On Sun, Oct 13, 2019 at 11:56:35AM -0400, Richard Henderson wrote: >On 10/12/19 10:11 PM, Wei Yang wrote: >> Use ROUND_UP() to define, which is a little bit easy to read. >> >> Signed-off-by: Wei Yang <richardw.y...@linux.intel.com> >> --- >> include/exec/cpu-all.h | 7 +++---- >> 1 file changed, 3 insertions(+), 4 deletions(-) >> >> diff --git a/include/exec/cpu-all.h b/include/exec/cpu-all.h >> index ad9ab85eb3..255bb186ac 100644 >> --- a/include/exec/cpu-all.h >> +++ b/include/exec/cpu-all.h >> @@ -220,7 +220,7 @@ extern int target_page_bits; >> >> #define TARGET_PAGE_SIZE (1 << TARGET_PAGE_BITS) >> #define TARGET_PAGE_MASK ~(TARGET_PAGE_SIZE - 1) >> -#define TARGET_PAGE_ALIGN(addr) (((addr) + TARGET_PAGE_SIZE - 1) & >> TARGET_PAGE_MASK) >> +#define TARGET_PAGE_ALIGN(addr) ROUND_UP((addr), TARGET_PAGE_SIZE) >> >> /* Using intptr_t ensures that qemu_*_page_mask is sign-extended even >> * when intptr_t is 32-bit and we are aligning a long long. >> @@ -228,9 +228,8 @@ extern int target_page_bits; >> extern uintptr_t qemu_host_page_size; >> extern intptr_t qemu_host_page_mask; >> >> -#define HOST_PAGE_ALIGN(addr) (((addr) + qemu_host_page_size - 1) & >> qemu_host_page_mask) >> -#define REAL_HOST_PAGE_ALIGN(addr) (((addr) + qemu_real_host_page_size - 1) >> & \ >> - qemu_real_host_page_mask) >> +#define HOST_PAGE_ALIGN(addr) ROUND_UP((addr), qemu_host_page_size) >> +#define REAL_HOST_PAGE_ALIGN(addr) ROUND_UP((addr), >> qemu_real_host_page_size) > > >No, please. > >(1) The compiler does not know that qemu_*host_page_size is a power of 2, and >will generate a real division at runtime. The same is true for >TARGET_PAGE_SIZE when TARGET_PAGE_BITS_VARY. >
Confused The definition of ROUND_UP is: #define ROUND_UP(n, d) (((n) + (d) - 1) & -(0 ? (n) : (d))) Why it will do division? This will be expanded to the same form as the original code, if my understanding is correct. Would you mind telling me more? >(2) The first hunk conflicts with an in-flight patch of mine: > >https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg04526.html > > >r~ -- Wei Yang Help you, Help me
