diff --git a/gcc/ree.cc b/gcc/ree.cc
index fc04249fa84..9f21f0e9907 100644
--- a/gcc/ree.cc
+++ b/gcc/ree.cc
@@ -514,7 +514,8 @@ get_uses (rtx_insn *insn, rtx reg)
     if (REGNO (DF_REF_REG (def)) == REGNO (reg))
       break;
 
-  gcc_assert (def != NULL);
+  if (def == NULL)
+    return NULL;
 
   ref_chain = DF_REF_CHAIN (def);
 
@@ -750,6 +751,124 @@ get_extended_src_reg (rtx src)
   return src;
 }
 
+/* Return TRUE if target mode is equal to source mode of zero_extend
+   or sign_extend otherwise false.  */
+
+static bool
+abi_target_promote_function_mode (machine_mode mode)
+{
+  int unsignedp;
+  machine_mode tgt_mode
+    = targetm.calls.promote_function_mode (NULL_TREE, mode, &unsignedp,
+					   NULL_TREE, 1);
+
+  if (tgt_mode == mode)
+    return true;
+  else
+    return false;
+}
+
+/* Return TRUE if the candidate insn is zero extend and regno is
+   a return registers.  */
+
+static bool
+abi_extension_candidate_return_reg_p (/*rtx_insn *insn, */int regno)
+{
+  if (targetm.calls.function_value_regno_p (regno))
+    return true;
+
+  return false;
+}
+
+/* Return TRUE if reg source operand of zero_extend is argument registers
+   and not return registers and source and destination operand are same
+   and mode of source and destination operand are not same.  */
+
+static bool
+abi_extension_candidate_p (rtx_insn *insn)
+{
+  rtx set = single_set (insn);
+  machine_mode dst_mode = GET_MODE (SET_DEST (set));
+  rtx orig_src = XEXP (SET_SRC (set), 0);
+
+  if (!FUNCTION_ARG_REGNO_P (REGNO (orig_src))
+      || abi_extension_candidate_return_reg_p (/*insn,*/ REGNO (orig_src)))
+    return false;
+
+  /* Mode of destination and source should be different.  */
+  if (dst_mode == GET_MODE (orig_src))
+    return false;
+
+  machine_mode mode = GET_MODE (XEXP (SET_SRC (set), 0));
+  bool promote_p = abi_target_promote_function_mode (mode);
+
+  /* REGNO of source and destination should be same if not
+      promoted.  */
+  if (!promote_p && REGNO (SET_DEST (set)) != REGNO (orig_src))
+    return false;
+
+  return true;
+}
+
+/* Return TRUE if the candidate insn is zero extend and regno is
+   an argument registers.  */
+
+static bool
+abi_extension_candidate_argno_p (/*rtx_code code, */int regno)
+{
+  if (FUNCTION_ARG_REGNO_P (regno))
+    return true;
+
+  return false;
+}
+
+/* Return TRUE if the candidate insn doesn't have defs and have
+ * uses without RTX_BIN_ARITH/RTX_COMM_ARITH/RTX_UNARY rtx class.  */
+
+static bool
+abi_handle_regs (rtx_insn *insn)
+{
+  if (side_effects_p (PATTERN (insn)))
+    return false;
+
+  struct df_link *uses = get_uses (insn, SET_DEST (PATTERN (insn)));
+
+  if (!uses)
+    return false;
+
+  for (df_link *use = uses; use; use = use->next)
+    {
+      if (!use->ref)
+	return false;
+
+      if (BLOCK_FOR_INSN (insn) != BLOCK_FOR_INSN (DF_REF_INSN (use->ref)))
+	return false;
+
+      rtx_insn *use_insn = DF_REF_INSN (use->ref);
+
+      if (GET_CODE (PATTERN (use_insn)) == SET)
+	{
+	  rtx_code code = GET_CODE (SET_SRC (PATTERN (use_insn)));
+
+	  if (GET_RTX_CLASS (code) == RTX_BIN_ARITH
+	      || GET_RTX_CLASS (code) == RTX_COMM_ARITH
+	      || GET_RTX_CLASS (code) == RTX_UNARY)
+	    return false;
+	}
+     }
+
+  rtx set = single_set (insn);
+
+  if (GET_CODE (SET_SRC (set)) == SIGN_EXTEND)
+    {
+      machine_mode mode = GET_MODE (XEXP (SET_SRC (set), 0));
+      bool promote_p = abi_target_promote_function_mode (mode);
+
+      return promote_p;
+    }
+  return true;
+}
+
 /* This function goes through all reaching defs of the source
    of the candidate for elimination (CAND) and tries to combine
    the extension with the definition instruction.  The changes
@@ -770,6 +889,11 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state)
 
   state->defs_list.truncate (0);
   state->copies_list.truncate (0);
+  rtx orig_src = XEXP (SET_SRC (cand->expr),0);
+
+  if (abi_extension_candidate_p (cand->insn)
+      && (!get_defs (cand->insn, orig_src, NULL)))
+    return abi_handle_regs (cand->insn);
 
   outcome = make_defs_and_copies_lists (cand->insn, set_pat, state);
 
@@ -1036,6 +1160,15 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state)
         }
     }
 
+  rtx insn_set = single_set (cand->insn);
+
+  machine_mode mode = (GET_MODE (XEXP (SET_SRC (insn_set), 0)));
+
+  bool promote_p = abi_target_promote_function_mode (mode);
+
+  if (promote_p)
+    return true;
+
   if (merge_successful)
     {
       /* Commit the changes here if possible
@@ -1112,6 +1245,14 @@ add_removable_extension (const_rtx expr, rtx_insn *insn,
       rtx reg = XEXP (src, 0);
       struct df_link *defs, *def;
       ext_cand *cand;
+      defs = get_defs (insn, reg, NULL);
+
+      if (!defs && abi_extension_candidate_argno_p (/*code,*/ REGNO (reg)))
+	{
+	  ext_cand e = {expr, code, mode, insn};
+	  insn_list->safe_push (e);
+	  return;
+	}
 
       /* Zero-extension of an undefined value is partly defined (it's
 	 completely undefined for sign-extension, though).  So if there exists
@@ -1131,7 +1272,6 @@ add_removable_extension (const_rtx expr, rtx_insn *insn,
 	}
 
       /* Second, make sure we can get all the reaching definitions.  */
-      defs = get_defs (insn, reg, NULL);
       if (!defs)
 	{
 	  if (dump_file)
@@ -1321,7 +1461,8 @@ find_and_remove_re (void)
 	      && (REGNO (SET_DEST (set)) != REGNO (XEXP (SET_SRC (set), 0))))
 	    {
               reinsn_copy_list.safe_push (curr_cand->insn);
-              reinsn_copy_list.safe_push (state.defs_list[0]);
+	      if (state.defs_list.length () != 0)
+		reinsn_copy_list.safe_push (state.defs_list[0]);
 	    }
 	  reinsn_del_list.safe_push (curr_cand->insn);
 	  state.modified[INSN_UID (curr_cand->insn)].deleted = 1;
@@ -1345,6 +1486,10 @@ find_and_remove_re (void)
   for (unsigned int i = 0; i < reinsn_copy_list.length (); i += 2)
     {
       rtx_insn *curr_insn = reinsn_copy_list[i];
+
+      if ((i+1) >= reinsn_copy_list.length ())
+	continue;
+
       rtx_insn *def_insn = reinsn_copy_list[i + 1];
 
       /* Use the mode of the destination of the defining insn
diff --git a/gcc/testsuite/g++.target/powerpc/zext-elim-3.C b/gcc/testsuite/g++.target/powerpc/zext-elim-3.C
new file mode 100644
index 00000000000..5a050df06ff
--- /dev/null
+++ b/gcc/testsuite/g++.target/powerpc/zext-elim-3.C
@@ -0,0 +1,13 @@
+/* { dg-options "-mcpu=power9 -O2" } */
+
+void *memset(void *b, int c, unsigned long len)
+{
+  unsigned long i;
+
+  for (i = 0; i < len; i++)
+    ((unsigned char *)b)[i] = c;
+
+   return b;
+}
+
+/* { dg-final { scan-assembler-not "\mrlwinm\M" } } */
