* 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.

From-SVN: r111644