[PATCH, rs6000] Optimization for PowerPC 64bit constant generation [PR94395]

[Alan Modra]

On Fri, Jan 29, 2021 at 11:11:23AM +0800, HAO CHEN GUI via Gcc-patches wrote:
>    This patch tries to optimize PowerPC 64 bit constant generation when the
> constant can be transformed from a 32 bit or 16 bit constant by rotating,
> shifting and mask AND.

All and more of what you are doing here for rotated 16-bit constants
is covered by
https://gcc.gnu.org/pipermail/gcc-patches/2020-October/555760.html

That patch is still waiting on review.  Hmm, I see my local copy of
that patch has one extra line in
gcc/testsuite/gcc.target/powerpc/rot_cst2.c
+/* { dg-additional-options "-mno-prefixed" { target { lp64 } } } */
in order to keep scan-assembler-times counts correct for power10.

-- 
Alan Modra
Australia Development Lab, IBM