...since the latter doesn't guarantee independence by itself.
Tested on aarch64-linux-gnu. OK to install?
Richard
2018-03-01 Richard Sandiford <richard.sandif...@linaro.org>
gcc/
* tree-vect-data-refs.c (vect_analyze_data_ref_dependence)
(vect_analyze_data_ref_access): Use loop->safe_len rather than
loop->force_vectorize to check whether there is no alias.
gcc/testsuite/
* gcc.dg/vect/vect-alias-check-13.c: New test.
Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c 2018-02-10 09:49:47.950776097 +0000
+++ gcc/tree-vect-data-refs.c 2018-03-01 18:17:41.631482331 +0000
@@ -466,7 +466,7 @@ vect_analyze_data_ref_dependence (struct
return true;
}
- if (!loop->force_vectorize)
+ if (loop->safelen < 2)
{
tree indicator = dr_zero_step_indicator (dra);
if (TREE_CODE (indicator) != INTEGER_CST)
@@ -2720,7 +2720,7 @@ vect_analyze_data_ref_access (struct dat
/* Allow references with zero step for outer loops marked
with pragma omp simd only - it guarantees absence of
loop-carried dependencies between inner loop iterations. */
- if (!loop->force_vectorize)
+ if (loop->safelen < 2)
{
if (dump_enabled_p ())
dump_printf_loc (MSG_NOTE, vect_location,
Index: gcc/testsuite/gcc.dg/vect/vect-alias-check-13.c
===================================================================
--- /dev/null 2018-03-01 08:17:49.562264353 +0000
+++ gcc/testsuite/gcc.dg/vect/vect-alias-check-13.c 2018-03-01
18:17:41.630484279 +0000
@@ -0,0 +1,21 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target vect_int } */
+
+void
+f1 (int *x, long step1, int n)
+{
+ for (int i = 0; i < n; ++i)
+ x[i * step1] += 1;
+}
+
+void
+f2 (int *x, long step2, int n)
+{
+#pragma GCC ivdep
+ for (int i = 0; i < n; ++i)
+ x[i * step2] += 2;
+}
+
+/* { dg-final { scan-tree-dump {need run-time check that [^\n]*step1[^\n]* is
nonzero} "vect" } } */
+/* { dg-final { scan-tree-dump-not {need run-time check that [^\n]*step2[^\n]*
is nonzero} "vect" } } */
+/* { dg-final { scan-tree-dump-times {LOOP VECTORIZED} 2 "vect" } } */
