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| author | Richard Sandiford <richard.sandiford@arm.com> | 2021-03-26 16:08:37 +0000 |
|---|---|---|
| committer | Richard Sandiford <richard.sandiford@arm.com> | 2021-03-26 16:08:37 +0000 |
| commit | e4180ab2fea0d3e8010f23b5e73095ac13cedafa (patch) | |
| tree | c8c8314edec0ca3007c0215746407e06c998c742 /gcc | |
| parent | 99f94ae5018e915d0c1db1b6d4110d68bc4d242e (diff) | |
| download | gcc-e4180ab2fea0d3e8010f23b5e73095ac13cedafa.zip gcc-e4180ab2fea0d3e8010f23b5e73095ac13cedafa.tar.gz gcc-e4180ab2fea0d3e8010f23b5e73095ac13cedafa.tar.bz2 | |
aarch64: Ignore inductions when costing vector code
In practice it seems to be better not to cost a vector induction.
The scalar code generally needs the same induction but doesn't
cost it, making an apples-for-apples comparison harder. Most
inductions also have a low latency and their cost usually gets
hidden by other operations.
Like with the 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_vector_stmt_subtype):
Assume a zero cost for induction phis.
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/config/aarch64/aarch64.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c index e97e71b..6d18d82 100644 --- a/gcc/config/aarch64/aarch64.c +++ b/gcc/config/aarch64/aarch64.c @@ -14541,6 +14541,12 @@ aarch64_detect_vector_stmt_subtype (vec_info *vinfo, vect_cost_for_stmt kind, if (aarch64_sve_mode_p (TYPE_MODE (vectype))) sve_costs = aarch64_tune_params.vec_costs->sve; + /* It's generally better to avoid costing inductions, since the induction + will usually be hidden by other operations. This is particularly true + for things like COND_REDUCTIONS. */ + if (is_a<gphi *> (stmt_info->stmt)) + return 0; + /* Detect cases in which vec_to_scalar is describing the extraction of a vector element in preparation for a scalar store. The store itself is costed separately. */ |