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Re: How to insert external global variable declarations and pointer assignment statements through GCC plugin GIMPLE pass
"Abhijit Nandy" <abhijit.nandy@gmail.com> writes:
> So I guess DECL_EXTERNAL(var_decl) = 1 causes the var_decl to be set
> as an external declaration in the following code :
Yes. DECL_EXTERNAL corresponds to the "extern" storage class specifier
in C/C++.
> I have another question. Right now I create the following declaration
> char *p;
>
> using :
> tree temp = create_tmp_var(TREE_TYPE(TREE_TYPE(elfset_decl)), "p");
>
> where elfset_decl is set to be char* in a separate function.
That creates a temporary variable.
> However is there another way to create a pointer to char, especially
> if I want the exact identifier 'p' instead of
> char * p.1;
>
> which the gimple pass dump is showing me.
>
> I tried to do it as follows :
> tree var_decl1 = build_decl(UNKNOWN_LOCATION, VAR_DECL,
> get_identifier("p"), char_type_node);
> TREE_STATIC(var_decl1) = 0;
> DECL_EXTERNAL(var_decl1) = 0;
> rest_of_decl_compilation (var_decl1, 1, 0);
>
> But nothing appears in the gimple pass dump. I think this may be due
> to not actually inserting the declaration in the tree using a gimple
> function.
For a local variable you don't need to call rest_of_decl_compilation.
If you want a local variable which is not a temporary variable, then you
need to build a BLOCK and a BIND_EXPR which define the variable in some
scope. The BIND_EXPR will point to the block, and the BIND_EXPR then
needs to be added into the function code somehow so that the rest of the
compiler sees it.
Ian