diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 336dda8c45d..39d733b51a9 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-23  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR rtl-optimization/81443
+	* rtlanal.c (num_sign_bit_copies1) <SUBREG>: Do not propagate results
+	from inner REGs to paradoxical SUBREGs.
+
 2018-01-21  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
 
 	Backport from mainline
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index 8e85f14525d..772a6a993bb 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -4976,7 +4976,7 @@ num_sign_bit_copies1 (const_rtx x, machine_mode mode, const_rtx known_x,
       if (WORD_REGISTER_OPERATIONS
 	  && load_extend_op (inner_mode) == SIGN_EXTEND
 	  && paradoxical_subreg_p (x)
-	  && (MEM_P (SUBREG_REG (x)) || REG_P (SUBREG_REG (x))))
+	  && MEM_P (SUBREG_REG (x)))
 	return cached_num_sign_bit_copies (SUBREG_REG (x), mode,
 					   known_x, known_mode, known_ret);
       break;