[llvm-commits] [llvm] r49006 - in /llvm/trunk/lib: CodeGen/DwarfWriter.cpp CodeGen/LLVMTargetMachine.cpp CodeGen/SelectionDAG/SelectionDAGISel.cpp Target/PowerPC/PPCAsmPrinter.cpp Target/PowerPC/PPCRegisterInfo.cpp Target/X86/X86AsmPrinter.cpp Ta

[Daniel Berlin]

On Tue, Apr 1, 2008 at 2:12 PM, Chris Lattner <clattner at apple.com> wrote:
>
>  On Apr 1, 2008, at 10:49 AM, Dale Johannesen wrote:
>
>  >
>  > On Apr 1, 2008, at 10:40 AM, Chris Lattner wrote:
>  >>>
>  >>> Hmm.  llvm-gcc does not, in fact, mark foo() as nounwind.
>  >>
>  >> In this case, that is because baz() could throw.  Try:
>  >>
>  >> int foo() {
>  >>  try {
>  >>    bar();
>  >>  } catch(...) {
>  >>    return 17
>  >>  }
>  >>  return 42;
>  >> }
>  >
>  > llvm-gcc still does not mark foo as nounwind.
>
>  Regardless of whether it does or not, it would be correct for it to be
>  marked nounwind.  This detail is a missed optimization in llvm-gcc,


Yes, and one intended to be fixed soon (along with a real definition
of TREE_NOTHROW that specifies whether the called functions by this
function are guaranteed not to throw either, since this is currently
underspecified, as you've all discovered :P).