On Thu, Jan 23, 2014 at 11:12 AM, Dallman, John <john.dall...@siemens.com> wrote: >> Do any common platforms, other than x86/x86_64, offer more-than-64-bit "long >> double"? > > Not that they support as full speed hardware operations, AFAIK. SPARC has > defined > registers and instructions for 128-bit floating point, but implements them as > sequences of operations on 64-bit floats, so they aren't terribly fast.
This is totally wrong. 1. The SPARCV9 specification *requires* support for 128bit floating point, including load/store and all other operations supported for single and double floating point operations. It also mandates specific libc interfaces. Each 128bit SPARCV9 floating point register uses two 64bit floating point registers, so you have half the number of registers but still can have decent performance 2. Until very recently the SPARCV9 hardware *implementations* did not support the 128bit floating point instructions in hardware, but since the SPARCV9 specification mandates their support they are emulated by kernel traps and separately via the mandated libc wrappers. This changed with recent Fujitsu CPU versions which implement 128bit floating point in hardware, including support for register renaming, with performance almost as fast as the double instructions. Older Fujitsu SPARCV9 CPU implementations have varying degree of SPARCV9 128bit floating point support, but at least the load/store and add instructions were always supported. 3. Some SPARC emulators like Transitive implement full SPARCV9 128bit floating point instruction support, i.e. using the SPARCV9 instructions directly results in faster execution than going through the libc wrappers and have them executed by Transitive > IBM System/390 onwards supports 128-bit float in hardware, according to > Wikipedia. Right Irek ------------------------------------------------------------------------------ CenturyLink Cloud: The Leader in Enterprise Cloud Services. Learn Why More Businesses Are Choosing CenturyLink Cloud For Critical Workloads, Development Environments & Everything In Between. Get a Quote or Start a Free Trial Today. http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk _______________________________________________ Valgrind-users mailing list Valgrind-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/valgrind-users
