This is the mail archive of the
gcc-help@gcc.gnu.org
mailing list for the GCC project.
[gcc front end] problem with -O* flags
- From: charfi asma <charfiasma at yahoo dot fr>
- To: gcc-help at gcc dot gnu dot org
- Date: Wed, 15 Jun 2011 18:14:55 +0100 (BST)
- Subject: [gcc front end] problem with -O* flags
Hello,
I built a new gcc front end that produce this GIMPLE:
main ()
gimple_bind <
<unnamed-signed:32> D.35;
struct MyClass x;
gimple_call <MyOperation1, NULL, &x>
gimple_assign <integer_cst, D.35, 0, NULL>
gimple_return <D.35>
>
MyOperation1 (struct MyClass * this)
gimple_bind <
gimple_assign <integer_cst, My_Var, 100, NULL>
gimple_assign <integer_cst, this->MyAttribute1, 50, NULL>
gimple_return <NULL>
>
which is equivalent to the C++ code:
class MyClass
{
public: void MyOperation1()
{
int My_Var=10;
My_Var=100;
myAttribute=50;
}
int myAttribute;
};
int main()
{
MyClass x ;
x.MyOperation1();
return 0;
}
when I run my compiler (called guml) : guml test.uml -fdump-tree-gimple-raw
, it generates the gimple above.
however when I run it using -O1, O2, O3 or Os guml test.uml
-fdump-tree-gimple-raw -Os, it generates a seg fault.
I used gdb to debug, and I discover that the error comes from the modifications
of MyAttribute1 gimple_assign <integer_cst, this->MyAttribute1, 50, NULL>
because if I remove the equivalent GENERIC tree, the compilation works fine even
with -Os.
the error comes more precisely when tring to run the ipa optimisations
Analyzing compilation unit
Performing interprocedural optimizations
<*free_lang_data> <visibility> <early_local_cleanups>
Breakpoint 1, execute_ipa_pass_list (pass=0x1168800) at
../../gcc/gcc/passes.c:1928
1928 do_per_function_toporder ((void (*)(void
*))execute_pass_list,
......
1131 for (i = nnodes - 1; i >= 0; i--)
(gdb) n
1133 struct cgraph_node *node = order[i];
(gdb) n
1136 order[i] = NULL;
(gdb) n
1137 node->process = 0;
(gdb) n
1138 if (node->analyzed)
(gdb) n
1140 push_cfun (DECL_STRUCT_FUNCTION (node->decl));
(gdb) n
1141 current_function_decl = node->decl;
(gdb) n
1142 callback (data);
(gdb) n
1141 current_function_decl = node->decl;
(gdb) n
1142 callback (data);
(gdb) n
Program received signal SIGSEGV, Segmentation fault.
fold_convertible_p (type=0x0, arg=0x7f2bf778a1e0) at
../../gcc/gcc/fold-const.c:1830
1830 || TREE_CODE (orig) == ERROR_MARK)
In a normal compilation, the debugger should print:
Performing interprocedural optimizations
<*free_lang_data> <visibility> <early_local_cleanups> <whole-program>
<inline>Assembling functions:
MyOperation1 main
so I think that the error comes from Whole-program optimization.
This is how I set MyOperation1() body
tree __func_param = NULL_TREE;
tree parm_type = build_pointer_type(class_t);
tree parm = build_decl (BUILTINS_LOCATION, PARM_DECL, get_identifier("this"),
parm_type);
TREE_CONSTANT (parm) = true;
TREE_READONLY (parm) = true;
DECL_CHAIN (parm) = __func_param;
__func_param = parm;
DECL_ARGUMENTS(operation)=(__func_param);
// return type preparation
tree __func_result = build_decl(BUILTINS_LOCATION, RESULT_DECL, NULL_TREE,
TREE_TYPE(operation));
DECL_CONTEXT(__func_result) = operation;
DECL_ARTIFICIAL(__func_result) = true;
DECL_IGNORED_P(__func_result) = true;
DECL_RESULT(operation) = __func_result;
// debug tree needed for bind exp
tree __func_art_block = build_block(NULL_TREE, NULL_TREE, NULL_TREE, NULL_TREE);
DECL_INITIAL(operation) = __func_art_block;
//stmt tree for the body
tree func_stmts = alloc_stmt_list ();
//set the body
tree var = build_decl(BUILTINS_LOCATION, VAR_DECL, get_identifier("My_Var"),
integer_type_node);
TREE_STATIC(var) = true;
TREE_PUBLIC(var) = true;
DECL_CONTEXT(var) = operation;
TREE_USED(var) = true;
DECL_INITIAL (var) = build_int_cst(integer_type_node, 10 );
layout_decl(var, false);
rest_of_decl_compilation(var, 1, 0);
append_to_statement_list(var, &func_stmts);
tree val = build_int_cst(integer_type_node, 100);
tree modify_att_tree = build2(MODIFY_EXPR, TREE_TYPE(var), var, val);
append_to_statement_list(modify_att_tree, &func_stmts);
tree t = TREE_TYPE(TREE_TYPE(parm));
tree ref = build1 (INDIRECT_REF, t, parm);
tree __struct_field0 = TYPE_FIELDS(TREE_TYPE(ref));
tree __struct_access_0 = build3(COMPONENT_REF, TREE_TYPE(__struct_field0),
ref, __struct_field0, NULL_TREE);
tree modify_att_tree0 = build2(MODIFY_EXPR, TREE_TYPE(__struct_field0),
__struct_access_0, build_int_cst(integer_type_node, 50));
append_to_statement_list(modify_att_tree0, &func_stmts);
// add the final return statement
tree func_ret_expr = build1(RETURN_EXPR, void_type_node, NULL_TREE);
append_to_statement_list(func_ret_expr, &func_stmts);
// bind and gimplification
DECL_SAVED_TREE(operation) = build3(BIND_EXPR, void_type_node, NULL_TREE,
func_stmts, __func_art_block);
// pass to middle end
gimplify_function_tree(operation);
cgraph_node(operation);
cgraph_finalize_function(operation,false);
did I miss something ?
thank you very much
Asma