On Thu, Mar 29, 2012 at 10:47 AM, Stephan Bergmann <sberg...@redhat.com> wrote: > On 03/29/2012 09:44 AM, Jakub Jelinek wrote: >> >> On Thu, Mar 29, 2012 at 09:05:29AM +0200, Stephan Bergmann wrote: >>> >>> In LibreOffice's ever-beloved low-level code to synthesize calls to >>> C++ virtual functions, I'm having the following problem (on Linux >>> x86_64). The function callVirtualMethod >>> at<http://cgit.freedesktop.org/libreoffice/core/tree/bridges/source/cpp_uno/gcc3_linux_x86-64/uno2cpp.cxx?id=571876c1234ae55aab0198c7e2caf9049fcd230e#n61> >>> effectively does the following: >>> >>> First, call dummy_can_throw_anything that can potentially throw (see >>> below for why that's there). Second, in an asm block, call some >>> virtual function (that can potentially throw). Third, call >>> x86_64::fill_struct that can potentially throw (it doesn't, but >>> nobody bothered to annotate it as "throw ()"). >> >> >> If the asm isn't in headers, but just in a single short source file >> or two, you could try compiling that file with -fnon-call-exceptions. >> It is nothing I'd recommend for the whole codebase though. > > > Turns out I had to move the callVirtualMethod function containing the asm > into a source file of its own, anyway. (Otherwise, even if it no longer > explicitly called functions that can throw, and thus no longer had > corresponding .gcc_except_table entries, exception throwing still lead to > std::terminate. There are other functions in the same source file > callVirtualMethod was originally in that do have .gcc_except_table entries. > Kind of invalidates my previous explanation of why exception handling > bailed out to std::terminate. Looks like I haven't groked it yet, anyway.) > > So an explicit -fnon-call-exceptions on the command line seems to indeed > help. Unfortunately, moving that into a > > #pragma GCC optimize ("non-call-exceptions") > > at the top of the source file that defines callVirtualMethod (and nothing > more) does *not* work. Is that a bug?
The optimize pragma has only very limited support for this kind of options, so yes, it's techincally a bug but don't hold your breath. > Anyway, would it be worthwhile filing an RFE for an asm annotation telling > the compiler that it contains code that can throw? I suppose yes. Richard. > Thanks, > Stephan
