Hi Tejas, On Mon, Sep 02, 2019 at 08:55:28AM +0530, Tejas Joshi wrote: > On Sat, 31 Aug 2019 at 02:05, Segher Boessenkool > <seg...@kernel.crashing.org> wrote: > > > > > > > > [ Please don't top-post ] > > > > (I delete everything under your signature, without looking, assuming you > > just forgot to). > > Oh sorry, I didn't know the reply button does evil things. :-)
You're supposed to write your email as if the time reading it is more valuable than the time writing it. You can afford to spend a few seconds deleting some stuff, or checking that what you wrote is good, etc. There is only one you, and there are many people reading this. > > If long double is double, faddl is the same as fadd, and daddl is just > > normal addition. > > > > If long double is double-double, faddl can be done as fadd on the first > > double precision component of both args, and daddl is just normal addition > > of those. > > > > If long double is IEEE QP, then it is more interesting :-) > > On what conditions does the mapping of long double to double/ > double-double or IEEE QP changes or depends, so that I can test it. gcc -Q --help=target | grep long -mlong-double-64 is to select double, and -mlong-double-128 says to use something 128 bits. These are not mentioned in the manual, and GCC often says it has a different number of bits selected, hrm. I'll open a PR. When having a 128-bit long double, -mabi=ibmlongdouble says to use the double-double format, and -mabi=ieeelongdouble says to use IEEE QP FP. HTH, Segher
