Gianni Tedesco, le Fri 07 Jan 2011 17:21:59 +0000, a écrit :
> On Fri, 2011-01-07 at 16:58 +0000, Samuel Thibault wrote:
> > Gianni Tedesco, le Fri 07 Jan 2011 16:52:49 +0000, a écrit :
> > > I'm not sure if this is a legit catch by gcc or a false positive due to
> > > extra cleverness in gcc-4.5. Either way it causes the build to barf.
> >
> > It seems a false positive to me. What is the warning message?
>
> lib/math.c:197:22: error: ‘tmp.ul[1]’ may be used uninitialized in this
> function
> lib/math.c:153:11: note: ‘tmp.ul[1]’ was declared here
>
> I figured it was a false positive but looking at it now, maybe not?
Oooh, is this perhaps on a 64bit machine? There is actually a bug: these
should be ints, not longs... Use this instead.
Samuel
Replace long/int/short sizes with proper exact-size types for 64bit
architectures.
Signed-off-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
diff -r a33886146b45 extras/mini-os/lib/math.c
--- a/extras/mini-os/lib/math.c Fri Oct 08 11:41:57 2010 +0100
+++ b/extras/mini-os/lib/math.c Fri Jan 07 20:26:34 2011 +0100
@@ -70,8 +70,8 @@
union uu {
int64_t q; /* as a (signed) quad */
int64_t uq; /* as an unsigned quad */
- long sl[2]; /* as two signed longs */
- unsigned long ul[2]; /* as two unsigned longs */
+ int32_t sl[2]; /* as two signed ints */
+ uint32_t ul[2]; /* as two unsigned ints */
};
/* XXX RN: Yuck hardcoded endianess :) */
#define _QUAD_HIGHWORD 1
@@ -91,17 +91,17 @@
#define CHAR_BIT 8 /* number of bits in a char */
#endif
#define QUAD_BITS (sizeof(int64_t) * CHAR_BIT)
-#define LONG_BITS (sizeof(long) * CHAR_BIT)
-#define HALF_BITS (sizeof(long) * CHAR_BIT / 2)
+#define LONG_BITS (sizeof(int32_t) * CHAR_BIT)
+#define HALF_BITS (sizeof(int32_t) * CHAR_BIT / 2)
/*
- * Extract high and low shortwords from longword, and move low shortword of
- * longword to upper half of long, i.e., produce the upper longword of
- * ((quad_t)(x) << (number_of_bits_in_long/2)). (`x' must actually be u_long.)
+ * Extract high and low shortwords from intword, and move low shortword of
+ * intword to upper half of int32_t, i.e., produce the upper intword of
+ * ((quad_t)(x) << (number_of_bits_in_int/2)). (`x' must actually be
uint32_t.)
*
- * These are used in the multiply code, to split a longword into upper
+ * These are used in the multiply code, to split a intword into upper
* and lower halves, and to reassemble a product as a quad_t, shifted left
- * (sizeof(long)*CHAR_BIT/2).
+ * (sizeof(int32_t)*CHAR_BIT/2).
*/
#define HHALF(x) ((x) >> HALF_BITS)
#define LHALF(x) ((x) & ((1UL << HALF_BITS) - 1))
@@ -114,14 +114,10 @@
#define B (1UL << HALF_BITS) /* digit base */
/* Combine two `digits' to make a single two-digit number. */
-#define COMBINE(a, b) (((u_long)(a) << HALF_BITS) | (b))
+#define COMBINE(a, b) (((uint32_t)(a) << HALF_BITS) | (b))
-/* select a type for digits in base B: use unsigned short if they fit */
-#if ULONG_MAX == 0xffffffff && USHRT_MAX >= 0xffff
-typedef unsigned short digit;
-#else
-typedef u_long digit;
-#endif
+/* select a type for digits in base B: */
+typedef uint16_t digit;
/*
@@ -143,7 +139,7 @@
* __qdivrem(u, v, rem) returns u/v and, optionally, sets *rem to u%v.
*
* We do this in base 2-sup-HALF_BITS, so that all intermediate products
- * fit within u_long. As a consequence, the maximum length dividend and
+ * fit within uint32_t. As a consequence, the maximum length dividend and
* divisor are 4 `digits' in this base (they are shorter if they have
* leading zeros).
*/
@@ -153,7 +149,7 @@
union uu tmp;
digit *u, *v, *q;
register digit v1, v2;
- u_long qhat, rhat, t;
+ uint32_t qhat, rhat, t;
int m, n, d, j, i;
digit uspace[5], vspace[5], qspace[5];
@@ -204,7 +200,7 @@
v[4] = LHALF(tmp.ul[L]);
for (n = 4; v[1] == 0; v++) {
if (--n == 1) {
- u_long rbj; /* r*B+u[j] (not root boy jim) */
+ uint32_t rbj; /* r*B+u[j] (not root boy jim) */
digit q1, q2, q3, q4;
/*
@@ -280,7 +276,7 @@
rhat = uj1;
goto qhat_too_big;
} else {
- u_long nn = COMBINE(uj0, uj1);
+ uint32_t nn = COMBINE(uj0, uj1);
qhat = nn / v1;
rhat = nn % v1;
}
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