On Fri, Apr 17, 2009 at 10:27 AM, Alexander Terekhov <terekhov@web.de> wrote:
Gabriel Dos Reis wrote:
On Fri, Apr 17, 2009 at 6:55 AM, Alexander Terekhov <terekhov@web.de> wrote:
Gabriel Dos Reis wrote:
On Thu, Apr 16, 2009 at 7:11 PM, Alexander Terekhov <terekhov@web.de> wrote:
Scott McMurray wrote: [...]
I don't see how you're going to get the "at throw point" you're asking for.
Two-phase EH.
An implementation strategy used by some compilers. It is not something required by C++. It is mysterious why some popular compilers insist on using that strategy when they know they are dealing with C++ applications.
Because that strategy allows to not unwind the stack for unexpected exceptions.
So, now we are talking of cost of doing something not required by C++ semantics; rarely used in practice, but with a cost imposed on those who don't want it. A strategy that hurts performance of C++ programs.
Wow. Are you sure?
Yes.
Let all the folks like
http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf
know about such disastrous nature of two-phase EH.
That document only provides the complement to the psABI for the so-called 'common vendor ABI' with its 'official' website at http://www.codesourcery.com/public/cxx-abi/abi-eh.html And quoting for the document: # A two-phase exception-handling model is not strictly necessary to implement # C++ language semantics, but it does provide some benefits. For example, # the first phase allows an exception-handling mechanism to dismiss an # exception before stack unwinding begins, which allows resumptive exception # handling (correcting the exceptional condition and resuming execution at # the point where it was raised). While C++ does not support resumptive # exception handling, other languages do, and the two-phase model allows # C++ to coexist with those languages on the stack. How many industrial strength languages support resumptive exception handling? -- Gaby