[PATCH] rs6000: Add split pattern to replace

[Xionghu Luo <luoxhu@linux.ibm.com>]

7: r120:V4SI=const_vector
8: r121:V4SI=unspec[r120:V4SI,r120:V4SI,0xc] 260

with r121:v4SI = r120:V4SI when r120 is a vector with same element.

Bootstrapped and regtested pass on powerpc64le-linux-gnu {P10, P9}
and powerpc64-linux-gnu {P8, P7}.  OK for master?

gcc/ChangeLog:

	* config/rs6000/altivec.md (sldoi_to_mov_<mode>): New.

gcc/testsuite/ChangeLog:

	* gcc.target/powerpc/sldoi_to_mov.c: New test.
---
 gcc/config/rs6000/altivec.md                    | 11 +++++++++++
 gcc/testsuite/gcc.target/powerpc/sldoi_to_mov.c | 15 +++++++++++++++
 2 files changed, 26 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/sldoi_to_mov.c

diff --git a/gcc/config/rs6000/altivec.md b/gcc/config/rs6000/altivec.md
index b2909857c34..25f86dbe828 100644
--- a/gcc/config/rs6000/altivec.md
+++ b/gcc/config/rs6000/altivec.md
@@ -383,6 +383,17 @@ (define_split
     }
 })
 
+(define_insn_and_split "sldoi_to_mov_<mode>"
+  [(set (match_operand:VM 0 "altivec_register_operand")
+	(unspec:VM [(match_operand:VM 1 "easy_vector_constant")
+	            (match_dup 1)
+		    (match_operand:VM 2 "u5bit_cint_operand")]
+		    UNSPEC_VSLDOI))]
+  "VECTOR_UNIT_ALTIVEC_OR_VSX_P (<MODE>mode) && can_create_pseudo_p ()"
+  "#"
+  "&& 1"
+  [(set (match_dup 0) (match_dup 1))])
+
 (define_insn "get_vrsave_internal"
   [(set (match_operand:SI 0 "register_operand" "=r")
 	(unspec:SI [(reg:SI VRSAVE_REGNO)] UNSPEC_GET_VRSAVE))]
diff --git a/gcc/testsuite/gcc.target/powerpc/sldoi_to_mov.c b/gcc/testsuite/gcc.target/powerpc/sldoi_to_mov.c
new file mode 100644
index 00000000000..2053243c456
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/sldoi_to_mov.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+#include <altivec.h>
+vector signed int foo1 (vector signed int a) {
+    vector signed int b = {0};
+    return vec_sum2s(a, b);
+}
+
+vector signed int foo2 (vector signed int a) {
+    vector signed int b = {0};
+    return vec_sld(b, b, 4);
+}
+
+/* { dg-final { scan-assembler-times {\mvsldoi\M} 1 {target le} } } */
-- 
2.27.0