On Fri, Nov 5, 2021 at 2:01 PM Michael Meissner <meiss...@linux.ibm.com> wrote: > > On Fri, Nov 05, 2021 at 12:52:51PM -0500, will schmidt wrote: > > > diff --git a/gcc/config/rs6000/predicates.md > > > b/gcc/config/rs6000/predicates.md > > > index 956e42bc514..e0d1c718e9f 100644 > > > --- a/gcc/config/rs6000/predicates.md > > > +++ b/gcc/config/rs6000/predicates.md > > > @@ -601,6 +601,14 @@ (define_predicate "easy_fp_constant" > > > if (TARGET_VSX && op == CONST0_RTX (mode)) > > > return 1; > > > > > > + /* Constants that can be generated with ISA 3.1 instructions are easy. > > > */ > > > > Easy is relative, but OK. > > The names of the function is easy_fp_constant. > > > > + vec_const_128bit_type vsx_const; > > > + if (TARGET_POWER10 && vec_const_128bit_to_bytes (op, mode, &vsx_const)) > > > + { > > > + if (constant_generates_lxvkq (&vsx_const) != 0) > > > + return true; > > > + } > > > + > > > /* Otherwise consider floating point constants hard, so that the > > > constant gets pushed to memory during the early RTL phases. This > > > has the advantage that double precision constants that can be > > > @@ -609,6 +617,23 @@ (define_predicate "easy_fp_constant" > > > return 0; > > > }) > > > > > > +;; Return 1 if the operand is a special IEEE 128-bit value that can be > > > loaded > > > +;; via the LXVKQ instruction. > > > + > > > +(define_predicate "easy_vector_constant_ieee128" > > > + (match_code "const_vector,const_double") > > > +{ > > > + vec_const_128bit_type vsx_const; > > > + > > > + /* Can we generate the LXVKQ instruction? */ > > > + if (!TARGET_IEEE128_CONSTANT || !TARGET_FLOAT128_HW || !TARGET_POWER10 > > > + || !TARGET_VSX) > > > + return false; > > > > Presumably all of the checks there are valid. (Can we have power10 > > without float128_hw or ieee128_constant flags set?) I do notice the > > addition of an ieee128_constant flag below. > > Yes, we can have power10 without float128_hw. At the moment, 32-bit big > endian > does not enable the 128-bit IEEE instructions. Also when we are building the > bits in libgcc that can switch between compiling the software routines and the > routines used for IEEE hardware, and when we are building the IEEE 128-bit > software emulation functions we need to explicitly turn off IEEE 128-bit > hardware support. > > Similarly for VSX, if the user explicitly says -mno-vsx, then we can't enable > this instruction. > > > Ok. I did look at this a bit before it clicked, so would suggest a > > comment stl "All of the constants that can be loaded by lxvkq will have > > zero in the bottom 3 words, so ensure those are zero before we use a > > switch based on the nonzero portion of the constant." > > > > It would be fine as-is too. :-) > > Ok.
Okay. Thanks, David