This patch adds a new cost function so that the targets can decide if the
store/load reordering will be profitable. It also adds the
`asf-default-cost-value` parameter, which is used as the default return
value for the cost function.
gcc/ChangeLog:
* doc/tm.texi: Regenerate.
* doc/tm.texi.in: Document new target hook.
* params.opt: New parameter.
* target.def: New DEFHOOK.
* targhooks.cc (default_avoid_store_forwarding_reorder_cost_p):
New function.
* targhooks.h (default_avoid_store_forwarding_reorder_cost_p):
New function declaration.
Signed-off-by: Konstantinos Eleftheriou <[email protected]>
---
(no changes since v1)
gcc/doc/tm.texi | 7 +++++++
gcc/doc/tm.texi.in | 2 ++
gcc/params.opt | 4 ++++
gcc/target.def | 9 +++++++++
gcc/targhooks.cc | 9 +++++++++
gcc/targhooks.h | 5 +++++
6 files changed, 36 insertions(+)
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index fd208f53844a..aef552aac5f8 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -7466,6 +7466,13 @@ needed, the sequence cost and additional relevant
information is given in
the arguments so that the target can make an informed decision.
@end deftypefn
+@deftypefn {Target Hook} bool TARGET_AVOID_STORE_FORWARDING_REORDER_COST_P
(machine_mode, @var{machine_mode}, @var{HOST_WIDE_INT})
+This hook decides if it's profitable for the target to rearrange a store
+and a load instruction to avoid a potential store forwarding stall.
+The store and load modes and the byte offset of the store within the
+load are given as arguments.
+@end deftypefn
+
@node Scheduling
@section Adjusting the Instruction Scheduler
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 14315dd50805..0c3168cb6dde 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -4781,6 +4781,8 @@ Define this macro if a non-short-circuit operation
produced by
@hook TARGET_AVOID_STORE_FORWARDING_P
+@hook TARGET_AVOID_STORE_FORWARDING_REORDER_COST_P
+
@node Scheduling
@section Adjusting the Instruction Scheduler
diff --git a/gcc/params.opt b/gcc/params.opt
index f8884e976e7f..96720651731d 100644
--- a/gcc/params.opt
+++ b/gcc/params.opt
@@ -1091,6 +1091,10 @@ Maximum size of a single store merging region in bytes.
Common Joined UInteger Var(param_store_forwarding_max_distance) Init(10)
IntegerRange(0, 1000) Param Optimization
Maximum number of instruction distance that a small store forwarded to a
larger load may stall. Value '0' disables the cost checks for the
avoid-store-forwarding pass.
+-param=asf-default-cost-value=
+Common Joined UInteger Var(param_asf_default_cost_value) Init(0)
IntegerRange(0, 1) Param Optimization
+Default return value for the avoid_store_forwarding_reorder_cost_p function.
+
-param=switch-conversion-max-branch-ratio=
Common Joined UInteger Var(param_switch_conversion_branch_ratio) Init(8)
IntegerRange(1, 65536) Param Optimization
The maximum ratio between array size and switch branches for a switch
conversion to take place.
diff --git a/gcc/target.def b/gcc/target.def
index f288329ffcab..d60510e5458e 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -7158,6 +7158,15 @@ the arguments so that the target can make an informed
decision.",
bool, (vec<store_fwd_info>, rtx, int, bool),
default_avoid_store_forwarding_p)
+DEFHOOK
+(avoid_store_forwarding_reorder_cost_p,
+ "This hook decides if it's profitable for the target to rearrange a store\n\
+and a load instruction to avoid a potential store forwarding stall.\n\
+The store and load modes and the byte offset of the store within the\n\
+load are given as arguments.",
+ bool, (machine_mode, machine_mode, HOST_WIDE_INT),
+ default_avoid_store_forwarding_reorder_cost_p)
+
/* Determine the type of unwind info to emit for debugging. */
DEFHOOK
(debug_unwind_info,
diff --git a/gcc/targhooks.cc b/gcc/targhooks.cc
index 1873d572ba3f..15d882f4703e 100644
--- a/gcc/targhooks.cc
+++ b/gcc/targhooks.cc
@@ -2352,6 +2352,15 @@ default_avoid_store_forwarding_p (vec<store_fwd_info>,
rtx, int total_cost,
return true;
}
+/* The default implementation of TARGET_AVOID_STORE_FORWARDING_COST_P. */
+
+bool
+default_avoid_store_forwarding_reorder_cost_p (machine_mode, machine_mode,
+ HOST_WIDE_INT)
+{
+ return param_asf_default_cost_value;
+}
+
/* Determine the debugging unwind mechanism for the target. */
enum unwind_info_type
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index 92e7a4cb10f1..5389ea1cb78b 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -264,6 +264,11 @@ extern unsigned char default_class_max_nregs (reg_class_t,
machine_mode);
extern bool default_avoid_store_forwarding_p (vec<store_fwd_info>, rtx, int,
bool);
+extern bool
+default_avoid_store_forwarding_reorder_cost_p (machine_mode store_mode,
+ machine_mode load_mode,
+ HOST_WIDE_INT offset);
+
extern enum unwind_info_type default_debug_unwind_info (void);
extern void default_canonicalize_comparison (int *, rtx *, rtx *, bool);
--
2.50.1
