tm.texi.in (SWITCHABLE_TARGET): Document.

gcc/
	* doc/tm.texi.in (SWITCHABLE_TARGET): Document.
	* doc/tm.texi: Regenerate.
	* Makefile.in (OBJS-common): Add target-globals.o.
	(gtype-desc.o): Depend on $(IPA_PROP_H), $(LTO_STREAMER_H)
	and target-globals.h.
	(target-globals.o): New rule.
	(GTFILES): Include $(srcdir)/target-globals.h.
	* defaults.h (SWITCHABLE_TARGET): Define.
	* gengtype.c (open_base_files): Add target-globals.h to the
	list of includes.
	* target-globals.h: New file.
	* target-globals.c: Likewise.

	* Makefile.in (target-globals.o): Depend on $(FLAGS_H).
	* flags.h (target_flag_state): New structure.
	(default_target_flag_state): Declare.
	(this_target_flag_state): Declare as a variable or define as a macro.
	(align_loops_log): Redefine as a macro.
	(align_loops_max_skip, align_jumps_log): Likewise.
	(align_jumps_max_skip, align_labels_log): Likewise.
	(align_labels_max_skip, align_functions_log): Likewise.
	* toplev.c (default_target_flag_state): New variable.
	(this_target_flag_state): New conditional variable.
	(align_loops_log): Delete.
	(align_loops_max_skip, align_jumps_log): Likewise.
	(align_jumps_max_skip, align_labels_log): Likewise.
	(align_labels_max_skip, align_functions_log): Likewise.
	* target-globals.h (this_target_flag_state): Declare.
	(target_globals): Add a flag_state field.
	(restore_target_globals): Copy the flag_state field to
	this_target_flag_state.
	* target-globals.c: Include flags.h.
	(default_target_globals): Initialize the flag_state field.
	(save_target_globals): Likewise.

From-SVN: r162086

10 files changed, 219 insertions, 27 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2cd8630..aa2ef84 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,40 @@
+2010-07-12  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	* doc/tm.texi.in (SWITCHABLE_TARGET): Document.
+	* doc/tm.texi: Regenerate.
+	* Makefile.in (OBJS-common): Add target-globals.o.
+	(gtype-desc.o): Depend on $(IPA_PROP_H), $(LTO_STREAMER_H)
+	and target-globals.h.
+	(target-globals.o): New rule.
+	(GTFILES): Include $(srcdir)/target-globals.h.
+	* defaults.h (SWITCHABLE_TARGET): Define.
+	* gengtype.c (open_base_files): Add target-globals.h to the
+	list of includes.
+	* target-globals.h: New file.
+	* target-globals.c: Likewise.
+
+	* Makefile.in (target-globals.o): Depend on $(FLAGS_H).
+	* flags.h (target_flag_state): New structure.
+	(default_target_flag_state): Declare.
+	(this_target_flag_state): Declare as a variable or define as a macro.
+	(align_loops_log): Redefine as a macro.
+	(align_loops_max_skip, align_jumps_log): Likewise.
+	(align_jumps_max_skip, align_labels_log): Likewise.
+	(align_labels_max_skip, align_functions_log): Likewise.
+	* toplev.c (default_target_flag_state): New variable.
+	(this_target_flag_state): New conditional variable.
+	(align_loops_log): Delete.
+	(align_loops_max_skip, align_jumps_log): Likewise.
+	(align_jumps_max_skip, align_labels_log): Likewise.
+	(align_labels_max_skip, align_functions_log): Likewise.
+	* target-globals.h (this_target_flag_state): Declare.
+	(target_globals): Add a flag_state field.
+	(restore_target_globals): Copy the flag_state field to
+	this_target_flag_state.
+	* target-globals.c: Include flags.h.
+	(default_target_globals): Initialize the flag_state field.
+	(save_target_globals): Likewise.
+
 2010-07-12  Jie Zhang  <jie@codesourcery.com>
 
 	* postreload.c (reg_symbol_ref[]): New.
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index a807e8e..6fd3b00 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -1337,6 +1337,7 @@ OBJS-common = \
 	stor-layout.o \
 	store-motion.o \
 	stringpool.o \
+	target-globals.o \
 	targhooks.o \
 	timevar.o \
 	toplev.o \
@@ -2249,7 +2250,8 @@ gtype-desc.o: gtype-desc.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
 	hard-reg-set.h $(BASIC_BLOCK_H) cselib.h $(INSN_ADDR_H) $(OPTABS_H) \
 	libfuncs.h debug.h $(GGC_H) $(CGRAPH_H) $(TREE_FLOW_H) reload.h \
 	$(CPP_ID_DATA_H) tree-chrec.h $(CFGLAYOUT_H) $(EXCEPT_H) output.h \
-	$(CFGLOOP_H) $(TARGET_H)
+	$(CFGLOOP_H) $(TARGET_H) $(IPA_PROP_H) $(LTO_STREAMER_H) \
+	target-globals.h
 
 ggc-common.o: ggc-common.c $(CONFIG_H) $(SYSTEM_H) coretypes.h		\
 	$(GGC_H) $(HASHTAB_H) $(TOPLEV_H) $(DIAGNOSTIC_CORE_H) $(PARAMS_H) hosthooks.h	\
@@ -3473,6 +3475,9 @@ lower-subreg.o : lower-subreg.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
    $(MACHMODE_H) $(TM_H) $(RTL_H) $(TM_P_H) $(TIMEVAR_H) $(FLAGS_H) \
    insn-config.h $(BASIC_BLOCK_H) $(RECOG_H) $(OBSTACK_H) $(BITMAP_H) \
    $(EXPR_H) $(EXCEPT_H) $(REGS_H) $(TREE_PASS_H) $(DF_H)
+target-globals.o : target-globals.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
+   $(TM_H) insn-config.h $(MACHMODE_H) $(GGC_H) $(TOPLEV_H) target-globals.h \
+   $(FLAGS_H)
 
 $(out_object_file): $(out_file) $(CONFIG_H) coretypes.h $(TM_H) $(TREE_H) \
    $(RTL_H) $(REGS_H) hard-reg-set.h insn-config.h conditions.h \
@@ -3750,6 +3755,7 @@ GTFILES = $(CPP_ID_DATA_H) $(srcdir)/input.h $(srcdir)/coretypes.h \
   $(srcdir)/tree-ssa-alias.h \
   $(srcdir)/ipa-prop.h \
   $(srcdir)/lto-streamer.h \
+  $(srcdir)/target-globals.h \
   @all_gtfiles@
 
 # Compute the list of GT header files from the corresponding C sources,
diff --git a/gcc/defaults.h b/gcc/defaults.h
index e7e32c4..5d56c75 100644
--- a/gcc/defaults.h
+++ b/gcc/defaults.h
@@ -1372,6 +1372,10 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define STACK_CHECK_MAX_VAR_SIZE (STACK_CHECK_MAX_FRAME_SIZE / 100)
 #endif
 
+#ifndef SWITCHABLE_TARGET
+#define SWITCHABLE_TARGET 0
+#endif
+
 #endif /* GCC_INSN_FLAGS_H  */
 
 #endif  /* ! GCC_DEFAULTS_H */
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index d3d9c1e..78f2f2f 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -842,6 +842,25 @@ pointer.  If this macro is defined, GCC will turn on the
 @option{-fomit-frame-pointer} option whenever @option{-O} is specified.
 @end defmac
 
+@defmac SWITCHABLE_TARGET
+Some targets need to switch between substantially different subtargets
+during compilation.  For example, the MIPS target has one subtarget for
+the traditional MIPS architecture and another for MIPS16.  Source code
+can switch between these two subarchitectures using the @code{mips16}
+and @code{nomips16} attributes.
+
+Such subtargets can differ in things like the set of available
+registers, the set of available instructions, the costs of various
+operations, and so on.  GCC caches a lot of this type of information
+in global variables, and recomputing them for each subtarget takes a
+significant amount of time.  The compiler therefore provides a facility
+for maintaining several versions of the global variables and quickly
+switching between them; see @file{target-globals.h} for details.
+
+Define this macro to 1 if your target needs this facility.  The default
+is 0.
+@end defmac
+
 @node Per-Function Data
 @section Defining data structures for per-function information.
 @cindex per-function data
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index 51a8e5e..2f35a42 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -842,6 +842,25 @@ pointer.  If this macro is defined, GCC will turn on the
 @option{-fomit-frame-pointer} option whenever @option{-O} is specified.
 @end defmac
 
+@defmac SWITCHABLE_TARGET
+Some targets need to switch between substantially different subtargets
+during compilation.  For example, the MIPS target has one subtarget for
+the traditional MIPS architecture and another for MIPS16.  Source code
+can switch between these two subarchitectures using the @code{mips16}
+and @code{nomips16} attributes.
+
+Such subtargets can differ in things like the set of available
+registers, the set of available instructions, the costs of various
+operations, and so on.  GCC caches a lot of this type of information
+in global variables, and recomputing them for each subtarget takes a
+significant amount of time.  The compiler therefore provides a facility
+for maintaining several versions of the global variables and quickly
+switching between them; see @file{target-globals.h} for details.
+
+Define this macro to 1 if your target needs this facility.  The default
+is 0.
+@end defmac
+
 @node Per-Function Data
 @section Defining data structures for per-function information.
 @cindex per-function data
diff --git a/gcc/flags.h b/gcc/flags.h
index 5e87c09..32f9fbf 100644
--- a/gcc/flags.h
+++ b/gcc/flags.h
@@ -239,6 +239,43 @@ extern enum excess_precision flag_excess_precision;
 
 /* Other basic status info about current function.  */
 
+/* Target-dependent global state.  */
+struct target_flag_state {
+  /* Values of the -falign-* flags: how much to align labels in code.
+     0 means `use default', 1 means `don't align'.
+     For each variable, there is an _log variant which is the power
+     of two not less than the variable, for .align output.  */
+  int x_align_loops_log;
+  int x_align_loops_max_skip;
+  int x_align_jumps_log;
+  int x_align_jumps_max_skip;
+  int x_align_labels_log;
+  int x_align_labels_max_skip;
+  int x_align_functions_log;
+};
+
+extern struct target_flag_state default_target_flag_state;
+#if SWITCHABLE_TARGET
+extern struct target_flag_state *this_target_flag_state;
+#else
+#define this_target_flag_state (&default_target_flag_state)
+#endif
+
+#define align_loops_log \
+  (this_target_flag_state->x_align_loops_log)
+#define align_loops_max_skip \
+  (this_target_flag_state->x_align_loops_max_skip)
+#define align_jumps_log \
+  (this_target_flag_state->x_align_jumps_log)
+#define align_jumps_max_skip \
+  (this_target_flag_state->x_align_jumps_max_skip)
+#define align_labels_log \
+  (this_target_flag_state->x_align_labels_log)
+#define align_labels_max_skip \
+  (this_target_flag_state->x_align_labels_max_skip)
+#define align_functions_log \
+  (this_target_flag_state->x_align_functions_log)
+
 /* Nonzero if subexpressions must be evaluated from left-to-right.  */
 extern int flag_evaluation_order;
 
@@ -252,19 +289,6 @@ extern bool sel_sched_switch_set;
 /* Whether to run the warn_unused_result attribute pass.  */
 extern bool flag_warn_unused_result;
 
-/* Values of the -falign-* flags: how much to align labels in code.
-   0 means `use default', 1 means `don't align'.
-   For each variable, there is an _log variant which is the power
-   of two not less than the variable, for .align output.  */
-
-extern int align_loops_log;
-extern int align_loops_max_skip;
-extern int align_jumps_log;
-extern int align_jumps_max_skip;
-extern int align_labels_log;
-extern int align_labels_max_skip;
-extern int align_functions_log;
-
 /* Nonzero if we dump in VCG format, not plain text.  */
 extern int dump_for_graph;
 
diff --git a/gcc/gengtype.c b/gcc/gengtype.c
index 4b6e60e..9127251 100644
--- a/gcc/gengtype.c
+++ b/gcc/gengtype.c
@@ -1571,7 +1571,7 @@ open_base_files (void)
       "optabs.h", "libfuncs.h", "debug.h", "ggc.h", "cgraph.h",
       "tree-flow.h", "reload.h", "cpp-id-data.h", "tree-chrec.h",
       "cfglayout.h", "except.h", "output.h", "gimple.h", "cfgloop.h",
-      "target.h", "ipa-prop.h", "lto-streamer.h", NULL
+      "target.h", "ipa-prop.h", "lto-streamer.h", "target-globals.h", NULL
     };
     const char *const *ifp;
     outf_p gtype_desc_c;
diff --git a/gcc/target-globals.c b/gcc/target-globals.c
new file mode 100644
index 0000000..ecbc76b
--- /dev/null
+++ b/gcc/target-globals.c
@@ -0,0 +1,48 @@
+/* Target-dependent globals.
+   Copyright (C) 2010  Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "insn-config.h"
+#include "machmode.h"
+#include "ggc.h"
+#include "toplev.h"
+#include "target-globals.h"
+#include "flags.h"
+
+#if SWITCHABLE_TARGET
+struct target_globals default_target_globals = {
+  &default_target_flag_state
+};
+
+struct target_globals *
+save_target_globals (void)
+{
+  struct target_globals *g;
+
+  g = ggc_alloc_target_globals ();
+  g->flag_state = XCNEW (struct target_flag_state);
+  restore_target_globals (g);
+  target_reinit ();
+  return g;
+}
+
+#endif
diff --git a/gcc/target-globals.h b/gcc/target-globals.h
new file mode 100644
index 0000000..496a507
--- /dev/null
+++ b/gcc/target-globals.h
@@ -0,0 +1,41 @@
+/* Target-dependent globals.
+   Copyright (C) 2010  Free Software Foundation, Inc.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 3, or (at your option) any later
+version.
+
+GCC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3.  If not see
+<http://www.gnu.org/licenses/>.  */
+
+#ifndef TARGET_GLOBALS_H
+#define TARGET_GLOBALS_H 1
+
+#if SWITCHABLE_TARGET
+extern struct target_flag_state *this_target_flag_state;
+
+struct GTY(()) target_globals {
+  struct target_flag_state *GTY((skip)) flag_state;
+};
+
+extern struct target_globals default_target_globals;
+
+extern struct target_globals *save_target_globals (void);
+
+static inline void
+restore_target_globals (struct target_globals *g)
+{
+  this_target_flag_state = g->flag_state;
+}
+#endif
+
+#endif
diff --git a/gcc/toplev.c b/gcc/toplev.c
index 276ae7e..1472579 100644
--- a/gcc/toplev.c
+++ b/gcc/toplev.c
@@ -317,18 +317,12 @@ enum stack_check_type flag_stack_check = NO_STACK_CHECK;
 
 bool user_defined_section_attribute = false;
 
-/* Values of the -falign-* flags: how much to align labels in code.
-   0 means `use default', 1 means `don't align'.
-   For each variable, there is an _log variant which is the power
-   of two not less than the variable, for .align output.  */
-
-int align_loops_log;
-int align_loops_max_skip;
-int align_jumps_log;
-int align_jumps_max_skip;
-int align_labels_log;
-int align_labels_max_skip;
-int align_functions_log;
+struct target_flag_state default_target_flag_state;
+#if SWITCHABLE_TARGET
+struct target_flag_state *this_target_flag_state = &default_target_flag_state;
+#else
+#define this_target_flag_state (&default_target_flag_state)
+#endif
 
 typedef struct
 {