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

	* 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.

From-SVN: r20719

1 files changed, 11 insertions, 1 deletions

diff --git a/gcc/expr.c b/gcc/expr.c
index 91134d3..bc19068a 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -415,6 +415,7 @@ protect_from_queue (x, modify)
 	  MEM_IN_STRUCT_P (new) = MEM_IN_STRUCT_P (x);
 	  RTX_UNCHANGING_P (new) = RTX_UNCHANGING_P (x);
 	  MEM_VOLATILE_P (new) = MEM_VOLATILE_P (x);
+	  MEM_ALIAS_SET (new) = MEM_ALIAS_SET (x);
 
 	  if (QUEUED_INSN (y))
 	    {
@@ -3063,7 +3064,11 @@ expand_assignment (to, from, want_value, suggest_reg)
      Don't re-expand if it was expanded already (in COMPONENT_REF case).  */
 
   if (to_rtx == 0)
-    to_rtx = expand_expr (to, NULL_RTX, VOIDmode, EXPAND_MEMORY_USE_WO);
+    {
+      to_rtx = expand_expr (to, NULL_RTX, VOIDmode, EXPAND_MEMORY_USE_WO);
+      if (GET_CODE (to_rtx) == MEM)
+	MEM_ALIAS_SET (to_rtx) = get_alias_set (to);
+    }
 
   /* Don't move directly into a return register.  */
   if (TREE_CODE (to) == RESULT_DECL && GET_CODE (to_rtx) == REG)
@@ -5719,6 +5724,7 @@ expand_expr (exp, target, tmode, modifier)
 		&& AGGREGATE_TYPE_P (TREE_TYPE (exp2))))
 	  MEM_IN_STRUCT_P (temp) = 1;
 	MEM_VOLATILE_P (temp) = TREE_THIS_VOLATILE (exp) | flag_volatile;
+	MEM_ALIAS_SET (temp) = get_alias_set (exp);
 
 	/* It is incorrect to set RTX_UNCHANGING_P from TREE_READONLY
 	   here, because, in C and C++, the fact that a location is accessed
@@ -6094,6 +6100,10 @@ expand_expr (exp, target, tmode, modifier)
 	  op0 = change_address (op0, mode1,
 				plus_constant (XEXP (op0, 0),
 					       (bitpos / BITS_PER_UNIT)));
+
+	if (GET_CODE (op0) == MEM)
+	  MEM_ALIAS_SET (op0) = get_alias_set (exp);
+
 	if (GET_CODE (XEXP (op0, 0)) == REG)
 	  mark_reg_pointer (XEXP (op0, 0), alignment);