __attribute__((aligned(1))) =
{ 0, 0, 1, 0, 2, 0, 3, 0, 4, 0, 5, 0, 6, 0, 7, 0, 8, 0, 9, 0,
10, 0, 11, 0, 12, 0, 13, 0, 14, 0, 15, 0, 16, 0, 17, 0, 18, 0, 19, 0,
20, 0, 21, 0, 22, 0, 23, 0, 24, 0, 25, 0, 26, 0, 27, 0, 28, 0, 29, 0,
diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index b03cb1e..f014d68 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -831,6 +831,19 @@ vect_compute_data_ref_alignment (struct data_reference *dr)
return true;
}
+ if (DECL_USER_ALIGN (base))
+ {
+ if (dump_enabled_p ())
+ {
+ dump_printf_loc (MSG_NOTE, vect_location,
+ "not forcing alignment of user-aligned "
+ "variable: ");
+ dump_generic_expr (MSG_NOTE, TDF_SLIM, base);
+ dump_printf (MSG_NOTE, "\n");
+ }
+ return true;
+ }
+
/* Force the alignment of the decl.
NOTE: This is the only change to the code we make during
the analysis phase, before deciding to vectorize the loop. */
diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 15aec21..c29e73d 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -1770,6 +1770,11 @@ get_group_load_store_type (gimple *stmt, tree vectype,
bool slp,
" non-consecutive accesses\n");
return false;
}
+ /* If the access is aligned an overrun is fine. */
+ if (overrun_p
+ && aligned_access_p
+ (STMT_VINFO_DATA_REF (vinfo_for_stmt (first_stmt))))
+ overrun_p = false;
if (overrun_p && !can_overrun_p)
{
if (dump_enabled_p ())
@@ -1789,6 +1794,10 @@ get_group_load_store_type (gimple *stmt, tree vectype,
bool slp,
/* If there is a gap at the end of the group then these optimizations
would access excess elements in the last iteration. */
bool would_overrun_p = (gap != 0);
+ /* If the access is aligned an overrun is fine. */
+ if (would_overrun_p
+ && aligned_access_p (STMT_VINFO_DATA_REF (stmt_info)))
+ would_overrun_p = false;
if (!STMT_VINFO_STRIDED_P (stmt_info)
&& (can_overrun_p || !would_overrun_p)
&& compare_step_with_zero (stmt) > 0)
