[gcc r13-3603] rs6000: Byte reverse V8HI on Power8 by vector rotation.

[HaoChen Gui <guihaoc@gcc.gnu.org>]

https://gcc.gnu.org/g:eaba55ffef961c28f6a15d845a4d6b77b8a8bab1

commit r13-3603-geaba55ffef961c28f6a15d845a4d6b77b8a8bab1
Author: Xionghu Luo <xionghuluo@tencent.com>
Date:   Wed Oct 12 10:43:38 2022 +0800

    rs6000: Byte reverse V8HI on Power8 by vector rotation.
    
    gcc/
            PR target/100866
            * config/rs6000/altivec.md: (*altivec_vrl<VI_char>): Named to...
            (altivec_vrl<VI_char>): ...this.
            * config/rs6000/vsx.md (revb_<mode>): Call vspltish and vrlh when
            target is Power8 and mode is V8HI.
    
    gcc/testsuite/
            PR target/100866
            * gcc.target/powerpc/pr100866-2.c: New.

Diff:
---
 gcc/config/rs6000/altivec.md                  |  2 +-
 gcc/config/rs6000/vsx.md                      | 21 +++++++++++++++------
 gcc/testsuite/gcc.target/powerpc/pr100866-2.c | 13 +++++++++++++
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/gcc/config/rs6000/altivec.md b/gcc/config/rs6000/altivec.md
index 2c4940f2e21..84660073f32 100644
--- a/gcc/config/rs6000/altivec.md
+++ b/gcc/config/rs6000/altivec.md
@@ -1875,7 +1875,7 @@
 }
   [(set_attr "type" "vecperm")])
 
-(define_insn "*altivec_vrl<VI_char>"
+(define_insn "altivec_vrl<VI_char>"
   [(set (match_operand:VI2 0 "register_operand" "=v")
         (rotate:VI2 (match_operand:VI2 1 "register_operand" "v")
 		    (match_operand:VI2 2 "register_operand" "v")))]
diff --git a/gcc/config/rs6000/vsx.md b/gcc/config/rs6000/vsx.md
index e0e34a78bca..fb5cf04147e 100644
--- a/gcc/config/rs6000/vsx.md
+++ b/gcc/config/rs6000/vsx.md
@@ -6087,12 +6087,21 @@
     emit_insn (gen_p9_xxbr<VSX_XXBR>_<mode> (operands[0], operands[1]));
   else
     {
-      /* Want to have the elements in reverse order relative
-	 to the endian mode in use, i.e. in LE mode, put elements
-	 in BE order.  */
-      rtx sel = swap_endian_selector_for_mode(<MODE>mode);
-      emit_insn (gen_altivec_vperm_<mode> (operands[0], operands[1],
-					   operands[1], sel));
+      if (<MODE>mode == V8HImode)
+	{
+	  rtx splt = gen_reg_rtx (V8HImode);
+	  emit_insn (gen_altivec_vspltish (splt, GEN_INT (8)));
+	  emit_insn (gen_altivec_vrlh (operands[0], operands[1], splt));
+	}
+      else
+	{
+	  /* Want to have the elements in reverse order relative
+	     to the endian mode in use, i.e. in LE mode, put elements
+	     in BE order.  */
+	  rtx sel = swap_endian_selector_for_mode (<MODE>mode);
+	  emit_insn (gen_altivec_vperm_<mode> (operands[0], operands[1],
+					       operands[1], sel));
+	}
     }
 
   DONE;
diff --git a/gcc/testsuite/gcc.target/powerpc/pr100866-2.c b/gcc/testsuite/gcc.target/powerpc/pr100866-2.c
new file mode 100644
index 00000000000..4357d1beb09
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr100866-2.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-options "-O2 -mdejagnu-cpu=power8" } */
+/* { dg-final { scan-assembler {\mvspltish\M} } } */
+/* { dg-final { scan-assembler {\mvrlh\M} } } */
+
+#include <altivec.h>
+
+vector unsigned short revb(vector unsigned short a)
+{
+   return vec_revb(a);
+}
+