[PATCH] Get rid of awkward semantics for subtypes

[Eric Botcazou]

Hi,

as explained in http://gcc.gnu.org/ml/gcc/2009-04/msg00323.html the attached 
patch gets rid of the awkward semantics implemented for subtypes (INTEGER_TYPE 
with a non-NULL TREE_TYPE).  It doesn't get rid of subtypes because they are 
needed for certain things but promotes them to first-class citizenship, so 
that it shouldn't be necessary to specifically check for them anymore in the 
middle-end, except for debugging information.  It's up to the front-end to 
make sure that range subtypes, e.g. built for arrays in all languages, don't 
leak into the code.

Tested on i586-suse-linux with the associated Gigi patch, OK for mainline?


2009-05-10  Eric Botcazou  <ebotcazou@adacore.com>

	* dbxout.c (dbxout_type): Be prepared to deal with subtypes.
	* dwarf2out.c (base_type_die): Likewise.
	(is_subrange_type): Delete.
	(subrange_type_die): Add LOW and HIGH parameters.  Use them for bounds.
	(modified_type_die): Call subrange_type_for_debug_p on subtypes.
	* fold-const.c (fold_truth_not_expr) <CONVERT_EXPR>: Do not strip
	it if the destination type is boolean.
	(build_range_check): Do not special-case subtypes.
	(fold_sign_changed_comparison): Likewise.
	(fold_unary): Likewise.
	* langhooks-def.h (LANG_HOOKS_GET_SUBRANGE_BOUNDS): Define.
	(LANG_HOOKS_FOR_TYPES_INITIALIZER): Add LANG_HOOKS_GET_SUBRANGE_BOUNDS.
	* langhooks.h (lang_hooks_for_types): Add get_subrange_bounds.
	* tree.h (subrange_type_for_debug_p): Declare.
	* tree.c (subrange_type_for_debug_p): New predicate based on the
	former is_subrange_type.
	* tree-chrec.c (avoid_arithmetics_in_type_p): Delete.
	(convert_affine_scev): Remove call to above function.
	(chrec_convert_aggressive): Likewise.
	* tree-ssa.c (useless_type_conversion_p_1): Do not specifically return
	false for conversions involving subtypes.
	* tree-vrp.c (vrp_val_max): Do not special-case subtypes.
	(vrp_val_min): Likewise.
	(needs_overflow_infinity): Likewise.
	(extract_range_from_unary_expr): Likewise.


-- 
Eric Botcazou
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