Add primitive type tutorial blog #321

yuehhua · 2019-03-02T12:15:14Z

With English and Traditional Chinese version.

yuehhua · 2019-03-02T12:22:59Z

@ViralBShah
@iblis17

ViralBShah · 2019-03-06T05:22:39Z

We need some reviews.

yuehhua · 2019-03-06T05:30:11Z

Sure.

matbesancon · 2019-04-09T15:56:17Z

blog/_posts/2019-03-02-custom-primitiv-type.md

+author: 鄭景文（Peter Cheng）, 杜岳華（Yueh-Hua Tu）
+---
+
+Julia provide some APIs for you to declare your own primitive types in Julia. However, when you open [the official docs about primitive type](https://docs.julialang.org/en/v1/manual/types/#Primitive-Types-1), you still don't know how to make your new primitive types work in your code. Therefore, here is a simple tutorial that tell you how to do so.


Julia provides

No need to repeat "in Julia" at the end :)

matbesancon · 2019-04-09T15:57:57Z

blog/_posts/2019-03-02-custom-primitiv-type.md

+    primitive type «name» «bits» end
+    primitive type «name» <: «supertype» «bits» end
+
+Currently, Julia only support sizes that are multiples of 8 bits. So like the `Bool` only take 1 bit, you still need to declare it as 8 bits. For example:


Julia only supports
So even though Bool only takes 1 bit, you need to declare it as 8 bits

StefanKarpinski · 2019-04-09T16:01:26Z

In the URL: primitiv => primitive.

chengchingwen · 2019-04-09T16:11:07Z

There is an English version included. We wrote in both Chinese and English

blog/_posts/2019-03-02-custom-primitiv-type.md

matbesancon · 2019-04-09T16:43:40Z

blog/_posts/2019-03-02-custom-primitiv-type.md

+
+    1.  `Core.Intrinsics.bitcase(type, value)`
+
+        `bitcase` told the LLVM to make a new same sized value of a primitive type instance `value`         and mark it as type `type`. The type of `value` must have the same bitsize as `type`.


why these spaces between value and "and". Same applies to next lines

Oh, I guess it's due to some problems in my editor, let me remove it.

primitive type chinese standard author name primitive type chinese reference fix primitive type chinese typo Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type-zh_tw.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> Update blog/_posts/2019-03-02-custom-primitiv-type.md Co-Authored-By: chengchingwen <adgjl5645@hotmail.com> add s, remove space fix typo in filename

blog/_posts/2019-03-02-custom-primitive-type.md

Co-Authored-By: chengchingwen <adgjl5645@hotmail.com>

chethega · 2019-04-10T17:56:57Z

Do we really want to document/blog about this as long as

julia> primitive type B 24 end
julia> B(i)=Core.Intrinsics.trunc_int(B,Int128(i));

julia> [B(i) for i=1:100]
signal (11): Segmentation fault

aka JuliaLang/julia#29193 JuliaLang/julia#29053 JuliaLang/julia#26026 ?

I'd feel much better if we deferred documentation / public blogging / advertisement of primitive types until they actually work reliably.

chethega · 2019-04-10T18:39:05Z

FWIW, the same issue appears with your bitsize, just harder to spot. Example:

julia> primitive type A 72 end
julia> A(i)=Core.Intrinsics.zext_int(A,i);
julia> arr=fill(A(1), 10^7);
ERROR: ReadOnlyMemoryError()
julia> arr=[A(i) for i=1:30]
30-element Array{A,1}:
 A(0x000000000000000001)
 A(0x000000000000000002)
 A(0x000000000000000003)
 A(0x000000000000000004)
 A(0x000000000000000005)
 A(0x000000000000000006)
 A(0x000000000000000007)
 A(0x000000000000000008)
 A(0x000000000000000009)
 A(0x00000000000000000a)
 ⋮                      
 A(0x600000000000000023)
 A(0xc000007fa6e4335630)
 A(0x020000000000000001)
 A(0x030000000000000023)
 A(0x050000000000000004)
 A(0x070000000000000006)
 A(0x090000000000000008)
 A(0x0b000000000000000a)
 A(0x0d000000000000000c)

The issue is that everybody has different opinions on whether the size of A is 9 byte or 16 byte (8 byte + 1 byte + 7 bytes padding for alignment). Hence the allocated buffer is sometimes too small and we corrupt memory. Also, arrayref, unsafe_load(pointer(arr, i)), unsafe_load(pointer(arr), i)) are inconsistent in computing offsets, and I think arrayref is inconsistent between interpretation (REPL) and compiled code.

yuehhua · 2019-04-11T08:59:36Z

@chethega Thank you for telling us these issues.
Maybe we could hold on the PR until the issues are solved.
@chengchingwen How do you think?

chengchingwen · 2019-04-11T09:13:54Z

Ah, so that's the reason why there is no documentation yet. @yuehhua I'm fine with it, but after that we might need to change the content a little bit.

ViralBShah · 2019-05-08T02:44:51Z

Bump. Is this happening?

chengchingwen · 2019-05-08T04:34:02Z

@ViralBShah As @chethega mentioned, there are still some bugs of primitive type. Should we just ignore those bugs, or should we close this PR for now?

ViralBShah · 2019-05-08T11:44:57Z

We can close for now and always reopen in the future