2009-05-22 Richard Guenther <rguenther@suse.de>

	PR middle-end/38964
	* alias.c (write_dependence_p): Do not use TBAA for answering
	anti-dependence or output-dependence.
	* tree-ssa-structalias.c (set_uids_in_ptset): Remove TBAA pruning
	code.
	(emit_pointer_definition): Remove.
	(emit_alias_warning): Likewise.
	(find_what_var_points_to): Remove TBAA pruning code.
	(find_what_p_points_to): Likewise.  Do not warn about strict-aliasing
	violations.
	(compute_points_to_sets): Remove code computing the set of
	dereferenced pointers.
	* tree-data-ref.c (dr_may_alias_p): Properly use the split
	oracle for querying anti and output dependencies.
	* tree-ssa-alias.c (refs_may_alias_p_1): Add argument specifying
	if TBAA may be applied.
	(refs_anti_dependent_p): New function.
	(refs_output_dependent_p): Likewise.
	* tree-ssa-alias.h (refs_anti_dependent_p): Declare.
	(refs_output_dependent_p): Likewise.

	* doc/tree-ssa.texi (Memory model): New section.

	testsuite/
	* g++.dg/warn/Wstrict-aliasing-float-ref-int-obj.C: XFAIL.
	* gcc.dg/Wstrict-aliasing-converted-assigned.c: Likewise.
	* gcc.dg/Wstrict-aliasing-float-ptr-int-obj.c: Likewise.

	* doc/c-tree.texi (CHANGE_DYNAMIC_TYPE_EXPR): Remove.
	* doc/gimple.texi (GIMPLE_CHANGE_DYNAMIC_TYPE): Remove.

	* cfgexpand.c (expand_gimple_basic_block): Do not handle
	GIMPLE_CHANGE_DYNAMIC_TYPE or CHANGE_DYNAMIC_TYPE_EXPR.
	* expr.c (expand_expr_real_1): Likewise.
	* gimple-low.c (lower_stmt): Likewise.
	* gimple-pretty-print.c (dump_gimple_stmt): Likewise.
	(dump_gimple_cdt): Remove.
	* gimple.c (gss_for_code): Do not handle GIMPLE_CHANGE_DYNAMIC_TYPE.
	(gimple_size): Likewise.
	(walk_gimple_op): Likewise.
	(is_gimple_stmt): Likewise.
	(walk_stmt_load_store_addr_ops): Likewise.
	(gimple_build_cdt): Remove.
	* gimple.def (GIMPLE_CHANGE_DYNAMIC_TYPE): Remove.
	* gimple.h (gimple_cdt_new_type): Remove.
	(gimple_cdt_new_type_ptr): Likewise.
	(gimple_cdt_set_new_type): Likewise.
	(gimple_cdt_location): Likewise.
	(gimple_cdt_location_ptr): Likewise.
	(gimple_cdt_set_location): Likewise.
	* gimplify.c (gimplify_expr): Do not handle CHANGE_DYNAMIC_TYPE_EXPR.
	* tree-cfg.c (remove_useless_stmts_1): Do not handle
	GIMPLE_CHANGE_DYNAMIC_TYPE.
	(verify_types_in_gimple_stmt): Likewise.
	* tree-inline.c (estimate_num_insns): Likewise.
	(expand_call_inline): Do not copy DECL_NO_TBAA_P.
	(copy_decl_to_var): Likewise.
	(copy_result_decl_to_var): Likewise.
	* tree-pretty-print.c (dump_generic_node): Do not handle
	CHANGE_DYNAMIC_TYPE_EXPR.
	* tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Likewise.
	* tree-ssa-operands.c (get_expr_operands): Likewise.
	* tree-ssa-structalias.c (struct variable_info): Remove
	no_tbaa_pruning member.
	(new_var_info): Do not set it based on DECL_NO_TBAA_P.
	(unify_nodes): Do not copy it.
	(find_func_aliases): Do not handle GIMPLE_CHANGE_DYNAMIC_TYPE.
	(dump_solution_for_var): Do not dump no_tbaa_pruning state.
	(set_uids_in_ptset): Do not check it.
	(find_what_var_points_to): Likewise.
	(compute_tbaa_pruning): Remove.
	(compute_points_to_sets): Do not call it.
	* tree.c (walk_tree_1): Do not handle CHANGE_DYNAMIC_TYPE_EXPR.
	* tree.def (CHANGE_DYNAMIC_TYPE_EXPR): Remove.
	* tree.h (CHANGE_DYNAMIC_TYPE_NEW_TYPE): Remove.
	(CHANGE_DYNAMIC_TYPE_LOCATION): Likewise.
	(DECL_NO_TBAA_P): Likewise.
	(struct tree_decl_common): Move no_tbaa_flag to unused flags section.
	* omp-low.c (copy_var_decl): Do not copy DECL_NO_TBAA_P.
	(expand_omp_atomic_pipeline): Do not set it.
	* print-tree.c (print_node): Do not dump it.
	* tree-ssa-copyrename.c (copy_rename_partition_coalesce): Remove
	redundant check.

	cp/
	* init.c (avoid_placement_new_aliasing): Remove.
	(build_new_1): Do not call it.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@147805 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 29 insertions, 0 deletions

diff --git a/gcc/doc/tree-ssa.texi b/gcc/doc/tree-ssa.texi
index 1442ce6f5b5..ebb85a05769 100644
--- a/gcc/doc/tree-ssa.texi
+++ b/gcc/doc/tree-ssa.texi
@@ -41,6 +41,7 @@ passes for GIMPLE@.
 * SSA Operands::  	SSA names referenced by GIMPLE statements.
 * SSA::                 Static Single Assignment representation.
 * Alias analysis::      Representing aliased loads and stores.
+* Memory model::        Memory model used by the middle-end.
 @end menu
 
 @node Annotations
@@ -892,3 +893,31 @@ providing its aliasing VDEF.  The walk stops if asked to.
 
 @end enumerate
 
+
+@node Memory model
+@section Memory model
+@cindex memory model
+
+The memory model used by the middle-end models that of the C/C++
+languages.  The middle-end has the notion of an effective type
+of a memory region which is used for type-based alias analysis.
+
+The following is a refinement of ISO C99 6.5/6, clarifying the block copy case
+to follow common sense and extending the concept of a dynamic effective
+type to objects with a declared type as required for C++.
+
+@smallexample
+The effective type of an object for an access to its stored value is
+the declared type of the object or the effective type determined by
+a previous store to it.  If a value is stored into an object through
+an lvalue having a type that is not a character type, then the
+type of the lvalue becomes the effective type of the object for that
+access and for subsequent accesses that do not modify the stored value.
+If a value is copied into an object using @code{memcpy} or @code{memmove},
+or is copied as an array of character type, then the effective type
+of the modified object for that access and for subsequent accesses that
+do not modify the value is undetermined.  For all other accesses to an
+object, the effective type of the object is simply the type of the
+lvalue used for the access.
+@end smallexample
+