Re: [Fwd: performance with gcc -O0/-O2]

Richard Guenther wrote: On Nov 27, 2007 2:23 PM, Howard Chu [EMAIL PROTECTED] wrote: A bit of a minor mystery. Not a problem, just a curiosity. If someone knew off the top of their head a reason for it, that'd be cool, but otherwise no sweat. I'd try -Os, you might run into ICache limitations

Re: [Fwd: performance with gcc -O0/-O2]

was doing interrupt processing. Anyway, thanks again for all your responses. -- -- Howard Chu Chief Architect, Symas Corp. http://www.symas.com Director, Highland Sunhttp://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/

Re: Does gcc support compiling for windows x86-64?

Dave Korn wrote: On 23 November 2007 23:32, Howard Chu wrote: And it looks like current bash on cygwin doesn't handle case/esac constructs correctly, so e.g. the configure script for BerkeleyDB 4.6.21 fails there. Could you possibly send a testcase to the cygwin mailing list? We haven't

Re: Re: Does gcc support compiling for windows x86-64?

immediately on Win64.) And it looks like current bash on cygwin doesn't handle case/esac constructs correctly, so e.g. the configure script for BerkeleyDB 4.6.21 fails there. Gotta hand it to Microsoft, they've sure made it hard to support their platform... -- -- Howard Chu Chief Architect

Re: strict aliasing question

Dave Korn wrote: On 12 November 2006 04:16, Howard Chu wrote: Dave Korn wrote: f = (struct foo *)(void *)buf; That's good, but why is it safe? Passing through void* means gcc has to assume it could alias anything, IIUIC, as a result of the standard

Threading the compiler

? -- -- Howard Chu Chief Architect, Symas Corp. http://www.symas.com Director, Highland Sunhttp://highlandsun.com/hyc OpenLDAP Core Teamhttp://www.openldap.org/project/

re: comments on getting the most out of multi-core machines

timesaver when you just need to fix one file in a very large program. -- -- Howard Chu Chief Architect, Symas Corp. http://www.symas.com Director, Highland Sunhttp://highlandsun.com/hyc OpenLDAP Core Teamhttp://www.openldap.org/project/

Re: strict aliasing question

Ian Lance Taylor wrote: Howard Chu [EMAIL PROTECTED] writes: Daniel Berlin wrote: We ask the TBAA analyzer can a store to a short * touch i. In this case, it says no, because it's not legal. If you know the code is not legal, why don't you abort the compilation with an error

Re: strict aliasing question

Mike Stump wrote: On Nov 10, 2006, at 9:48 AM, Howard Chu wrote: Richard Guenther wrote: If you compile with -O3 -combine *.c -o alias it will break. Thanks for pointing that out. But that's not a realistic danger for the actual application. The accessor function is always going

Re: strict aliasing question

that memory, aliasing doesn't matter -- -- Howard Chu Chief Architect, Symas Corp. http://www.symas.com Director, Highland Sunhttp://highlandsun.com/hyc OpenLDAP Core Teamhttp://www.openldap.org/project/

strict aliasing question

The program prints the expected result with both strict-aliasing and no-strict-aliasing on my x86_64 box. As such, when/why would I need to worry about this warning? -- -- Howard Chu Chief Architect, Symas Corp. http://www.symas.com Director, Highland Sunhttp://highlandsun.com/hyc

Re: strict aliasing question

Richard Guenther wrote: On 11/10/06, Howard Chu [EMAIL PROTECTED] wrote: The program prints the expected result with both strict-aliasing and no-strict-aliasing on my x86_64 box. As such, when/why would I need to worry about this warning? If you compile with -O3 -combine *.c -o alias

Re: strict aliasing question

Mike Stump wrote: On Nov 10, 2006, at 9:48 AM, Howard Chu wrote: Richard Guenther wrote: If you compile with -O3 -combine *.c -o alias it will break. Thanks for pointing that out. But that's not a realistic danger for the actual application. The accessor function is always going

Re: strict aliasing question

Richard Guenther wrote: On 11/10/06, Howard Chu [EMAIL PROTECTED] wrote: I see a lot of APIs (e.g. Cyrus SASL) that have accessor functions returning values through a void ** argument. As far as I can tell, this doesn't actually cause any problems, but gcc 4.1 with -Wstrict-aliasing

Re: strict aliasing question

Joe Buck wrote: On Fri, Nov 10, 2006 at 04:18:25PM -0800, Howard Chu wrote: Richard Guenther wrote: If you compile with -O3 -combine *.c -o alias it will break. Hm, actually it still prints the correct result for me. What platform are you using where it actually makes

Re: strict aliasing question

Andreas Schwab wrote: Howard Chu [EMAIL PROTECTED] writes: I understand that logic, in the general case. In this specific example, none of those conditions apply. foo is an uninitialized local variable. Therefore the compiler cannot know that it has a valid copy of it in any register

Re: strict aliasing question

be accessing the same memory. I can understand strange results occurring when there's ambiguity, but there is no ambiguity here. -- -- Howard Chu Chief Architect, Symas Corp. http://www.symas.com Director, Highland Sunhttp://highlandsun.com/hyc OpenLDAP Core Teamhttp

Re: strict aliasing question

); /* system(text); */ } The above code compiles without warning with -O2 / -O3 -Wstrict-aliasing, but the result is quite different from compiling without optimization. -- -- Howard Chu Chief Architect, Symas Corp. http://www.symas.com Director, Highland Sunhttp

Re: strict aliasing question

Andrew Pinski wrote: On Fri, 2006-11-10 at 23:05 -0800, Howard Chu wrote: Daniel Berlin wrote: We ask the TBAA analyzer can a store to a short * touch i. In this case, it says no, because it's not legal. If you know the code is not legal, why don't you abort the compilation