* doc/tm.texi (TARGET_HAVE_SWITCHABLE_BSS_SECTIONS): Document.

	(ASM_OUTPUT_BSS): Describe the two ways of handling global BSS,
	and say that only one is needed.
	* doc/rtl.texi (SYMBOL_REF_BLOCK): Say that the block can be null.
	* target.h (have_switchable_bss_sections): New hook.
	* explow.c (use_anchored_address): Check that the symbol is in a block.
	* varasm.c (tls_comm_section, comm_section, lcomm_section)
	(bss_noswitch_section): New variables.
	(get_unnamed_section): Add SECTION_UNNAMED to the flags.
	(get_noswitch_section): New function.
	(get_block_for_section): Allow SECT to be null.
	(unlikely_text_section_p): Use SECTION_STYLE.
	(bss_initializer_p): New function.
	(get_variable_section): Move earlier in file.  Take a new argument,
	prefer_noswitch_p.  Move bss checks from assemble_variable to here.
	Return one of the new *_sections in such cases.
	(get_block_for_decl): New function, extracting some logic from
	use_blocks_for_decl_p.
	(change_symbol_section): Remove in favor of...
	(change_symbol_block): ...this new function.
	(use_blocks_for_decl_p): Remove checks now performed by
	get_block_for_decl.
	(make_decl_rtl): Use change_symbol_block and get_block_for_decl.
	(ASM_EMIT_LOCAL, ASM_EMIT_BSS, ASM_EMIT_COMMON): Delete in favor of...
	(emit_local, emit_bss, emit_common): ...these new functions.
	Return true if the alignment was honored.
	(emit_tls_common): New function.
	(asm_emit_uninitialised): Delete.
	(assemble_variable_noswitch): New function, split out from...
	(assemble_variable): ...here.  Don't make decisions about common
	variables here.  Globalize all public decls that go into non-common
	sections.  Check whether SYMBOL_REF_BLOCK is null.
	(output_constant_def_contents): Check whether SYMBOL_REF_BLOCK is null.
	(output_constant_pool): Likewise.
	(init_varasm_once): Initialize the new section variables.
	(have_global_bss_p): New function.
	(categorize_decl_for_section): Use bss_initializer_p.
	(switch_to_section): Use SECTION_STYLE.  Abort for SECTION_NOSWITCH.
	(place_block_symbol): Assert that the symbol must be in a block.
	* target-def.h (TARGET_HAVE_SWITCHABLE_BSS_SECTIONS): New macro.
	(TARGET_INITIALIZER): Include it.
	* rtl.h (SYMBOL_REF_BLOCK): Document the null alternative.
	* output.h (SECTION_STYLE_MASK, SECTION_COMMON): New macros.
	(SECTION_MACH_DEP): Bump by two.
	(SECTION_UNNAMED, SECTION_NOSWITCH): New macros.
	(unnamed_section): Mention SECTION_UNNAMED in comment.
	(named_section): Likewise SECTION_NAMED.
	(noswitch_section_callback): New type.
	(noswitch_section): New structure.
	(section): Add a noswitch_section alternative.
	(SECTION_STYLE): New macro.
	(tls_comm_section, comm_section, lcomm_section): Declare.
	(bss_noswitch_section, have_global_bss_p): Declare.
	* config/elfos.h (TARGET_HAVE_SWITCHABLE_BSS_SECTIONS): Override.
	* config/iq2000/iq2000.c (TARGET_HAVE_SWITCHABLE_BSS_SECTIONS):
	Override.
	* config/v850/v850.c (TARGET_HAVE_SWITCHABLE_BSS_SECTIONS): Override.
	* config/stormy16/stormy16.c (TARGET_HAVE_SWITCHABLE_BSS_SECTIONS):
	Override.

cp/
	* decl.c (start_decl): Use have_global_bss_p when deciding
	whether to make the decl common.

ada/
	* utils.c (create_var_decl): Use have_global_bss_p when deciding
	whether to make the decl common.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@111644 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 50 insertions, 6 deletions

diff --git a/gcc/output.h b/gcc/output.h
index 5fda5eaa3fc..89743516050 100644
--- a/gcc/output.h
+++ b/gcc/output.h
@@ -402,8 +402,22 @@ extern void no_asm_to_stream (FILE *);
 #define SECTION_TLS	 0x40000	/* contains thread-local storage */
 #define SECTION_NOTYPE	 0x80000	/* don't output @progbits */
 #define SECTION_DECLARED 0x100000	/* section has been used */
-#define SECTION_NAMED	 0x200000	/* section has a name */
-#define SECTION_MACH_DEP 0x400000	/* subsequent bits reserved for target */
+#define SECTION_STYLE_MASK 0x600000	/* bits used for SECTION_STYLE */
+#define SECTION_COMMON   0x800000	/* contains common data */
+#define SECTION_MACH_DEP 0x1000000	/* subsequent bits reserved for target */
+
+/* This SECTION_STYLE is used for unnamed sections that we can switch
+   to using a special assembler directive.  */
+#define SECTION_UNNAMED	 0x000000
+
+/* This SECTION_STYLE is used for named sections that we can switch
+   to using a general section directive.  */
+#define SECTION_NAMED	 0x200000
+
+/* This SECTION_STYLE is used for sections that we cannot switch to at
+   all.  The choice of section is implied by the directive that we use
+   to declare the object.  */
+#define SECTION_NOSWITCH 0x400000
 
 /* A helper function for default_elf_select_section and
    default_elf_unique_section.  Categorizes the DECL.  */
@@ -448,7 +462,7 @@ struct section_common GTY(()) {
   unsigned int flags;
 };
 
-/* Information that is provided by named sections.  */
+/* Information about a SECTION_NAMED section.  */
 struct named_section GTY(()) {
   struct section_common common;
 
@@ -464,7 +478,7 @@ struct named_section GTY(()) {
    section.  The argument provides callback-specific data.  */
 typedef void (*unnamed_section_callback) (const void *);
 
-/* Information that is provided by unnamed sections.  */
+/* Information about a SECTION_UNNAMED section.  */
 struct unnamed_section GTY(()) {
   struct section_common common;
 
@@ -477,14 +491,39 @@ struct unnamed_section GTY(()) {
   section *next;
 };
 
+/* A callback that writes the assembly code for a decl in a
+   SECTION_NOSWITCH section.  DECL is the decl that should be assembled
+   and NAME is the name of its SYMBOL_REF.  SIZE is the size of the decl
+   in bytes and ROUNDED is that size rounded up to the next
+   BIGGEST_ALIGNMENT / BITS_PER_UNIT boundary.
+
+   Return true if the callback used DECL_ALIGN to set the object's
+   alignment.  A false return value implies that we are relying
+   on the rounded size to align the decl.  */
+typedef bool (*noswitch_section_callback) (tree decl, const char *name,
+					   unsigned HOST_WIDE_INT size,
+					   unsigned HOST_WIDE_INT rounded);
+
+/* Information about a SECTION_NOSWITCH section.  */
+struct noswitch_section GTY(()) {
+  struct section_common common;
+
+  /* The callback used to assemble decls in this section.  */
+  noswitch_section_callback GTY ((skip)) callback;
+};
+
 /* Information about a section, which may be named or unnamed.  */
-union section GTY ((desc ("(%h).common.flags & SECTION_NAMED")))
+union section GTY ((desc ("SECTION_STYLE (&(%h))")))
 {
   struct section_common GTY ((skip)) common;
   struct named_section GTY ((tag ("SECTION_NAMED"))) named;
-  struct unnamed_section GTY ((tag ("0"))) unnamed;
+  struct unnamed_section GTY ((tag ("SECTION_UNNAMED"))) unnamed;
+  struct noswitch_section GTY ((tag ("SECTION_NOSWITCH"))) noswitch;
 };
 
+/* Return the style of section SECT.  */
+#define SECTION_STYLE(SECT) ((SECT)->common.flags & SECTION_STYLE_MASK)
+
 struct object_block;
 
 /* Special well-known sections.  */
@@ -498,6 +537,10 @@ extern GTY(()) section *bss_section;
 extern GTY(()) section *sbss_section;
 extern GTY(()) section *exception_section;
 extern GTY(()) section *eh_frame_section;
+extern GTY(()) section *tls_comm_section;
+extern GTY(()) section *comm_section;
+extern GTY(()) section *lcomm_section;
+extern GTY(()) section *bss_noswitch_section;
 
 extern GTY(()) section *in_section;
 extern GTY(()) bool in_cold_section_p;
@@ -523,6 +566,7 @@ extern void output_section_asm_op (const void *);
 extern unsigned int default_section_type_flags (tree, const char *, int);
 extern unsigned int default_section_type_flags_1 (tree, const char *, int, int);
 
+extern bool have_global_bss_p (void);
 extern void default_no_named_section (const char *, unsigned int, tree);
 extern void default_elf_asm_named_section (const char *, unsigned int, tree);
 extern enum section_category categorize_decl_for_section (tree, int, int);