2005-01-08 Jeff Law <law@redhat.com>

[pf3gnuchains/gcc-fork.git] / gcc / tree-ssa-operands.c

diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index 9138e67..2ca208e 100644 (file)
--- a/gcc/tree-ssa-operands.c
+++ b/gcc/tree-ssa-operands.c
@@ -120,7 +120,7 @@ static GTY (()) varray_type build_v_must_defs;
 bool ssa_call_clobbered_cache_valid;
 bool ssa_ro_call_cache_valid;
 
-/* These arrays are the cached operand vectors for call clobberd calls.  */
+/* These arrays are the cached operand vectors for call clobbered calls.  */
 static GTY (()) varray_type clobbered_v_may_defs;
 static GTY (()) varray_type clobbered_vuses;
 static GTY (()) varray_type ro_call_vuses;
@@ -893,20 +893,33 @@ build_ssa_operands (tree stmt, stmt_ann_t ann, stmt_operands_p old_ops,
   switch (code)
     {
     case MODIFY_EXPR:
-      get_expr_operands (stmt, &TREE_OPERAND (stmt, 1), opf_none);
-      if (TREE_CODE (TREE_OPERAND (stmt, 0)) == ARRAY_REF 
-         || TREE_CODE (TREE_OPERAND (stmt, 0)) == ARRAY_RANGE_REF
-         || TREE_CODE (TREE_OPERAND (stmt, 0)) == COMPONENT_REF
-         || TREE_CODE (TREE_OPERAND (stmt, 0)) == REALPART_EXPR
-         || TREE_CODE (TREE_OPERAND (stmt, 0)) == IMAGPART_EXPR
-         /* Use a V_MAY_DEF if the RHS might throw, as the LHS won't be
-            modified in that case.  FIXME we should represent somehow
-            that it is killed on the fallthrough path.  */
-         || tree_could_throw_p (TREE_OPERAND (stmt, 1)))
-        get_expr_operands (stmt, &TREE_OPERAND (stmt, 0), opf_is_def);
-      else
-        get_expr_operands (stmt, &TREE_OPERAND (stmt, 0), 
-                          opf_is_def | opf_kill_def);
+      /* First get operands from the RHS.  For the LHS, we use a V_MAY_DEF if
+        either only part of LHS is modified or if the RHS might throw,
+        otherwise, use V_MUST_DEF.
+
+        ??? If it might throw, we should represent somehow that it is killed
+        on the fallthrough path.  */
+      {
+       tree lhs = TREE_OPERAND (stmt, 0);
+       int lhs_flags = opf_is_def;
+
+       get_expr_operands (stmt, &TREE_OPERAND (stmt, 1), opf_none);
+
+       /* If the LHS is a VIEW_CONVERT_EXPR, it isn't changing whether
+          or not the entire LHS is modified; that depends on what's
+          inside the VIEW_CONVERT_EXPR.  */
+       if (TREE_CODE (lhs) == VIEW_CONVERT_EXPR)
+         lhs = TREE_OPERAND (lhs, 0);
+
+       if (TREE_CODE (lhs) != ARRAY_REF && TREE_CODE (lhs) != ARRAY_RANGE_REF
+           && TREE_CODE (lhs) != COMPONENT_REF
+           && TREE_CODE (lhs) != BIT_FIELD_REF
+           && TREE_CODE (lhs) != REALPART_EXPR
+           && TREE_CODE (lhs) != IMAGPART_EXPR)
+         lhs_flags |= opf_kill_def;
+
+        get_expr_operands (stmt, &TREE_OPERAND (stmt, 0), lhs_flags);
+      }
       break;
 
     case COND_EXPR:
@@ -1361,18 +1374,6 @@ get_indirect_ref_operands (tree stmt, tree expr, int flags)
   /* Stores into INDIRECT_REF operands are never killing definitions.  */
   flags &= ~opf_kill_def;
 
-  if (REF_ORIGINAL (expr))
-    {
-      enum tree_code ocode = TREE_CODE (REF_ORIGINAL (expr));
-
-      /* If we originally accessed part of a structure, we do it still.  */
-      if (ocode == ARRAY_REF
-         || ocode == COMPONENT_REF
-         || ocode == REALPART_EXPR
-         || ocode == IMAGPART_EXPR)
-       flags &= ~opf_kill_def;
-    }
-
   if (SSA_VAR_P (ptr))
     {
       struct ptr_info_def *pi = NULL;
@@ -1519,13 +1520,10 @@ add_stmt_operand (tree *var_p, stmt_ann_t s_ann, int flags)
   sym = (TREE_CODE (var) == SSA_NAME ? SSA_NAME_VAR (var) : var);
   v_ann = var_ann (sym);
 
-  /* Don't expose volatile variables to the optimizers.  */
-  if (TREE_THIS_VOLATILE (sym))
-    {
-      if (s_ann)
-       s_ann->has_volatile_ops = true;
-      return;
-    }
+  /* Mark statements with volatile operands.  Optimizers should back
+     off from statements having volatile operands.  */
+  if (TREE_THIS_VOLATILE (sym) && s_ann)
+    s_ann->has_volatile_ops = true;
 
   if (is_real_op)
     {
@@ -1709,7 +1707,7 @@ add_call_clobber_ops (tree stmt)
       s_ann->makes_aliased_stores = empty_ann.makes_aliased_stores;
     }
 
-  /* Perpare empty cache vectors.  */
+  /* Prepare empty cache vectors.  */
   if (clobbered_v_may_defs)
     {
       VARRAY_POP_ALL (clobbered_vuses);
@@ -1780,7 +1778,7 @@ add_call_read_ops (tree stmt)
   if (s_ann)
     s_ann->makes_aliased_loads = empty_ann.makes_aliased_loads;
 
-  /* Perpare empty cache vectors.  */
+  /* Prepare empty cache vectors.  */
   if (ro_call_vuses)
     VARRAY_POP_ALL (ro_call_vuses);
   else