From: Nicolai Stange <nicstange@gmail.com>
To: linux-sparse@vger.kernel.org
Cc: Nicolai Stange <nicstange@gmail.com>,
Christopher Li <sparse@chrisli.org>,
Josh Triplett <josh@joshtriplett.org>,
Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: [PATCH v2 07/13] evaluate: check static storage duration objects' intializers' constness
Date: Mon, 25 Jan 2016 15:57:45 +0100 [thread overview]
Message-ID: <87zivtemfq.fsf@gmail.com> (raw)
In-Reply-To: <87twm1g1go.fsf@gmail.com> (Nicolai Stange's message of "Mon, 25 Jan 2016 15:47:51 +0100")
Initializers of static storage duration objects shall be constant
expressions [6.7.8(4)].
Warn if that requirement is not met and the -Wstatic-initializer-not-const
flag has been given on sparse's command line.
Identify static storage duration objects by having either of
MOD_TOPLEVEL or MOD_STATIC set.
Check an initializer's constness at the lowest possible subobject
level, i.e. at the level of the "assignment-expression" production
in [6.7.8].
For compound objects, make handle_list_initializer() pass the
surrounding object's storage duration modifiers down to
handle_simple_initializer() at subobject initializer evaluation.
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
---
evaluate.c | 26 ++++++++++-
lib.c | 2 +
lib.h | 2 +-
sparse.1 | 7 +++
validation/constexpr-init.c | 110 ++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 145 insertions(+), 2 deletions(-)
create mode 100644 validation/constexpr-init.c
diff --git a/evaluate.c b/evaluate.c
index 70f419f..e3b08e4 100644
--- a/evaluate.c
+++ b/evaluate.c
@@ -2468,6 +2468,7 @@ static void handle_list_initializer(struct expression *expr,
{
struct expression *e, *last = NULL, *top = NULL, *next;
int jumped = 0;
+ unsigned long old_modifiers;
FOR_EACH_PTR(expr->expr_list, e) {
struct expression **v;
@@ -2522,8 +2523,21 @@ found:
else
v = &top->ident_expression;
- if (handle_simple_initializer(v, 1, lclass, top->ctype))
+ /*
+ * Temporarily copy storage modifiers down from
+ * surrounding type such that
+ * handle_simple_initializer() can check
+ * initializations of subobjects with static storage
+ * duration.
+ */
+ old_modifiers = top->ctype->ctype.modifiers;
+ top->ctype->ctype.modifiers =
+ old_modifiers | (ctype->ctype.modifiers & MOD_STORAGE);
+ if (handle_simple_initializer(v, 1, lclass, top->ctype)) {
+ top->ctype->ctype.modifiers = old_modifiers;
continue;
+ }
+ top->ctype->ctype.modifiers = old_modifiers;
if (!(lclass & TYPE_COMPOUND)) {
warning(e->pos, "bogus scalar initializer");
@@ -2633,6 +2647,16 @@ static int handle_simple_initializer(struct expression **ep, int nested,
if (!evaluate_expression(e))
return 1;
compatible_assignment_types(e, ctype, ep, "initializer");
+ /*
+ * Initializers for static storage duration objects
+ * shall be constant expressions or a string literal [6.7.8(4)].
+ */
+ if ((ctype->ctype.modifiers & (MOD_TOPLEVEL | MOD_STATIC)) &&
+ !(e->flags & (EXPR_FLAG_ARITH_CONST_EXPR
+ | EXPR_FLAG_ADDR_CONST_EXPR)) &&
+ Wstatic_initializer_not_const)
+ warning(e->pos, "initializer for static storage duration object is not a constant expression");
+
return 1;
}
diff --git a/lib.c b/lib.c
index 8dc5bcf..855fb3e 100644
--- a/lib.c
+++ b/lib.c
@@ -241,6 +241,7 @@ int Wtypesign = 0;
int Wundef = 0;
int Wuninitialized = 1;
int Wvla = 1;
+int Wstatic_initializer_not_const = 0;
int dbg_entry = 0;
int dbg_dead = 0;
@@ -464,6 +465,7 @@ static const struct warning {
{ "undef", &Wundef },
{ "uninitialized", &Wuninitialized },
{ "vla", &Wvla },
+ { "static-initializer-not-const", &Wstatic_initializer_not_const},
};
enum {
diff --git a/lib.h b/lib.h
index 15b69fa..1b38db2 100644
--- a/lib.h
+++ b/lib.h
@@ -127,7 +127,7 @@ extern int Wtypesign;
extern int Wundef;
extern int Wuninitialized;
extern int Wvla;
-
+extern int Wstatic_initializer_not_const;
extern int dbg_entry;
extern int dbg_dead;
diff --git a/sparse.1 b/sparse.1
index 4adaf6c..0df27f9 100644
--- a/sparse.1
+++ b/sparse.1
@@ -308,6 +308,13 @@ C99 does not specify the sizeof a _Bool. gcc uses 1.
Sparse does not issue these warnings by default.
.
.TP
+.B \-Wstatic-initializer-not-const
+Warn when initializing an object of static storage duration with an initializer
+which is not a constant expression.
+
+Sparse does not issue these warnings by default.
+.
+.TP
.B \-Wtransparent\-union
Warn about any declaration using the GCC extension
\fB__attribute__((transparent_union))\fR.
diff --git a/validation/constexpr-init.c b/validation/constexpr-init.c
new file mode 100644
index 0000000..b357de1
--- /dev/null
+++ b/validation/constexpr-init.c
@@ -0,0 +1,110 @@
+static int a = 1; // OK
+static int b[2] = {1, 1}; // OK
+static void c(void) {}
+
+static int *d = &a; // OK
+static int *e = &b[1]; // OK
+static int *f = b; // OK
+static void (*g)(void) = c; // OK
+static void (*h)(void) = &c; // OK
+static int *i = (int*)0; // OK
+static int *j = d; // KO
+static int *k = (int*)0 + 1; // OK
+
+static int *l = &a + 1; // OK
+static int *m = &b[1] + 1; // OK
+static int *n = b + 1; // OK
+static int *o = d + 1; // KO
+
+static int *p = &*&a; // OK
+static int *q = &*&b[1]; // OK
+static int *r = &*b; // OK
+static int *s = &*d; // KO
+
+static int *t = &*(&a + 1); // OK
+static int *u = &*(&b[1] + 1); // OK
+static int *v = &*(b + 1); // OK
+static int *w = &*(d + 1); // KO
+
+
+struct A {
+ int a;
+ int b[2];
+};
+
+struct B {
+ int c;
+ struct A d;
+};
+
+static struct B x= {1, {1, {1, 1}}}; // OK
+static struct B y= {a, {1, {1, 1}}}; // KO
+static struct B z= {1, {a, {1, 1}}}; // KO
+static struct B aa= {1, {1, {a, 1}}}; // KO
+static struct B ab= {1, {1, {1, a}}}; // KO
+static struct B ac= {.c = 1, .d = {.a = 1, .b = {1, 1}}}; // OK
+static struct B ad= {.c = a, .d = {.a = 1, .b = {1, 1}}}; // KO
+static struct B ae= {.c = 1, .d = {.a = a, .b = {1, 1}}}; // KO
+static struct B af= {.c = 1, .d = {.a = 1, .b = {a, 1}}}; // KO
+static struct B ag= {.c = 1, .d = {.a = 1, .b = {1, a}}}; // KO
+
+static int *ah = &x.d.a; // OK
+static int *ai = &(&x.d)->a; // OK
+static int *aj = x.d.b; // OK
+static int *ak = (&x.d)->b; // OK
+static int *al = &x.d.b[1]; // OK
+static int *am = &(&x.d)->b[1]; // OK
+
+static int an[] = {a, 1}; // KO
+static int ao[] = {1, a}; // KO
+static int ap[] = {[0] = a, [1] = 1}; // KO
+static int aq[] = {[0] = 1, [1] = a}; // KO
+
+static char *ar = "foobar"; // OK
+
+static void as(void) {
+ int a = 0;
+ int b = a; // OK
+}
+
+static void at(void) {
+ int a = 1;
+ static int b = a; // KO
+}
+
+static void au(void) {
+ int a = 1;
+ static int *b = &a; // KO
+}
+
+static void av(void) {
+ static int a = 1;
+ static int *b = &a; // OK
+}
+
+
+/*
+ * check-name: Static storage object initializer constness verification.
+ * check-command: sparse -Wstatic-initializer-not-const $file
+ *
+ * check-error-start
+constexpr-init.c:11:17: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:17:19: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:22:19: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:27:22: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:41:21: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:42:25: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:43:30: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:44:33: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:46:27: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:47:41: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:48:50: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:49:53: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:58:20: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:59:23: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:60:26: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:61:35: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:72:24: warning: initializer for static storage duration object is not a constant expression
+constexpr-init.c:77:26: warning: initializer for static storage duration object is not a constant expression
+ * check-error-end
+ */
--
2.7.0
next prev parent reply other threads:[~2016-01-25 14:57 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 14:47 [PATCH v2 00/13] improve constexpr handling Nicolai Stange
2016-01-25 14:49 ` [PATCH v2 01/13] expression: introduce additional expression constness tracking flags Nicolai Stange
2016-01-25 21:51 ` Luc Van Oostenryck
2016-01-26 15:26 ` Nicolai Stange
2016-01-26 15:37 ` Nicolai Stange
2016-01-25 14:51 ` [PATCH v2 02/13] expression: examine constness of casts at evaluation only Nicolai Stange
2016-01-25 22:02 ` Luc Van Oostenryck
2016-01-26 16:11 ` Nicolai Stange
2016-01-25 14:52 ` [PATCH v2 03/13] expression: examine constness of binops and alike " Nicolai Stange
2016-01-26 0:14 ` Luc Van Oostenryck
2016-01-26 15:50 ` Nicolai Stange
2016-01-26 17:24 ` Luc Van Oostenryck
2016-01-27 10:42 ` Nicolai Stange
2016-01-27 18:00 ` Luc Van Oostenryck
2016-01-26 0:59 ` Luc Van Oostenryck
2016-01-25 14:53 ` [PATCH v2 04/13] expression: examine constness of preops " Nicolai Stange
2016-01-26 1:10 ` Luc Van Oostenryck
2016-01-25 14:55 ` [PATCH v2 05/13] expression: examine constness of conditionals " Nicolai Stange
2016-01-26 1:16 ` Luc Van Oostenryck
2016-01-25 14:56 ` [PATCH v2 06/13] expression, evaluate: add support for recognizing address constants Nicolai Stange
2016-01-26 1:27 ` Luc Van Oostenryck
2016-01-26 3:10 ` Luc Van Oostenryck
2016-01-25 14:57 ` Nicolai Stange [this message]
2016-01-26 1:42 ` [PATCH v2 07/13] evaluate: check static storage duration objects' intializers' constness Luc Van Oostenryck
2016-01-26 16:08 ` Nicolai Stange
2016-01-26 17:56 ` Luc Van Oostenryck
2016-01-26 20:18 ` Luc Van Oostenryck
2016-02-01 3:00 ` Nicolai Stange
2016-01-25 14:59 ` [PATCH v2 08/13] expression: recognize references to labels as address constants Nicolai Stange
2016-01-26 1:45 ` Luc Van Oostenryck
2016-01-25 15:00 ` [PATCH v2 09/13] expression: examine constness of __builtin_offsetof at evaluation only Nicolai Stange
2016-01-26 1:57 ` Luc Van Oostenryck
2016-02-01 3:06 ` Nicolai Stange
2016-01-25 15:02 ` [PATCH v2 10/13] symbol: flag builtins constant_p, safe_p and warning as constexprs Nicolai Stange
2016-01-26 2:00 ` Luc Van Oostenryck
2016-01-25 15:03 ` [PATCH v2 11/13] evaluate: relax some constant expression rules for pointer expressions Nicolai Stange
2016-01-26 2:05 ` Luc Van Oostenryck
2016-01-25 15:04 ` [PATCH v2 12/13] expression, evaluate: support compound literals as address constants Nicolai Stange
2016-01-26 2:07 ` Luc Van Oostenryck
2016-01-25 15:05 ` [PATCH v2 13/13] symbol: do not inherit storage modifiers from base types at examination Nicolai Stange
2016-01-26 2:54 ` Luc Van Oostenryck
2016-01-25 21:01 ` [PATCH v2 00/13] improve constexpr handling Luc Van Oostenryck
2016-01-25 21:26 ` Nicolai Stange
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