static tree optimize_minmax_comparison (tree);
static tree extract_muldiv (tree, tree, enum tree_code, tree);
static tree extract_muldiv_1 (tree, tree, enum tree_code, tree);
-static tree strip_compound_expr (tree, tree);
static int multiple_of_p (tree, tree, tree);
static tree constant_boolean_node (int, tree);
-static int count_cond (tree, int);
static tree fold_binary_op_with_conditional_arg (enum tree_code, tree, tree,
tree, int);
static bool fold_real_zero_addition_p (tree, tree, int);
return 0;
}
\f
-/* If T contains a COMPOUND_EXPR which was inserted merely to evaluate
- S, a SAVE_EXPR, return the expression actually being evaluated. Note
- that we may sometimes modify the tree. */
-
-static tree
-strip_compound_expr (tree t, tree s)
-{
- enum tree_code code = TREE_CODE (t);
-
- /* See if this is the COMPOUND_EXPR we want to eliminate. */
- if (code == COMPOUND_EXPR && TREE_CODE (TREE_OPERAND (t, 0)) == CONVERT_EXPR
- && TREE_OPERAND (TREE_OPERAND (t, 0), 0) == s)
- return TREE_OPERAND (t, 1);
-
- /* See if this is a COND_EXPR or a simple arithmetic operator. We
- don't bother handling any other types. */
- else if (code == COND_EXPR)
- {
- TREE_OPERAND (t, 0) = strip_compound_expr (TREE_OPERAND (t, 0), s);
- TREE_OPERAND (t, 1) = strip_compound_expr (TREE_OPERAND (t, 1), s);
- TREE_OPERAND (t, 2) = strip_compound_expr (TREE_OPERAND (t, 2), s);
- }
- else if (TREE_CODE_CLASS (code) == '1')
- TREE_OPERAND (t, 0) = strip_compound_expr (TREE_OPERAND (t, 0), s);
- else if (TREE_CODE_CLASS (code) == '<'
- || TREE_CODE_CLASS (code) == '2')
- {
- TREE_OPERAND (t, 0) = strip_compound_expr (TREE_OPERAND (t, 0), s);
- TREE_OPERAND (t, 1) = strip_compound_expr (TREE_OPERAND (t, 1), s);
- }
-
- return t;
-}
-\f
/* Return a node which has the indicated constant VALUE (either 0 or
1), and is of the indicated TYPE. */
}
}
-/* Utility function for the following routine, to see how complex a nesting of
- COND_EXPRs can be. EXPR is the expression and LIMIT is a count beyond which
- we don't care (to avoid spending too much time on complex expressions.). */
-
-static int
-count_cond (tree expr, int lim)
-{
- int ctrue, cfalse;
-
- if (TREE_CODE (expr) != COND_EXPR)
- return 0;
- else if (lim <= 0)
- return 0;
-
- ctrue = count_cond (TREE_OPERAND (expr, 1), lim - 1);
- cfalse = count_cond (TREE_OPERAND (expr, 2), lim - 1 - ctrue);
- return MIN (lim, 1 + ctrue + cfalse);
-}
-
/* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
tree test, true_value, false_value;
tree lhs = NULL_TREE;
tree rhs = NULL_TREE;
- /* In the end, we'll produce a COND_EXPR. Both arms of the
- conditional expression will be binary operations. The left-hand
- side of the expression to be executed if the condition is true
- will be pointed to by TRUE_LHS. Similarly, the right-hand side
- of the expression to be executed if the condition is true will be
- pointed to by TRUE_RHS. FALSE_LHS and FALSE_RHS are analogous --
- but apply to the expression to be executed if the conditional is
- false. */
- tree *true_lhs;
- tree *true_rhs;
- tree *false_lhs;
- tree *false_rhs;
- /* These are the codes to use for the left-hand side and right-hand
- side of the COND_EXPR. Normally, they are the same as CODE. */
- enum tree_code lhs_code = code;
- enum tree_code rhs_code = code;
- /* And these are the types of the expressions. */
- tree lhs_type = type;
- tree rhs_type = type;
- int save = 0;
-
- if (TREE_CODE (cond) != COND_EXPR
- && TREE_CODE_CLASS (code) == '<')
- return NULL_TREE;
-
- if (TREE_CODE (arg) == COND_EXPR
- && count_cond (cond, 25) + count_cond (arg, 25) > 25)
- return NULL_TREE;
- if (TREE_SIDE_EFFECTS (arg)
- && (lang_hooks.decls.global_bindings_p () != 0
- || CONTAINS_PLACEHOLDER_P (arg)))
+ /* This transformation is only worthwhile if we don't have to wrap
+ arg in a SAVE_EXPR, and the operation can be simplified on atleast
+ one of the branches once its pushed inside the COND_EXPR. */
+ if (!TREE_CONSTANT (arg))
return NULL_TREE;
- if (cond_first_p)
- {
- true_rhs = false_rhs = &arg;
- true_lhs = &true_value;
- false_lhs = &false_value;
- }
- else
- {
- true_lhs = false_lhs = &arg;
- true_rhs = &true_value;
- false_rhs = &false_value;
- }
-
if (TREE_CODE (cond) == COND_EXPR)
{
test = TREE_OPERAND (cond, 0);
false_value = TREE_OPERAND (cond, 2);
/* If this operand throws an expression, then it does not make
sense to try to perform a logical or arithmetic operation
- involving it. Instead of building `a + throw 3' for example,
- we simply build `a, throw 3'. */
+ involving it. */
if (VOID_TYPE_P (TREE_TYPE (true_value)))
- {
- if (! cond_first_p)
- {
- lhs_code = COMPOUND_EXPR;
- lhs_type = void_type_node;
- }
- else
- lhs = true_value;
- }
+ lhs = true_value;
if (VOID_TYPE_P (TREE_TYPE (false_value)))
- {
- if (! cond_first_p)
- {
- rhs_code = COMPOUND_EXPR;
- rhs_type = void_type_node;
- }
- else
- rhs = false_value;
- }
+ rhs = false_value;
}
else
{
false_value = fold_convert (testtype, integer_zero_node);
}
- /* If ARG is complex we want to make sure we only evaluate it once. Though
- this is only required if it is volatile, it might be more efficient even
- if it is not. However, if we succeed in folding one part to a constant,
- we do not need to make this SAVE_EXPR. Since we do this optimization
- primarily to see if we do end up with constant and this SAVE_EXPR
- interferes with later optimizations, suppressing it when we can is
- important.
-
- If we are not in a function, we can't make a SAVE_EXPR, so don't try to
- do so. Don't try to see if the result is a constant if an arm is a
- COND_EXPR since we get exponential behavior in that case. */
-
- if (saved_expr_p (arg))
- save = 1;
- else if (lhs == 0 && rhs == 0
- && !TREE_CONSTANT (arg)
- && lang_hooks.decls.global_bindings_p () == 0
- && ((TREE_CODE (arg) != VAR_DECL && TREE_CODE (arg) != PARM_DECL)
- || TREE_SIDE_EFFECTS (arg)))
- {
- if (TREE_CODE (true_value) != COND_EXPR)
- lhs = fold (build (lhs_code, lhs_type, *true_lhs, *true_rhs));
-
- if (TREE_CODE (false_value) != COND_EXPR)
- rhs = fold (build (rhs_code, rhs_type, *false_lhs, *false_rhs));
-
- if ((lhs == 0 || ! TREE_CONSTANT (lhs))
- && (rhs == 0 || !TREE_CONSTANT (rhs)))
- {
- arg = save_expr (arg);
- lhs = rhs = 0;
- save = saved_expr_p (arg);
- }
- }
-
if (lhs == 0)
- lhs = fold (build (lhs_code, lhs_type, *true_lhs, *true_rhs));
+ lhs = fold (cond_first_p ? build2 (code, type, true_value, arg)
+ : build2 (code, type, arg, true_value));
if (rhs == 0)
- rhs = fold (build (rhs_code, rhs_type, *false_lhs, *false_rhs));
-
- test = fold (build (COND_EXPR, type, test, lhs, rhs));
-
- /* If ARG involves a SAVE_EXPR, we need to ensure it is evaluated
- ahead of the COND_EXPR we made. Otherwise we would have it only
- evaluated in one branch, with the other branch using the result
- but missing the evaluation code. Beware that the save_expr call
- above might not return a SAVE_EXPR, so testing the TREE_CODE
- of ARG is not enough to decide here. */
- if (save)
- return build (COMPOUND_EXPR, type,
- fold_convert (void_type_node, arg),
- strip_compound_expr (test, arg));
- else
- return fold_convert (type, test);
+ rhs = fold (cond_first_p ? build2 (code, type, false_value, arg)
+ : build2 (code, type, arg, false_value));
+
+ test = fold (build3 (COND_EXPR, type, test, lhs, rhs));
+ return fold_convert (type, test);
}
\f
projects / gcc.git / commitdiff