Messages in this thread | | | Date | Wed, 12 May 2004 14:01:58 -0700 (PDT) | From | Davide Libenzi <> | Subject | Re: MSEC_TO_JIFFIES is messed up... |
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On Wed, 12 May 2004, Ingo Molnar wrote:
> > * Davide Libenzi <davidel@xmailserver.org> wrote: > > > > why is it wrong? > > > > For HZ == 1000 it's fine, even if it'd better to explicitly make it HZ > > dependent and let the compiler to discard them. > > the compiler cannot discard the multiplication and the division from the > following: > > x * 1000 / 1000 > > due to overflows.
$ cat foo.c
int foo(int i) {
return i * 1000 / 1000; }
$ gcc -S -c foo.c $ cat foo.s
.file "foo.c" .text .globl foo .type foo, @function foo: pushl %ebp movl %esp, %ebp movl 8(%ebp), %eax leave ret .size foo, .-foo .section .note.GNU-stack,"",@progbits .ident "GCC: (GNU) 3.3.2 20031022 (Red Hat Linux 3.3.2-1)"
$ gcc -v Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.3.2/specs Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --disable-checking --with-system-zlib --enable-__cxa_atexit --host=i386-redhat-linux Thread model: posix gcc version 3.3.2 20031022 (Red Hat Linux 3.3.2-1)
- Davide
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