re PR rtl-optimization/53160 (likely wrong code bug)

	PR rtl-optimization/53160
	* ree.c (combine_reaching_defs): Handle the case where cand->insn
	has been modified by ree pass already.

	* gcc.c-torture/execute/pr53160.c: New test.

From-SVN: r187035

gcc/ChangeLog

+2012-05-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/53160
+	* ree.c (combine_reaching_defs): Handle the case where cand->insn
+	has been modified by ree pass already.
+
 2012-05-01  Ian Lance Taylor  <iant@google.com>
 
 	PR c/37303

gcc/ree.c

@@ -667,6 +667,24 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state)
   if (!outcome)
     return false;
 
+  /* If cand->insn has been already modified, update cand->mode to a wider
+     mode if possible, or punt.  */
+  if (state->modified[INSN_UID (cand->insn)].kind != EXT_MODIFIED_NONE)
+    {
+      enum machine_mode mode;
+      rtx set;
+
+      if (state->modified[INSN_UID (cand->insn)].kind
+	  != (cand->code == ZERO_EXTEND
+	      ? EXT_MODIFIED_ZEXT : EXT_MODIFIED_SEXT)
+	  || state->modified[INSN_UID (cand->insn)].mode != cand->mode
+	  || (set = single_set (cand->insn)) == NULL_RTX)
+	return false;
+      mode = GET_MODE (SET_DEST (set));
+      gcc_assert (GET_MODE_SIZE (mode) >= GET_MODE_SIZE (cand->mode));
+      cand->mode = mode;
+    }
+
   merge_successful = true;
 
   /* Go through the defs vector and try to merge all the definitions

gcc/testsuite/ChangeLog

+2012-05-02  Jakub Jelinek  <jakub@redhat.com>
+
+	PR rtl-optimization/53160
+	* gcc.c-torture/execute/pr53160.c: New test.
+
 2012-05-01  Ian Lance Taylor  <iant@google.com>
 
 	PR c/37303

gcc/testsuite/gcc.c-torture/execute/pr53160.c

+/* PR rtl-optimization/53160 */
+
+extern void abort (void);
+
+int a, c = 1, d, e, g;
+volatile int b;
+volatile char f;
+long h;
+short i;
+
+void
+foo (void)
+{
+  for (e = 0; e; ++e)
+    ;
+}
+
+int
+main ()
+{
+  if (g)
+    (void) b;
+  foo ();
+  for (d = 0; d >= 0; d--)
+    {
+      short j = f;
+      int k = 0;
+      i = j ? j : j << k;
+    }
+  h = c == 0 ? 0 : i;
+  a = h;
+  if (a != 0)
+    abort ();
+  return 0;
+}