[PATCH] dissect: introduce sym_is_local() for reporter

[PATCH] dissect: introduce sym_is_local() for reporter

[Oleg Nesterov]

Can be used to filter out the usage of local variables.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
 dissect.c      |  2 +-
 dissect.h      |  5 +++++
 test-dissect.c | 18 ++++++++++++++----
 3 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/dissect.c b/dissect.c
index d9ca142..823a348 100644
--- a/dissect.c
+++ b/dissect.c
@@ -165,7 +165,7 @@ static inline struct symbol *expr_symbol(struct expression *expr)
 		if (!sym) {
 			sym = alloc_symbol(expr->pos, SYM_BAD);
 			bind_symbol(sym, expr->symbol_name, NS_SYMBOL);
-			sym->ctype.modifiers = MOD_EXTERN;
+			sym->ctype.modifiers = MOD_EXTERN | MOD_TOPLEVEL;
 			sym->kind = expr->op ?: 'v'; /* see EXPR_CALL */
 		}
 	}
diff --git a/dissect.h b/dissect.h
index efe2c0b..178dba5 100644
--- a/dissect.h
+++ b/dissect.h
@@ -27,6 +27,11 @@ struct reporter
 
 extern struct symbol *dissect_ctx;
 
+static inline bool sym_is_local(struct symbol *sym)
+{
+	return sym->kind == 'v' && !(sym->ctype.modifiers & MOD_TOPLEVEL);
+}
+
 extern void dissect(struct symbol_list *, struct reporter *);
 
 #endif
diff --git a/test-dissect.c b/test-dissect.c
index ece2253..c4b454c 100644
--- a/test-dissect.c
+++ b/test-dissect.c
@@ -37,6 +37,16 @@ static void print_usage(struct position *pos, struct symbol *sym, unsigned mode)
 
 }
 
+static char symscope(struct symbol *sym)
+{
+	if (sym_is_local(sym)) {
+		if (!dissect_ctx)
+			warning(sym->pos, "no context");
+		return '.';
+	}
+	return ' ';
+}
+
 static void r_symbol(unsigned mode, struct position *pos, struct symbol *sym)
 {
 	print_usage(pos, sym, mode);
@@ -44,8 +54,8 @@ static void r_symbol(unsigned mode, struct position *pos, struct symbol *sym)
 	if (!sym->ident)
 		sym->ident = built_in_ident("__asm__");
 
-	printf("%c %-32.*s %s\n",
-		sym->kind, sym->ident->len, sym->ident->name,
+	printf("%c %c %-32.*s %s\n",
+		symscope(sym), sym->kind, sym->ident->len, sym->ident->name,
 		show_typename(sym->ctype.base_type));
 
 	switch (sym->kind) {
@@ -80,8 +90,8 @@ static void r_member(unsigned mode, struct position *pos, struct symbol *sym, st
 	/* mem == NULL means entire struct accessed */
 	mi = mem ? mem->ident : built_in_ident("*");
 
-	printf("m %.*s.%-*.*s %s\n",
-		si->len, si->name,
+	printf("%c m %.*s.%-*.*s %s\n",
+		symscope(sym), si->len, si->name,
 		32-1 - si->len, mi->len, mi->name,
 		show_typename(mem ? mem->ctype.base_type : sym));
 
-- 
2.5.0

Re: [PATCH] dissect: introduce sym_is_local() for reporter

[Luc Van Oostenryck]

On Tue, Feb 11, 2020 at 05:01:36PM +0100, Oleg Nesterov wrote:
> Can be used to filter out the usage of local variables.

...
 
> diff --git a/dissect.h b/dissect.h
> index efe2c0b..178dba5 100644
> --- a/dissect.h
> +++ b/dissect.h
> @@ -27,6 +27,11 @@ struct reporter
>  
>  extern struct symbol *dissect_ctx;
>  
> +static inline bool sym_is_local(struct symbol *sym)
> +{
> +	return sym->kind == 'v' && !(sym->ctype.modifiers & MOD_TOPLEVEL);
> +}
> +

Shouldn't MOD_STATIC be added to the test?
It depends on what exactly you want for 'local'.

-- Luc

Re: [PATCH] dissect: introduce sym_is_local() for reporter

[Oleg Nesterov]

On 02/12, Luc Van Oostenryck wrote:
>
> On Tue, Feb 11, 2020 at 05:01:36PM +0100, Oleg Nesterov wrote:
> > Can be used to filter out the usage of local variables.
>
> ...
>
> > diff --git a/dissect.h b/dissect.h
> > index efe2c0b..178dba5 100644
> > --- a/dissect.h
> > +++ b/dissect.h
> > @@ -27,6 +27,11 @@ struct reporter
> >
> >  extern struct symbol *dissect_ctx;
> >
> > +static inline bool sym_is_local(struct symbol *sym)
> > +{
> > +	return sym->kind == 'v' && !(sym->ctype.modifiers & MOD_TOPLEVEL);
> > +}
> > +
>
> Shouldn't MOD_STATIC be added to the test?

perhaps I misread bind_symbol() ... but it seems to me MOD_TOPLEVEL is
enough. bind_symbol() does

	scope = block_scope;
	if (ns == NS_SYMBOL && toplevel(scope)) {
		mod = MOD_ADDRESSABLE | MOD_TOPLEVEL;
		...
		sym->ctype.modifiers |= mod;
	}

toplevel(block_scope) should be true after start_file_scope() sets
"block_scope = file_scope" and until start_function_scope(), right?

> It depends on what exactly you want for 'local'.

Yes, it should only return T if the symbol was defined inside some function.
If we have

	static int I;

in file scope, sym_is_local() should return false and so it does, test-dissect
outputs

	1:12                   def   v I                                int

Thanks for looking!

Oleg.

Re: [PATCH] dissect: introduce sym_is_local() for reporter

[Luc Van Oostenryck]

On Wed, Feb 12, 2020 at 10:06:27AM +0100, Oleg Nesterov wrote:
> On 02/12, Luc Van Oostenryck wrote:
> > It depends on what exactly you want for 'local'.
> 
> Yes, it should only return T if the symbol was defined inside some function.
> If we have
> 
> 	static int I;
> 
> in file scope, sym_is_local() should return false and so it does, test-dissect
> outputs
> 
> 	1:12                   def   v I                                int

OK, then everything is fine.
 
> Thanks for looking!

You're welcome!
This and the other pending ones are now pushed to main.

-- Luc