fold-const.c (target.h): Include.

2008-03-26  Richard Guenther  <rguenther@suse.de>

	* fold-const.c (target.h): Include.
	(fold_comparison): Fold comparison of addresses of two decls
	that bind locally.  Consolidate address folding code.

	* gcc.dg/fold-addr-1.c: New testcase.

From-SVN: r133599

4 files changed, 61 insertions, 34 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index d31e6ad..e1f0e34 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2008-03-26  Richard Guenther  <rguenther@suse.de>
+
+	* fold-const.c (target.h): Include.
+	(fold_comparison): Fold comparison of addresses of two decls
+	that bind locally.  Consolidate address folding code.
+
 2008-03-26  Nick Clifton  <nickc@redhat.com>
 
 	PR target/31232
@@ -577,8 +583,8 @@
 2008-03-19  Richard Guenther  <rguenther@suse.de>
 
 	PR middle-end/35609
-	* tree-ssa.c (always_executed): New global flag.
-	(warn_uninitialized_var): If !always_executed warn with "maybe"
+	* tree-ssa.c (walk_data): New structure.
+	(warn_uninitialized_var): If not always_executed warn with "maybe"
 	instead of "is".
 	(execute_early_warn_uninitialized): Compute post-dominators.
 	Initialize always_executed before processing each basic block.
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 3bfe52e..4964ef7 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -58,6 +58,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "rtl.h"
 #include "expr.h"
 #include "tm_p.h"
+#include "target.h"
 #include "toplev.h"
 #include "intl.h"
 #include "ggc.h"
@@ -8481,11 +8482,12 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
       HOST_WIDE_INT bitsize, bitpos0 = 0, bitpos1 = 0;
       enum machine_mode mode;
       int volatilep, unsignedp;
-      bool indirect_base0 = false;
+      bool indirect_base0 = false, indirect_base1 = false;
 
       /* Get base and offset for the access.  Strip ADDR_EXPR for
 	 get_inner_reference, but put it back by stripping INDIRECT_REF
-	 off the base object if possible.  */
+	 off the base object if possible.  indirect_baseN will be true
+	 if baseN is not an address but refers to the object itself.  */
       base0 = arg0;
       if (TREE_CODE (arg0) == ADDR_EXPR)
 	{
@@ -8509,24 +8511,19 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
 	  base1 = get_inner_reference (TREE_OPERAND (arg1, 0),
 				       &bitsize, &bitpos1, &offset1, &mode,
 				       &unsignedp, &volatilep, false);
-	  /* We have to make sure to have an indirect/non-indirect base1
-	     just the same as we did for base0.  */
-	  if (TREE_CODE (base1) == INDIRECT_REF
-	      && !indirect_base0)
+	  if (TREE_CODE (base1) == INDIRECT_REF)
 	    base1 = TREE_OPERAND (base1, 0);
-	  else if (!indirect_base0)
-	    base1 = NULL_TREE;
+	  else
+	    indirect_base1 = true;
 	}
       else if (TREE_CODE (arg1) == POINTER_PLUS_EXPR)
 	{
 	  base1 = TREE_OPERAND (arg1, 0);
 	  offset1 = TREE_OPERAND (arg1, 1);
 	}
-      else if (indirect_base0)
-	base1 = NULL_TREE;
 
       /* If we have equivalent bases we might be able to simplify.  */
-      if (base0 && base1
+      if (indirect_base0 == indirect_base1
 	  && operand_equal_p (base0, base1, 0))
 	{
 	  /* We can fold this expression to a constant if the non-constant
@@ -8581,6 +8578,37 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
 	      return fold_build2 (code, type, offset0, offset1);
 	    }
 	}
+      /* For non-equal bases we can simplify if they are plain decls.  */
+      else if (!indirect_base0 && !indirect_base1
+	       && TREE_CODE (arg0) == ADDR_EXPR
+	       && TREE_CODE (arg1) == ADDR_EXPR
+	       && DECL_P (base0) && DECL_P (base1)
+	       && !operand_equal_p (base0, base1, 0)
+	       && targetm.binds_local_p (base0)
+	       && targetm.binds_local_p (base1))
+	{
+	  if (code == EQ_EXPR)
+	    return omit_two_operands (type, boolean_false_node, arg0, arg1);
+	  else if (code == NE_EXPR)
+	    return omit_two_operands (type, boolean_true_node, arg0, arg1);
+	}
+      /* For equal offsets we can simplify to a comparison of the
+	 base addresses.  */
+      else if (bitpos0 == bitpos1
+	       && (indirect_base0
+		   ? base0 != TREE_OPERAND (arg0, 0) : base0 != arg0)
+	       && (indirect_base1
+		   ? base1 != TREE_OPERAND (arg1, 0) : base1 != arg1)
+	       && ((offset0 == offset1)
+		   || (offset0 && offset1
+		       && operand_equal_p (offset0, offset1, 0))))
+	{
+	  if (indirect_base0)
+	    base0 = fold_addr_expr (base0);
+	  if (indirect_base1)
+	    base1 = fold_addr_expr (base1);
+	  return fold_build2 (code, type, base0, base1);
+	}
     }
 
   /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
@@ -8927,27 +8955,6 @@ fold_comparison (enum tree_code code, tree type, tree op0, tree op1)
 	}
     }
 
-  /* Fold a comparison of the address of COMPONENT_REFs with the same
-     type and component to a comparison of the address of the base
-     object.  In short, &x->a OP &y->a to x OP y and
-     &x->a OP &y.a to x OP &y  */
-  if (TREE_CODE (arg0) == ADDR_EXPR
-      && TREE_CODE (TREE_OPERAND (arg0, 0)) == COMPONENT_REF
-      && TREE_CODE (arg1) == ADDR_EXPR
-      && TREE_CODE (TREE_OPERAND (arg1, 0)) == COMPONENT_REF)
-    {
-      tree cref0 = TREE_OPERAND (arg0, 0);
-      tree cref1 = TREE_OPERAND (arg1, 0);
-      if (TREE_OPERAND (cref0, 1) == TREE_OPERAND (cref1, 1))
-	{
-	  tree op0 = TREE_OPERAND (cref0, 0);
-	  tree op1 = TREE_OPERAND (cref1, 0);
-	  return fold_build2 (code, type,
-			      fold_addr_expr (op0),
-			      fold_addr_expr (op1));
-	}
-    }
-
   /* We can fold X/C1 op C2 where C1 and C2 are integer constants
      into a single range test.  */
   if ((TREE_CODE (arg0) == TRUNC_DIV_EXPR
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6c8c190..64ffcb0 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,9 @@
 2008-03-26  Richard Guenther  <rguenther@suse.de>
 
+	* gcc.dg/fold-addr-1.c: New testcase.
+
+2008-03-26  Richard Guenther  <rguenther@suse.de>
+
 	* gcc.dg/tree-ssa/20030731-2.c: Scan dce1 dump.
 	* gcc.dg/tree-ssa/20030917-1.c: Scan optimized dump.
 	* gcc.dg/tree-ssa/20030917-3.c: Scan ccp1 dump.
diff --git a/gcc/testsuite/gcc.dg/fold-addr-1.c b/gcc/testsuite/gcc.dg/fold-addr-1.c
new file mode 100644
index 0000000..7323ffd
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-addr-1.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-fdump-tree-original" } */
+
+int bar(char p1, char p2)
+{
+  return &p1 == &p2;
+}
+
+/* { dg-final { scan-tree-dump "return 0;" "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */