diff --git a/gcc/combine.cc b/gcc/combine.cc
index 22bf8e1ec89..0106092e456 100644
--- a/gcc/combine.cc
+++ b/gcc/combine.cc
@@ -10055,9 +10055,12 @@ simplify_and_const_int_1 (scalar_int_mode mode, rtx varop,
 
   /* See what bits may be nonzero in VAROP.  Unlike the general case of
      a call to nonzero_bits, here we don't care about bits outside
-     MODE.  */
+     MODE unless WORD_REGISTER_OPERATIONS is true.  */
 
-  nonzero = nonzero_bits (varop, mode) & GET_MODE_MASK (mode);
+  scalar_int_mode tmode = mode;
+  if (WORD_REGISTER_OPERATIONS && GET_MODE_BITSIZE (mode) < BITS_PER_WORD)
+    tmode = word_mode;
+  nonzero = nonzero_bits (varop, tmode) & GET_MODE_MASK (tmode);
 
   /* Turn off all bits in the constant that are known to already be zero.
      Thus, if the AND isn't needed at all, we will have CONSTOP == NONZERO_BITS
@@ -10071,7 +10074,7 @@ simplify_and_const_int_1 (scalar_int_mode mode, rtx varop,
 
   /* If VAROP is a NEG of something known to be zero or 1 and CONSTOP is
      a power of two, we can replace this with an ASHIFT.  */
-  if (GET_CODE (varop) == NEG && nonzero_bits (XEXP (varop, 0), mode) == 1
+  if (GET_CODE (varop) == NEG && nonzero_bits (XEXP (varop, 0), tmode) == 1
       && (i = exact_log2 (constop)) >= 0)
     return simplify_shift_const (NULL_RTX, ASHIFT, mode, XEXP (varop, 0), i);
 
diff --git a/gcc/simplify-rtx.cc b/gcc/simplify-rtx.cc
index 3b33afa2461..ee75079917f 100644
--- a/gcc/simplify-rtx.cc
+++ b/gcc/simplify-rtx.cc
@@ -3752,7 +3752,13 @@ simplify_context::simplify_binary_operation_1 (rtx_code code,
 	return op0;
       if (HWI_COMPUTABLE_MODE_P (mode))
 	{
-	  HOST_WIDE_INT nzop0 = nonzero_bits (trueop0, mode);
+	  /* When WORD_REGISTER_OPERATIONS is true, we need to know the
+	     nonzero bits in WORD_MODE rather than MODE.  */
+	  scalar_int_mode tmode = as_a <scalar_int_mode> (mode);
+	  if (WORD_REGISTER_OPERATIONS
+	      && GET_MODE_BITSIZE (tmode) < BITS_PER_WORD)
+	    tmode = word_mode;
+	  HOST_WIDE_INT nzop0 = nonzero_bits (trueop0, tmode);
 	  HOST_WIDE_INT nzop1;
 	  if (CONST_INT_P (trueop1))
 	    {
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr109040.c b/gcc/testsuite/gcc.c-torture/execute/pr109040.c
new file mode 100644
index 00000000000..b0dedd50e79
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr109040.c
@@ -0,0 +1,23 @@
+/* PR target/109040 */
+
+typedef unsigned short __attribute__((__vector_size__ (32))) V;
+
+unsigned short a, b, c, d;
+
+void
+foo (V m, unsigned short *ret)
+{
+  V v = 6 > ((V) { 2124, 8 } & m);
+  unsigned short uc = v[0] + a + b + c + d;
+  *ret = uc;
+}
+
+int
+main ()
+{
+  unsigned short x;
+  foo ((V) { 0, 15 }, &x);
+  if (x != (unsigned short) ~0)
+    __builtin_abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/pr108947.c b/gcc/testsuite/gcc.dg/pr108947.c
new file mode 100644
index 00000000000..2fe2f5c6e57
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr108947.c
@@ -0,0 +1,21 @@
+/* PR target/108947 */
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-forward-propagate -Wno-psabi" } */
+
+typedef unsigned short __attribute__((__vector_size__ (2 * sizeof (short)))) V;
+
+__attribute__((__noipa__)) V
+foo (V v)
+{
+  V w = 3 > (v & 3992);
+  return w;
+}
+
+int
+main ()
+{
+  V w = foo ((V) { 0, 9 });
+  if (w[0] != 0xffff || w[1] != 0)
+    __builtin_abort ();
+  return 0;
+}