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aarch64: Detect scalar extending loads

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If the scalar code does an integer load followed by an integer
extension, we've tended to cost that as two separate operations,
even though the extension is probably going to be free in practice.
This patch treats the extension as having zero cost, like we already
do for extending SVE loads.

Like with previous patches, this one only becomes active if
a CPU selects use_new_vector_costs.  It should therefore have
a very low impact on other CPUs.

gcc/
	* config/aarch64/aarch64.c (aarch64_detect_scalar_stmt_subtype):
	New function.
	(aarch64_add_stmt_cost): Call it.
This commit is contained in:
Richard Sandiford 2021-03-26 16:08:35 +00:00
parent 3b924b0d7c
commit ed17ad5ea1
1 changed files with 27 additions and 4 deletions
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31
gcc/config/aarch64/aarch64.c
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@ -14492,6 +14492,23 @@ aarch64_sve_in_loop_reduction_latency (vec_info *vinfo,
return 0;
}
/* STMT_COST is the cost calculated by aarch64_builtin_vectorization_cost
for STMT_INFO, which has cost kind KIND. If this is a scalar operation,
try to subdivide the target-independent categorization provided by KIND
to get a more accurate cost. */
static unsigned int
aarch64_detect_scalar_stmt_subtype (vec_info *vinfo, vect_cost_for_stmt kind,
stmt_vec_info stmt_info,
unsigned int stmt_cost)
{
/* Detect an extension of a loaded value. In general, we'll be able to fuse
the extension with the load. */
if (kind == scalar_stmt && aarch64_extending_load_p (vinfo, stmt_info))
return 0;
return stmt_cost;
}
/* STMT_COST is the cost calculated by aarch64_builtin_vectorization_cost
for the vectorized form of STMT_INFO, which has cost kind KIND and which
when vectorized would operate on vector type VECTYPE. Try to subdivide
@ -14702,10 +14719,16 @@ aarch64_add_stmt_cost (class vec_info *vinfo, void *data, int count,
/* Try to get a more accurate cost by looking at STMT_INFO instead
of just looking at KIND. */
if (stmt_info && vectype && aarch64_use_new_vector_costs_p ())
stmt_cost = aarch64_detect_vector_stmt_subtype (vinfo, kind,
stmt_info, vectype,
where, stmt_cost);
if (stmt_info && aarch64_use_new_vector_costs_p ())
{
stmt_cost = aarch64_detect_scalar_stmt_subtype
(vinfo, kind, stmt_info, stmt_cost);
if (vectype && costs->vec_flags)
stmt_cost = aarch64_detect_vector_stmt_subtype (vinfo, kind,
stmt_info, vectype,
where, stmt_cost);
}
/* Do any SVE-specific adjustments to the cost. */
if (stmt_info && vectype && aarch64_sve_mode_p (TYPE_MODE (vectype)))