[Bug rtl-optimization/63281] powerpc64le creates 64 bit constants from scratch instead of loading them

[guojiufu at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63281

--- Comment #20 from Jiu Fu Guo <guojiufu at gcc dot gnu.org> ---
Created attachment 52114
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52114&action=edit
testcases

With these test cases, invoke 'foo' in these cases 1000,000,000 times, to see
the runtime:
building 'constant' through 1 insn is fastest.
next faster is building const by 2 instructions, or loading from rodata, or
loading from toc.
building const by 3 instructions is slower than loading from rodata, building
const by 5 ins is slowest.