From: "H. Peter Anvin" <hpa@zytor.com>
Declaring a function to return a const scalar value is pretty meaningless.
These functions are really trying to say that they don't alter any external
state.
Fix that up by using __attribute__((const)), if the compiler supports that.
include/asm-cris/arch-v10/byteorder.h | 5 +++--
include/asm-i386/byteorder.h | 20 ++++++--------------
include/asm-ia64/byteorder.h | 7 ++++---
include/asm-m68k/byteorder.h | 3 ++-
include/asm-parisc/byteorder.h | 11 ++++++-----
include/asm-ppc/byteorder.h | 5 +++--
include/asm-ppc64/byteorder.h | 7 ++++---
include/asm-s390/byteorder.h | 13 +++++++------
include/asm-sh/byteorder.h | 5 +++--
include/asm-v850/byteorder.h | 5 +++--
include/asm-x86_64/byteorder.h | 5 +++--
include/linux/byteorder/swab.h | 8 +++++---
include/linux/compiler-gcc+.h | 1 +
include/linux/compiler-gcc2.h | 1 +
include/linux/compiler-gcc3.h | 1 +
include/linux/compiler.h | 18 ++++++++++++++++++
16 files changed, 70 insertions(+), 45 deletions(-)
diff -puN include/asm-cris/arch-v10/byteorder.h~const-fixes include/asm-cris/arch-v10/byteorder.h
--- 25/include/asm-cris/arch-v10/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-cris/arch-v10/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -2,20 +2,21 @@
#define _CRIS_ARCH_BYTEORDER_H
#include <asm/types.h>
+#include <linux/compiler.h>
/* we just define these two (as we can do the swap in a single
* asm instruction in CRIS) and the arch-independent files will put
* them together into ntohl etc.
*/
-extern __inline__ __const__ __u32 ___arch__swab32(__u32 x)
+extern __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 x)
{
__asm__ ("swapwb %0" : "=r" (x) : "0" (x));
return(x);
}
-extern __inline__ __const__ __u16 ___arch__swab16(__u16 x)
+extern __inline__ __attribute_const__ __u16 ___arch__swab16(__u16 x)
{
__asm__ ("swapb %0" : "=r" (x) : "0" (x));
diff -puN include/asm-i386/byteorder.h~const-fixes include/asm-i386/byteorder.h
--- 25/include/asm-i386/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-i386/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -2,6 +2,7 @@
#define _I386_BYTEORDER_H
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
@@ -10,7 +11,7 @@
#include <linux/config.h>
#endif
-static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 x)
{
#ifdef CONFIG_X86_BSWAP
__asm__("bswap %0" : "=r" (x) : "0" (x));
@@ -24,18 +25,7 @@ static __inline__ __const__ __u32 ___arc
return x;
}
-/* gcc should generate this for open coded C now too. May be worth switching to
- it because inline assembly cannot be scheduled. -AK */
-static __inline__ __const__ __u16 ___arch__swab16(__u16 x)
-{
- __asm__("xchgb %b0,%h0" /* swap bytes */
- : "=q" (x)
- : "0" (x));
- return x;
-}
-
-
-static inline __u64 ___arch__swab64(__u64 val)
+static __inline__ __attribute_const__ __u64 ___arch__swab64(__u64 val)
{
union {
struct { __u32 a,b; } s;
@@ -54,9 +44,11 @@ static inline __u64 ___arch__swab64(__u6
return v.u;
}
+/* Do not define swab16. Gcc is smart enough to recognize "C" version and
+ convert it into rotation or exhange. */
+
#define __arch__swab64(x) ___arch__swab64(x)
#define __arch__swab32(x) ___arch__swab32(x)
-#define __arch__swab16(x) ___arch__swab16(x)
#define __BYTEORDER_HAS_U64__
diff -puN include/asm-ia64/byteorder.h~const-fixes include/asm-ia64/byteorder.h
--- 25/include/asm-ia64/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-ia64/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -8,8 +8,9 @@
#include <asm/types.h>
#include <asm/intrinsics.h>
+#include <linux/compiler.h>
-static __inline__ __const__ __u64
+static __inline__ __attribute_const__ __u64
__ia64_swab64 (__u64 x)
{
__u64 result;
@@ -18,13 +19,13 @@ __ia64_swab64 (__u64 x)
return result;
}
-static __inline__ __const__ __u32
+static __inline__ __attribute_const__ __u32
__ia64_swab32 (__u32 x)
{
return __ia64_swab64(x) >> 32;
}
-static __inline__ __const__ __u16
+static __inline__ __attribute_const__ __u16
__ia64_swab16(__u16 x)
{
return __ia64_swab64(x) >> 48;
diff -puN include/asm-m68k/byteorder.h~const-fixes include/asm-m68k/byteorder.h
--- 25/include/asm-m68k/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-m68k/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -2,10 +2,11 @@
#define _M68K_BYTEORDER_H
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
-static __inline__ __const__ __u32 ___arch__swab32(__u32 val)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 val)
{
__asm__("rolw #8,%0; swap %0; rolw #8,%0" : "=d" (val) : "0" (val));
return val;
diff -puN include/asm-parisc/byteorder.h~const-fixes include/asm-parisc/byteorder.h
--- 25/include/asm-parisc/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-parisc/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -2,10 +2,11 @@
#define _PARISC_BYTEORDER_H
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
-static __inline__ __const__ __u16 ___arch__swab16(__u16 x)
+static __inline__ __attribute_const__ __u16 ___arch__swab16(__u16 x)
{
__asm__("dep %0, 15, 8, %0\n\t" /* deposit 00ab -> 0bab */
"shd %%r0, %0, 8, %0" /* shift 000000ab -> 00ba */
@@ -14,7 +15,7 @@ static __inline__ __const__ __u16 ___arc
return x;
}
-static __inline__ __const__ __u32 ___arch__swab24(__u32 x)
+static __inline__ __attribute_const__ __u32 ___arch__swab24(__u32 x)
{
__asm__("shd %0, %0, 8, %0\n\t" /* shift xabcxabc -> cxab */
"dep %0, 15, 8, %0\n\t" /* deposit cxab -> cbab */
@@ -24,7 +25,7 @@ static __inline__ __const__ __u32 ___arc
return x;
}
-static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 x)
{
unsigned int temp;
__asm__("shd %0, %0, 16, %1\n\t" /* shift abcdabcd -> cdab */
@@ -47,7 +48,7 @@ static __inline__ __const__ __u32 ___arc
** HSHR 67452301 -> *6*4*2*0 into %0
** OR %0 | %1 -> 76543210 into %0 (all done!)
*/
-static __inline__ __const__ __u64 ___arch__swab64(__u64 x) {
+static __inline__ __attribute_const__ __u64 ___arch__swab64(__u64 x) {
__u64 temp;
__asm__("permh,3210 %0, %0\n\t"
"hshl %0, 8, %1\n\t"
@@ -60,7 +61,7 @@ static __inline__ __const__ __u64 ___arc
#define __arch__swab64(x) ___arch__swab64(x)
#define __BYTEORDER_HAS_U64__
#elif !defined(__STRICT_ANSI__)
-static __inline__ __const__ __u64 ___arch__swab64(__u64 x)
+static __inline__ __attribute_const__ __u64 ___arch__swab64(__u64 x)
{
__u32 t1 = ___arch__swab32((__u32) x);
__u32 t2 = ___arch__swab32((__u32) (x >> 32));
diff -puN include/asm-ppc64/byteorder.h~const-fixes include/asm-ppc64/byteorder.h
--- 25/include/asm-ppc64/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-ppc64/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -9,6 +9,7 @@
*/
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
#ifdef __KERNEL__
@@ -40,7 +41,7 @@ static __inline__ void st_le32(volatile
}
#if 0
-static __inline__ __const__ __u16 ___arch__swab16(__u16 value)
+static __inline__ __attribute_const__ __u16 ___arch__swab16(__u16 value)
{
__u16 result;
@@ -50,7 +51,7 @@ static __inline__ __const__ __u16 ___arc
return result;
}
-static __inline__ __const__ __u32 ___arch__swab32(__u32 value)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 value)
{
__u32 result;
@@ -62,7 +63,7 @@ static __inline__ __const__ __u32 ___arc
return result;
}
-static __inline__ __const__ __u64 ___arch__swab64(__u64 value)
+static __inline__ __attribute_const__ __u64 ___arch__swab64(__u64 value)
{
__u64 result;
#error implement me
diff -puN include/asm-ppc/byteorder.h~const-fixes include/asm-ppc/byteorder.h
--- 25/include/asm-ppc/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-ppc/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -2,6 +2,7 @@
#define _PPC_BYTEORDER_H
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
#ifdef __KERNEL__
@@ -32,7 +33,7 @@ extern __inline__ void st_le32(volatile
__asm__ __volatile__ ("stwbrx %1,0,%2" : "=m" (*addr) : "r" (val), "r" (addr));
}
-static __inline__ __const__ __u16 ___arch__swab16(__u16 value)
+static __inline__ __attribute_const__ __u16 ___arch__swab16(__u16 value)
{
__u16 result;
@@ -40,7 +41,7 @@ static __inline__ __const__ __u16 ___arc
return result;
}
-static __inline__ __const__ __u32 ___arch__swab32(__u32 value)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 value)
{
__u32 result;
diff -puN include/asm-s390/byteorder.h~const-fixes include/asm-s390/byteorder.h
--- 25/include/asm-s390/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-s390/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -10,11 +10,12 @@
*/
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
#ifdef __s390x__
-static __inline__ __const__ __u64 ___arch__swab64p(__u64 *x)
+static __inline__ __attribute_const__ __u64 ___arch__swab64p(__u64 *x)
{
__u64 result;
@@ -24,7 +25,7 @@ static __inline__ __const__ __u64 ___arc
return result;
}
-static __inline__ __const__ __u64 ___arch__swab64(__u64 x)
+static __inline__ __attribute_const__ __u64 ___arch__swab64(__u64 x)
{
__u64 result;
@@ -40,7 +41,7 @@ static __inline__ void ___arch__swab64s(
}
#endif /* __s390x__ */
-static __inline__ __const__ __u32 ___arch__swab32p(__u32 *x)
+static __inline__ __attribute_const__ __u32 ___arch__swab32p(__u32 *x)
{
__u32 result;
@@ -58,7 +59,7 @@ static __inline__ __const__ __u32 ___arc
return result;
}
-static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 x)
{
#ifndef __s390x__
return ___arch__swab32p(&x);
@@ -77,7 +78,7 @@ static __inline__ void ___arch__swab32s(
*x = ___arch__swab32p(x);
}
-static __inline__ __const__ __u16 ___arch__swab16p(__u16 *x)
+static __inline__ __attribute_const__ __u16 ___arch__swab16p(__u16 *x)
{
__u16 result;
@@ -93,7 +94,7 @@ static __inline__ __const__ __u16 ___arc
return result;
}
-static __inline__ __const__ __u16 ___arch__swab16(__u16 x)
+static __inline__ __attribute_const__ __u16 ___arch__swab16(__u16 x)
{
return ___arch__swab16p(&x);
}
diff -puN include/asm-sh/byteorder.h~const-fixes include/asm-sh/byteorder.h
--- 25/include/asm-sh/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-sh/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -6,8 +6,9 @@
*/
#include <asm/types.h>
+#include <linux/compiler.h>
-static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 x)
{
__asm__("swap.b %0, %0\n\t"
"swap.w %0, %0\n\t"
@@ -17,7 +18,7 @@ static __inline__ __const__ __u32 ___arc
return x;
}
-static __inline__ __const__ __u16 ___arch__swab16(__u16 x)
+static __inline__ __attribute_const__ __u16 ___arch__swab16(__u16 x)
{
__asm__("swap.b %0, %0"
: "=r" (x)
diff -puN include/asm-v850/byteorder.h~const-fixes include/asm-v850/byteorder.h
--- 25/include/asm-v850/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-v850/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -15,17 +15,18 @@
#define __V850_BYTEORDER_H__
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
-static __inline__ __const__ __u32 ___arch__swab32 (__u32 word)
+static __inline__ __attribute_const__ __u32 ___arch__swab32 (__u32 word)
{
__u32 res;
__asm__ ("bsw %1, %0" : "=r" (res) : "r" (word));
return res;
}
-static __inline__ __const__ __u16 ___arch__swab16 (__u16 half_word)
+static __inline__ __attribute_const__ __u16 ___arch__swab16 (__u16 half_word)
{
__u16 res;
__asm__ ("bsh %1, %0" : "=r" (res) : "r" (half_word));
diff -puN include/asm-x86_64/byteorder.h~const-fixes include/asm-x86_64/byteorder.h
--- 25/include/asm-x86_64/byteorder.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/asm-x86_64/byteorder.h 2003-12-21 23:45:22.000000000 -0800
@@ -2,16 +2,17 @@
#define _X86_64_BYTEORDER_H
#include <asm/types.h>
+#include <linux/compiler.h>
#ifdef __GNUC__
-static __inline__ __const__ __u64 ___arch__swab64(__u64 x)
+static __inline__ __attribute_const__ __u64 ___arch__swab64(__u64 x)
{
__asm__("bswapq %0" : "=r" (x) : "0" (x));
return x;
}
-static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
+static __inline__ __attribute_const__ __u32 ___arch__swab32(__u32 x)
{
__asm__("bswapl %0" : "=r" (x) : "0" (x));
return x;
diff -puN include/linux/byteorder/swab.h~const-fixes include/linux/byteorder/swab.h
--- 25/include/linux/byteorder/swab.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/linux/byteorder/swab.h 2003-12-21 23:45:22.000000000 -0800
@@ -15,6 +15,8 @@
*
*/
+#include <linux/compiler.h>
+
/* casts are necessary for constants, because we never know how for sure
* how U/UL/ULL map to __u16, __u32, __u64. At least not in a portable way.
*/
@@ -128,7 +130,7 @@
#endif /* OPTIMIZE */
-static __inline__ __const__ __u16 __fswab16(__u16 x)
+static __inline__ __attribute_const__ __u16 __fswab16(__u16 x)
{
return __arch__swab16(x);
}
@@ -141,7 +143,7 @@ static __inline__ void __swab16s(__u16 *
__arch__swab16s(addr);
}
-static __inline__ __const__ __u32 __fswab32(__u32 x)
+static __inline__ __attribute_const__ __u32 __fswab32(__u32 x)
{
return __arch__swab32(x);
}
@@ -155,7 +157,7 @@ static __inline__ void __swab32s(__u32 *
}
#ifdef __BYTEORDER_HAS_U64__
-static __inline__ __const__ __u64 __fswab64(__u64 x)
+static __inline__ __attribute_const__ __u64 __fswab64(__u64 x)
{
# ifdef __SWAB_64_THRU_32__
__u32 h = x >> 32;
diff -puN include/linux/compiler-gcc2.h~const-fixes include/linux/compiler-gcc2.h
--- 25/include/linux/compiler-gcc2.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/linux/compiler-gcc2.h 2003-12-21 23:45:22.000000000 -0800
@@ -20,4 +20,5 @@
*/
#if __GNUC_MINOR__ >= 96
# define __attribute_pure__ __attribute__((pure))
+# define __attribute_const__ __attribute__((__const__))
#endif
diff -puN include/linux/compiler-gcc3.h~const-fixes include/linux/compiler-gcc3.h
--- 25/include/linux/compiler-gcc3.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/linux/compiler-gcc3.h 2003-12-21 23:45:22.000000000 -0800
@@ -20,3 +20,4 @@
#endif
#define __attribute_pure__ __attribute__((pure))
+#define __attribute_const__ __attribute__((__const__))
diff -puN include/linux/compiler-gcc+.h~const-fixes include/linux/compiler-gcc+.h
--- 25/include/linux/compiler-gcc+.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/linux/compiler-gcc+.h 2003-12-21 23:45:22.000000000 -0800
@@ -12,3 +12,4 @@
#define __deprecated __attribute__((deprecated))
#define __attribute_used__ __attribute__((__used__))
#define __attribute_pure__ __attribute__((pure))
+#define __attribute_const__ __attribute__((__const__))
diff -puN include/linux/compiler.h~const-fixes include/linux/compiler.h
--- 25/include/linux/compiler.h~const-fixes 2003-12-21 23:45:22.000000000 -0800
+++ 25-akpm/include/linux/compiler.h 2003-12-21 23:45:22.000000000 -0800
@@ -76,6 +76,24 @@
# define __attribute_pure__ /* unimplemented */
#endif
+/*
+ * From the GCC manual:
+ *
+ * Many functions do not examine any values except their arguments,
+ * and have no effects except the return value. Basically this is
+ * just slightly more strict class than the `pure' attribute above,
+ * since function is not allowed to read global memory.
+ *
+ * Note that a function that has pointer arguments and examines the
+ * data pointed to must _not_ be declared `const'. Likewise, a
+ * function that calls a non-`const' function usually must not be
+ * `const'. It does not make sense for a `const' function to return
+ * `void'.
+ */
+#ifndef __attribute_const__
+# define __attribute_const__ /* unimplemented */
+#endif
+
/* Optimization barrier */
#ifndef barrier
# define barrier() __memory_barrier()
_