The following code calls terminate() at runtime because copying the exception
object into the catch parameter throws an exception:
struct A
{
A() { }
A (const A&) { throw 1; }
};
int main()
{
try
{
throw A();
}
catch (A) { }
}
In G++ 3.4 this was handled by just leaving the copy constructor call out of
the LSDA action table, so the personality function knew to call terminate. As
of the tree-ssa merge, this changed so that we started emitting code to check
the exception against a random filter and then call terminate from within the
function. This is a significant code size regression: a 25% jump in text size
from 3.4 to 4.0.
4.0 and up also unnecessarily think that __cxa_end_catch might throw; since A
has a trivial destructor, it can't throw in this case.
--
Summary: [4.3/4.4/4.5/4.6 Regression] G++ emits unnecessary EH
code
Product: gcc
Version: 4.6.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: c++
AssignedTo: jason at gcc dot gnu dot org
ReportedBy: jason at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44127
