tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Remove special casing of constant qualifiers.

2008-03-20  Richard Guenther  <rguenther@suse.de>

	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Remove
	special casing of constant qualifiers.
	* tree-ssa.c (useless_type_conversion_p_1): Instead do not
	care about them in general.
	* tree-ssa-ccp.c (ccp_fold): Addresses are constant or not
	regardless of their type.
	(fold_stmt_r): Forcefully fold *& if we end up with that.

	* gcc.dg/tree-ssa/ssa-ccp-17.c: New testcase.

From-SVN: r133400

6 files changed, 67 insertions, 22 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bd4ada6..559c1dd 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,13 @@
+2008-03-20  Richard Guenther  <rguenther@suse.de>
+
+	* tree-ssa-forwprop.c (forward_propagate_addr_expr_1): Remove
+	special casing of constant qualifiers.
+	* tree-ssa.c (useless_type_conversion_p_1): Instead do not
+	care about them in general.
+	* tree-ssa-ccp.c (ccp_fold): Addresses are constant or not
+	regardless of their type.
+	(fold_stmt_r): Forcefully fold *& if we end up with that.
+
 2008-03-20  Paul Brook  <paul@codesourcery.com>
 
 	* config.gcc (arm*-*-uclinux*): Remove duplicate arm/uclinux-elf.h.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 737dbba..5eb84fe3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,7 @@
+2008-03-20  Richard Guenther  <rguenther@suse.de>
+
+	* gcc.dg/tree-ssa/ssa-ccp-17.c: New testcase.
+
 2008-03-20 Victor Kaplansky  <victork@gcc.gnu.org>
 	   Uros Bizjak  <ubizjak@gmail.com>
 
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-17.c b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-17.c
new file mode 100644
index 0000000..7d769ae
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/ssa-ccp-17.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+int foo(void)
+{
+  int i = 0;
+  char *p = (char *)&i;
+  return *(int *)p;
+}
+
+struct Foo {
+  int i;
+} f;
+
+int bar(void)
+{
+  char *p = (char *)&f;
+  return ((struct Foo *)p)->i;
+}
+
+const struct Foo g;
+
+int foobar(void)
+{
+  struct Foo *p = (struct Foo *)&g;
+  return ((const struct Foo *)p)->i;
+}
+
+/* { dg-final { scan-tree-dump "= i;" "ccp1" } } */
+/* { dg-final { scan-tree-dump "= f.i;" "ccp1" } } */
+/* { dg-final { scan-tree-dump "= g.i;" "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 2a82c04..7797de1 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -947,8 +947,15 @@ ccp_fold (tree stmt)
 	    op0 = get_value (op0)->value;
 	}
 
+      /* Conversions are useless for CCP purposes if they are
+	 value-preserving.  Thus the restrictions that
+	 useless_type_conversion_p places for pointer type conversions do
+	 not apply here.  Substitution later will only substitute to
+	 allowed places.  */
       if ((code == NOP_EXPR || code == CONVERT_EXPR)
-	  && useless_type_conversion_p (TREE_TYPE (rhs), TREE_TYPE (op0)))
+	  && ((POINTER_TYPE_P (TREE_TYPE (rhs))
+	       && POINTER_TYPE_P (TREE_TYPE (op0)))
+	      || useless_type_conversion_p (TREE_TYPE (rhs), TREE_TYPE (op0))))
 	return op0;
       return fold_unary (code, TREE_TYPE (rhs), op0);
     }
@@ -2160,6 +2167,11 @@ fold_stmt_r (tree *expr_p, int *walk_subtrees, void *data)
 
       t = maybe_fold_stmt_indirect (expr, TREE_OPERAND (expr, 0),
 				    integer_zero_node);
+      if (!t
+	  && TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
+	/* If we had a good reason for propagating the address here,
+	   make sure we end up with valid gimple.  See PR34989.  */
+	t = TREE_OPERAND (TREE_OPERAND (expr, 0), 0);
       break;
 
     case NOP_EXPR:
diff --git a/gcc/tree-ssa-forwprop.c b/gcc/tree-ssa-forwprop.c
index 84553fb..e6402ad 100644
--- a/gcc/tree-ssa-forwprop.c
+++ b/gcc/tree-ssa-forwprop.c
@@ -601,14 +601,8 @@ forward_propagate_addr_expr_1 (tree name, tree def_rhs, tree use_stmt,
      propagate the ADDR_EXPR into the use of NAME and fold the result.  */
   if (TREE_CODE (lhs) == INDIRECT_REF
       && TREE_OPERAND (lhs, 0) == name
-      /* This will not allow stripping const qualification from
-	 pointers which we want to allow specifically here to clean up
-	 the IL for initialization of constant objects.   */
-      && (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (lhs, 0)),
-				     TREE_TYPE (def_rhs))
-	  /* So explicitly check for this here.  */
-	  || (TYPE_QUALS (TREE_TYPE (TREE_TYPE (TREE_OPERAND (lhs, 0))))
-	      ^ TYPE_QUALS (TREE_TYPE (TREE_TYPE (def_rhs)))) == TYPE_QUAL_CONST)
+      && useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (lhs, 0)),
+				    TREE_TYPE (def_rhs))
       /* ???  This looks redundant, but is required for bogus types
 	 that can sometimes occur.  */
       && useless_type_conversion_p (TREE_TYPE (lhs),
@@ -635,13 +629,10 @@ forward_propagate_addr_expr_1 (tree name, tree def_rhs, tree use_stmt,
      propagate the ADDR_EXPR into the use of NAME and fold the result.  */
   if (TREE_CODE (rhs) == INDIRECT_REF
       && TREE_OPERAND (rhs, 0) == name
-      /* ???  This doesn't allow stripping const qualification to
-	 streamline the IL for reads from non-constant objects.  */
-      && (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (rhs, 0)),
-				     TREE_TYPE (def_rhs))
-	  /* So explicitly check for this here.  */
-	  || (TYPE_QUALS (TREE_TYPE (TREE_TYPE (TREE_OPERAND (rhs, 0))))
-	      ^ TYPE_QUALS (TREE_TYPE (TREE_TYPE (def_rhs)))) == TYPE_QUAL_CONST)
+      && useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (rhs, 0)),
+				    TREE_TYPE (def_rhs))
+      /* ???  This looks redundant, but is required for bogus types
+	 that can sometimes occur.  */
       && useless_type_conversion_p (TREE_TYPE (rhs),
 				    TREE_TYPE (TREE_OPERAND (def_rhs, 0))))
     {
diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index 128b4e8..f7306b1 100644
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -1117,12 +1117,8 @@ useless_type_conversion_p_1 (tree outer_type, tree inner_type)
 	      != get_alias_set (TREE_TYPE (outer_type))))
 	return false;
 
-      /* Do not lose casts from const qualified to non-const
-	 qualified.  */
-      if ((TYPE_READONLY (TREE_TYPE (outer_type))
-	   != TYPE_READONLY (TREE_TYPE (inner_type)))
-	  && TYPE_READONLY (TREE_TYPE (inner_type)))
-	return false;
+      /* We do not care for const qualification of the pointed-to types
+	 as const qualification has no semantic value to the middle-end.  */
 
       /* Do not lose casts to restrict qualified pointers.  */
       if ((TYPE_RESTRICT (outer_type)