On Tue, 2013-05-14 at 11:25 +1000, Michael Neuling wrote: > > > So, if we are just stealing the output of gcc, why not just use the C > > version (at least for 32 bit)? > > Woodhouse: can we just do this?
Sure, if you don't mind GCC optimising the contents of your C function by turning it into a call to libgcc's __bswapdi2() :) OK, you might be able to do some archaeology and determine that the only compiler that emits calls to __bswapdi2() is GCC 4.4, and furthermore that the same compiler *doesn't* have the wit to notice that the contents of the function are a 64-bit byteswap, so it's never going to happen. But I don't like that approach. I'd feel I have to sacrifice a goat *anyway*, and I don't have a spare goat. Although now I come to explicitly explain why I did it that way... it occurs to me that the libgcc version is just written in C, and the compiler evidently trusts itself not to optimise that into a recursive call. Is there a compiler switch which guarantees that, which we could use without other unwanted side-effects? -- David Woodhouse Open Source Technology Centre david.woodho...@intel.com Intel Corporation
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