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aarch64: Make sure the UF divides the VF [PR105254]

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In this PR, we were trying to set the unroll factor to a value higher
than the minimum VF (or more specifically, to a value that doesn't
divide the VF).  I guess there are two approaches to this: let the
target pick any value it likes and make target-independent code pare
it back to something that makes sense, or require targets to supply
sensible values from the outset.  This patch goes for the latter
approach.

gcc/
	PR tree-optimization/105254
	* config/aarch64/aarch64.cc
	(aarch64_vector_costs::determine_suggested_unroll_factor): Take a
	loop_vec_info as argument.  Restrict the unroll factor to values
	that divide the VF.
	(aarch64_vector_costs::finish_cost): Update call accordingly.

gcc/testsuite/
	PR tree-optimization/105254
	* g++.dg/vect/pr105254.cc: New test.
This commit is contained in:
Richard Sandiford 2022-04-13 17:53:54 +01:00
parent 469fad0161
commit f2ebf2d98e
2 changed files with 34 additions and 4 deletions
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12
gcc/config/aarch64/aarch64.cc
View File

@ -15637,7 +15637,7 @@ private:
unsigned int adjust_body_cost (loop_vec_info, const aarch64_vector_costs *,
unsigned int);
bool prefer_unrolled_loop () const;
unsigned int determine_suggested_unroll_factor ();
unsigned int determine_suggested_unroll_factor (loop_vec_info);
/* True if we have performed one-time initialization based on the
vec_info. */
@ -16746,7 +16746,8 @@ adjust_body_cost_sve (const aarch64_vec_op_count *ops,
}
unsigned int
aarch64_vector_costs::determine_suggested_unroll_factor ()
aarch64_vector_costs::
determine_suggested_unroll_factor (loop_vec_info loop_vinfo)
{
bool sve = m_vec_flags & VEC_ANY_SVE;
/* If we are trying to unroll an Advanced SIMD main loop that contains
@ -16760,6 +16761,7 @@ aarch64_vector_costs::determine_suggested_unroll_factor ()
return 1;
unsigned int max_unroll_factor = 1;
auto vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
for (auto vec_ops : m_ops)
{
aarch64_simd_vec_issue_info const *vec_issue
@ -16768,7 +16770,8 @@ aarch64_vector_costs::determine_suggested_unroll_factor ()
return 1;
/* Limit unroll factor to a value adjustable by the user, the default
value is 4. */
unsigned int unroll_factor = aarch64_vect_unroll_limit;
unsigned int unroll_factor = MIN (aarch64_vect_unroll_limit,
(int) known_alignment (vf));
unsigned int factor
= vec_ops.reduction_latency > 1 ? vec_ops.reduction_latency : 1;
unsigned int temp;
@ -16946,7 +16949,8 @@ aarch64_vector_costs::finish_cost (const vector_costs *uncast_scalar_costs)
{
m_costs[vect_body] = adjust_body_cost (loop_vinfo, scalar_costs,
m_costs[vect_body]);
m_suggested_unroll_factor = determine_suggested_unroll_factor ();
m_suggested_unroll_factor
= determine_suggested_unroll_factor (loop_vinfo);
}
/* Apply the heuristic described above m_stp_sequence_cost. Prefer

26
gcc/testsuite/g++.dg/vect/pr105254.cc Normal file
View File

@ -0,0 +1,26 @@
/* { dg-do compile } */
/* { dg-additional-options "-fvect-cost-model=dynamic -mcpu=zeus" { target aarch64*-*-* } } */
template <typename>
struct complex;
template <>
struct complex<double> {
void operator+= (complex r) { v_ += r.v_; }
_Complex v_;
};
template <typename T>
void
bar (T);
void
foo (complex<double> *x)
{
complex<double> s = {0.0};
for (int i = 0; i < 16; ++i)
s += x[i];
bar<complex<double> > (s);
}