On x86_64, when the expected size of memcpy/memset is known (e.g, with
FDO), libcall strategy is used with the size is > 8192. This value is
hard coded, which makes it hard to do performance tuning. This patch
adds two new parameters to do that. Potential usage includes
per-application libcall strategy min-size tuning based on summary data
with FDO (e.g, instruction workset size).
Bootstrap and tested on x86_64/linux. Ok for trunk?
thanks,
David
2013-08-02 Xinliang David Li <davi...@google.com>
* params.def: New parameters.
* config/i386/i386.c (ix86_option_override_internal):
Override default libcall size limit with parameters.
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c (revision 201458)
+++ config/i386/i386.c (working copy)
@@ -156,7 +156,7 @@ struct processor_costs ix86_size_cost =
};
/* Processor costs (relative to an add) */
-static const
+static
struct processor_costs i386_cost = { /* 386 specific costs */
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1), /* cost of a lea instruction */
@@ -226,7 +226,7 @@ struct processor_costs i386_cost = { /*
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs i486_cost = { /* 486 specific costs */
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1), /* cost of a lea instruction */
@@ -298,7 +298,7 @@ struct processor_costs i486_cost = { /*
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs pentium_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1), /* cost of a lea instruction */
@@ -368,7 +368,7 @@ struct processor_costs pentium_cost = {
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs pentiumpro_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1), /* cost of a lea instruction */
@@ -447,7 +447,7 @@ struct processor_costs pentiumpro_cost =
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs geode_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1), /* cost of a lea instruction */
@@ -518,7 +518,7 @@ struct processor_costs geode_cost = {
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs k6_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (2), /* cost of a lea instruction */
@@ -591,7 +591,7 @@ struct processor_costs k6_cost = {
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs athlon_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (2), /* cost of a lea instruction */
@@ -664,7 +664,7 @@ struct processor_costs athlon_cost = {
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs k8_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (2), /* cost of a lea instruction */
@@ -1265,7 +1265,7 @@ struct processor_costs btver2_cost = {
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs pentium4_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (3), /* cost of a lea instruction */
@@ -1336,7 +1336,7 @@ struct processor_costs pentium4_cost = {
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs nocona_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1), /* cost of a lea instruction */
@@ -1409,7 +1409,7 @@ struct processor_costs nocona_cost = {
1, /* cond_not_taken_branch_cost. */
};
-static const
+static
struct processor_costs atom_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1) + 1, /* cost of a lea instruction */
@@ -1556,7 +1556,7 @@ struct processor_costs slm_cost = {
};
/* Generic64 should produce code tuned for Nocona and K8. */
-static const
+static
struct processor_costs generic64_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
/* On all chips taken into consideration lea is 2 cycles and more. With
@@ -1635,7 +1635,7 @@ struct processor_costs generic64_cost =
};
/* core_cost should produce code tuned for Core familly of CPUs. */
-static const
+static
struct processor_costs core_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
/* On all chips taken into consideration lea is 2 cycles and more. With
@@ -1717,7 +1717,7 @@ struct processor_costs core_cost = {
/* Generic32 should produce code tuned for PPro, Pentium4, Nocona,
Athlon and K8. */
-static const
+static
struct processor_costs generic32_cost = {
COSTS_N_INSNS (1), /* cost of an add instruction */
COSTS_N_INSNS (1) + 1, /* cost of a lea instruction */
@@ -4021,6 +4021,34 @@ ix86_option_override_internal (bool main
/* Handle stack protector */
if (!global_options_set.x_ix86_stack_protector_guard)
ix86_stack_protector_guard = TARGET_HAS_BIONIC ? SSP_GLOBAL : SSP_TLS;
+
+ /* Now override the memcpy/memset inline strategy parameters */
+ if (PARAM_VALUE (PARAM_MEMCPY_LIBCALL_MIN_SIZE) != -1
+ || PARAM_VALUE (PARAM_MEMSET_LIBCALL_MIN_SIZE) != -1)
+ {
+ const struct stringop_algs *algs[2];
+ int k;
+ int min_sizes[2];
+
+ algs[0] = &ix86_cost->memset[TARGET_64BIT != 0];
+ algs[1] = &ix86_cost->memcpy[TARGET_64BIT != 0];
+
+ min_sizes[0] = PARAM_VALUE (PARAM_MEMSET_LIBCALL_MIN_SIZE);
+ min_sizes[1] = PARAM_VALUE (PARAM_MEMCPY_LIBCALL_MIN_SIZE);
+
+ for (k = 0; k < 2; k++)
+ {
+ if (min_sizes[k] == -1)
+ continue;
+
+ for (i = 0; i < MAX_STRINGOP_ALGS - 1; i++)
+ {
+ if (algs[k]->size[i].max >= min_sizes[k]
+ || algs[k]->size[i + 1].alg == libcall)
+ *const_cast<int *>(&algs[k]->size[i].max) = min_sizes[k] - 1;
+ }
+ }
+ }
}
/* Implement the TARGET_OPTION_OVERRIDE hook. */
Index: params.def
===================================================================
--- params.def (revision 201458)
+++ params.def (working copy)
@@ -117,6 +117,18 @@ DEFPARAM (PARAM_COMDAT_SHARING_PROBABILI
"Probability that COMDAT function will be shared with different
compilation unit",
20, 0, 0)
+/* Use libcall strategy when the expected size is no less than this parameter
for memcpy. */
+DEFPARAM (PARAM_MEMCPY_LIBCALL_MIN_SIZE,
+ "memcpy-libcall-min-size",
+ "The minimal expected size to force libcall expansion strategy for
memcpy",
+ -1, 1, 0)
+
+/* Use libcall strategy when the expected size is no less than this parameter
for memset. */
+DEFPARAM (PARAM_MEMSET_LIBCALL_MIN_SIZE,
+ "memset-libcall-min-size",
+ "The minimal expected size to force libcall expansion strategy for
memset",
+ -1, 1, 0)
+
/* Limit on probability of entry BB. */
DEFPARAM (PARAM_PARTIAL_INLINING_ENTRY_PROBABILITY,
"partial-inlining-entry-probability",
