* Makefile.in (tree-ssa-alias.o): Depend on tree-ssa-structalias.h

	* tree-cfg.c (CHECK_OP): Only test for is_gimple_val.
	* tree-dfa.c (dump_subvars_for): New.
	(debug_subvars_for): New.
	(dump_variable): Show subvariables if VAR has them.
	* tree-flow-inline.h (get_subvar_at): New.
	(overlap_subvar): Change offset and size to unsigned HOST_WIDE_INT.
	* tree-flow.h (struct ptr_info_def): Remove field pt_malloc.
	Update all users.
	(struct subvar): Change fields offset and size to unsigned
	HOST_WIDE_INT.
	(dump_subvars_for): Declare.
	(debug_subvars_for): Declare.
	(get_subvar_at): Declare.
	(okay_component_ref_for_subvars): Change 2nd and 3rd argument
	to unsigned HOST_WIDE_INT *.
	(overlap_subvar): Likewise.
	* tree-gimple.c (is_gimple_reg): Always return false for
	SFTs and memory tags.
	* tree-pass.h (pass_build_pta, pass_del_pta): Remove.
	Update all callers.
	* tree-ssa-alias.c: Include tree-ssa-structalias.h.
	(compute_may_aliases): Call compute_points_to_sets.
	(collect_points_to_info_for): Remove.
	(compute_points_to_and_addr_escape): Remove.
	(delete_alias_info): Call delete_points_to_sets.
	(compute_flow_sensitive_aliasing): If the call to
	find_what_p_points_to returns false, call set_pt_anything.
	(add_may_alias): Set TREE_ADDRESSABLE when adding a new alias.
	(set_pt_anything): Clear pi->pt_vars.
	(set_pt_malloc): Remove.
	(merge_pointed_to_info): Remove.
	(add_pointed_to_expr): Remove.
	(add_pointed_to_var): Remove.
	(collect_points_to_info_r): Remove.
	(is_escape_site): Make extern.
	(create_sft): New.
	(create_overlap_variables_for): Call it.
	* tree-ssa-copy.c (merge_alias_info): Never merge
	flow-sensitive alias information.
	* tree-ssa-operands.c (get_expr_operands): Adjust variables
	offset and size to be unsigned HOST_WIDE_INT.
	(add_to_addressable_set): Rename from note_addressable.
	Set TREE_ADDRESSABLE as the variables are added to the set.
	Update all users.
	(add_stmt_operand): Do not try to micro-optimize unmodifiable
	operands into VUSEs when adding V_MAY_DEFs for members in an
	alias set.
	* tree-ssa-operands.h (add_to_addressable_set): Declare.
	* tree-ssa-structalias.c: Include tree-ssa-structalias.h last.
	(struct variable_info): Add bitfield is_heap_var.
	(var_anyoffset, anyoffset_tree, anyoffset_id): Declare.
	(new_var_info): Initialize is_heap_var.
	(get_constraint_for): Add HEAP variables to the symbol table.
	Mark them with is_heap_var.
	(update_alias_info): New.  Taken mostly from the old
	compute_points_to_and_addr_escape.
	(handle_ptr_arith): New.
	(find_func_aliases): Call update_alias_info.
	Call handle_ptr_info for tcc_binary expressions.
	Call mark_stmt_modified.
	(create_variable_info_for): If DECL has subvars, do not create
	variables for its subvars.  Always add all the fields.
	(set_uids_in_ptset): If the solution includes ANYOFFSET and
	SFTs, then add all the SFTs of the structure.
	If VI->DECL is an aggregate with subvariables, add the SFT at
	VI->OFFSET.
	(find_what_p_points_to): If VI is an artificial variable,
	translate to bitfields in SSA_NAME_PTR_INFO.
	If the solution is empty, set pi->pt_vars to NULL
	(init_base_vars): Create ANYOFFSET.
	(compute_points_to_sets): Rename from create_alias_vars.
	Make extern.
	(pass_build_pta): Remove.
	(delete_points_to_sets): Rename from delete_alias_vars.
	(pass_del_pta): Remove.
	* tree-ssa-structalias.h (struct alias_info): Move from
	tree-ssa-alias.h.
	(NUM_REFERENCES, NUM_REFERENCES_CLEAR, NUM_REFERENCES_INC,
	NUM_REFERENCES_SET): Likewise.
	(compute_points_to_sets, delete_points_to_sets): Declare.

testsuite/ChangeLog

	* gcc.dg/tree-ssa/pta-fp.c: Use -fdump-tree-alias1.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@101841 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 34 insertions, 23 deletions

diff --git a/gcc/tree-ssa-copy.c b/gcc/tree-ssa-copy.c
index 71119608237..28b19d945e4 100644
--- a/gcc/tree-ssa-copy.c
+++ b/gcc/tree-ssa-copy.c
@@ -188,7 +188,9 @@ merge_alias_info (tree orig, tree new)
 #endif
 
   /* Synchronize the type tags.  If both pointers had a tag and they
-     are different, then something has gone wrong.  */
+     are different, then something has gone wrong.  Type tags can
+     always be merged because they are flow insensitive, all the SSA
+     names of the same base DECL share the same type tag.  */
   if (new_ann->type_mem_tag == NULL_TREE)
     new_ann->type_mem_tag = orig_ann->type_mem_tag;
   else if (orig_ann->type_mem_tag == NULL_TREE)
@@ -196,32 +198,41 @@ merge_alias_info (tree orig, tree new)
   else
     gcc_assert (new_ann->type_mem_tag == orig_ann->type_mem_tag);
 
-  /* Synchronize the name tags.  If NEW did not have a name tag, get
-     it from ORIG.  This happens when NEW is a compiler generated
-     temporary which still hasn't had its points-to information filled
-     in.  */
-  if (SSA_NAME_PTR_INFO (orig))
+  /* Check that flow-sensitive information is compatible.  Notice that
+     we may not merge flow-sensitive information here.  This function
+     is called when propagating equivalences dictated by the IL, like
+     a copy operation P_i = Q_j, and from equivalences dictated by
+     control-flow, like if (P_i == Q_j).
+     
+     In the former case, P_i and Q_j are equivalent in every block
+     dominated by the assignment, so their flow-sensitive information
+     is always the same.  However, in the latter case, the pointers
+     P_i and Q_j are only equivalent in one of the sub-graphs out of
+     the predicate, so their flow-sensitive information is not the
+     same in every block dominated by the predicate.
+
+     Since we cannot distinguish one case from another in this
+     function, we can only make sure that if P_i and Q_j have
+     flow-sensitive information, they should be compatible.  */
+  if (SSA_NAME_PTR_INFO (orig) && SSA_NAME_PTR_INFO (new))
     {
       struct ptr_info_def *orig_ptr_info = SSA_NAME_PTR_INFO (orig);
       struct ptr_info_def *new_ptr_info = SSA_NAME_PTR_INFO (new);
 
-      if (new_ptr_info == NULL)
-	duplicate_ssa_name_ptr_info (new, orig_ptr_info);
-      else if (orig_ptr_info->name_mem_tag
-	       && new_ptr_info->name_mem_tag
-	       && orig_ptr_info->pt_vars
-	       && new_ptr_info->pt_vars)
-	{
-	  /* Note that pointer NEW may actually have a different set
-	     of pointed-to variables.  However, since NEW is being
-	     copy-propagated into ORIG, it must always be true that
-	     the pointed-to set for pointer NEW is the same, or a
-	     subset, of the pointed-to set for pointer ORIG.  If this
-	     isn't the case, we shouldn't have been able to do the
-	     propagation of NEW into ORIG.  */
-	  gcc_assert (bitmap_intersect_p (new_ptr_info->pt_vars,
-		orig_ptr_info->pt_vars));
-	}
+      /* Note that pointer NEW and ORIG may actually have different
+	 pointed-to variables (e.g., PR 18291 represented in
+	 testsuite/gcc.c-torture/compile/pr18291.c).  However, since
+	 NEW is being copy-propagated into ORIG, it must always be
+	 true that the pointed-to set for pointer NEW is the same, or
+	 a subset, of the pointed-to set for pointer ORIG.  If this
+	 isn't the case, we shouldn't have been able to do the
+	 propagation of NEW into ORIG.  */
+      if (orig_ptr_info->name_mem_tag
+	  && new_ptr_info->name_mem_tag
+	  && orig_ptr_info->pt_vars
+	  && new_ptr_info->pt_vars)
+	gcc_assert (bitmap_intersect_p (new_ptr_info->pt_vars,
+					orig_ptr_info->pt_vars));
     }
 }