[16/20] cast: add support for -Wpointer-to-int-cast

Commit Message

Luc Van Oostenryck June 14, 2018, 7:04 p.m. UTC

It's relatively common to cast a pointer to an unsigned long,
for example to make some bit operations.
It's much less sensical to cast a pointer to an integer smaller
(or bigger) than a pointer is.

So, emit a diagnostic for this, under the control of a new
warning flag: -Wpointer-to-int-cast.

Signed-off-by: Luc Van Oostenryck <[e-mail]>
---
 lib.c                          | 2 ++
 lib.h                          | 1 +
 linearize.c                    | 5 +++++
 validation/cast-kinds-check.c  | 2 +-
 validation/linear/cast-kinds.c | 2 +-
 5 files changed, 10 insertions(+), 2 deletions(-)

Patch

diff --git a/lib.c b/lib.c
index dd7374b53..a6e94ee8a 100644
--- a/lib.c
+++ b/lib.c
@@ -269,6 +269,7 @@  int Woverride_init_all = 0;
 int Woverride_init_whole_range = 0;
 int Wparen_string = 0;
 int Wpointer_arith = 0;
+int Wpointer_to_int_cast = 1;
 int Wptr_subtraction_blows = 0;
 int Wreturn_void = 0;
 int Wshadow = 0;
@@ -694,6 +695,7 @@  static const struct flag warnings[] = {
 	{ "override-init", &Woverride_init },
 	{ "override-init-all", &Woverride_init_all },
 	{ "paren-string", &Wparen_string },
+	{ "pointer-to-int-cast", &Wpointer_to_int_cast },
 	{ "ptr-subtraction-blows", &Wptr_subtraction_blows },
 	{ "return-void", &Wreturn_void },
 	{ "shadow", &Wshadow },
diff --git a/lib.h b/lib.h
index afa02ec18..e5ba0a0e9 100644
--- a/lib.h
+++ b/lib.h
@@ -159,6 +159,7 @@  extern int Woverride_init_all;
 extern int Woverride_init_whole_range;
 extern int Wparen_string;
 extern int Wpointer_arith;
+extern int Wpointer_to_int_cast;
 extern int Wptr_subtraction_blows;
 extern int Wreturn_void;
 extern int Wshadow;
diff --git a/linearize.c b/linearize.c
index 45f8d05ee..6f67c4c2f 100644
--- a/linearize.c
+++ b/linearize.c
@@ -1293,6 +1293,11 @@  static pseudo_t cast_pseudo(struct entrypoint *ep, pseudo_t src, struct symbol *
 		src = cast_pseudo(ep, src, from, size_t_ctype);
 		from = size_t_ctype;
 		break;
+	case OP_PTRTU:
+		if (from->bit_size == to->bit_size)
+			break;
+		if (Wpointer_to_int_cast)
+			warning(to->pos, "non size-preserving pointer to integer cast");
 	default:
 		break;
 	}
diff --git a/validation/cast-kinds-check.c b/validation/cast-kinds-check.c
index 736ab3910..e22b6136f 100644
--- a/validation/cast-kinds-check.c
+++ b/validation/cast-kinds-check.c
@@ -2,7 +2,7 @@ 
 
 /*
  * check-name: cast-kinds check
- * check-command: sparse -m64 -v $file
+ * check-command: sparse -m64 -v -Wno-pointer-to-int-cast $file
  *
  * check-error-start
 linear/cast-kinds.c:5:45: warning: cast drops bits
diff --git a/validation/linear/cast-kinds.c b/validation/linear/cast-kinds.c
index 6683ea931..fb16d335e 100644
--- a/validation/linear/cast-kinds.c
+++ b/validation/linear/cast-kinds.c
@@ -55,7 +55,7 @@  static double double_2_double(double a) { return a; }
 
 /*
  * check-name: cast-kinds
- * check-command: test-linearize -Wno-int-to-pointer-cast -m64 $file
+ * check-command: test-linearize -Wno-int-to-pointer-cast -Wno-pointer-to-int-cast -m64 $file
  *
  * check-output-start
 uint_2_int: