diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a2abec15d11..d0610f5a9df 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2010-06-07  Kazu Hirata  <kazu@codesourcery.com>
+
+	PR rtl-optimization/44404
+	* auto-inc-dec.c (find_inc): Use reg_overlap_mentioned_p instead
+	of count_occurrences to see if it's safe to modify mem_insn.insn.
+	gcc/testsuite/
+
 2010-06-07  Richard Guenther  <rguenther@suse.de>
 
 	* gimplify.c (gimplify_cleanup_point_expr): For empty body
diff --git a/gcc/auto-inc-dec.c b/gcc/auto-inc-dec.c
index 6b5c3adecbf..94dffc95eb2 100644
--- a/gcc/auto-inc-dec.c
+++ b/gcc/auto-inc-dec.c
@@ -1068,6 +1068,13 @@ find_inc (bool first_try)
       /* For the post_add to work, the result_reg of the inc must not be
 	 used in the mem insn since this will become the new index
 	 register.  */
+      if (count_occurrences (PATTERN (mem_insn.insn), inc_insn.reg_res, 1) == 0
+	  && reg_overlap_mentioned_p (inc_insn.reg_res, PATTERN (mem_insn.insn)))
+	{
+	  debug_rtx (mem_insn.insn);
+	  debug_rtx (inc_insn.reg_res);
+	  gcc_unreachable ();
+	}
       if (count_occurrences (PATTERN (mem_insn.insn), inc_insn.reg_res, 1) != 0)
 	{
 	  if (dump_file)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 7020fc7aa73..d9348276052 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2010-06-07  Kazu Hirata  <kazu@codesourcery.com>
+
+	PR rtl-optimization/44404
+	* gcc.dg/pr44404.c: New.
+
 2010-06-07  Kai Tietz  <kai.tietz@onevision.com>
 
 	PR target/44159
diff --git a/gcc/testsuite/gcc.dg/pr44404.c b/gcc/testsuite/gcc.dg/pr44404.c
new file mode 100644
index 00000000000..a0b4ceb98ca
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr44404.c
@@ -0,0 +1,35 @@
+/* PR rtl-optimization/44404
+   foo() used to be miscompiled on ARM due to a bug in auto-inc-dec.c,
+   which resulted in "strb r1, [r1], #-36".  */
+
+/* { dg-do run } */
+/* { dg-options "-O2 -fno-unroll-loops" } */
+
+extern char *strcpy (char *, const char *);
+extern int strcmp (const char*, const char*);
+extern void abort (void);
+
+char buf[128];
+
+void __attribute__((noinline))
+bar (int a, const char *p)
+{
+  if (strcmp (p, "0123456789abcdefghijklmnopqrstuvwxyz") != 0)
+    abort ();
+}
+
+void __attribute__((noinline))
+foo (int a)
+{
+  if (a)
+    bar (0, buf);
+  strcpy (buf, "0123456789abcdefghijklmnopqrstuvwxyz");
+  bar (0, buf);
+}
+
+int
+main (void)
+{
+  foo (0);
+  return 0;
+}