* invoke.texi (-fstrict-aliasing): Document.

	* rtl.texi (MEM_ALIAS_SET): Document.
	* flags.h (flag_strict_aliasing): Declare.
	* toplev.c (flag_strict_aliasing): Define.
	(f_options): Add -strict-aliasing.
	(main): Set flag_strict_aliasing if -O2 or higher.
	* tree.h (tree_type): Add alias_set field.
	(TYPE_ALIAS_SET): New macro.
	(TYPE_ALIAS_SET_KNOWN_P): Likewise.
	(get_alias_set): Declare.
	* tree.c (lang_get_alias_set): Define.
	(make_node): Initialize TYPE_ALIAS_SET.
	(get_alias_set): New function.
	* print-tree.c (print_node): Dump the alias set for a type.
	* c-tree.h (c_get_alias_set): Declare.
	* c-common.c (c_get_alias_set): New function.
	* c-decl.c (init_decl_processing): Set lang_get_alias_set.
	* expr.c (protect_from_queue): Propogage alias sets.
	(expand_assignment): Calculate alias set for new MEMs.
	(expand_expr): Likewise.
	* function.c (put_var_into_stack): Likewise.
	(put_reg_into_stack): Likewise.
	(gen_mem_addressof): Likewise.
	(assign_parms): Likewise.
	* stmt.c (expand_decl): Likewise.
	* varasm.c (make_decl_rtl): Eliminate redundant clearing of
	DECL_RTL.  Calculate alias set for new MEMs.
	* rtl.def (REG): Add dummy operand.
	(MEM): Add extra operand to store the MEM_ALIAS_SET.
	* rtl.h (MEM_ALIAS_SET): New macro.
	(gen_rtx_MEM): Declare.
	* emit-rtl.c (gen_rtx_MEM): New function.
	* gengenrtl.c (sepcial_rtx): Make MEMs special.
	* alias.c (CHECK_ALIAS_SETS_FOR_CONSISTENCY): New macro.
	(DIFFERENT_ALIAS_SETS_P): Likewise.
	(canon_rtx): Propogate the alias set to the new MEM.
	(true_dependence): Check the alias sets.
	(anti_dependence): Likewise.
	(output_dependence): Likewise.
	* explow.c (stabilize): Progoate alias sets.
	* integrate.c (copy_rtx_and_substitute): Likewise.
	* final.c (alter_subreg): Make sure not to leave MEM_IN_STRUCT_P
	in an unpredictable state.  Propogate alias sets.
	* reload1.c (reload): Clear MEM_ALIAS_SET for new MEMs about which
	we have no alias information.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@20719 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 12 insertions, 3 deletions

diff --git a/gcc/rtl.texi b/gcc/rtl.texi
index 0127fcea456..4d5139956dc 100644
--- a/gcc/rtl.texi
+++ b/gcc/rtl.texi
@@ -287,9 +287,9 @@ to access them.
 @section Flags in an RTL Expression
 @cindex flags in RTL expression
 
-RTL expressions contain several flags (one-bit bitfields) that are used
-in certain types of expression.  Most often they are accessed with the
-following macros:
+RTL expressions contain several flags (one-bit bitfields) and other
+values that are used in certain types of expression.  Most often they
+are accessed with the following macros:
 
 @table @code
 @findex MEM_VOLATILE_P
@@ -310,6 +310,15 @@ structure, union or array, or to a component of one.  Zero for
 references to a scalar variable or through a pointer to a scalar.
 Stored in the @code{in_struct} field and printed as @samp{/s}.
 
+@findex MEM_ALIAS_SET
+@item MEM_ALIAS_SET (@var{x})
+In @code{mem} expressions, the alias set to which @var{x} belongs.  If
+zero, @var{x} is not in any alias set, and may alias anything.  If
+nonzero, @var{x} may only alias objects in the same alias set.  This
+value is set (in a language-specific manner) by the front-end.  This
+field is not a bit-field; it is in an integer, found as the second
+argument to the @code{mem}.
+
 @findex REG_LOOP_TEST_P
 @cindex @code{reg} and @samp{/s}
 @cindex @code{in_struct}, in @code{reg}