[Patch 1/2 ifcvt costs] New target hook: max_noce_ifcvt_seq_cost

gcc/

	* target.def (max_noce_ifcvt_seq_cost): New.
	* doc/tm.texi.in (TARGET_MAX_NOCE_IFCVT_SEQ_COST): Document it.
	* doc/tm.texi: Regenerate.
	* targhooks.h (default_max_noce_ifcvt_seq_cost): New.
	* targhooks.c (default_max_noce_ifcvt_seq_cost): New.
	* params.def (PARAM_MAX_RTL_IF_CONVERSION_PREDICTABLE_COST): New.
	(PARAM_MAX_RTL_IF_CONVERSION_UNPREDICTABLE_COST): Likewise.
	* doc/invoke.texi: Document new params.

From-SVN: r238593

gcc/ChangeLog

+2016-07-21  James Greenhalgh  <james.greenhalgh@arm.com>
+
+	* target.def (max_noce_ifcvt_seq_cost): New.
+	* doc/tm.texi.in (TARGET_MAX_NOCE_IFCVT_SEQ_COST): Document it.
+	* doc/tm.texi: Regenerate.
+	* targhooks.h (default_max_noce_ifcvt_seq_cost): New.
+	* targhooks.c (default_max_noce_ifcvt_seq_cost): New.
+	* params.def (PARAM_MAX_RTL_IF_CONVERSION_PREDICTABLE_COST): New.
+	(PARAM_MAX_RTL_IF_CONVERSION_UNPREDICTABLE_COST): Likewise.
+	* doc/invoke.texi: Document new params.
+
 2016-07-21  Richard Biener  <rguenther@suse.de>
 
 	PR tree-optimization/71947

gcc/doc/invoke.texi

@@ -8869,6 +8869,17 @@ considered for if-conversion.  The default is 10, though the compiler will
 also use other heuristics to decide whether if-conversion is likely to be
 profitable.
 
+@item max-rtl-if-conversion-predictable-cost
+@item max-rtl-if-conversion-unpredictable-cost
+RTL if-conversion will try to remove conditional branches around a block
+and replace them with conditionally executed instructions.  These parameters
+give the maximum permissible cost for the sequence that would be generated
+by if-conversion depending on whether the branch is statically determined
+to be predictable or not.  The units for this parameter are the same as
+those for the GCC internal seq_cost metric.  The compiler will try to
+provide a reasonable default for this parameter using the BRANCH_COST
+target macro.
+
 @item max-crossjump-edges
 The maximum number of incoming edges to consider for cross-jumping.
 The algorithm used by @option{-fcrossjumping} is @math{O(N^2)} in

gcc/doc/tm.texi

@@ -6526,6 +6526,26 @@ should probably only be given to addresses with different numbers of
 registers on machines with lots of registers.
 @end deftypefn
 
+@deftypefn {Target Hook} {unsigned int} TARGET_MAX_NOCE_IFCVT_SEQ_COST (edge @var{e})
+This hook returns a value in the same units as @code{TARGET_RTX_COSTS},
+giving the maximum acceptable cost for a sequence generated by the RTL
+if-conversion pass when conditional execution is not available.
+The RTL if-conversion pass attempts to convert conditional operations
+that would require a branch to a series of unconditional operations and
+@code{mov@var{mode}cc} insns.  This hook returns the maximum cost of the
+unconditional instructions and the @code{mov@var{mode}cc} insns.
+RTL if-conversion is cancelled if the cost of the converted sequence
+is greater than the value returned by this hook.
+
+@code{e} is the edge between the basic block containing the conditional
+branch to the basic block which would be executed if the condition
+were true.
+
+The default implementation of this hook uses the
+@code{max-rtl-if-conversion-[un]predictable} parameters if they are set,
+and uses a multiple of @code{BRANCH_COST} otherwise.
+@end deftypefn
+
 @deftypefn {Target Hook} bool TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P (void)
 This predicate controls the use of the eager delay slot filler to disallow
 speculatively executed instructions being placed in delay slots.  Targets

gcc/doc/tm.texi.in

@@ -4762,6 +4762,8 @@ Define this macro if a non-short-circuit operation produced by
 
 @hook TARGET_ADDRESS_COST
 
+@hook TARGET_MAX_NOCE_IFCVT_SEQ_COST
+
 @hook TARGET_NO_SPECULATION_IN_DELAY_SLOTS_P
 
 @node Scheduling

gcc/params.def

@@ -1222,6 +1222,20 @@ DEFPARAM (PARAM_MAX_RTL_IF_CONVERSION_INSNS,
 	  "if-conversion.",
 	  10, 0, 99)
 
+DEFPARAM (PARAM_MAX_RTL_IF_CONVERSION_PREDICTABLE_COST,
+	  "max-rtl-if-conversion-predictable-cost",
+	  "Maximum permissible cost for the sequence that would be "
+	  "generated by the RTL if-conversion pass for a branch that "
+	  "is considered predictable.",
+	  20, 0, 200)
+
+DEFPARAM (PARAM_MAX_RTL_IF_CONVERSION_UNPREDICTABLE_COST,
+	  "max-rtl-if-conversion-unpredictable-cost",
+	  "Maximum permissible cost for the sequence that would be "
+	  "generated by the RTL if-conversion pass for a branch that "
+	  "is considered unpredictable.",
+	  40, 0, 200)
+
 DEFPARAM (PARAM_HSA_GEN_DEBUG_STORES,
 	  "hsa-gen-debug-stores",
 	  "Level of hsa debug stores verbosity",

gcc/target.def

@@ -3586,6 +3586,30 @@ registers on machines with lots of registers.",
  int, (rtx address, machine_mode mode, addr_space_t as, bool speed),
  default_address_cost)
 
+/* Give a cost, in RTX Costs units, for an edge.  Like BRANCH_COST, but with
+   well defined units.  */
+DEFHOOK
+(max_noce_ifcvt_seq_cost,
+ "This hook returns a value in the same units as @code{TARGET_RTX_COSTS},\n\
+giving the maximum acceptable cost for a sequence generated by the RTL\n\
+if-conversion pass when conditional execution is not available.\n\
+The RTL if-conversion pass attempts to convert conditional operations\n\
+that would require a branch to a series of unconditional operations and\n\
+@code{mov@var{mode}cc} insns.  This hook returns the maximum cost of the\n\
+unconditional instructions and the @code{mov@var{mode}cc} insns.\n\
+RTL if-conversion is cancelled if the cost of the converted sequence\n\
+is greater than the value returned by this hook.\n\
+\n\
+@code{e} is the edge between the basic block containing the conditional\n\
+branch to the basic block which would be executed if the condition\n\
+were true.\n\
+\n\
+The default implementation of this hook uses the\n\
+@code{max-rtl-if-conversion-[un]predictable} parameters if they are set,\n\
+and uses a multiple of @code{BRANCH_COST} otherwise.",
+unsigned int, (edge e),
+default_max_noce_ifcvt_seq_cost)
+
 /* Permit speculative instructions in delay slots during delayed-branch 
    scheduling.  */
 DEFHOOK

gcc/targhooks.c

@@ -74,6 +74,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "intl.h"
 #include "opts.h"
 #include "gimplify.h"
+#include "predict.h"
+#include "params.h"
 
 
 bool
@@ -1986,4 +1988,24 @@ default_optab_supported_p (int, machine_mode, machine_mode, optimization_type)
   return true;
 }
 
+/* Default implementation of TARGET_MAX_NOCE_IFCVT_SEQ_COST.  */
+
+unsigned int
+default_max_noce_ifcvt_seq_cost (edge e)
+{
+  bool predictable_p = predictable_edge_p (e);
+
+  enum compiler_param param
+    = (predictable_p
+       ? PARAM_MAX_RTL_IF_CONVERSION_PREDICTABLE_COST
+       : PARAM_MAX_RTL_IF_CONVERSION_UNPREDICTABLE_COST);
+
+  /* If we have a parameter set, use that, otherwise take a guess using
+     BRANCH_COST.  */
+  if (global_options_set.x_param_values[param])
+    return PARAM_VALUE (param);
+  else
+    return BRANCH_COST (true, predictable_p) * COSTS_N_INSNS (3);
+}
+
 #include "gt-targhooks.h"

gcc/targhooks.h

@@ -256,4 +256,6 @@ extern void default_setup_incoming_vararg_bounds (cumulative_args_t ca ATTRIBUTE
 extern bool default_optab_supported_p (int, machine_mode, machine_mode,
 				       optimization_type);
 
+extern unsigned int default_max_noce_ifcvt_seq_cost (edge);
+
 #endif /* GCC_TARGHOOKS_H */