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fold-const.c (fold_binary_op_with_conditional_arg): New function, split out from ...

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* fold-const.c (fold_binary_op_with_conditional_arg): New
	function, split out from ...
	(fold): ... here.
	* tree.def (COND_EXPR): Document the use of VOID_TYPE for
	conditional arms that throw exceptions.

From-SVN: r39822
This commit is contained in:
Mark Mitchell 2001-02-18 06:53:19 +00:00 committed by Mark Mitchell
parent 9c2c54dc94
commit 68626d4f0e
4 changed files with 160 additions and 116 deletions
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6
gcc/ChangeLog
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@ -1,5 +1,11 @@
2001-02-17 Mark Mitchell <mark@codesourcery.com>
* fold-const.c (fold_binary_op_with_conditional_arg): New
function, split out from ...
(fold): ... here.
* tree.def (COND_EXPR): Document the use of VOID_TYPE for
conditional arms that throw exceptions.
* print-tree.c (print_node): Do not use BLOCK_CHAIN when we're not
looking at a BLOCK.

252
gcc/fold-const.c
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@ -101,7 +101,9 @@ static tree strip_compound_expr PARAMS ((tree, tree));
static int multiple_of_p PARAMS ((tree, tree, tree));
static tree constant_boolean_node PARAMS ((int, tree));
static int count_cond PARAMS ((tree, int));
static tree fold_binary_op_with_conditional_arg
PARAMS ((enum tree_code, tree, tree, tree, int));
#ifndef BRANCH_COST
#define BRANCH_COST 1
#endif
@ -4698,6 +4700,135 @@ count_cond (expr, lim)
false = count_cond (TREE_OPERAND (expr, 2), lim - 1 - true);
return MIN (lim, 1 + true + false);
}
/* Transform `a + (b ? x : y)' into `x ? (a + b) : (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)'
expression, and ARG to `a'. If COND_FIRST_P is non-zero, then the
COND is the first argument to CODE; otherwise (as in the example
given here), it is the second argument. TYPE is the type of the
original expression. */
static tree
fold_binary_op_with_conditional_arg (code, type, cond, arg, cond_first_p)
enum tree_code code;
tree type;
tree cond;
tree arg;
int cond_first_p;
{
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 analagous --
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;
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);
true_value = TREE_OPERAND (cond, 1);
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'. */
if (VOID_TYPE_P (TREE_TYPE (true_value)))
{
lhs_code = COMPOUND_EXPR;
if (!cond_first_p)
lhs_type = void_type_node;
}
if (VOID_TYPE_P (TREE_TYPE (false_value)))
{
rhs_code = COMPOUND_EXPR;
if (!cond_first_p)
rhs_type = void_type_node;
}
}
else
{
tree testtype = TREE_TYPE (cond);
test = cond;
true_value = convert (testtype, integer_one_node);
false_value = 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 (TREE_CODE (arg) != SAVE_EXPR && ! TREE_CONSTANT (arg)
&& 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;
}
if (lhs == 0)
lhs = fold (build (lhs_code, lhs_type, *true_lhs, *true_rhs));
if (rhs == 0)
rhs = fold (build (rhs_code, rhs_type, *false_lhs, *false_rhs));
test = fold (build (COND_EXPR, type, test, lhs, rhs));
if (TREE_CODE (arg) == SAVE_EXPR)
return build (COMPOUND_EXPR, type,
convert (void_type_node, arg),
strip_compound_expr (test, arg));
else
return convert (type, test);
}
/* Perform constant folding and related simplification of EXPR.
The related simplifications include x*1 => x, x*0 => 0, etc.,
@ -4919,70 +5050,9 @@ fold (expr)
&& (! TREE_SIDE_EFFECTS (arg0)
|| (global_bindings_p () == 0
&& ! contains_placeholder_p (arg0))))
{
tree test, true_value, false_value;
tree lhs = 0, rhs = 0;
if (TREE_CODE (arg1) == COND_EXPR)
{
test = TREE_OPERAND (arg1, 0);
true_value = TREE_OPERAND (arg1, 1);
false_value = TREE_OPERAND (arg1, 2);
}
else
{
tree testtype = TREE_TYPE (arg1);
test = arg1;
true_value = convert (testtype, integer_one_node);
false_value = convert (testtype, integer_zero_node);
}
/* If ARG0 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 (TREE_CODE (arg0) != SAVE_EXPR && ! TREE_CONSTANT (arg0)
&& global_bindings_p () == 0
&& ((TREE_CODE (arg0) != VAR_DECL
&& TREE_CODE (arg0) != PARM_DECL)
|| TREE_SIDE_EFFECTS (arg0)))
{
if (TREE_CODE (true_value) != COND_EXPR)
lhs = fold (build (code, type, arg0, true_value));
if (TREE_CODE (false_value) != COND_EXPR)
rhs = fold (build (code, type, arg0, false_value));
if ((lhs == 0 || ! TREE_CONSTANT (lhs))
&& (rhs == 0 || !TREE_CONSTANT (rhs)))
arg0 = save_expr (arg0), lhs = rhs = 0;
}
if (lhs == 0)
lhs = fold (build (code, type, arg0, true_value));
if (rhs == 0)
rhs = fold (build (code, type, arg0, false_value));
test = fold (build (COND_EXPR, type, test, lhs, rhs));
if (TREE_CODE (arg0) == SAVE_EXPR)
return build (COMPOUND_EXPR, type,
convert (void_type_node, arg0),
strip_compound_expr (test, arg0));
else
return convert (type, test);
}
return
fold_binary_op_with_conditional_arg (code, type, arg1, arg0,
/*cond_first_p=*/0);
else if (TREE_CODE (arg0) == COMPOUND_EXPR)
return build (COMPOUND_EXPR, type, TREE_OPERAND (arg0, 0),
fold (build (code, type, TREE_OPERAND (arg0, 1), arg1)));
@ -4994,55 +5064,9 @@ fold (expr)
&& (! TREE_SIDE_EFFECTS (arg1)
|| (global_bindings_p () == 0
&& ! contains_placeholder_p (arg1))))
{
tree test, true_value, false_value;
tree lhs = 0, rhs = 0;
if (TREE_CODE (arg0) == COND_EXPR)
{
test = TREE_OPERAND (arg0, 0);
true_value = TREE_OPERAND (arg0, 1);
false_value = TREE_OPERAND (arg0, 2);
}
else
{
tree testtype = TREE_TYPE (arg0);
test = arg0;
true_value = convert (testtype, integer_one_node);
false_value = convert (testtype, integer_zero_node);
}
if (TREE_CODE (arg1) != SAVE_EXPR && ! TREE_CONSTANT (arg0)
&& global_bindings_p () == 0
&& ((TREE_CODE (arg1) != VAR_DECL
&& TREE_CODE (arg1) != PARM_DECL)
|| TREE_SIDE_EFFECTS (arg1)))
{
if (TREE_CODE (true_value) != COND_EXPR)
lhs = fold (build (code, type, true_value, arg1));
if (TREE_CODE (false_value) != COND_EXPR)
rhs = fold (build (code, type, false_value, arg1));
if ((lhs == 0 || ! TREE_CONSTANT (lhs))
&& (rhs == 0 || !TREE_CONSTANT (rhs)))
arg1 = save_expr (arg1), lhs = rhs = 0;
}
if (lhs == 0)
lhs = fold (build (code, type, true_value, arg1));
if (rhs == 0)
rhs = fold (build (code, type, false_value, arg1));
test = fold (build (COND_EXPR, type, test, lhs, rhs));
if (TREE_CODE (arg1) == SAVE_EXPR)
return build (COMPOUND_EXPR, type,
convert (void_type_node, arg1),
strip_compound_expr (test, arg1));
else
return convert (type, test);
}
return
fold_binary_op_with_conditional_arg (code, type, arg0, arg1,
/*cond_first_p=*/1);
}
else if (TREE_CODE_CLASS (code) == '<'
&& TREE_CODE (arg0) == COMPOUND_EXPR)

12
gcc/testsuite/g++.old-deja/g++.eh/crash5.C Normal file
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@ -0,0 +1,12 @@
// Build don't link:
// Origin: Mark Mitchell <mark@codesourcery.com>
int i;
int j;
void
f ()
{
j = j + (i ? 7 : throw 1);
}

6
gcc/tree.def
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@ -425,8 +425,10 @@ DEFTREECODE (TARGET_EXPR, "target_expr", 'e', 4)
Operand 0 is the condition.
Operand 1 is the then-value.
Operand 2 is the else-value.
Operand 0 may be of any type, but the types of operands 1 and 2
must be the same and the same as the type of this expression. */
Operand 0 may be of any type.
Operand 1 must have the same type as the entire expression, unless
it unconditionally throws an exception, in which case it should
have VOID_TYPE. The same constraints apply to operand 2. */
DEFTREECODE (COND_EXPR, "cond_expr", 'e', 3)
/* Declare local variables, including making RTL and allocating space.