diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
index eb579ad3ad7..f7aa6a66cdf 100644
--- a/gcc/rtl-ssa/changes.cc
+++ b/gcc/rtl-ssa/changes.cc
@@ -1106,6 +1106,24 @@ recog_level2 (insn_change &change, add_regno_clobber_fn add_regno_clobber)
 	    }
 	}
 
+  // Per rtl.texi, registers that are modified using RTX_AUTOINC operations
+  // cannot also appear outside an address.
+  vec_rtx_properties properties;
+  properties.add_pattern (pat);
+  for (rtx_obj_reference def : properties.refs ())
+    if (def.is_pre_post_modify ())
+      for (rtx_obj_reference use : properties.refs ())
+	if (def.regno == use.regno && !use.in_address ())
+	  {
+	    if (dump_file && (dump_flags & TDF_DETAILS))
+	      {
+		fprintf (dump_file, "register %d is both auto-modified"
+			 " and used outside an address:\n", def.regno);
+		print_rtl_single (dump_file, pat);
+	      }
+	    return false;
+	  }
+
   // check_asm_operands checks the constraints after RA, so we don't
   // need to do it again.
   if (reload_completed && !asm_p)
diff --git a/gcc/rtlanal.cc b/gcc/rtlanal.cc
index 86a5e473308..900f53e252a 100644
--- a/gcc/rtlanal.cc
+++ b/gcc/rtlanal.cc
@@ -2235,7 +2235,7 @@ rtx_properties::try_to_add_src (const_rtx x, unsigned int flags)
 	{
 	  has_pre_post_modify = true;
 
-	  unsigned int addr_flags = (base_flags
+	  unsigned int addr_flags = (flags
 				     | rtx_obj_flags::IS_PRE_POST_MODIFY
 				     | rtx_obj_flags::IS_READ);
 	  try_to_add_dest (XEXP (x, 0), addr_flags);
diff --git a/gcc/testsuite/gcc.dg/torture/pr120347.c b/gcc/testsuite/gcc.dg/torture/pr120347.c
new file mode 100644
index 00000000000..a2d187bbc5c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr120347.c
@@ -0,0 +1,13 @@
+/* { dg-do assemble } */
+/* { dg-additional-options "-march=armv7-a -mthumb" { target { arm_arch_v7a_ok && arm_thumb2_ok } } } */
+
+void *end;
+void **start;
+void main(void)
+{
+  for (; end; start++) {
+    if (*start)
+      return;
+    *start = start;
+  }
+}