no, it's intel P4 platform. that's why I feeled strange. and it's my fault, as Joerg memtioned, i forget to open the '-OX' option :(
2007/9/12, Garrett D'Amore <[EMAIL PROTECTED]>: > > Is this on SPARC? > > There is a branch delay on many RISC systems including SPARC, where the > instruction following the branch is also executed. > > Usually the compiler can optimize away the nop, by putting some useful > work in the branch delay slot. But sometimes, it is not possible to > easily fill that. Also, if the compiler is not run with optimization > turned on, it might not bother to even *try* to fill those branch delay > slots. > > Btw, many RISC systems also have other kinds of delays... such as load > delays (the value in the register might not be available in the next > instruction yet), etc. I don't remember which instructions in SPARC > have this kind of delay, as its been a while since I did much SPARC > assembler coding. I do know that branches do have that delay. > > Of course, if you're seeing this behavior on x86 (a CISC architecture) > then I have no idea.... > > -- Garrett > > On Tue, 2007-09-11 at 23:40 +0800, 陶捷 TaoJie wrote: > > Dear all: > > > > there's no sun studio mailling list in opensolaris.org, i raise my > > problem here :) > > > > a simple piece of code, 2 nested while loops, and some if statements > > inside each while loop. > > > > i compiled this program in Solaris with sun cc (sun studio 12) and > > gcc. > > and i compiled it in Debian with gcc as well. > > > > Then I dumped (disassembled) these 3 programs. > > I found that there were alway serveral nop instructions followed with > > the jmp instruction in the program generated by suncc. > > and this problem didn't exist in the other 2 program generated by gcc. > > > > err... Why does sun cc generate code using this pattern (a jmp > > followed by serveral nops)? For what? > > > > TIA > > > > > > Regards, > > TJ > > _______________________________________________ > > opensolaris-code mailing list > > opensolaris-code@opensolaris.org > > http://mail.opensolaris.org/mailman/listinfo/opensolaris-code > >
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