2012-03-06  Ramana Radhakrishnan  <ramana.radhakrishnan@linaro.org>

	LP:942307
    	gcc/
    	PR target/50305
    	* config/arm/arm.c (arm_legitimize_reload_address): Recognize
    	output of a previous pass through legitimize_reload_address.
    	Do not attempt to optimize addresses if the base register is
    	equivalent to a constant.
    	gcc/testsuite/
    	PR target/50305
    	* gcc.target/arm/pr50305.c: New test.

=== modified file 'gcc/config/arm/arm.c'
--- old/gcc/config/arm/arm.c	2012-03-02 13:53:14 +0000
+++ new/gcc/config/arm/arm.c	2012-03-06 11:01:55 +0000
@@ -6632,9 +6632,26 @@
 			       int opnum, int type,
 			       int ind_levels ATTRIBUTE_UNUSED)
 {
+  /* We must recognize output that we have already generated ourselves.  */
+  if (GET_CODE (*p) == PLUS
+      && GET_CODE (XEXP (*p, 0)) == PLUS
+      && GET_CODE (XEXP (XEXP (*p, 0), 0)) == REG
+      && GET_CODE (XEXP (XEXP (*p, 0), 1)) == CONST_INT
+      && GET_CODE (XEXP (*p, 1)) == CONST_INT)
+    {
+      push_reload (XEXP (*p, 0), NULL_RTX, &XEXP (*p, 0), NULL,
+		   MODE_BASE_REG_CLASS (mode), GET_MODE (*p),
+		   VOIDmode, 0, 0, opnum, (enum reload_type) type);
+      return true;
+    }
+
   if (GET_CODE (*p) == PLUS
       && GET_CODE (XEXP (*p, 0)) == REG
       && ARM_REGNO_OK_FOR_BASE_P (REGNO (XEXP (*p, 0)))
+      /* If the base register is equivalent to a constant, let the generic
+	 code handle it.  Otherwise we will run into problems if a future
+	 reload pass decides to rematerialize the constant.  */
+      && !reg_equiv_constant [ORIGINAL_REGNO (XEXP (*p, 0))]
       && GET_CODE (XEXP (*p, 1)) == CONST_INT)
     {
       HOST_WIDE_INT val = INTVAL (XEXP (*p, 1));

=== added file 'gcc/testsuite/gcc.target/arm/pr50305.c'
--- old/gcc/testsuite/gcc.target/arm/pr50305.c	1970-01-01 00:00:00 +0000
+++ new/gcc/testsuite/gcc.target/arm/pr50305.c	2012-03-01 13:07:48 +0000
@@ -0,0 +1,60 @@
+/* { dg-do compile } */
+/* { dg-skip-if "incompatible options" { arm*-*-* } { "-march=*" } { "-march=armv7-a" } } */
+/* { dg-options "-O2 -fno-omit-frame-pointer -marm -march=armv7-a -mfpu=vfp3" } */
+
+struct event {
+ unsigned long long id;
+ unsigned int flag;
+};
+
+void dummy(void)
+{
+  /* This is here to ensure that the offset of perf_event_id below
+     relative to the LANCHOR symbol exceeds the allowed displacement.  */
+  static int __warned[300];
+ __warned[0] = 1;
+}
+
+extern void *kmem_cache_alloc_trace (void *cachep);
+extern void *cs_cachep;
+extern int nr_cpu_ids;
+
+struct event *
+event_alloc (int cpu)
+{
+ static unsigned long long __attribute__((aligned(8))) perf_event_id;
+ struct event *event;
+ unsigned long long result;
+ unsigned long tmp;
+
+ if (cpu >= nr_cpu_ids)
+  return 0;
+
+ event = kmem_cache_alloc_trace (cs_cachep);
+
+ __asm__ __volatile__ ("dmb" : : : "memory");
+
+ __asm__ __volatile__("@ atomic64_add_return\n"
+"1:	ldrexd	%0, %H0, [%3]\n"
+"	adds	%0, %0, %4\n"
+"	adc	%H0, %H0, %H4\n"
+"	strexd	%1, %0, %H0, [%3]\n"
+"	teq	%1, #0\n"
+"	bne	1b"
+ : "=&r" (result), "=&r" (tmp), "+Qo" (perf_event_id)
+ : "r" (&perf_event_id), "r" (1LL)
+ : "cc");
+
+ __asm__ __volatile__ ("dmb" : : : "memory");
+
+ event->id = result;
+
+ if (cpu)
+  event->flag = 1;
+
+ for (cpu = 0; cpu < nr_cpu_ids; cpu++)
+   kmem_cache_alloc_trace (cs_cachep);
+
+ return event;
+}
+