revert: re PR rtl-optimization/57381 (array of volatile pointers hangs gcc)

2013-05-27  Richard Biener  <rguenther@suse.de>

	Revert
	PR middle-end/57381
	* fold-const.c (operand_equal_p): Compare FIELD_DECLs with
	OEP_CONSTANT_ADDRESS_OF retained.

	PR tree-optimization/57417
	* tree-ssa-sccvn.c (vn_reference_fold_indirect): Fix test
	for unchanged base.
	(set_ssa_val_to): Compare addresses using
	get_addr_base_and_unit_offset.

	* gcc.dg/torture/pr57417.c: New testcase.

From-SVN: r199356

5 files changed, 45 insertions, 4 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a8c366b..8b7bed8 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,16 @@
+2013-05-27  Richard Biener  <rguenther@suse.de>
+
+	Revert
+	PR middle-end/57381
+	* fold-const.c (operand_equal_p): Compare FIELD_DECLs with
+	OEP_CONSTANT_ADDRESS_OF retained.
+
+	PR tree-optimization/57417
+	* tree-ssa-sccvn.c (vn_reference_fold_indirect): Fix test
+	for unchanged base.
+	(set_ssa_val_to): Compare addresses using
+	get_addr_base_and_unit_offset.
+
 2013-05-27  Joern Rennecke <joern.rennecke@embecosm.com>
 
 	PR rtl-optimization/56833
diff --git a/gcc/fold-const.c b/gcc/fold-const.c
index 38db3f1..a2b7ac1 100644
--- a/gcc/fold-const.c
+++ b/gcc/fold-const.c
@@ -2664,10 +2664,10 @@ operand_equal_p (const_tree arg0, const_tree arg1, unsigned int flags)
 	case COMPONENT_REF:
 	  /* Handle operand 2 the same as for ARRAY_REF.  Operand 0
 	     may be NULL when we're called to compare MEM_EXPRs.  */
-	  if (!OP_SAME_WITH_NULL (0) || !OP_SAME (1))
+	  if (!OP_SAME_WITH_NULL (0))
 	    return 0;
 	  flags &= ~OEP_CONSTANT_ADDRESS_OF;
-	  return OP_SAME_WITH_NULL (2);
+	  return OP_SAME (1) && OP_SAME_WITH_NULL (2);
 
 	case BIT_FIELD_REF:
 	  if (!OP_SAME (0))
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d0f01c8..7cf47c4 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,10 @@
 2013-05-27  Richard Biener  <rguenther@suse.de>
 
+	PR tree-optimization/57417
+	* gcc.dg/torture/pr57417.c: New testcase.
+
+2013-05-27  Richard Biener  <rguenther@suse.de>
+
 	PR tree-optimization/57396
 	* gfortran.fortran-torture/execute/pr57396.f90: New testcase.
 
diff --git a/gcc/testsuite/gcc.dg/torture/pr57417.c b/gcc/testsuite/gcc.dg/torture/pr57417.c
new file mode 100644
index 0000000..6eac6f9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr57417.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+
+int a, b;
+volatile int *c;
+
+void foo ()
+{
+  volatile int d[1];
+  b = 0;
+  for (;; a--)
+    c = &d[b];
+}
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index 0e7a74c..6886efb 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -1145,7 +1145,7 @@ vn_reference_fold_indirect (vec<vn_reference_op_s> *ops,
   addr_base = get_addr_base_and_unit_offset (TREE_OPERAND (op->op0, 0),
 					     &addr_offset);
   gcc_checking_assert (addr_base && TREE_CODE (addr_base) != MEM_REF);
-  if (addr_base != op->op0)
+  if (addr_base != TREE_OPERAND (op->op0, 0))
     {
       double_int off = tree_to_double_int (mem_op->op0);
       off = off.sext (TYPE_PRECISION (TREE_TYPE (mem_op->op0)));
@@ -2608,6 +2608,7 @@ static inline bool
 set_ssa_val_to (tree from, tree to)
 {
   tree currval = SSA_VAL (from);
+  HOST_WIDE_INT toff, coff;
 
   if (from != to)
     {
@@ -2643,7 +2644,17 @@ set_ssa_val_to (tree from, tree to)
       print_generic_expr (dump_file, to, 0);
     }
 
-  if (currval != to  && !operand_equal_p (currval, to, OEP_PURE_SAME))
+  if (currval != to
+      && !operand_equal_p (currval, to, 0)
+      /* ???  For addresses involving volatile objects or types operand_equal_p
+         does not reliably detect ADDR_EXPRs as equal.  We know we are only
+	 getting invariant gimple addresses here, so can use
+	 get_addr_base_and_unit_offset to do this comparison.  */
+      && !(TREE_CODE (currval) == ADDR_EXPR
+	   && TREE_CODE (to) == ADDR_EXPR
+	   && (get_addr_base_and_unit_offset (TREE_OPERAND (currval, 0), &coff)
+	       == get_addr_base_and_unit_offset (TREE_OPERAND (to, 0), &toff))
+	   && coff == toff))
     {
       VN_INFO (from)->valnum = to;
       if (dump_file && (dump_flags & TDF_DETAILS))