As per the KernelJanitors ToDo list, change the following:
char *foo = "bar"; => char foo[] = "bar";
Signed-off-by: John Daiker <[email protected]>
---
fs/ntfs/attrib.c | 2 +-
fs/ntfs/inode.c | 6 ++--
fs/ntfs/mft.c | 4 +-
fs/ntfs/super.c | 60 +++++++++++++++++++++++++++---------------------------
4 files changed, 36 insertions(+), 36 deletions(-)
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 50d3b0c..a8aaa48 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -866,7 +866,7 @@ static int ntfs_external_attr_find(const ATTR_TYPE type,
ntfschar *al_name;
u32 al_name_len;
int err = 0;
- static const char *es = " Unmount and run chkdsk.";
+ static const char es[] = " Unmount and run chkdsk.";
ni = ctx->ntfs_ino;
base_ni = ctx->base_ntfs_ino;
diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index 9938034..e22aa8c 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -1867,7 +1867,7 @@ int ntfs_read_inode_mount(struct inode *vi)
} else /* if (!err) */ {
ATTR_LIST_ENTRY *al_entry, *next_al_entry;
u8 *al_end;
- static const char *es = " Not allowed. $MFT is corrupt. "
+ static const char es[] = " Not allowed. $MFT is corrupt. "
"You should run chkdsk.";
ntfs_debug("Attribute list attribute found in $MFT.");
@@ -2328,7 +2328,7 @@ int ntfs_show_options(struct seq_file *sf, struct vfsmount *mnt)
#ifdef NTFS_RW
-static const char *es = " Leaving inconsistent metadata. Unmount and run "
+static const char es[] = " Leaving inconsistent metadata. Unmount and run "
"chkdsk.";
/**
@@ -2364,7 +2364,7 @@ int ntfs_truncate(struct inode *vi)
ntfs_attr_search_ctx *ctx;
MFT_RECORD *m;
ATTR_RECORD *a;
- const char *te = " Leaving file length out of sync with i_size.";
+ const char te[] = " Leaving file length out of sync with i_size.";
int err, mp_size, size_change, alloc_change;
u32 attr_len;
diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
index 1caa0ef..261a107 100644
--- a/fs/ntfs/mft.c
+++ b/fs/ntfs/mft.c
@@ -408,7 +408,7 @@ void __mark_mft_record_dirty(ntfs_inode *ni)
__mark_inode_dirty(VFS_I(base_ni), I_DIRTY_SYNC | I_DIRTY_DATASYNC);
}
-static const char *ntfs_please_email = "Please email "
+static const char ntfs_please_email[] = "Please email "
"[email protected] and say that you saw "
"this message. Thank you.";
@@ -1105,7 +1105,7 @@ bool ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no,
return true;
}
-static const char *es = " Leaving inconsistent metadata. Unmount and run "
+static const char es[] = " Leaving inconsistent metadata. Unmount and run "
"chkdsk.";
/**
diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
index 80b0477..e6dcd71 100644
--- a/fs/ntfs/super.c
+++ b/fs/ntfs/super.c
@@ -461,7 +461,7 @@ static int ntfs_remount(struct super_block *sb, int *flags, char *opt)
* have occured.
*/
if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
- static const char *es = ". Cannot remount read-write.";
+ static const char es[] = ". Cannot remount read-write.";
/* Remounting read-write. */
if (NVolErrors(vol)) {
@@ -659,7 +659,7 @@ not_ntfs:
static struct buffer_head *read_ntfs_boot_sector(struct super_block *sb,
const int silent)
{
- const char *read_err_str = "Unable to read %s boot sector.";
+ const char read_err_str[] = "Unable to read %s boot sector.";
struct buffer_head *bh_primary, *bh_backup;
sector_t nr_blocks = NTFS_SB(sb)->nr_blocks;
@@ -1768,9 +1768,9 @@ static bool load_system_files(ntfs_volume *vol)
#ifdef NTFS_RW
/* Get mft mirror inode compare the contents of $MFT and $MFTMirr. */
if (!load_and_init_mft_mirror(vol) || !check_mft_mirror(vol)) {
- static const char *es1 = "Failed to load $MFTMirr";
- static const char *es2 = "$MFTMirr does not match $MFT";
- static const char *es3 = ". Run ntfsfix and/or chkdsk.";
+ static const char es1[] = "Failed to load $MFTMirr";
+ static const char es2[] = "$MFTMirr does not match $MFT";
+ static const char es3[] = ". Run ntfsfix and/or chkdsk.";
/* If a read-write mount, convert it to a read-only mount. */
if (!(sb->s_flags & MS_RDONLY)) {
@@ -1892,11 +1892,11 @@ get_ctx_vol_failed:
#ifdef NTFS_RW
/* Make sure that no unsupported volume flags are set. */
if (vol->vol_flags & VOLUME_MUST_MOUNT_RO_MASK) {
- static const char *es1a = "Volume is dirty";
- static const char *es1b = "Volume has been modified by chkdsk";
- static const char *es1c = "Volume has unsupported flags set";
- static const char *es2a = ". Run chkdsk and mount in Windows.";
- static const char *es2b = ". Mount in Windows.";
+ static const char es1a[] = "Volume is dirty";
+ static const char es1b[] = "Volume has been modified by chkdsk";
+ static const char es1c[] = "Volume has unsupported flags set";
+ static const char es2a[] = ". Run chkdsk and mount in Windows.";
+ static const char es2b[] = ". Mount in Windows.";
const char *es1, *es2;
es2 = es2a;
@@ -1938,9 +1938,9 @@ get_ctx_vol_failed:
rp = NULL;
if (!load_and_check_logfile(vol, &rp) ||
!ntfs_is_logfile_clean(vol->logfile_ino, rp)) {
- static const char *es1a = "Failed to load $LogFile";
- static const char *es1b = "$LogFile is not clean";
- static const char *es2 = ". Mount in Windows.";
+ static const char es1a[] = "Failed to load $LogFile";
+ static const char es1b[] = "$LogFile is not clean";
+ static const char es2[] = ". Mount in Windows.";
const char *es1;
es1 = !vol->logfile_ino ? es1a : es1b;
@@ -1986,10 +1986,10 @@ get_ctx_vol_failed:
*/
err = check_windows_hibernation_status(vol);
if (unlikely(err)) {
- static const char *es1a = "Failed to determine if Windows is "
+ static const char es1a[] = "Failed to determine if Windows is "
"hibernated";
- static const char *es1b = "Windows is hibernated";
- static const char *es2 = ". Run chkdsk.";
+ static const char es1b[] = "Windows is hibernated";
+ static const char es2[] = ". Run chkdsk.";
const char *es1;
es1 = err < 0 ? es1a : es1b;
@@ -2014,9 +2014,9 @@ get_ctx_vol_failed:
/* If (still) a read-write mount, mark the volume dirty. */
if (!(sb->s_flags & MS_RDONLY) &&
ntfs_set_volume_flags(vol, VOLUME_IS_DIRTY)) {
- static const char *es1 = "Failed to set dirty bit in volume "
+ static const char es1[] = "Failed to set dirty bit in volume "
"information flags";
- static const char *es2 = ". Run chkdsk.";
+ static const char es2[] = ". Run chkdsk.";
/* Convert to a read-only mount. */
if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
@@ -2042,8 +2042,8 @@ get_ctx_vol_failed:
*/
if (!(sb->s_flags & MS_RDONLY) && (vol->major_ver > 1) &&
ntfs_set_volume_flags(vol, VOLUME_MOUNTED_ON_NT4)) {
- static const char *es1 = "Failed to set NT4 compatibility flag";
- static const char *es2 = ". Run chkdsk.";
+ static const char es1[] = "Failed to set NT4 compatibility flag";
+ static const char es2[] = ". Run chkdsk.";
/* Convert to a read-only mount. */
if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
@@ -2061,8 +2061,8 @@ get_ctx_vol_failed:
/* If (still) a read-write mount, empty the logfile. */
if (!(sb->s_flags & MS_RDONLY) &&
!ntfs_empty_logfile(vol->logfile_ino)) {
- static const char *es1 = "Failed to empty $LogFile";
- static const char *es2 = ". Mount in Windows.";
+ static const char es1[] = "Failed to empty $LogFile";
+ static const char es2[] = ". Mount in Windows.";
/* Convert to a read-only mount. */
if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
@@ -2101,8 +2101,8 @@ get_ctx_vol_failed:
#ifdef NTFS_RW
/* Find the quota file, load it if present, and set it up. */
if (!load_and_init_quota(vol)) {
- static const char *es1 = "Failed to load $Quota";
- static const char *es2 = ". Run chkdsk.";
+ static const char es1[] = "Failed to load $Quota";
+ static const char es2[] = ". Run chkdsk.";
/* If a read-write mount, convert it to a read-only mount. */
if (!(sb->s_flags & MS_RDONLY)) {
@@ -2125,8 +2125,8 @@ get_ctx_vol_failed:
/* If (still) a read-write mount, mark the quotas out of date. */
if (!(sb->s_flags & MS_RDONLY) &&
!ntfs_mark_quotas_out_of_date(vol)) {
- static const char *es1 = "Failed to mark quotas out of date";
- static const char *es2 = ". Run chkdsk.";
+ static const char es1[] = "Failed to mark quotas out of date";
+ static const char es2[] = ". Run chkdsk.";
/* Convert to a read-only mount. */
if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
@@ -2145,8 +2145,8 @@ get_ctx_vol_failed:
* it, and set it up.
*/
if (!load_and_init_usnjrnl(vol)) {
- static const char *es1 = "Failed to load $UsnJrnl";
- static const char *es2 = ". Run chkdsk.";
+ static const char es1[] = "Failed to load $UsnJrnl";
+ static const char es2[] = ". Run chkdsk.";
/* If a read-write mount, convert it to a read-only mount. */
if (!(sb->s_flags & MS_RDONLY)) {
@@ -2168,9 +2168,9 @@ get_ctx_vol_failed:
}
/* If (still) a read-write mount, stamp the transaction log. */
if (!(sb->s_flags & MS_RDONLY) && !ntfs_stamp_usnjrnl(vol)) {
- static const char *es1 = "Failed to stamp transaction log "
+ static const char es1[] = "Failed to stamp transaction log "
"($UsnJrnl)";
- static const char *es2 = ". Run chkdsk.";
+ static const char es2[] = ". Run chkdsk.";
/* Convert to a read-only mount. */
if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
--
1.6.3.3
Hi,
On 3 Dec 2009, at 02:53, John Daiker wrote:
> As per the KernelJanitors ToDo list, change the following:
> char *foo = "bar"; => char foo[] = "bar";
Can you please explain the rational for making this change? Visually it uses an extra character so I prefer the *string notation rather than the string[] notation. If there is some actual functional difference then I would like to know what the difference is.
If it is explained in the ToDo list you mention, feel free to post a link to that instead of explaining.
Thanks a lot in advance!
Best regards,
Anton
> Signed-off-by: John Daiker <[email protected]>
> ---
> fs/ntfs/attrib.c | 2 +-
> fs/ntfs/inode.c | 6 ++--
> fs/ntfs/mft.c | 4 +-
> fs/ntfs/super.c | 60 +++++++++++++++++++++++++++---------------------------
> 4 files changed, 36 insertions(+), 36 deletions(-)
>
> diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
> index 50d3b0c..a8aaa48 100644
> --- a/fs/ntfs/attrib.c
> +++ b/fs/ntfs/attrib.c
> @@ -866,7 +866,7 @@ static int ntfs_external_attr_find(const ATTR_TYPE type,
> ntfschar *al_name;
> u32 al_name_len;
> int err = 0;
> - static const char *es = " Unmount and run chkdsk.";
> + static const char es[] = " Unmount and run chkdsk.";
>
> ni = ctx->ntfs_ino;
> base_ni = ctx->base_ntfs_ino;
> diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
> index 9938034..e22aa8c 100644
> --- a/fs/ntfs/inode.c
> +++ b/fs/ntfs/inode.c
> @@ -1867,7 +1867,7 @@ int ntfs_read_inode_mount(struct inode *vi)
> } else /* if (!err) */ {
> ATTR_LIST_ENTRY *al_entry, *next_al_entry;
> u8 *al_end;
> - static const char *es = " Not allowed. $MFT is corrupt. "
> + static const char es[] = " Not allowed. $MFT is corrupt. "
> "You should run chkdsk.";
>
> ntfs_debug("Attribute list attribute found in $MFT.");
> @@ -2328,7 +2328,7 @@ int ntfs_show_options(struct seq_file *sf, struct vfsmount *mnt)
>
> #ifdef NTFS_RW
>
> -static const char *es = " Leaving inconsistent metadata. Unmount and run "
> +static const char es[] = " Leaving inconsistent metadata. Unmount and run "
> "chkdsk.";
>
> /**
> @@ -2364,7 +2364,7 @@ int ntfs_truncate(struct inode *vi)
> ntfs_attr_search_ctx *ctx;
> MFT_RECORD *m;
> ATTR_RECORD *a;
> - const char *te = " Leaving file length out of sync with i_size.";
> + const char te[] = " Leaving file length out of sync with i_size.";
> int err, mp_size, size_change, alloc_change;
> u32 attr_len;
>
> diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
> index 1caa0ef..261a107 100644
> --- a/fs/ntfs/mft.c
> +++ b/fs/ntfs/mft.c
> @@ -408,7 +408,7 @@ void __mark_mft_record_dirty(ntfs_inode *ni)
> __mark_inode_dirty(VFS_I(base_ni), I_DIRTY_SYNC | I_DIRTY_DATASYNC);
> }
>
> -static const char *ntfs_please_email = "Please email "
> +static const char ntfs_please_email[] = "Please email "
> "[email protected] and say that you saw "
> "this message. Thank you.";
>
> @@ -1105,7 +1105,7 @@ bool ntfs_may_write_mft_record(ntfs_volume *vol, const unsigned long mft_no,
> return true;
> }
>
> -static const char *es = " Leaving inconsistent metadata. Unmount and run "
> +static const char es[] = " Leaving inconsistent metadata. Unmount and run "
> "chkdsk.";
>
> /**
> diff --git a/fs/ntfs/super.c b/fs/ntfs/super.c
> index 80b0477..e6dcd71 100644
> --- a/fs/ntfs/super.c
> +++ b/fs/ntfs/super.c
> @@ -461,7 +461,7 @@ static int ntfs_remount(struct super_block *sb, int *flags, char *opt)
> * have occured.
> */
> if ((sb->s_flags & MS_RDONLY) && !(*flags & MS_RDONLY)) {
> - static const char *es = ". Cannot remount read-write.";
> + static const char es[] = ". Cannot remount read-write.";
>
> /* Remounting read-write. */
> if (NVolErrors(vol)) {
> @@ -659,7 +659,7 @@ not_ntfs:
> static struct buffer_head *read_ntfs_boot_sector(struct super_block *sb,
> const int silent)
> {
> - const char *read_err_str = "Unable to read %s boot sector.";
> + const char read_err_str[] = "Unable to read %s boot sector.";
> struct buffer_head *bh_primary, *bh_backup;
> sector_t nr_blocks = NTFS_SB(sb)->nr_blocks;
>
> @@ -1768,9 +1768,9 @@ static bool load_system_files(ntfs_volume *vol)
> #ifdef NTFS_RW
> /* Get mft mirror inode compare the contents of $MFT and $MFTMirr. */
> if (!load_and_init_mft_mirror(vol) || !check_mft_mirror(vol)) {
> - static const char *es1 = "Failed to load $MFTMirr";
> - static const char *es2 = "$MFTMirr does not match $MFT";
> - static const char *es3 = ". Run ntfsfix and/or chkdsk.";
> + static const char es1[] = "Failed to load $MFTMirr";
> + static const char es2[] = "$MFTMirr does not match $MFT";
> + static const char es3[] = ". Run ntfsfix and/or chkdsk.";
>
> /* If a read-write mount, convert it to a read-only mount. */
> if (!(sb->s_flags & MS_RDONLY)) {
> @@ -1892,11 +1892,11 @@ get_ctx_vol_failed:
> #ifdef NTFS_RW
> /* Make sure that no unsupported volume flags are set. */
> if (vol->vol_flags & VOLUME_MUST_MOUNT_RO_MASK) {
> - static const char *es1a = "Volume is dirty";
> - static const char *es1b = "Volume has been modified by chkdsk";
> - static const char *es1c = "Volume has unsupported flags set";
> - static const char *es2a = ". Run chkdsk and mount in Windows.";
> - static const char *es2b = ". Mount in Windows.";
> + static const char es1a[] = "Volume is dirty";
> + static const char es1b[] = "Volume has been modified by chkdsk";
> + static const char es1c[] = "Volume has unsupported flags set";
> + static const char es2a[] = ". Run chkdsk and mount in Windows.";
> + static const char es2b[] = ". Mount in Windows.";
> const char *es1, *es2;
>
> es2 = es2a;
> @@ -1938,9 +1938,9 @@ get_ctx_vol_failed:
> rp = NULL;
> if (!load_and_check_logfile(vol, &rp) ||
> !ntfs_is_logfile_clean(vol->logfile_ino, rp)) {
> - static const char *es1a = "Failed to load $LogFile";
> - static const char *es1b = "$LogFile is not clean";
> - static const char *es2 = ". Mount in Windows.";
> + static const char es1a[] = "Failed to load $LogFile";
> + static const char es1b[] = "$LogFile is not clean";
> + static const char es2[] = ". Mount in Windows.";
> const char *es1;
>
> es1 = !vol->logfile_ino ? es1a : es1b;
> @@ -1986,10 +1986,10 @@ get_ctx_vol_failed:
> */
> err = check_windows_hibernation_status(vol);
> if (unlikely(err)) {
> - static const char *es1a = "Failed to determine if Windows is "
> + static const char es1a[] = "Failed to determine if Windows is "
> "hibernated";
> - static const char *es1b = "Windows is hibernated";
> - static const char *es2 = ". Run chkdsk.";
> + static const char es1b[] = "Windows is hibernated";
> + static const char es2[] = ". Run chkdsk.";
> const char *es1;
>
> es1 = err < 0 ? es1a : es1b;
> @@ -2014,9 +2014,9 @@ get_ctx_vol_failed:
> /* If (still) a read-write mount, mark the volume dirty. */
> if (!(sb->s_flags & MS_RDONLY) &&
> ntfs_set_volume_flags(vol, VOLUME_IS_DIRTY)) {
> - static const char *es1 = "Failed to set dirty bit in volume "
> + static const char es1[] = "Failed to set dirty bit in volume "
> "information flags";
> - static const char *es2 = ". Run chkdsk.";
> + static const char es2[] = ". Run chkdsk.";
>
> /* Convert to a read-only mount. */
> if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
> @@ -2042,8 +2042,8 @@ get_ctx_vol_failed:
> */
> if (!(sb->s_flags & MS_RDONLY) && (vol->major_ver > 1) &&
> ntfs_set_volume_flags(vol, VOLUME_MOUNTED_ON_NT4)) {
> - static const char *es1 = "Failed to set NT4 compatibility flag";
> - static const char *es2 = ". Run chkdsk.";
> + static const char es1[] = "Failed to set NT4 compatibility flag";
> + static const char es2[] = ". Run chkdsk.";
>
> /* Convert to a read-only mount. */
> if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
> @@ -2061,8 +2061,8 @@ get_ctx_vol_failed:
> /* If (still) a read-write mount, empty the logfile. */
> if (!(sb->s_flags & MS_RDONLY) &&
> !ntfs_empty_logfile(vol->logfile_ino)) {
> - static const char *es1 = "Failed to empty $LogFile";
> - static const char *es2 = ". Mount in Windows.";
> + static const char es1[] = "Failed to empty $LogFile";
> + static const char es2[] = ". Mount in Windows.";
>
> /* Convert to a read-only mount. */
> if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
> @@ -2101,8 +2101,8 @@ get_ctx_vol_failed:
> #ifdef NTFS_RW
> /* Find the quota file, load it if present, and set it up. */
> if (!load_and_init_quota(vol)) {
> - static const char *es1 = "Failed to load $Quota";
> - static const char *es2 = ". Run chkdsk.";
> + static const char es1[] = "Failed to load $Quota";
> + static const char es2[] = ". Run chkdsk.";
>
> /* If a read-write mount, convert it to a read-only mount. */
> if (!(sb->s_flags & MS_RDONLY)) {
> @@ -2125,8 +2125,8 @@ get_ctx_vol_failed:
> /* If (still) a read-write mount, mark the quotas out of date. */
> if (!(sb->s_flags & MS_RDONLY) &&
> !ntfs_mark_quotas_out_of_date(vol)) {
> - static const char *es1 = "Failed to mark quotas out of date";
> - static const char *es2 = ". Run chkdsk.";
> + static const char es1[] = "Failed to mark quotas out of date";
> + static const char es2[] = ". Run chkdsk.";
>
> /* Convert to a read-only mount. */
> if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
> @@ -2145,8 +2145,8 @@ get_ctx_vol_failed:
> * it, and set it up.
> */
> if (!load_and_init_usnjrnl(vol)) {
> - static const char *es1 = "Failed to load $UsnJrnl";
> - static const char *es2 = ". Run chkdsk.";
> + static const char es1[] = "Failed to load $UsnJrnl";
> + static const char es2[] = ". Run chkdsk.";
>
> /* If a read-write mount, convert it to a read-only mount. */
> if (!(sb->s_flags & MS_RDONLY)) {
> @@ -2168,9 +2168,9 @@ get_ctx_vol_failed:
> }
> /* If (still) a read-write mount, stamp the transaction log. */
> if (!(sb->s_flags & MS_RDONLY) && !ntfs_stamp_usnjrnl(vol)) {
> - static const char *es1 = "Failed to stamp transaction log "
> + static const char es1[] = "Failed to stamp transaction log "
> "($UsnJrnl)";
> - static const char *es2 = ". Run chkdsk.";
> + static const char es2[] = ". Run chkdsk.";
>
> /* Convert to a read-only mount. */
> if (!(vol->on_errors & (ON_ERRORS_REMOUNT_RO |
--
Anton Altaparmakov <aia21 at cam.ac.uk> (replace at with @)
Unix Support, Computing Service, University of Cambridge, CB2 3QH, UK
Linux NTFS maintainer, http://www.linux-ntfs.org/
On Tue, 2009-12-08 at 00:57 +0000, Anton Altaparmakov wrote:
> Can you please explain the rational for making this change?
Perhaps it's not worth much, but it saves a pointer reference.
$ cat pointer.c
#include <string.h>
#include <stdio.h>
int main (int argc, char** argv)
{
static const char *foo = "abcdefg";
printf("%s\n", foo);
return 0;
}
$ gcc -c pointer.c
$ size pointer.o
text data bss dec hex filename
37 4 0 41 29 pointer.o
$ cat reference.c
#include <string.h>
#include <stdio.h>
int main (int argc, char** argv)
{
static const char foo[] = "abcdefg";
printf("%s\n", foo);
return 0;
}
$ gcc -c reference.c
$ size reference.o
text data bss dec hex filename
36 0 0 36 24 reference.o
On 12/07/2009 05:47 PM, Joe Perches wrote:
> On Tue, 2009-12-08 at 00:57 +0000, Anton Altaparmakov wrote:
>> Can you please explain the rational for making this change?
>
> Perhaps it's not worth much, but it saves a pointer reference.
>
> $ cat pointer.c
> #include<string.h>
> #include<stdio.h>
>
> int main (int argc, char** argv)
> {
> static const char *foo = "abcdefg";
> printf("%s\n", foo);
> return 0;
> }
>
> $ gcc -c pointer.c
> $ size pointer.o
> text data bss dec hex filename
> 37 4 0 41 29 pointer.o
>
> $ cat reference.c
> #include<string.h>
> #include<stdio.h>
>
> int main (int argc, char** argv)
> {
> static const char foo[] = "abcdefg";
> printf("%s\n", foo);
> return 0;
> }
>
> $ gcc -c reference.c
> $ size reference.o
> text data bss dec hex filename
> 36 0 0 36 24 reference.o
>
>
>
As Joe mentioned above (thanks Joe!) it saves a pointer reference.
It is also listed as a KernelJanitors ToDo item (about 2/3 of the way
down the page). Searching for 'From: Jeff Garzik' should find it.
John
[1] http://kernelnewbies.org/KernelJanitors/Todo
On Mon, Dec 07, 2009 at 05:47:13PM -0800, Joe Perches wrote:
> On Tue, 2009-12-08 at 00:57 +0000, Anton Altaparmakov wrote:
> > Can you please explain the rational for making this change?
>
> Perhaps it's not worth much, but it saves a pointer reference.
>
> $ cat pointer.c
> #include <string.h>
> #include <stdio.h>
>
> int main (int argc, char** argv)
> {
> static const char *foo = "abcdefg";
> printf("%s\n", foo);
> return 0;
> }
>
> $ gcc -c pointer.c
> $ size pointer.o
> text data bss dec hex filename
> 37 4 0 41 29 pointer.o
>
> $ cat reference.c
> #include <string.h>
> #include <stdio.h>
>
> int main (int argc, char** argv)
> {
> static const char foo[] = "abcdefg";
> printf("%s\n", foo);
> return 0;
> }
>
> $ gcc -c reference.c
> $ size reference.o
> text data bss dec hex filename
> 36 0 0 36 24 reference.o
Yeah, for static variables it's better. But for automatic variables
it's worse, because it now has to do a copy at runtime.
And the patch changes both types.
$ size pointer.o reference.o
text data bss dec hex filename
101 8 0 109 6d pointer.o
96 0 0 96 60 reference.o
$ size pointer-nonstatic.o reference-nonstatic.o
text data bss dec hex filename
106 0 0 106 6a pointer-nonstatic.o
109 0 0 109 6d reference-nonstatic.o
Marcin Slusarz schrieb:
> On Mon, Dec 07, 2009 at 05:47:13PM -0800, Joe Perches wrote:
>> On Tue, 2009-12-08 at 00:57 +0000, Anton Altaparmakov wrote:
>>> Can you please explain the rational for making this change?
>> Perhaps it's not worth much, but it saves a pointer reference.
>>
>> $ cat pointer.c
>> #include <string.h>
>> #include <stdio.h>
>>
>> int main (int argc, char** argv)
>> {
>> static const char *foo = "abcdefg";
>> printf("%s\n", foo);
>> return 0;
>> }
>>
>> $ gcc -c pointer.c
>> $ size pointer.o
>> text data bss dec hex filename
>> 37 4 0 41 29 pointer.o
>>
>> $ cat reference.c
>> #include <string.h>
>> #include <stdio.h>
>>
>> int main (int argc, char** argv)
>> {
>> static const char foo[] = "abcdefg";
>> printf("%s\n", foo);
>> return 0;
>> }
>>
>> $ gcc -c reference.c
>> $ size reference.o
>> text data bss dec hex filename
>> 36 0 0 36 24 reference.o
>
> Yeah, for static variables it's better. But for automatic variables
> it's worse, because it now has to do a copy at runtime.
> And the patch changes both types.
>
> $ size pointer.o reference.o
> text data bss dec hex filename
> 101 8 0 109 6d pointer.o
> 96 0 0 96 60 reference.o
>
> $ size pointer-nonstatic.o reference-nonstatic.o
> text data bss dec hex filename
> 106 0 0 106 6a pointer-nonstatic.o
> 109 0 0 109 6d reference-nonstatic.o
> --
nobody should spend to much time on this. gcc <what ever next version>
will have different results. It is better to spend time improving
the compiler and make it generate shorter/faster code.
just my 2 cents,
wh