This is an update of a patch originally posted and discussed in this  
thread:
http://gcc.gnu.org/ml/gcc-patches/2010-06/threads.html#00995

I guess it needs a global approver - so cc-ing Diego who, IIRC,  
approved the previous EMUTLS changes.

changes from the previous thread.
(a) emutls.c is no longer modified in any way.
(b) I have taken on board the comments about not rearranging code.
(c) the cases where we should not have emutls variables are now asserts.

tested on {i686,powerpc*}-apple-darwin{8,9},  x86_64-apple-darwin10 -  
EMUTLS target without aliases.
    {i686,x86_64}unknown-linux-gnu - native TLS targets (i.e. for a  
null response)
   cris-elf(sim)  - EMUTLS target with aliases
  + armel-linux-eabi(compile-only), mipsabi64-elf(sim), s390x(sompile  
only).

The test-suite additions are motivated by:
(a) the fact that initialization of the emults vars was a weakness  
w.r.t. optimization,
(b) to include the test that is used as the configury check for TLS  
compliance.


OK for trunk now? (and eventually 4.5)?

Iain

gcc/Changelog (email addresses omitted)
	
	Iain Sandoe
	Jan Hubika

	PR target/44132
	* expr.c (emutls_var_address): Remove.
	(expand_expr_addr_expr_1): Remove TLS emulation hook.
	(expand_expr_real_1): Ditto.

	* gimplify.c (emutls_var_address): Add proc.
	(gimplify_decl_expr): expand TLS vars.
	(gimplify_var_or_parm_decl): Ditto.
	(omp_notice_variable): Recognize TLS_MODEL_EMULATED.

	* passes.c (rest_of_decl_compilation): Substitute TLS control vars  
for the master.

	* varasm.c (get_emutls_init_templ_addr): Do not reset the caller's  
DECL_INITIAL.
	(emutls_decl): copy DECL_PRESERVE_P instead of setting it, copy
	TREE_ADDRESSABLE.  Create the init template as soon as we see a valid  
initializer.
	 Mark the original var with error_mark_node so that re- 
initializations will be diagnosed
	properly.  Mark the original var as not to be output.
	(emutls_common_1): Do not rely on DECL_COMMON as a decision on  
whether a constructor
	is needed, it is also required for lcomm.   Ensure that the var is  
laid out before the constructor
	is built.
	(emutls_finalize_control_var): Assert on incorrect type, copy USED.
	(asm_output_bss): Assert on DECL_THREAD_LOCAL_P for EMUTLS targets.
	(asm_output_aligned_bss): Likewise.
	(assemble_variable): Remove TLS var. substitution.  Back up  
TREE_ASM_WRITTEN so that
	assemble_variable() has no side-effects for unwritten vars.  Assert  
on DECL_THREAD_LOCAL_P
	for EMUTLS targets.
	(do_assemble_alias): Assert on DECL_THREAD_LOCAL_P for EMUTLS targets.
	(var_decl_for_asm): New.
	(finish_aliases_1): Walk alias pairs substituting tls controls for  
originals.

	* passes.c (rest_of_decl_compilation): Substitute TLS control vars  
for the master.

	* varpool.c (varpool_mark_needed_node): Do not handle TLS  
substitution here.
	(decide_is_variable_needed): Or here.
	(varpool_finalize_decl): Handle TLS substitution.
	Remove early calls to varpool_assemble_pending_decls().
	Check enqueuing of vars after all tests for need are complete.
	(varpool_analyze_pending_decls): Do not record references if the  
initializer is error_mark.

testsuite:
	
	PR target/44132
	* gcc.dg/tls/thr-init-1.c: New.
	* gcc.dg/tls/thr-init-2.c: New.
	* gcc.dg/torture/tls New.
	* gcc.dg/torture/tls/tls-test.c: New.
	* gcc.dg/torture/tls/thr-init-1.c: New.
	* gcc.dg/torture/tls/tls.exp: New.
	* gcc.dg/torture/tls/thr-init-2.c: New.