Viewing file:  Constant_folding.cpp (1.21 KB) -rw-rw-r--
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/*
* phc -- the open source PHP compiler
* See doc/license/README.license for licensing information
*
* Fold constant binary and unary expressions.
* Note lack of constant propagation.
*/
#include "Constant_folding.h"
#include "process_ir/stats.h"
#include "embed/embed.h"
using namespace AST;
Expr* Constant_folding::post_bin_op (Bin_op* in)
{
Literal* left = dynamic_cast<Literal*> (in->left);
Literal* right = dynamic_cast<Literal*> (in->right);
if (left == NULL || right == NULL)
return in;
CTS ("folded_bin_op");
return PHP::fold_constant_expr (in);
}
Expr* Constant_folding::post_unary_op (Unary_op* in)
{
// TODO I expect there is a constant, near LONG_MAX, for which the '-' sign
// turns it into a float, and the second '-' turns it into a positive float,
// yet if we remove both '-' signs, we get an int. I couldn't find it with
// some quick tests.
// Match (- - f())
Wildcard<Expr>* expr = new Wildcard<Expr>;
if (in->match (new Unary_op (new Unary_op (expr, "-"), "-")))
{
CTS ("folded_double_minus");
return expr;
}
// match constant
Literal* lit = dynamic_cast<Literal*> (in->expr);
if (lit)
{
CTS ("folded_unary_op");
return PHP::fold_constant_expr (in);
}
return in;
}
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