[foreign] RFR: refresh layout grammar

[Henry Jen]

On May 23, 2018, at 11:40 AM, Maurizio Cimadamore <maurizio.cimadamore at oracle.com> wrote:
> 
> 
> 
> On 23/05/18 19:10, Henry Jen wrote:
>> 
>>> On May 23, 2018, at 9:46 AM, Maurizio Cimadamore <maurizio.cimadamore at oracle.com> wrote:
>>> 
>>> Hi,
>>> I've put together a change which tweaks the grammar of layout descriptions used in annotations to correspond to what's described here [1].
>>> 
>>> The big changes are in DescriptorParser, which now has to understand the new grammar, and also in TestDescriptorGrammar, which has to combinatorially generate sentences of the new grammar.
>>> 
>>> All the other tedious changes are test changes, required to go from the old to the new grammar; I've adhered to the following rules:
>>> 
>>> 'b' -> ‘u8'
>> b is a bit, so should it be u1?
> uhm - booleans don't exist in C, so typically a byte will be allocated holding a 1 or a 0. You can think of it as u8[u1(value)u7(padding)] if you want, but the results are the same?

b is for bit-field, so that definitely a u1.
B is for boolean, that is _Bool in C, the x64 ABI state is 1 byte in size and alignment, so u8 is fine.

Cheers,
Henry

>> o is octet, which is the byte and should be u8.
> ok, I haven't seen octets around in existing tests
>> 
>>> 'c' -> ‘i8'
>> char is either signed or unsigned depends on platform. Since we are targeting x64 for now, unsigned is correct.
> ok
> 
> Maurizio
>> 
>>> 's' -> 'i16'
>>> 'i' -> 'i32'
>>> 'l' -> 'i64'
>>> 'q' -> 'i64'
>>> 
>>> Also note that in the new grammar capital letter denote big-endiannes, while in the old one they meant unsigned-ness.
>>> 
>>> There's a trivia in the DoubleUpcall test, which was using 'unsigned double' ('D') - not sure why…
>> Hmm, not sure.
>> 
>> Cheers,
>> Henry
>> 
>>> Webrev here:
>>> 
>>> http://cr.openjdk.java.net/~mcimadamore/panama/layout-grammar-refresh/
>>> 
>>> P.S.
>>> Might be useful to give it a spin on Mac and see if UnixSystemTest works (the layout conversion was not very trivial w/o jextract support :-))
>>> 
>>> Cheers
>>> 
>>> Maurizio