[PATCH] Disable optimization for volatile object

[Eric Botcazou]

> C if you like, but Ada is also fine ;)

OK, here's the complete patch + testcase.  This exercises pragma Atomic in 
Ada, whose implementation strategy is to generate extra temporaries and block 
moves in the FE, put pragma Volatile on the atomic objects and hope that the 
middle-end won't retrofit things.  The testcase doesn't pass without the bits 
in the gimplifier.

Tested on i586-suse-linux, applied on the mainline.


2009-04-23  Eric Botcazou  <ebotcazou@adacore.com>

        * gimplify.c (gimplify_modify_expr_rhs) <VAR_DECL>: Do not do a direct
        assignment from the constructor either if the target is volatile.
ada/
	* einfo.ads (Is_True_Constant): Lift restriction on atomic objects.
	* sinfo.ads (Object Declaration): Likewise.
	(Assignment Statement): Likewise.
	* freeze.adb (Expand_Atomic_Aggregate): Remove useless test.
	Do not force Is_True_Constant to false on the temporary.
	(Freeze_Entity): Do not force Is_True_Constant to false on names on
	the RHS of object declarations.
	* gcc-interface/trans.c (lvalue_required_p) <N_Object_Declaration>:
	New case.  Return 1 if the object is atomic.
	<N_Assignment_Statement>: Likewise.


2009-04-23  Eric Botcazou  <ebotcazou@adacore.com>

	* gnat.dg/atomic1.adb: New test.
	* gnat.dg/atomic1_pkg.ads: New helper.


-- 
Eric Botcazou
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