llvm dev - Jan 2012 - [LLVMdev] landingpad instruction documentation is vague

On Wed, Jan 11, 2012 at 11:37:50AM +0100, Duncan Sands
wrote:
> Hi Yuri,
> 
> > I am new to the landingpad (which is relatively new too).
> > Documentation http://llvm.org/docs/LangRef.html#i_landingpad leaves
some
> > questions open:
> >
> > 1. What happens when actual exception type isn't listed in catch
or
> > filter clauses? Does it still return the corresponding structure like
if
> > it was listed? Or behavior is undefined?
> 
> if it doesn't match a clause then the exception continues to be
unwound.
> Note that you can match a catch clause without being equal to the type
> in the catch clause (for example because the catch clause type represents
> some class B, and thus will also match a class A if B derives from A).
[snippet]

  It would be great if this can be put somewhere on the website to clear
LLVM exception handling further. ;)

Regards,
chenwj

-- 
Wei-Ren Chen (陳韋任)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj

On Jan 11, 2012, at 3:15 AM, 陳韋任 wrote:
> On Wed, Jan 11, 2012 at 11:37:50AM +0100, Duncan Sands wrote:
>> Hi Yuri,
>> 
>>> I am new to the landingpad (which is relatively new too).
>>> Documentation http://llvm.org/docs/LangRef.html#i_landingpad leaves
some
>>> questions open:
>>> 
>>> 1. What happens when actual exception type isn't listed in
catch or
>>> filter clauses? Does it still return the corresponding structure
like if
>>> it was listed? Or behavior is undefined?
>> 
>> if it doesn't match a clause then the exception continues to be
unwound.
>> Note that you can match a catch clause without being equal to the type
>> in the catch clause (for example because the catch clause type
represents
>> some class B, and thus will also match a class A if B derives from A).
> 
> [snippet]
> 
>  It would be great if this can be put somewhere on the website to clear
> LLVM exception handling further. ;)
> 
Hi 陳韋任,

This isn't an llvm-specific feature, but how exceptions work in general.

-bw

> This isn't an llvm-specific feature, but how exceptions work in
general.
  Ugh, Q2 and Q3 are also not llvm-specific feature?

Regards,
chenwj

-- 
Wei-Ren Chen (陳韋任)
Computer Systems Lab, Institute of Information Science,
Academia Sinica, Taiwan (R.O.C.)
Tel:886-2-2788-3799 #1667
Homepage: http://people.cs.nctu.edu.tw/~chenwj

Hi 陳韋任,
> On Wed, Jan 11, 2012 at 11:37:50AM +0100, Duncan Sands wrote:
>> Hi Yuri,
>>
>>> I am new to the landingpad (which is relatively new too).
>>> Documentation http://llvm.org/docs/LangRef.html#i_landingpad leaves
some
>>> questions open:
>>>
>>> 1. What happens when actual exception type isn't listed in
catch or
>>> filter clauses? Does it still return the corresponding structure
like if
>>> it was listed? Or behavior is undefined?
>>
>> if it doesn't match a clause then the exception continues to be
unwound.
>> Note that you can match a catch clause without being equal to the type
>> in the catch clause (for example because the catch clause type
represents
>> some class B, and thus will also match a class A if B derives from A).
>
> [snippet]
>
>    It would be great if this can be put somewhere on the website to clear
> LLVM exception handling further. ;)
I added some text to the landingpad section of the LangRef.

Ciao, Duncan.