[backport from gcc-4.8/trunk r191484, depends on reload-subreg-{1,2} patches <mikpe@it.uu.se>]

gcc/

2012-09-19  Eric Botcazou  <ebotcazou@adacore.com>

	PR rtl-optimization/54290
	* reload1.c (choose_reload_regs): Also take into account secondary MEMs
	to remove address replacements for inherited reloads.
	(replaced_subreg): Move around.

gcc/testsuite/

2012-09-19  Eric Botcazou  <ebotcazou@adacore.com>

	* gcc.c-torture/execute/20120919-1.c: New test.

--- gcc-4.7.2/gcc/reload1.c.~1~	2012-09-22 15:12:42.000000000 +0200
+++ gcc-4.7.2/gcc/reload1.c	2012-09-22 15:12:55.000000000 +0200
@@ -6355,6 +6355,20 @@ choose_reload_regs_init (struct insn_cha
 			      rld[i].when_needed, rld[i].mode);
 }
 
+#ifdef SECONDARY_MEMORY_NEEDED
+/* If X is not a subreg, return it unmodified.  If it is a subreg,
+   look up whether we made a replacement for the SUBREG_REG.  Return
+   either the replacement or the SUBREG_REG.  */
+
+static rtx
+replaced_subreg (rtx x)
+{
+  if (GET_CODE (x) == SUBREG)
+    return find_replacement (&SUBREG_REG (x));
+  return x;
+}
+#endif
+
 /* Assign hard reg targets for the pseudo-registers we must reload
    into hard regs for this insn.
    Also output the instructions to copy them in and out of the hard regs.
@@ -6945,7 +6959,7 @@ choose_reload_regs (struct insn_chain *c
       for (j = 0; j < n_reloads; j++)
 	{
 	  int r = reload_order[j];
-	  rtx check_reg;
+	  rtx check_reg, tem;
 	  if (reload_inherited[r] && rld[r].reg_rtx)
 	    check_reg = rld[r].reg_rtx;
 	  else if (reload_override_in[r]
@@ -6977,10 +6991,26 @@ choose_reload_regs (struct insn_chain *c
 	     If we succeeded removing some reload and we are doing a preliminary
 	     pass just to remove such reloads, make another pass, since the
 	     removal of one reload might allow us to inherit another one.  */
-	  else if (rld[r].in
+	  else if (pass
+		   && rld[r].in
+		   && rld[r].out != rld[r].in
+		   && remove_address_replacements (rld[r].in))
+	    pass = 2;
+#ifdef SECONDARY_MEMORY_NEEDED
+	  /* If we needed a memory location for the reload, we also have to
+	     remove its related reloads.  */
+	  else if (pass
+	           && rld[r].in
 		   && rld[r].out != rld[r].in
-		   && remove_address_replacements (rld[r].in) && pass)
+		   && (tem = replaced_subreg (rld[r].in), REG_P (tem))		   
+		   && REGNO (tem) < FIRST_PSEUDO_REGISTER
+		   && SECONDARY_MEMORY_NEEDED (REGNO_REG_CLASS (REGNO (tem)),
+					       rld[r].rclass, rld[r].inmode)
+		   && remove_address_replacements
+		      (get_secondary_mem (tem, rld[r].inmode, rld[r].opnum,
+					  rld[r].when_needed)))
 	    pass = 2;
+#endif
 	}
     }
 
@@ -8461,20 +8491,6 @@ emit_insn_if_valid_for_reload (rtx insn)
   return NULL;
 }
 
-#ifdef SECONDARY_MEMORY_NEEDED
-/* If X is not a subreg, return it unmodified.  If it is a subreg,
-   look up whether we made a replacement for the SUBREG_REG.  Return
-   either the replacement or the SUBREG_REG.  */
-
-static rtx
-replaced_subreg (rtx x)
-{
-  if (GET_CODE (x) == SUBREG)
-    return find_replacement (&SUBREG_REG (x));
-  return x;
-}
-#endif
-
 /* Emit code to perform a reload from IN (which may be a reload register) to
    OUT (which may also be a reload register).  IN or OUT is from operand
    OPNUM with reload type TYPE.
--- gcc-4.7.2/gcc/testsuite/gcc.c-torture/execute/20120919-1.c.~1~	1970-01-01 01:00:00.000000000 +0100
+++ gcc-4.7.2/gcc/testsuite/gcc.c-torture/execute/20120919-1.c	2012-09-22 15:12:55.000000000 +0200
@@ -0,0 +1,37 @@
+/* PR rtl-optimization/54290 */
+/* Testcase by Eric Volk <eriksnga@gmail.com> */
+
+double vd[2] = {1., 0.};
+int vi[2] = {1234567890, 0};
+double *pd = vd;
+int *pi = vi;
+
+extern void abort(void);
+
+void init (int *n, int *dummy) __attribute__ ((noinline,noclone));
+
+void init (int *n, int *dummy)
+{
+  if(0 == n) dummy[0] = 0;
+}
+
+int main (void)
+{
+  int dummy[1532];
+  int i = -1, n = 1, s = 0;
+  init (&n, dummy);
+  while (i < n) {
+    if (i == 0) {
+      if (pd[i] > 0) {
+        if (pi[i] > 0) {
+          s += pi[i];
+        }
+      }
+      pd[i] = pi[i];
+    }
+    ++i;
+  }
+  if (s != 1234567890)
+    abort ();
+  return 0;
+}