Out of curiosity I built HEAD with Intel's icc 8.1 compiler on my Debian
laptop today. The full set of warnings (425k worth) are at:
http://lerdorf.com/icc_warnings.txt
There are some fun ones in there, like these:
/home/rasmus/php-src/Zend/zend_alloc.c(252): warning #186: pointless comparison of unsigned integer with zero
&& offset >= 0) {
^
Zend/zend_execute.h(83): warning #1572: floating-point equality and inequality comparisons are unreliable
result = (op->value.dval ? 1 : 0);
^
/home/rasmus/php-src/sapi/cli/php_cli.c(773): warning #25: quoted string should contain at least one character
case '': /* generate indented source mode*/
^
/home/rasmus/php-src/ext/session/mod_files.c(332): warning #266: function declared implicitly
n = pread(data->fd, *val, sbuf.st_size, 0);
^
/home/rasmus/php-src/ext/session/mod_files.c(368): warning #266: function declared implicitly
n = pwrite(data->fd, val, vallen, 0);
^
The invalid attribute and unsigned vs. signed warnings really clutter
things up making it hard to find the more interesting warnings.
The icc compiled libphp5.so was 9,816,098 bytes vs. 11,804,220 for gcc.
Other things I compiled also consistently showed icc creating much smaller
binaries. But that appears to just be due to a lot more symbol info. If
I strip both I get:
gcc libphp5.so 2,590,412
icc libphp5.so 2,793,780
Performance-wise it seems the icc binary is slower, but that is only from
a very unscientific benchmark and I wonder if loading an icc php binary
into a gcc Apache binary might not slow things down a bit. I haven't
looked into the gcc compatibility libraries icc ships with to understand
that well enough. But on first glance icc appears to generate a larger
and slower libphp5.so.
-Rasmus
Hello,
my experiences with performance and icc are, it is only faster
if you use the highest optimization flags and the exact target processor
flags. If you have a amd based notebook you are not in business
with icc.
-meno
I have done some playing around with Intel compiler.
It usually tends to be faster 10-20% but it depends on the flags you use,
inlining of the program (Intel compiler seems to optimize inlines much better).
Andi
At 10:34 PM 9/18/2004 -0700, Rasmus Lerdorf wrote:
Out of curiosity I built HEAD with Intel's icc 8.1 compiler on my Debian
laptop today. The full set of warnings (425k worth) are at:http://lerdorf.com/icc_warnings.txt
There are some fun ones in there, like these:
/home/rasmus/php-src/Zend/zend_alloc.c(252): warning #186: pointless
comparison of unsigned integer with zero
&& offset >= 0) {
^Zend/zend_execute.h(83): warning #1572: floating-point equality and
inequality comparisons are unreliable
result = (op->value.dval ? 1 : 0);
^/home/rasmus/php-src/sapi/cli/php_cli.c(773): warning #25: quoted string
should contain at least one character
case '': /* generate indented source mode*/
^/home/rasmus/php-src/ext/session/mod_files.c(332): warning #266: function
declared implicitly
n = pread(data->fd, *val, sbuf.st_size, 0);
^/home/rasmus/php-src/ext/session/mod_files.c(368): warning #266: function
declared implicitly
n = pwrite(data->fd, val, vallen, 0);
^The invalid attribute and unsigned vs. signed warnings really clutter
things up making it hard to find the more interesting warnings.The icc compiled libphp5.so was 9,816,098 bytes vs. 11,804,220 for gcc.
Other things I compiled also consistently showed icc creating much smaller
binaries. But that appears to just be due to a lot more symbol info. If
I strip both I get:gcc libphp5.so 2,590,412
icc libphp5.so 2,793,780Performance-wise it seems the icc binary is slower, but that is only from
a very unscientific benchmark and I wonder if loading an icc php binary
into a gcc Apache binary might not slow things down a bit. I haven't
looked into the gcc compatibility libraries icc ships with to understand
that well enough. But on first glance icc appears to generate a larger
and slower libphp5.so.-Rasmus