patch to fix PR56246

patch to fix PR56246

[Vladimir Makarov]

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The following patch fixes

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56246

LRA was not able to find enough regs for insn reloads.  One reason of 
that was
it did not try to reuse the same reload reg for the same value. Another 
reason was it
tried to assign hard reg to a pseudo in any case, as the code account 
the pseudo as
reload one and the pseudo is actually optional reload pseudo (the code 
lost track of
this on the second constraint subpass iteration).

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

Committed as rev. 195502.

2013-02-08  Vladimir Makarov  <vmakarov@redhat.com>

     PR rtl-optimization/56246
     * lra-constraints.c (simplify_operand_subreg): Try tor reuse
     reload pseudo.
     * lra.c (lra): Clear lra_optional_reload_pseudos only when all
     constraints are satisfied.

2013-02-08  Vladimir Makarov  <vmakarov@redhat.com>

         PR rtl-optimization/56246
         * gcc.target/i386/pr56246.c: New test.


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Index: lra.c
===================================================================
--- lra.c	(revision 195901)
+++ lra.c	(working copy)
@@ -2272,7 +2272,6 @@ lra (FILE *f)
     {
       for (;;)
 	{
-	  bitmap_clear (&lra_optional_reload_pseudos);
 	  /* We should try to assign hard registers to scratches even
 	     if there were no RTL transformations in
 	     lra_constraints.  */
@@ -2311,6 +2310,7 @@ lra (FILE *f)
 		live_p = false;
 	    }
 	}
+      bitmap_clear (&lra_optional_reload_pseudos);
       bitmap_clear (&lra_inheritance_pseudos);
       bitmap_clear (&lra_split_regs);
       if (! lra_need_for_spills_p ())
Index: lra-constraints.c
===================================================================
--- lra-constraints.c	(revision 195901)
+++ lra-constraints.c	(working copy)
@@ -1213,24 +1213,26 @@ simplify_operand_subreg (int nop, enum m
       enum reg_class rclass
 	= (enum reg_class) targetm.preferred_reload_class (reg, ALL_REGS);
 
-      new_reg = lra_create_new_reg_with_unique_value (reg_mode, reg, rclass,
-						      "subreg reg");
-      bitmap_set_bit (&lra_optional_reload_pseudos, REGNO (new_reg));
-      if (type != OP_OUT
-	  || GET_MODE_SIZE (GET_MODE (reg)) > GET_MODE_SIZE (mode))
+      if (get_reload_reg (curr_static_id->operand[nop].type, reg_mode, reg,
+			  rclass, "subreg reg", &new_reg))
 	{
-	  push_to_sequence (before);
-	  lra_emit_move (new_reg, reg);
-	  before = get_insns ();
-	  end_sequence ();
-	}
-      if (type != OP_IN)
-	{
-	  start_sequence ();
-	  lra_emit_move (reg, new_reg);
-	  emit_insn (after);
-	  after = get_insns ();
-	  end_sequence ();
+	  bitmap_set_bit (&lra_optional_reload_pseudos, REGNO (new_reg));
+	  if (type != OP_OUT
+	      || GET_MODE_SIZE (GET_MODE (reg)) > GET_MODE_SIZE (mode))
+	    {
+	      push_to_sequence (before);
+	      lra_emit_move (new_reg, reg);
+	      before = get_insns ();
+	      end_sequence ();
+	    }
+	  if (type != OP_IN)
+	    {
+	      start_sequence ();
+	      lra_emit_move (reg, new_reg);
+	      emit_insn (after);
+	      after = get_insns ();
+	      end_sequence ();
+	    }
 	}
       SUBREG_REG (operand) = new_reg;
       lra_process_new_insns (curr_insn, before, after,
Index: testsuite/gcc.target/i386/pr56246.c
===================================================================
--- testsuite/gcc.target/i386/pr56246.c	(revision 0)
+++ testsuite/gcc.target/i386/pr56246.c	(working copy)
@@ -0,0 +1,7 @@
+/* PR target/56225 */
+/* { dg-do compile { target { ia32 } } } */
+/* { dg-options "-O2 -fno-omit-frame-pointer -march=i686 -fpic" } */
+
+void NoBarrier_AtomicExchange (long long *ptr) {
+  while (__sync_val_compare_and_swap (ptr, 1, 0) );
+}