| Message ID | 202004020103.731F201@keescook (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | gcc-plugins/stackleak: Avoid assignment for unused macro argument | expand |
Hello Kees, On 02.04.2020 11:10, Kees Cook wrote: > With GCC version >= 8, the cgraph_create_edge() macro argument using > "frequency" goes unused. Instead of assigning a temporary variable for > the argument, pass the compute_call_stmt_bb_frequency() call directly > as the macro argument so that it will just not be uncalled when it is > not wanted by the macros. Do you mean "it will just not be called"? Thanks! > Silences the warning: > > scripts/gcc-plugins/stackleak_plugin.c:54:6: warning: variable ‘frequency’ set but not used [-Wunused-but-set-variable] > > Now builds cleanly with gcc-7 and gcc-9. Both boot and pass > STACKLEAK_ERASING LKDTM test. > > Signed-off-by: Kees Cook <keescook@chromium.org> > --- > scripts/gcc-plugins/stackleak_plugin.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c > index dbd37460c573..cc75eeba0be1 100644 > --- a/scripts/gcc-plugins/stackleak_plugin.c > +++ b/scripts/gcc-plugins/stackleak_plugin.c > @@ -51,7 +51,6 @@ static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) > gimple stmt; > gcall *stackleak_track_stack; > cgraph_node_ptr node; > - int frequency; > basic_block bb; > > /* Insert call to void stackleak_track_stack(void) */ > @@ -68,9 +67,9 @@ static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) > bb = gimple_bb(stackleak_track_stack); > node = cgraph_get_create_node(track_function_decl); > gcc_assert(node); > - frequency = compute_call_stmt_bb_frequency(current_function_decl, bb); > cgraph_create_edge(cgraph_get_node(current_function_decl), node, > - stackleak_track_stack, bb->count, frequency); > + stackleak_track_stack, bb->count, > + compute_call_stmt_bb_frequency(current_function_decl, bb)); > } > > static bool is_alloca(gimple stmt) >
On Tue, Apr 07, 2020 at 06:30:18PM +0300, Alexander Popov wrote: > Hello Kees, > > On 02.04.2020 11:10, Kees Cook wrote: > > With GCC version >= 8, the cgraph_create_edge() macro argument using > > "frequency" goes unused. Instead of assigning a temporary variable for > > the argument, pass the compute_call_stmt_bb_frequency() call directly > > as the macro argument so that it will just not be uncalled when it is > > not wanted by the macros. > > Do you mean "it will just not be called"? I really did. ;) Thanks, I'll adjust this. -Kees > > Thanks! > > > Silences the warning: > > > > scripts/gcc-plugins/stackleak_plugin.c:54:6: warning: variable ‘frequency’ set but not used [-Wunused-but-set-variable] > > > > Now builds cleanly with gcc-7 and gcc-9. Both boot and pass > > STACKLEAK_ERASING LKDTM test. > > > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > scripts/gcc-plugins/stackleak_plugin.c | 5 ++--- > > 1 file changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c > > index dbd37460c573..cc75eeba0be1 100644 > > --- a/scripts/gcc-plugins/stackleak_plugin.c > > +++ b/scripts/gcc-plugins/stackleak_plugin.c > > @@ -51,7 +51,6 @@ static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) > > gimple stmt; > > gcall *stackleak_track_stack; > > cgraph_node_ptr node; > > - int frequency; > > basic_block bb; > > > > /* Insert call to void stackleak_track_stack(void) */ > > @@ -68,9 +67,9 @@ static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) > > bb = gimple_bb(stackleak_track_stack); > > node = cgraph_get_create_node(track_function_decl); > > gcc_assert(node); > > - frequency = compute_call_stmt_bb_frequency(current_function_decl, bb); > > cgraph_create_edge(cgraph_get_node(current_function_decl), node, > > - stackleak_track_stack, bb->count, frequency); > > + stackleak_track_stack, bb->count, > > + compute_call_stmt_bb_frequency(current_function_decl, bb)); > > } > > > > static bool is_alloca(gimple stmt) > > >
diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index dbd37460c573..cc75eeba0be1 100644 --- a/scripts/gcc-plugins/stackleak_plugin.c +++ b/scripts/gcc-plugins/stackleak_plugin.c @@ -51,7 +51,6 @@ static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) gimple stmt; gcall *stackleak_track_stack; cgraph_node_ptr node; - int frequency; basic_block bb; /* Insert call to void stackleak_track_stack(void) */ @@ -68,9 +67,9 @@ static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) bb = gimple_bb(stackleak_track_stack); node = cgraph_get_create_node(track_function_decl); gcc_assert(node); - frequency = compute_call_stmt_bb_frequency(current_function_decl, bb); cgraph_create_edge(cgraph_get_node(current_function_decl), node, - stackleak_track_stack, bb->count, frequency); + stackleak_track_stack, bb->count, + compute_call_stmt_bb_frequency(current_function_decl, bb)); } static bool is_alloca(gimple stmt)
With GCC version >= 8, the cgraph_create_edge() macro argument using "frequency" goes unused. Instead of assigning a temporary variable for the argument, pass the compute_call_stmt_bb_frequency() call directly as the macro argument so that it will just not be uncalled when it is not wanted by the macros. Silences the warning: scripts/gcc-plugins/stackleak_plugin.c:54:6: warning: variable ‘frequency’ set but not used [-Wunused-but-set-variable] Now builds cleanly with gcc-7 and gcc-9. Both boot and pass STACKLEAK_ERASING LKDTM test. Signed-off-by: Kees Cook <keescook@chromium.org> --- scripts/gcc-plugins/stackleak_plugin.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)