The vectorizer thinks it can align a vector access to 16 bytes when
using a vectorization factor of 8 and 1 byte elements. That of
course does not work for the 2nd vector iteration. Apparently we
lack a guard against such nonsense.
Bootstrapped on x86_64-unknown-linux-gnu, testing in progress.
PR tree-optimization/118749
* tree-vect-data-refs.cc (vector_alignment_reachable_p): Pass
in the vectorization factor, when that cannot maintain
the DRs target alignment do not claim we can reach that
by peeling.
* gcc.dg/vect/pr118749.c: New testcase.
---
gcc/testsuite/gcc.dg/vect/pr118749.c | 41 ++++++++++++++++++++++++++++
gcc/tree-vect-data-refs.cc | 24 ++++++++++------
2 files changed, 57 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/vect/pr118749.c
diff --git a/gcc/testsuite/gcc.dg/vect/pr118749.c
b/gcc/testsuite/gcc.dg/vect/pr118749.c
new file mode 100644
index 00000000000..eed8bd0d7e0
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr118749.c
@@ -0,0 +1,41 @@
+/* { dg-additional-options "-mtune=pentium4" { target ia32 } } */
+
+#include "tree-vect.h"
+
+typedef unsigned char FcChar8;
+typedef unsigned short FcChar16;
+typedef unsigned int FcChar32;
+typedef int FcBool;
+
+#define FcFalse 0
+#define FcTrue 1
+#define FcDontCare 2
+
+__attribute__((noipa))
+static FcBool
+FcLooksLikeSJIS (FcChar8 *string, int len)
+{
+ int nhigh = 0, nlow = 0;
+
+ while (len-- > 0)
+ {
+ if (*string++ & 0x80) nhigh++;
+ else nlow++;
+ }
+ /*
+ * Heuristic -- if more than 1/3 of the bytes have the high-bit set,
+ * this is likely to be SJIS and not ROMAN
+ */
+ if (nhigh * 2 > nlow)
+ return FcTrue;
+ return FcFalse;
+}
+
+int main()
+{
+ check_vect ();
+ unsigned char* s = "DejaVuMathTeXGyre-Regulardtd!";
+ if (FcLooksLikeSJIS(s, 29))
+ abort ();
+ return 0;
+}
diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc
index 6eda40267bd..6d5854ac7c7 100644
--- a/gcc/tree-vect-data-refs.cc
+++ b/gcc/tree-vect-data-refs.cc
@@ -1722,31 +1722,37 @@ not_size_aligned (tree exp)
a few loop iterations. Return false otherwise. */
static bool
-vector_alignment_reachable_p (dr_vec_info *dr_info)
+vector_alignment_reachable_p (dr_vec_info *dr_info, poly_uint64 vf)
{
stmt_vec_info stmt_info = dr_info->stmt;
tree vectype = STMT_VINFO_VECTYPE (stmt_info);
+ poly_uint64 nelements = TYPE_VECTOR_SUBPARTS (vectype);
+ poly_uint64 vector_size = GET_MODE_SIZE (TYPE_MODE (vectype));
+ unsigned elem_size = vector_element_size (vector_size, nelements);
+ unsigned group_size = 1;
if (STMT_VINFO_GROUPED_ACCESS (stmt_info))
{
/* For interleaved access we peel only if number of iterations in
the prolog loop ({VF - misalignment}), is a multiple of the
number of the interleaved accesses. */
- int elem_size, mis_in_elements;
/* FORNOW: handle only known alignment. */
if (!known_alignment_for_access_p (dr_info, vectype))
return false;
- poly_uint64 nelements = TYPE_VECTOR_SUBPARTS (vectype);
- poly_uint64 vector_size = GET_MODE_SIZE (TYPE_MODE (vectype));
- elem_size = vector_element_size (vector_size, nelements);
- mis_in_elements = dr_misalignment (dr_info, vectype) / elem_size;
-
+ unsigned mis_in_elements = dr_misalignment (dr_info, vectype) /
elem_size;
if (!multiple_p (nelements - mis_in_elements, DR_GROUP_SIZE (stmt_info)))
return false;
+
+ group_size = DR_GROUP_SIZE (DR_GROUP_FIRST_ELEMENT (stmt_info));
}
+ /* If the vectorization factor does not guarantee DR advancement of
+ a multiple of the target alignment no peeling will help. */
+ if (!multiple_p (elem_size * group_size * vf, dr_target_alignment (dr_info)))
+ return false;
+
/* If misalignment is known at the compile time then allow peeling
only if natural alignment is reachable through peeling. */
if (known_alignment_for_access_p (dr_info, vectype)
@@ -2346,7 +2352,9 @@ vect_enhance_data_refs_alignment (loop_vec_info
loop_vinfo)
stmt_vec_info stmt_info = dr_info->stmt;
tree vectype = STMT_VINFO_VECTYPE (stmt_info);
- do_peeling = vector_alignment_reachable_p (dr_info);
+ do_peeling
+ = vector_alignment_reachable_p (dr_info,
+ LOOP_VINFO_VECT_FACTOR (loop_vinfo));
if (do_peeling)
{
if (known_alignment_for_access_p (dr_info, vectype))
--
2.43.0
