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 =
--- sst28sf040.c        2009-03-06 01:04:49.000000000 +0100
@@ -35,13 +35,6 @@ static __inline__ void protect_28sf040(v
        /* 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 + 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/

Signed-off-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
Acked-by: Joseph Smith <joe@settoplinux.org>
--
http://www.hailfinger.org/

git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3973 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1

diff --git a/util/flashrom/sst28sf040.c b/util/flashrom/sst28sf040.c
index ee8ee809907ee10888b205deead4d0b0f778811b..7adfcfda46d4b4818dc0e1ff7394bae7de1bf449 100644 (file)
--- a/util/flashrom/sst28sf040.c
+++ b/util/flashrom/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);