The SUIF library includes a number of functions for error handling. These functions handle three kinds of problems: errors, warnings, and assertions. Assertions are tests for things that should never occur in a correct program. Any problem that could potentially occur in a correct program due to bad input or other external conditions should be treated as an error rather than an assertion failure. Warnings are used to report potentially troublesome conditions that are not serious enough to cause a fatal error.
Two macros are available to implement assertions. The assert
macro takes a single expression as an argument. If the expression
evaluates to zero, a message is printed showing the current line number,
file name, and the expression that failed, and then the abort
function is called to terminate the program. The assert_msg
macro is similar except that it also prints a user-defined message if
the assertion fails. Besides the expression to be tested,
assert_msg takes an argument that contains the message to
be printed. This second argument must hold the printf format
string and the arguments for the call to printf, separated by
commas. To keep the commas from splitting up the second argument, it
must be surrounded by parentheses. For example:
assert_msg(sym->parent(), ("no parent for %s", sym->name()));
Errors may be reported using the error_line function. The
return_code parameter specifies the method of terminating the
program. If the return code is negative, the abort function is
called. If it is greater than zero, the exit function is called
with the specified return code. If the return code is zero, the error
message will be printed but the program will not terminate. The
the_node parameter is optional and may be set to NULL. If
used, it points to the AST node closest to the point where the error was
detected, and the library tries to use it to find and print the
corresponding source line number. Finally, the fmt parameter
specifies the printf format string used to print the error
message and any additional parameters are passed on to printf.
The verror_line function is identical to error_line except
that it passes the variable arguments for printf using a
varargs-style list. This is just like the standard
vprintf function.
The warning_line and vwarning_line functions are just like
the corresponding error functions, except that they print warning
messages and do not terminate the program. Consequently, they do not
have return_code parameters.