1 files changed, 19 insertions, 0 deletions
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 55c338e..ec7a062 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -6940,3 +6940,22 @@ register_asm_p (const_rtx x)
 	  && DECL_ASSEMBLER_NAME_SET_P (REG_EXPR (x))
 	  && DECL_REGISTER (REG_EXPR (x)));
 }
+
+/* Return true if, for all OP of mode OP_MODE:
+
+     (vec_select:RESULT_MODE OP SEL)
+
+   is equivalent to the lowpart RESULT_MODE of OP.  */
+
+bool
+vec_series_lowpart_p (machine_mode result_mode, machine_mode op_mode, rtx sel)
+{
+  int nunits;
+  if (GET_MODE_NUNITS (op_mode).is_constant (&nunits)
+      && targetm.can_change_mode_class (op_mode, result_mode, ALL_REGS))
+    {
+      int offset = BYTES_BIG_ENDIAN ? nunits - XVECLEN (sel, 0) : 0;
+      return rtvec_series_p (XVEC (sel, 0), offset);
+    }
+  return false;
+}