RealView Compilation Tools Compiler Reference Guide - ARM ...

C and C++ Implementation Details
5.2.7 C++ exception handling
C++ exception handling is fully supported in RVCT. However, the compiler does not
support this by default. You must enable C++ exception handling with the --exceptions
option. See --[no_]exceptions on page 2-35 for more information.
Note
The Rogue Wave Standard C++ Library is provided with C++ exceptions enabled.
You can exercise limited control over exception table generation.
Function unwinding at runtime
By default, functions compiled with --exceptions can be unwound at runtime. See
--[no_]exceptions on page 2-35 for more information. Function unwinding includes
destroying C++ automatic variables, and restoring register values saved in the stack
frame. Function unwinding is implemented by emitting an exception table describing
the operations to be performed.
You can enable or disable unwinding for specific functions with the pragmas #pragma
exceptions_unwind and #pragma no_exceptions_unwind, see Pragmas on page 4-49 for
more information. The --exceptions_unwind option sets the initial value of this pragma.
Disabling function unwinding for a function has the following effects:
• Exceptions cannot be thrown through that function at runtime, and no stack
unwinding occurs for that throw. If the throwing language is C++, then
std::terminate is called.
• A very compact exception table representation can be used to describe the
function, which assists smart linkers with table optimization.
• Function inlining is restricted, because the caller and callee must interact
correctly.
Therefore, #pragma no_exceptions_unwind can be used to forcibly prevent unwinding in
a way that requires no additional source decoration.
By contrast, in C++ an empty function exception specification permits unwinding as far
as the protected function, then calls std::unexpected() in accordance with the ISO C++
Standard.
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