Paul E. McKenney wrote: > > Does some version of gcc, under the options which we insist upon, > > make such optimizations on any of the architectures which we support? > > Pretty much any production-quality compiler will do double-fetch > and old-value-reuse optimizations, the former especially on 32-bit > x86. I don't know of any production-quality compilers that do value > speculation, which would make the compiler act like DEC Alpha hardware, > and I would hope that if this does appear, (1) we would have warning > and (2) it could be turned off. But there has been a lot of work on > this topic, so we would be foolish to rule it out.
GCC documentation for IA-64: -msched-ar-data-spec -mno-sched-ar-data-spec (En/Dis)able data speculative scheduling after reload. This results in generation of ld.a instructions and the corresponding check instructions (ld.c / chk.a). The default is 'enable'. I don't know if that results in value speculation of the relevant kind. -- Jamie -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/