Hi Andreas,
On 07/04/11 18:22, Andreas Schwab wrote:
Greg Ungerer<gerg@xxxxxxxxxxxx> writes:
That does seem odd. One way or another strcpy is defined in
arch/m68k/include/asm/string.h. I would expect no real calls to
strcpy() after that. (And for me on my hand built gcc-4.5.1 I
don't end up with any).
Did you compile with -Os?
No, -O2. Here is a typical gcc line:
m68k-linux-gcc -Wp,-MD,kernel/.printk.o.d -nostdinc -isystem
/usr/local/lib/gcc/m68k-linux/4.5.1/include
-I/home/gerg/new-wave.merge/linux-2.6.x/arch/m68k/include -Iinclude
-include include/generated/autoconf.h -D__KERNEL__ -Wall -Wundef
-Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common
-Werror-implicit-function-declaration -Wno-format-security
-fno-delete-null-pointer-checks -O2 -pipe -fno-strength-reduce
-ffixed-a2 -Wframe-larger-than=1024 -fno-stack-protector
-fomit-frame-pointer -Wdeclaration-after-statement -Wno-pointer-sign
-fno-strict-overflow -fconserve-stack -DCC_HAVE_ASM_GOTO
-D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(printk)"
-D"KBUILD_MODNAME=KBUILD_STR(printk)" -c -o kernel/printk.o kernel/printk.c
This is vanilla 2.6.39-rc2...
At a guess the section for __GNUC__> 4 must end up still trying
to use a real strcpy (presumably the __builtom_strcpy call) on
some versions of gcc.
#if __GNUC__>= 4
#define strcpy(d, s) (__builtin_constant_p(s)&& \
__builtin_strlen(s)<= 32 ? \
__builtin_strcpy(d, s) : \
__kernel_strcpy(d, s))
#else
#define strcpy(d, s) __kernel_strcpy(d, s)
#endif
Is there any reason we don't just drop the __GNUC__>= 4 bit
and always just use __kernel_strcpy()? After all kernel_strcpy
is a pretty tight optimized loop for m68k anyway.
The compiler can generate libcalls to strcpy any time while optimizing
any other standard C function, and those libcalls won't see the macros,
of course. The only way to stop the compiler from doing that is to
disable all builtin functions (just -fno-builtin-strcpy is not enough),
but that would disable a lot of useful opimisations.
Yes, ok. It is just that I hadn't seen gcc emit calls to strcpy
on my m68knommu builds (at least not in recent years since we
removed the local strcpy).
Regards
Greg
------------------------------------------------------------------------
Greg Ungerer -- Principal Engineer EMAIL: gerg@xxxxxxxxxxxx
SnapGear Group, McAfee PHONE: +61 7 3435 2888
8 Gardner Close FAX: +61 7 3217 5323
Milton, QLD, 4064, Australia WEB: http://www.SnapGear.com
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