Hello,this lets alias analysis handle the implicit 'this' parameter in C++ constructors as if it was restrict.
Bootstrap+regtest on powerpc64le-unknown-linux-gnu. 2018-05-18 Marc Glisse <marc.gli...@inria.fr> PR c++/82899 gcc/ * tree-ssa-structalias.c (create_variable_info_for_1): Extra argument. (intra_create_variable_infos): Handle C++ constructors. gcc/testsuite/ * g++.dg/pr82899.C: New testcase. -- Marc Glisse
Index: gcc/testsuite/g++.dg/pr82899.C =================================================================== --- gcc/testsuite/g++.dg/pr82899.C (nonexistent) +++ gcc/testsuite/g++.dg/pr82899.C (working copy) @@ -0,0 +1,14 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fdump-tree-optimized" } */ + +struct A { + int i; + A(A&); +}; +int X; +A::A(A&a):i(42){ + a.i=0; + X=i; +} + +/* { dg-final { scan-tree-dump "X = 42;" "optimized" } } */ Index: gcc/tree-ssa-structalias.c =================================================================== --- gcc/tree-ssa-structalias.c (revision 260347) +++ gcc/tree-ssa-structalias.c (working copy) @@ -5928,25 +5928,28 @@ check_for_overlaps (vec<fieldoff_s> fiel return true; lastoffset = fo->offset; } return false; } /* Create a varinfo structure for NAME and DECL, and add it to VARMAP. This will also create any varinfo structures necessary for fields of DECL. DECL is a function parameter if HANDLE_PARAM is set. HANDLED_STRUCT_TYPE is used to register struct types reached by following - restrict pointers. This is needed to prevent infinite recursion. */ + restrict pointers. This is needed to prevent infinite recursion. + If ADD_RESTRICT, pretend that the pointer NAME is restrict even if DECL + does not advertise it. */ static varinfo_t create_variable_info_for_1 (tree decl, const char *name, bool add_id, - bool handle_param, bitmap handled_struct_type) + bool handle_param, bitmap handled_struct_type, + bool add_restrict = false) { varinfo_t vi, newvi; tree decl_type = TREE_TYPE (decl); tree declsize = DECL_P (decl) ? DECL_SIZE (decl) : TYPE_SIZE (decl_type); auto_vec<fieldoff_s> fieldstack; fieldoff_s *fo; unsigned int i; if (!declsize || !tree_fits_uhwi_p (declsize)) @@ -6006,21 +6009,21 @@ create_variable_info_for_1 (tree decl, c if (fieldstack.length () == 0 || fieldstack.length () > MAX_FIELDS_FOR_FIELD_SENSITIVE) { vi = new_var_info (decl, name, add_id); vi->offset = 0; vi->may_have_pointers = true; vi->fullsize = tree_to_uhwi (declsize); vi->size = vi->fullsize; vi->is_full_var = true; if (POINTER_TYPE_P (decl_type) - && TYPE_RESTRICT (decl_type)) + && (TYPE_RESTRICT (decl_type) || add_restrict)) vi->only_restrict_pointers = 1; if (vi->only_restrict_pointers && !type_contains_placeholder_p (TREE_TYPE (decl_type)) && handle_param && !bitmap_bit_p (handled_struct_type, TYPE_UID (TREE_TYPE (decl_type)))) { varinfo_t rvi; tree heapvar = build_fake_var_decl (TREE_TYPE (decl_type)); DECL_EXTERNAL (heapvar) = 1; @@ -6235,35 +6238,38 @@ make_param_constraints (varinfo_t vi) } /* Create varinfo structures for all of the variables in the function for intraprocedural mode. */ static void intra_create_variable_infos (struct function *fn) { tree t; bitmap handled_struct_type = NULL; + bool this_parm_in_ctor = DECL_CXX_CONSTRUCTOR_P (fn->decl); /* For each incoming pointer argument arg, create the constraint ARG = NONLOCAL or a dummy variable if it is a restrict qualified passed-by-reference argument. */ for (t = DECL_ARGUMENTS (fn->decl); t; t = DECL_CHAIN (t)) { if (handled_struct_type == NULL) handled_struct_type = BITMAP_ALLOC (NULL); varinfo_t p = create_variable_info_for_1 (t, alias_get_name (t), false, true, - handled_struct_type); + handled_struct_type, this_parm_in_ctor); insert_vi_for_tree (t, p); make_param_constraints (p); + + this_parm_in_ctor = false; } if (handled_struct_type != NULL) BITMAP_FREE (handled_struct_type); /* Add a constraint for a result decl that is passed by reference. */ if (DECL_RESULT (fn->decl) && DECL_BY_REFERENCE (DECL_RESULT (fn->decl))) { varinfo_t p, result_vi = get_vi_for_tree (DECL_RESULT (fn->decl));