Re: [PATCH] LoongArch: Slightly simplify loongarch_block_move_straight

[chenglulu]

在 2023/9/8 上午12:33, Xi Ruoyao 写道:

gcc/ChangeLog:

        * config/loongarch/loongarch.cc (loongarch_block_move_straight):
        Check precondition (delta must be a power of 2) and use
        popcount_hwi instead of a homebrew loop.
---

I've not run a full bootstrap with this, but it should be obvious.
Ok for trunk?

LGTM!

Thanks!

  gcc/config/loongarch/loongarch.cc | 5 ++---
  1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/gcc/config/loongarch/loongarch.cc 
b/gcc/config/loongarch/loongarch.cc
index 509ef2b97f1..845fad5a8e8 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -5225,9 +5225,8 @@ loongarch_block_move_straight (rtx dest, rtx src, 
HOST_WIDE_INT length,
       emit two ld.d/st.d pairs, one ld.w/st.w pair, and one ld.b/st.b
       pair.  For each load/store pair we use a dedicated register to keep
       the pipeline as populated as possible.  */
-  HOST_WIDE_INT num_reg = length / delta;
-  for (delta_cur = delta / 2; delta_cur != 0; delta_cur /= 2)
-    num_reg += !!(length & delta_cur);
+  gcc_assert (pow2p_hwi (delta));
+  HOST_WIDE_INT num_reg = length / delta + popcount_hwi (length % delta);

/* Allocate a buffer for the temporary registers. */

    regs = XALLOCAVEC (rtx, num_reg);