[LLVMdev] Question about FMA formation
eli.friedman at gmail.com
Wed Dec 12 15:59:02 PST 2012
On Wed, Dec 12, 2012 at 3:40 PM, Shuxin Yang <shuxin.llvm at gmail.com> wrote:
> Hi, Dear All:
> I'm going implement FMA formation. On some architectures, "FMA a, b, c"
> is more precise than
> "a * b + c".
If it isn't more accurate, it isn't an FMA, at least not in the
commonly used sense. (ARM has an instruction which does a multiply
and add which isn't more precise, but it would just be confusing to
refer to that as an FMA.)
> In the former
> case, can we enable FMA
> formation despite restrictive FP mode?
No. There have already been very long discussions about fma; try
searching the llvmdev archives.
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