With recent SLP vectorization patches I see RISC-V divison by zero
for gfortran.dg/matmul_10.f90 and others in get_group_load_store_type
which does
&& can_div_trunc_p (group_size
* LOOP_VINFO_VECT_FACTOR (loop_vinfo) - gap,
nunits, &tem, &remain)
&& (known_eq (remain, 0u)
|| (constant_multiple_p (nunits, remain, &num)
&& (vector_vector_composition_type (vectype, num,
&half_vtype)
!= NULL_TREE))))
overrun_p = false;
where for [2, 2] / [0, 2] the condition doesn't reflect what we
are trying to test - that, when remain is zero or, when non-zero,
nunits is a multiple of remain, we can avoid touching a gap via
loading smaller pieces and vector composition. Changing known_eq
to maybe_eq wouldn't be correct I think since for example if it
were [0, 4] then we cannot load smaller parts. Note we know
that remain is in [0, nunits - 1] given we compute it as
X % nunits so maybe we can indeed use maybe_eq (remain, 0u) here
in this particular case?
The following adds constant_multiple_if_divisor_nonzero_p to
express the intent of no interest in the 'multiple' value for
the case B is zero.
Bootstrapped and tested on x86_64-unknown-linux-gnu.
Is the reasoning that maybe_eq is "safe" sound in this particular
case? I think we should avoid adding
constant_multiple_if_divisor_nonzero_p if not absolutely necessary.
Thanks,
Richard.
* poly-int.h (constant_multiple_if_divisor_nonzero_p): New.
* tree-vect-stmts.cc (get_group_load_store_type): Use it.
---
gcc/poly-int.h | 45 ++++++++++++++++++++++++++++++++++++++++++
gcc/tree-vect-stmts.cc | 3 ++-
2 files changed, 47 insertions(+), 1 deletion(-)
diff --git a/gcc/poly-int.h b/gcc/poly-int.h
index 94708165961..29337513eb8 100644
--- a/gcc/poly-int.h
+++ b/gcc/poly-int.h
@@ -1986,6 +1986,51 @@ constant_multiple_p (const poly_int<N, Ca> &a,
return true;
}
+/* Return true if A is a constant multiple of B, storing the
+ multiple in *MULTIPLE if so. The case of B being zero is
+ excluded but it shall not be known equal to zero. */
+
+template<unsigned int N, typename Ca, typename Cb, typename Cm>
+inline bool
+constant_multiple_if_divisor_nonzero_p (const poly_int<N, Ca> &a,
+ const poly_int<N, Cb> &b, Cm *multiple)
+{
+ typedef POLY_CAST (Ca, Cb) NCa;
+ typedef POLY_CAST (Cb, Ca) NCb;
+ typedef POLY_INT_TYPE (Ca) ICa;
+ typedef POLY_INT_TYPE (Cb) ICb;
+ typedef POLY_BINARY_COEFF (Ca, Cb) C;
+
+ C r = 0;
+ if (b.coeffs[0] != ICb (0))
+ {
+ if (NCa (a.coeffs[0]) % NCb (b.coeffs[0]) != 0)
+ return false;
+ r = NCa (a.coeffs[0]) / NCb (b.coeffs[0]);
+ }
+ for (unsigned int i = 1; i < N; ++i)
+ if (b.coeffs[i] == ICb (0))
+ {
+ if (a.coeffs[i] != ICa (0))
+ return false;
+ }
+ else
+ {
+ if (NCa (a.coeffs[i]) % NCb (b.coeffs[i]) != 0)
+ return false;
+ if (r == 0)
+ r = NCa (a.coeffs[i]) / NCb (b.coeffs[i]);
+ else if (NCa (a.coeffs[i]) / NCb (b.coeffs[i]) != r)
+ return false;
+ }
+
+ if (r == 0)
+ return false;
+
+ *multiple = r;
+ return true;
+}
+
/* Return true if A is a constant multiple of B. */
template<unsigned int N, typename Ca, typename Cb>
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index f8bb637342e..2641833b3aa 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -2135,7 +2135,8 @@ get_group_load_store_type (vec_info *vinfo, stmt_vec_info
stmt_info,
* LOOP_VINFO_VECT_FACTOR (loop_vinfo) - gap,
nunits, &tem, &remain)
&& (known_eq (remain, 0u)
- || (constant_multiple_p (nunits, remain, &num)
+ || (constant_multiple_if_divisor_nonzero_p (nunits, remain,
+ &num)
&& (vector_vector_composition_type (vectype, num,
&half_vtype)
!= NULL_TREE))))
--
2.43.0
