diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 9dce4240230..b9af7109b40 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2012-02-11  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	PR rtl-optimization/52175
+	* reorg.c (fill_slots_from_thread): Don't apply add/sub optimization
+	to frame-related instructions.
+
 2012-02-10  Jason Merrill  <jason@redhat.com>
 
 	PR c++/51910
diff --git a/gcc/reorg.c b/gcc/reorg.c
index 3fa53939d5e..dfc9747c5f7 100644
--- a/gcc/reorg.c
+++ b/gcc/reorg.c
@@ -2937,6 +2937,7 @@ fill_slots_from_thread (rtx insn, rtx condition, rtx thread,
   if (delay_list == 0 && likely
       && new_thread && !ANY_RETURN_P (new_thread)
       && NONJUMP_INSN_P (new_thread)
+      && !RTX_FRAME_RELATED_P (new_thread)
       && GET_CODE (PATTERN (new_thread)) != ASM_INPUT
       && asm_noperands (PATTERN (new_thread)) < 0)
     {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 812cee10c3b..03fba5450dd 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2012-02-11  Richard Sandiford  <rdsandiford@googlemail.com>
+
+	PR rtl-optimization/52175
+	* gcc.c-torture/compile/pr52175.c: New test.
+
 2012-02-10  Jason Merrill  <jason@redhat.com>
 
 	PR c++/51910
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr52175.c b/gcc/testsuite/gcc.c-torture/compile/pr52175.c
new file mode 100644
index 00000000000..e0aed77044d
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr52175.c
@@ -0,0 +1,25 @@
+void bad (void);
+char *foo (char *src, char **last)
+{
+  char *dst;
+  int ch;
+  dst = src = (src ? src : *last);
+
+  if (*src == 0)
+    return 0;
+
+  while (src[0])
+    {
+      if (!src[1])
+	{
+	  bad ();
+	  break;
+	}
+      *dst = *src;
+      dst += 1;
+      src += 2;
+    }
+  *last = src;
+  *dst = 0;
+  return *last;
+}