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authorCarl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>2009-03-06 00:40:25 +0000
committerCarl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>2009-03-06 00:40:25 +0000
commitb88556979b65914d8b0fc85861efeaa9ad9a1d3c (patch)
tree6cff97d21bb2d3648a3103d55cd22b6a4ce1eb6d
parent61a8bd27fb5ff27db98e96b462957994e7cca946 (diff)
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Reduce use of volatile variables
During the conversion of flash chip accesses to helper functions, I spotted assignments to volatile variables which were neither placed inside the mmapped ROM area nor were they counters. Due to the use of accessor functions, volatile usage can be reduced significantly because the accessor functions take care of actually performing the reads/writes correctly. The following semantic patch spotted them (linebreak in python string for readability reasons, please remove before usage): @r exists@ expression b; typedef uint8_t; volatile uint8_t a; position p1; @@ a@p1 = readb(b); @script:python@ p1 << r.p1; a << r.a; b << r.b; @@ print "* file: %s line %s has assignment to unnecessarily volatile variable: %s = readb(%s);" % (p1[0].file, p1[0].line, a, b) Result was: HANDLING: sst28sf040.c * file: sst28sf040.c line 44 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 43 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 42 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 41 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 40 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 39 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 38 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 58 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 57 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 56 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 55 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 54 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 53 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); * file: sst28sf040.c line 52 has assignment to unnecessarily volatile variable: tmp = readb(TODO: Binary); The following semantic patch uses the spatch builtin match printing functionality by prepending a "*" to the line with the pattern: @@ expression b; typedef uint8_t; volatile uint8_t a; @@ * a = readb(b); Result is: HANDLING: sst28sf040.c diff = - tmp = readb(bios + 0x1823); - tmp = readb(bios + 0x1820); - tmp = readb(bios + 0x1822); - tmp = readb(bios + 0x0418); - tmp = readb(bios + 0x041B); - tmp = readb(bios + 0x0419); - tmp = readb(bios + 0x040A); } static __inline__ void unprotect_28sf040(volatile uint8_t *bios) @@ -49,13 +42,6 @@ static __inline__ void unprotect_28sf040 /* ask compiler not to optimize this */ volatile uint8_t tmp; - tmp = readb(bios + 0x1823); - tmp = readb(bios + 0x1820); - tmp = readb(bios + 0x1822); - tmp = readb(bios + 0x0418); - tmp = readb(bios + 0x041B); - tmp = readb(bios + 0x0419); - tmp = readb(bios + 0x041A); } static __inline__ int erase_sector_28sf040(volatile uint8_t *bios, It's arguably a bit easier to read if you get used to the leading "-" for matching lines. This patch was enabled by Coccinelle: http://www.emn.fr/x-info/coccinelle/ Corresponding to flashrom svn r419 and coreboot v2 svn r3973. Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net> Acked-by: Joseph Smith <joe@settoplinux.org>
-rw-r--r--sst28sf040.c6
1 files changed, 2 insertions, 4 deletions
diff --git a/sst28sf040.c b/sst28sf040.c
index ee8ee809..7adfcfda 100644
--- a/sst28sf040.c
+++ b/sst28sf040.c
@@ -32,8 +32,7 @@
static __inline__ void protect_28sf040(volatile uint8_t *bios)
{
- /* ask compiler not to optimize this */
- volatile uint8_t tmp;
+ uint8_t tmp;
tmp = readb(bios + 0x1823);
tmp = readb(bios + 0x1820);
@@ -46,8 +45,7 @@ static __inline__ void protect_28sf040(volatile uint8_t *bios)
static __inline__ void unprotect_28sf040(volatile uint8_t *bios)
{
- /* ask compiler not to optimize this */
- volatile uint8_t tmp;
+ uint8_t tmp;
tmp = readb(bios + 0x1823);
tmp = readb(bios + 0x1820);