patch to fix PR57559 for s390

[Vladimir Makarov <vmakarov@redhat.com>]

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The following patch fixes

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57559

The problem was in systematic discouraging reload symbol address in 
memory.  The patch actually reverts a fix for a x86/x86-64 PR for 
-fpie.  The patch implements another solution for this problem (see 
changes for lra_emit_add).

The patch was successfully bootstrapped and tested on x86/x86-64 and s390.

Committed as rev. 199859.

2013-06-08  Vladimir Makarov  <vmakarov@redhat.com>

         PR rtl-optimization/57559
         * lra-constraints.c (process_alt_operands): Don't discourage
         memory with known offset for offsetable memory constraint.
         * lra.c (lra_emit_add): Exchange y and z for 2-op add insn.

2013-06-08  Vladimir Makarov  <vmakarov@redhat.com>

         PR rtl-optimization/57559
         * gcc.target/s390/pr57559.c : New    test.


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Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 199762)
+++ lra-constraints.c	(working copy)
@@ -1997,15 +1997,8 @@ process_alt_operands (int only_alternati
 			      (op, this_alternative) == NO_REGS))))
 		reject += LRA_MAX_REJECT;
 
-	      if (MEM_P (op) && offmemok)
-		{
-		  /* If we know offset and this non-offsetable memory,
-		     something wrong with this memory and it is better
-		     to try other memory possibilities.  */
-		  if (MEM_OFFSET_KNOWN_P (op))
-		    reject += LRA_MAX_REJECT;
-		}
-	      else if (! (const_to_mem && constmemok))
+	      if (! (MEM_P (op) && offmemok)
+		  && ! (const_to_mem && constmemok))
 		{
 		  /* We prefer to reload pseudos over reloading other
 		     things, since such reloads may be able to be
Index: lra.c
===================================================================
--- lra.c	(revision 199753)
+++ lra.c	(working copy)
@@ -306,11 +306,11 @@ lra_emit_add (rtx x, rtx y, rtx z)
 	  || (disp != NULL_RTX && ! CONSTANT_P (disp))
 	  || (scale != NULL_RTX && ! CONSTANT_P (scale)))
 	{
-	  /* Its is not an address generation.	Probably we have no 3 op
+	  /* It is not an address generation.	Probably we have no 3 op
 	     add.  Last chance is to use 2-op add insn.	 */
 	  lra_assert (x != y && x != z);
-	  emit_move_insn (x, z);
-	  insn = gen_add2_insn (x, y);
+	  emit_move_insn (x, y);
+	  insn = gen_add2_insn (x, z);
 	  emit_insn (insn);
 	}
       else
Index: testsuite/gcc.target/s390/pr57559.c
===================================================================
--- testsuite/gcc.target/s390/pr57559.c	(revision 0)
+++ testsuite/gcc.target/s390/pr57559.c	(working copy)
@@ -0,0 +1,24 @@
+/* PR rtl-optimization/57559  */
+
+/* { dg-do compile } */
+/* { dg-options "-march=z10 -m64 -mzarch  -O1" } */
+
+typedef int int32_t;
+typedef unsigned char uint8_t;
+typedef unsigned int uint32_t;
+struct _IO_marker
+{
+};
+static const int32_t mfcone = 1;
+static const uint8_t *mfctop = (const uint8_t *) &mfcone;
+int32_t
+decContextTestEndian (uint8_t quiet)
+{
+  int32_t res = 0;
+  uint32_t dle = (uint32_t) 0;
+  if (*(int *) 10 != 0)
+    {
+      res = (int32_t) * mfctop - dle;
+    }
+  return res;
+}