Red Hat ENTERPRISE LINUX 4 Manual page 121

Chapter 4. GCC Command Options
-fbounds-check
For front-ends that support it, generate additional code to check that indices used to access arrays
are within the declared range. This is currently only supported by the Java and Fortran 77 front-
ends, where this option defaults to true and false respectively.
-ftrapv
This option generates traps for signed overflow on addition, subtraction, multiplication opera-
tions.
-fwrapv
This option instructs the compiler to assume that signed arithmetic overflow of addition, subtrac-
tion and multiplication wraps around using twos-complement representation. This flag enables
some optimizations and disables other. This option is enabled by default for the Java front-end,
as required by the Java language specification.
-fexceptions
Enable exception handling. Generates extra code needed to propagate exceptions. For some tar-
gets, this implies GCC will generate frame unwind information for all functions, which can pro-
duce significant data size overhead, although it does not affect execution. If you do not specify
this option, GCC will enable it by default for languages like C++ which normally require excep-
tion handling, and disable it for languages like C that do not normally require it. However, you
may need to enable this option when compiling C code that needs to interoperate properly with
exception handlers written in C++. You may also wish to disable this option if you are compiling
older C++ programs that don't use exception handling.
-fnon-call-exceptions
Generate code that allows trapping instructions to throw exceptions. Note that this requires
platform-specific runtime support that does not exist everywhere. Moreover, it only allows trap-
ping instructions to throw exceptions, i.e. memory references or floating point instructions. It
does not allow exceptions to be thrown from arbitrary signal handlers such as
-funwind-tables
Similar to
-fexceptions
affect the generated code in any other way. You will normally not enable this option; instead, a
language processor that needs this handling would enable it on your behalf.
-fasynchronous-unwind-tables
Generate unwind table in dwarf2 format, if supported by target machine. The table is exact at
each instruction boundary, so it can be used for stack unwinding from asynchronous events (such
as debugger or garbage collector).
-fpcc-struct-return
Return "short"
struct
This convention is less efficient, but it has the advantage of allowing intercallability between
GCC-compiled files and files compiled with other compilers, particularly the Portable C Com-
piler (pcc).
The precise convention for returning structures in memory depends on the target configuration
macros.
Short structures and unions are those whose size and alignment match that of some integer type.
Warning: code compiled with the
code compiled with the
application binary interface.
, except that it will just generate any needed static data, but will not
and values in memory like longer ones, rather than in registers.
union
-fpcc-struct-return
-freg-struct-return
switch is not binary compatible with
switch. Use it to conform to a non-default
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.
SIGALRM