From d3ff498c478acefce35de04402f99171b4f64a1a Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Sun, 2 Feb 2025 07:10:55 +0800
Subject: [PATCH] ira: Add a target hook for callee-saved register cost scale
commit 3b9b8d6cfdf59337f4b7ce10ce92a98044b2657b
Author: Surya Kumari Jangala <jskumari@linux.ibm.com>
Date: Tue Jun 25 08:37:49 2024 -0500
ira: Scale save/restore costs of callee save registers with block frequency
scales the cost of saving/restoring a callee-save hard register in epilogue
and prologue with the entry block frequency, which, if not optimizing for
size, is 10000, for all targets. As the result, callee-saved registers
may not be used to preserve local variable values across calls on some
targets, like x86. Add a target hook for the callee-saved register cost
scale in epilogue and prologue used by IRA. The default version of this
target hook returns 1 if optimizing for size, otherwise returns the entry
block frequency. Add an x86 version of this target hook to restore the
old behavior prior to the above commit.
PR rtl-optimization/111673
PR rtl-optimization/115932
PR rtl-optimization/116028
PR rtl-optimization/117081
PR rtl-optimization/117082
PR rtl-optimization/118497
* ira-color.cc (assign_hard_reg): Call the target hook for the
callee-saved register cost scale in epilogue and prologue.
* target.def (ira_callee_saved_register_cost_scale): New target
hook.
* targhooks.cc (default_ira_callee_saved_register_cost_scale):
New.
* targhooks.h (default_ira_callee_saved_register_cost_scale):
Likewise.
* config/i386/i386.cc (ix86_ira_callee_saved_register_cost_scale):
New.
(TARGET_IRA_CALLEE_SAVED_REGISTER_COST_SCALE): Likewise.
* doc/tm.texi: Regenerated.
* doc/tm.texi.in (TARGET_IRA_CALLEE_SAVED_REGISTER_COST_SCALE):
New.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
gcc/config/i386/i386.cc | 11 +++++++++++
gcc/doc/tm.texi | 8 ++++++++
gcc/doc/tm.texi.in | 2 ++
gcc/ira-color.cc | 3 +--
gcc/target.def | 12 ++++++++++++
gcc/targhooks.cc | 8 ++++++++
gcc/targhooks.h | 1 +
7 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index f89201684a8a..3128973ba79c 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -20600,6 +20600,14 @@ ix86_class_likely_spilled_p (reg_class_t rclass)
return false;
}
+/* Implement TARGET_IRA_CALLEE_SAVED_REGISTER_COST_SCALE. */
+
+static int
+ix86_ira_callee_saved_register_cost_scale (int)
+{
+ return 1;
+}
+
/* Return true if a set of DST by the expression SRC should be allowed.
This prevents complex sets of likely_spilled hard regs before split1. */
@@ -27078,6 +27086,9 @@ ix86_libgcc_floating_mode_supported_p
#define TARGET_PREFERRED_OUTPUT_RELOAD_CLASS ix86_preferred_output_reload_class
#undef TARGET_CLASS_LIKELY_SPILLED_P
#define TARGET_CLASS_LIKELY_SPILLED_P ix86_class_likely_spilled_p
+#undef TARGET_IRA_CALLEE_SAVED_REGISTER_COST_SCALE
+#define TARGET_IRA_CALLEE_SAVED_REGISTER_COST_SCALE \
+ ix86_ira_callee_saved_register_cost_scale
#undef TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST
#define TARGET_VECTORIZE_BUILTIN_VECTORIZATION_COST \
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 0de24eda6f01..9f42913a4efb 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -3047,6 +3047,14 @@ A target hook which can change allocno class for given pseudo from
The default version of this target hook always returns given class.
@end deftypefn
+@deftypefn {Target Hook} int TARGET_IRA_CALLEE_SAVED_REGISTER_COST_SCALE (int @var{hard_regno})
+A target hook which returns the callee-saved register @var{hard_regno}
+cost scale in epilogue and prologue used by IRA.
+
+The default version of this target hook returns 1 if optimizing for
+size, otherwise returns the entry block frequency.
+@end deftypefn
+
@deftypefn {Target Hook} bool TARGET_LRA_P (void)
A target hook which returns true if we use LRA instead of reload pass.
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 631d04131e39..6dbe22581ca1 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -2388,6 +2388,8 @@ in the reload pass.
@hook TARGET_IRA_CHANGE_PSEUDO_ALLOCNO_CLASS
+@hook TARGET_IRA_CALLEE_SAVED_REGISTER_COST_SCALE
+
@hook TARGET_LRA_P
@hook TARGET_REGISTER_PRIORITY
diff --git a/gcc/ira-color.cc b/gcc/ira-color.cc
index 0699b349a1af..233060e15876 100644
--- a/gcc/ira-color.cc
+++ b/gcc/ira-color.cc
@@ -2180,8 +2180,7 @@ assign_hard_reg (ira_allocno_t a, bool retry_p)
+ ira_memory_move_cost[mode][rclass][1])
* saved_nregs / hard_regno_nregs (hard_regno,
mode) - 1)
- * (optimize_size ? 1 :
- REG_FREQ_FROM_BB (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
+ * targetm.ira_callee_saved_register_cost_scale (hard_regno);
cost += add_cost;
full_cost += add_cost;
}
diff --git a/gcc/target.def b/gcc/target.def
index 4050b2ebdd41..c348b15815a7 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -5714,6 +5714,18 @@ DEFHOOK
reg_class_t, (int, reg_class_t, reg_class_t),
default_ira_change_pseudo_allocno_class)
+/* Scale of callee-saved register cost in epilogue and prologue used by
+ IRA. */
+DEFHOOK
+(ira_callee_saved_register_cost_scale,
+ "A target hook which returns the callee-saved register @var{hard_regno}\n\
+cost scale in epilogue and prologue used by IRA.\n\
+\n\
+The default version of this target hook returns 1 if optimizing for\n\
+size, otherwise returns the entry block frequency.",
+ int, (int hard_regno),
+ default_ira_callee_saved_register_cost_scale)
+
/* Return true if we use LRA instead of reload. */
DEFHOOK
(lra_p,
diff --git a/gcc/targhooks.cc b/gcc/targhooks.cc
index f80dc8b2e7e1..344075efa417 100644
--- a/gcc/targhooks.cc
+++ b/gcc/targhooks.cc
@@ -1305,6 +1305,14 @@ default_ira_change_pseudo_allocno_class (int regno ATTRIBUTE_UNUSED,
return cl;
}
+int
+default_ira_callee_saved_register_cost_scale (int)
+{
+ return (optimize_size
+ ? 1
+ : REG_FREQ_FROM_BB (ENTRY_BLOCK_PTR_FOR_FN (cfun)));
+}
+
extern bool
default_lra_p (void)
{
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index 7d15f632c232..8871e01430c7 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -173,6 +173,7 @@ extern void default_emit_call_builtin___clear_cache (rtx, rtx);
extern poly_int64 default_return_pops_args (tree, tree, poly_int64);
extern reg_class_t default_ira_change_pseudo_allocno_class (int, reg_class_t,
reg_class_t);
+extern int default_ira_callee_saved_register_cost_scale (int);
extern bool default_lra_p (void);
extern int default_register_priority (int);
extern bool default_register_usage_leveling_p (void);
--
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