rs6000: Splat vector small V2DI constants with vspltisw and vupkhsw

This patch adds a new insn for vector splat with small V2DI constants on P8.
If the value of constant is in RANGE (-16, 15) but not 0 or -1, it can be
loaded with vspltisw and vupkhsw on P8.

gcc/
	PR target/104124
	* config/rs6000/altivec.md (*altivec_vupkhs<VU_char>_direct): Rename
	to...
	(altivec_vupkhs<VU_char>_direct): ...this.
	* config/rs6000/predicates.md (vspltisw_vupkhsw_constant_split): New
	predicate to test if a constant can be loaded with vspltisw and
	vupkhsw.
	(easy_vector_constant): Call vspltisw_vupkhsw_constant_p to Check if
	a vector constant can be synthesized with a vspltisw and a vupkhsw.
	* config/rs6000/rs6000-protos.h (vspltisw_vupkhsw_constant_p):
	Declare.
	* config/rs6000/rs6000.cc (vspltisw_vupkhsw_constant_p): New
	function to return true if OP mode is V2DI and can be synthesized
	with vupkhsw and vspltisw.
	* config/rs6000/vsx.md (*vspltisw_v2di_split): New insn to load up
	constants with vspltisw and vupkhsw.

gcc/testsuite/
	PR target/104124
	* gcc.target/powerpc/pr104124.c: New.

6 files changed, 81 insertions, 1 deletions

diff --git a/gcc/config/rs6000/altivec.md b/gcc/config/rs6000/altivec.md
index ad1224e..70db5cf 100644
--- a/gcc/config/rs6000/altivec.md
+++ b/gcc/config/rs6000/altivec.md
@@ -2550,7 +2550,7 @@
 }
   [(set_attr "type" "vecperm")])
 
-(define_insn "*altivec_vupkhs<VU_char>_direct"
+(define_insn "altivec_vupkhs<VU_char>_direct"
   [(set (match_operand:VP 0 "register_operand" "=v")
 	(unspec:VP [(match_operand:<VP_small> 1 "register_operand" "v")]
 		     UNSPEC_VUNPACK_HI_SIGN_DIRECT))]
diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
index 6b56483..8479331 100644
--- a/gcc/config/rs6000/predicates.md
+++ b/gcc/config/rs6000/predicates.md
@@ -694,6 +694,12 @@
   return num_insns > 1;
 })
 
+;; Return true if the operand is a constant that can be loaded with a vspltisw
+;; instruction and then a vupkhsw instruction.
+
+(define_predicate "vspltisw_vupkhsw_constant_split"
+  (and (match_code "const_vector")
+       (match_test "vspltisw_vupkhsw_constant_p (op, mode)")))
 
 ;; Return 1 if the operand is constant that can loaded directly with a XXSPLTIB
 ;; instruction.
@@ -742,6 +748,11 @@
           && xxspltib_constant_p (op, mode, &num_insns, &value))
 	return true;
 
+      /* V2DI constant within RANGE (-16, 15) can be synthesized with a
+	 vspltisw and a vupkhsw.  */
+      if (vspltisw_vupkhsw_constant_p (op, mode, &value))
+	return true;
+
       return easy_altivec_constant (op, mode);
     }
 
diff --git a/gcc/config/rs6000/rs6000-protos.h b/gcc/config/rs6000/rs6000-protos.h
index 9a4cc18..f70118e 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -32,6 +32,7 @@ extern void init_cumulative_args (CUMULATIVE_ARGS *, tree, rtx, int, int, int,
 
 extern int easy_altivec_constant (rtx, machine_mode);
 extern bool xxspltib_constant_p (rtx, machine_mode, int *, int *);
+extern bool vspltisw_vupkhsw_constant_p (rtx, machine_mode, int * = nullptr);
 extern int vspltis_shifted (rtx);
 extern HOST_WIDE_INT const_vector_elt_as_int (rtx, unsigned int);
 extern bool macho_lo_sum_memory_operand (rtx, machine_mode);
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index 546c353..07c3a3d 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -6642,6 +6642,36 @@ xxspltib_constant_p (rtx op,
   return true;
 }
 
+/* Return true if OP mode is V2DI and can be synthesized with ISA 2.07
+   instructions vupkhsw and vspltisw.
+
+   Return the constant that is being split via CONSTANT_PTR.  */
+
+bool
+vspltisw_vupkhsw_constant_p (rtx op, machine_mode mode, int *constant_ptr)
+{
+  HOST_WIDE_INT value;
+  rtx elt;
+
+  if (!TARGET_P8_VECTOR)
+    return false;
+
+  if (mode != V2DImode)
+    return false;
+
+  if (!const_vec_duplicate_p (op, &elt))
+    return false;
+
+  value = INTVAL (elt);
+  if (value == 0 || value == 1
+      || !EASY_VECTOR_15 (value))
+    return false;
+
+  if (constant_ptr)
+    *constant_ptr = (int) value;
+  return true;
+}
+
 const char *
 output_vec_const_move (rtx *operands)
 {
diff --git a/gcc/config/rs6000/vsx.md b/gcc/config/rs6000/vsx.md
index e017381..0c269e4 100644
--- a/gcc/config/rs6000/vsx.md
+++ b/gcc/config/rs6000/vsx.md
@@ -1177,6 +1177,30 @@
   [(set_attr "type" "vecperm")
    (set_attr "length" "8")])
 
+(define_insn_and_split "*vspltisw_v2di_split"
+  [(set (match_operand:V2DI 0 "altivec_register_operand" "=v")
+	(match_operand:V2DI 1 "vspltisw_vupkhsw_constant_split" "W"))]
+  "TARGET_P8_VECTOR && vspltisw_vupkhsw_constant_split (operands[1], V2DImode)"
+  "#"
+  "&& 1"
+  [(const_int 0)]
+{
+  rtx op0 = operands[0];
+  rtx op1 = operands[1];
+  rtx tmp = can_create_pseudo_p ()
+	    ? gen_reg_rtx (V4SImode)
+	    : gen_lowpart (V4SImode, op0);
+  int value;
+
+  vspltisw_vupkhsw_constant_p (op1, V2DImode, &value);
+  emit_insn (gen_altivec_vspltisw (tmp, GEN_INT (value)));
+  emit_insn (gen_altivec_vupkhsw_direct (op0, tmp));
+
+  DONE;
+}
+  [(set_attr "type" "vecperm")
+   (set_attr "length" "8")])
+
 
 ;; Prefer using vector registers over GPRs.  Prefer using ISA 3.0's XXSPLTISB
 ;; or Altivec VSPLITW 0/-1 over XXLXOR/XXLORC to set a register to all 0's or
diff --git a/gcc/testsuite/gcc.target/powerpc/pr104124.c b/gcc/testsuite/gcc.target/powerpc/pr104124.c
new file mode 100644
index 0000000..30e3b6f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr104124.c
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-mdejagnu-cpu=power8 -mpower8-vector -O2" } */
+/* { dg-require-effective-target powerpc_p8vector_ok } */
+/* { dg-final { scan-assembler {\mvspltisw\M} } } */
+/* { dg-final { scan-assembler {\mvupkhsw\M} } } */
+/* { dg-final { scan-assembler-not {\mlvx\M} } } */
+
+#include <altivec.h>
+
+vector unsigned long long 
+foo ()
+{
+  return vec_splats ((unsigned long long) 12);
+}