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-rw-r--r--gcc/ChangeLog20
-rw-r--r--gcc/config/aarch64/aarch64-protos.h3
-rw-r--r--gcc/config/aarch64/aarch64.c11
-rw-r--r--gcc/doc/invoke.texi10
-rw-r--r--gcc/params.def9
-rw-r--r--gcc/params.h2
-rw-r--r--gcc/tree-ssa-loop-prefetch.c10
7 files changed, 65 insertions, 0 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 535204d..64a385e 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -2,6 +2,26 @@
gcc/
* config/aarch64/aarch64-protos.h (cpu_prefetch_tune)
+ <prefetch_dynamic_strides>: New const bool field.
+ * config/aarch64/aarch64.c (generic_prefetch_tune): Update to include
+ prefetch_dynamic_strides.
+ (exynosm1_prefetch_tune): Likewise.
+ (thunderxt88_prefetch_tune): Likewise.
+ (thunderx_prefetch_tune): Likewise.
+ (thunderx2t99_prefetch_tune): Likewise.
+ (qdf24xx_prefetch_tune): Likewise. Set prefetch_dynamic_strides to false.
+ (aarch64_override_options_internal): Update to set
+ PARAM_PREFETCH_DYNAMIC_STRIDES.
+ * doc/invoke.texi (prefetch-dynamic-strides): Document new option.
+ * params.def (PARAM_PREFETCH_DYNAMIC_STRIDES): New.
+ * params.h (PARAM_PREFETCH_DYNAMIC_STRIDES): Define.
+ * tree-ssa-loop-prefetch.c (should_issue_prefetch_p): Account for
+ prefetch-dynamic-strides setting.
+
+2018-05-07 Luis Machado <luis.machado@linaro.org>
+
+ gcc/
+ * config/aarch64/aarch64-protos.h (cpu_prefetch_tune)
<minimum_stride>: New const int field.
* config/aarch64/aarch64.c (generic_prefetch_tune): Update to include
minimum_stride field.
diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index 5d3b9d7..157308d 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -230,6 +230,9 @@ struct cpu_prefetch_tune
const int l1_cache_size;
const int l1_cache_line_size;
const int l2_cache_size;
+ /* Whether software prefetch hints should be issued for non-constant
+ strides. */
+ const bool prefetch_dynamic_strides;
/* The minimum constant stride beyond which we should use prefetch
hints for. */
const int minimum_stride;
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 7d0ba35..3d3a976 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -547,6 +547,7 @@ static const cpu_prefetch_tune generic_prefetch_tune =
-1, /* l1_cache_size */
-1, /* l1_cache_line_size */
-1, /* l2_cache_size */
+ true, /* prefetch_dynamic_strides */
-1, /* minimum_stride */
-1 /* default_opt_level */
};
@@ -557,6 +558,7 @@ static const cpu_prefetch_tune exynosm1_prefetch_tune =
-1, /* l1_cache_size */
64, /* l1_cache_line_size */
-1, /* l2_cache_size */
+ true, /* prefetch_dynamic_strides */
-1, /* minimum_stride */
-1 /* default_opt_level */
};
@@ -567,6 +569,7 @@ static const cpu_prefetch_tune qdf24xx_prefetch_tune =
32, /* l1_cache_size */
64, /* l1_cache_line_size */
1024, /* l2_cache_size */
+ false, /* prefetch_dynamic_strides */
2048, /* minimum_stride */
3 /* default_opt_level */
};
@@ -577,6 +580,7 @@ static const cpu_prefetch_tune thunderxt88_prefetch_tune =
32, /* l1_cache_size */
128, /* l1_cache_line_size */
16*1024, /* l2_cache_size */
+ true, /* prefetch_dynamic_strides */
-1, /* minimum_stride */
3 /* default_opt_level */
};
@@ -587,6 +591,7 @@ static const cpu_prefetch_tune thunderx_prefetch_tune =
32, /* l1_cache_size */
128, /* l1_cache_line_size */
-1, /* l2_cache_size */
+ true, /* prefetch_dynamic_strides */
-1, /* minimum_stride */
-1 /* default_opt_level */
};
@@ -597,6 +602,7 @@ static const cpu_prefetch_tune thunderx2t99_prefetch_tune =
32, /* l1_cache_size */
64, /* l1_cache_line_size */
256, /* l2_cache_size */
+ true, /* prefetch_dynamic_strides */
-1, /* minimum_stride */
-1 /* default_opt_level */
};
@@ -10602,6 +10608,11 @@ aarch64_override_options_internal (struct gcc_options *opts)
aarch64_tune_params.prefetch->l2_cache_size,
opts->x_param_values,
global_options_set.x_param_values);
+ if (!aarch64_tune_params.prefetch->prefetch_dynamic_strides)
+ maybe_set_param_value (PARAM_PREFETCH_DYNAMIC_STRIDES,
+ 0,
+ opts->x_param_values,
+ global_options_set.x_param_values);
if (aarch64_tune_params.prefetch->minimum_stride >= 0)
maybe_set_param_value (PARAM_PREFETCH_MINIMUM_STRIDE,
aarch64_tune_params.prefetch->minimum_stride,
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 7c90abc..7e57e96 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -10733,6 +10733,16 @@ The size of L1 cache, in kilobytes.
@item l2-cache-size
The size of L2 cache, in kilobytes.
+@item prefetch-dynamic-strides
+Whether the loop array prefetch pass should issue software prefetch hints
+for strides that are non-constant. In some cases this may be
+beneficial, though the fact the stride is non-constant may make it
+hard to predict when there is clear benefit to issuing these hints.
+
+Set to 1, the default, if the prefetch hints should be issued for non-constant
+strides. Set to 0 if prefetch hints should be issued only for strides that
+are known to be constant and below @option{prefetch-minimum-stride}.
+
@item prefetch-minimum-stride
Minimum constant stride, in bytes, to start using prefetch hints for. If
the stride is less than this threshold, prefetch hints will not be issued.
diff --git a/gcc/params.def b/gcc/params.def
index 2166deb..7408843 100644
--- a/gcc/params.def
+++ b/gcc/params.def
@@ -790,6 +790,15 @@ DEFPARAM (PARAM_L2_CACHE_SIZE,
"The size of L2 cache.",
512, 0, 0)
+/* Whether software prefetch hints should be issued for non-constant
+ strides. */
+
+DEFPARAM (PARAM_PREFETCH_DYNAMIC_STRIDES,
+ "prefetch-dynamic-strides",
+ "Whether software prefetch hints should be issued for non-constant "
+ "strides.",
+ 1, 0, 1)
+
/* The minimum constant stride beyond which we should use prefetch hints
for. */
diff --git a/gcc/params.h b/gcc/params.h
index 96012db..8aa960a 100644
--- a/gcc/params.h
+++ b/gcc/params.h
@@ -196,6 +196,8 @@ extern void init_param_values (int *params);
PARAM_VALUE (PARAM_L1_CACHE_LINE_SIZE)
#define L2_CACHE_SIZE \
PARAM_VALUE (PARAM_L2_CACHE_SIZE)
+#define PREFETCH_DYNAMIC_STRIDES \
+ PARAM_VALUE (PARAM_PREFETCH_DYNAMIC_STRIDES)
#define PREFETCH_MINIMUM_STRIDE \
PARAM_VALUE (PARAM_PREFETCH_MINIMUM_STRIDE)
#define USE_CANONICAL_TYPES \
diff --git a/gcc/tree-ssa-loop-prefetch.c b/gcc/tree-ssa-loop-prefetch.c
index 5310402..af89d70 100644
--- a/gcc/tree-ssa-loop-prefetch.c
+++ b/gcc/tree-ssa-loop-prefetch.c
@@ -992,6 +992,16 @@ prune_by_reuse (struct mem_ref_group *groups)
static bool
should_issue_prefetch_p (struct mem_ref *ref)
{
+ /* Do we want to issue prefetches for non-constant strides? */
+ if (!cst_and_fits_in_hwi (ref->group->step) && PREFETCH_DYNAMIC_STRIDES == 0)
+ {
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file,
+ "Skipping non-constant step for reference %u:%u\n",
+ ref->group->uid, ref->uid);
+ return false;
+ }
+
/* Some processors may have a hardware prefetcher that may conflict with
prefetch hints for a range of strides. Make sure we don't issue
prefetches for such cases if the stride is within this particular
generated by cgit v1.1 at 2025-05-19 11:06:32 +0000