On Monday, 4 November 2013 at 23:07:27 UTC, deadalnix wrote:
> On Monday, 4 November 2013 at 22:56:48 UTC, jerro wrote:
>>> Then it look like a dmd backend bug. Can you post the generated assembly ?
>>
>> 000000000043050c <_Dmain>:
>>   43050c:       push   %rbp
>>   43050d:       mov    %rsp,%rbp
>>   430510:       sub    $0x40,%rsp
>>   430514:       movabs $0x3ff0000000000000,%rax
>>   43051b:
>>   43051e:       mov    %rax,-0x40(%rbp)
>>   430522:       movsd  -0x40(%rbp),%xmm0
>>   430527:       rex.W movsd %xmm0,-0x30(%rbp)
>>   43052d:       xor    %edx,%edx
>>   43052f:       mov    %rax,-0x10(%rbp)
>>   430533:       mov    %rdx,-0x8(%rbp)
>>   430537:       mov    %rax,-0x28(%rbp)
>>   43053b:       mov    %rdx,-0x20(%rbp)
>
>>   43053f:       mov    0x28022(%rip),%rdx
>>   430546:       mov    0x28013(%rip),%rsi
>
> What are these ? What are they referering to

My guess is they are refering to length and
ptr for "%x" string literal, which is passed to writefln.

>
>>   43054d:       mov    -0x28(%rbp),%rdi
>>   430551:       callq  430874 <void
>> std.stdio.writefln!(immutable(char)[],
>> ulong).writefln(immutable(char)[], ulong)>
>>   430556:       xor    %eax,%eax
>>   430558:       leaveq
>>   430559:       retq
>
> This calls writefln, this is not what your code does just above. Are you sure you are posting the right assembly ? Do you use the inline flag ?

I think you are confusing my post with some other post (I am not
OP).
My code sample was:

import std.stdio;

struct Y {
      int[] _data;
}

struct CFS {
      double x;
      Y growth;
}

void main() {
      auto s = CFS(1.0);
      writefln("%x", s.growth._data.length); // prints
3ff0000000000000
}

The constructor's argument was 2.0 in my previous sample, but it
should have been 1.0.

On Monday, 4 November 2013 at 23:14:08 UTC, jerro wrote:
> On Monday, 4 November 2013 at 23:07:27 UTC, deadalnix wrote:
>> On Monday, 4 November 2013 at 22:56:48 UTC, jerro wrote:
>>>> Then it look like a dmd backend bug. Can you post the generated assembly ?
>>>
>>> 000000000043050c <_Dmain>:
>>>  43050c:       push   %rbp
>>>  43050d:       mov    %rsp,%rbp
>>>  430510:       sub    $0x40,%rsp
>>>  430514:       movabs $0x3ff0000000000000,%rax
>>>  43051b:
>>>  43051e:       mov    %rax,-0x40(%rbp)
>>>  430522:       movsd  -0x40(%rbp),%xmm0
>>>  430527:       rex.W movsd %xmm0,-0x30(%rbp)
>>>  43052d:       xor    %edx,%edx
>>>  43052f:       mov    %rax,-0x10(%rbp)
>>>  430533:       mov    %rdx,-0x8(%rbp)
>>>  430537:       mov    %rax,-0x28(%rbp)
>>>  43053b:       mov    %rdx,-0x20(%rbp)
>>
>>>  43053f:       mov    0x28022(%rip),%rdx
>>>  430546:       mov    0x28013(%rip),%rsi
>>
>> What are these ? What are they referering to
>
> My guess is they are refering to length and
> ptr for "%x" string literal, which is passed to writefln.
>
>>
>>>  43054d:       mov    -0x28(%rbp),%rdi
>>>  430551:       callq  430874 <void
>>> std.stdio.writefln!(immutable(char)[],
>>> ulong).writefln(immutable(char)[], ulong)>
>>>  430556:       xor    %eax,%eax
>>>  430558:       leaveq
>>>  430559:       retq
>>
>> This calls writefln, this is not what your code does just above. Are you sure you are posting the right assembly ? Do you use the inline flag ?
>
> I think you are confusing my post with some other post (I am not
> OP).

OK, my mistake.

> My code sample was:
>
> import std.stdio;
>
> struct Y {
>       int[] _data;
> }
>
> struct CFS {
>       double x;
>       Y growth;
> }
>
> void main() {
>       auto s = CFS(1.0);
>       writefln("%x", s.growth._data.length); // prints
> 3ff0000000000000
> }
>
> The constructor's argument was 2.0 in my previous sample, but it
> should have been 1.0.

I'm not sure what DMD is trying to do, but the function call to writefln is clearly wrong.

On Monday, 4 November 2013 at 22:09:45 UTC, jerro wrote:
>>> void main() {
>>> auto s = CFS(1.0);      // crash
>>> //auto s = CFS(1, Y()); // crash
>>> //auto s = CFS(1, Y([])); // works
>>> writeln(s);
>>> }
>>
>> What do you mean by crash ?
>
> It's segfaults. It doesn't happen if you change 1.0 literal to
> some other value,
> say 2.0. It's a truly bizarre bug.
>
> Here's a slightly simplified case:
>
> import std.stdio;
>
> struct Y {
>      int[] _data;
> }
>
> struct CFS {
>      double x;
>      Y growth;
> }
>
> void main() {
>      auto s = CFS(2.0);
>      writefln("%x", s.growth._data.length); // prints
> 3ff0000000000000
> }
>
> It doesn't happen with -O, or when compiled with LDC or GDC.

Can't reproduce on Git master x86_64 linux. Prints 0 no matter what flags are used.

On Tuesday, 5 November 2013 at 09:34:47 UTC, John Colvin wrote:
> On Monday, 4 November 2013 at 22:09:45 UTC, jerro wrote:
>>>> void main() {
>>>> auto s = CFS(1.0);      // crash
>>>> //auto s = CFS(1, Y()); // crash
>>>> //auto s = CFS(1, Y([])); // works
>>>> writeln(s);
>>>> }
>>>
>>> What do you mean by crash ?
>>
>> It's segfaults. It doesn't happen if you change 1.0 literal to
>> some other value,
>> say 2.0. It's a truly bizarre bug.
>>
>> Here's a slightly simplified case:
>>
>> import std.stdio;
>>
>> struct Y {
>>     int[] _data;
>> }
>>
>> struct CFS {
>>     double x;
>>     Y growth;
>> }
>>
>> void main() {
>>     auto s = CFS(2.0);
>>     writefln("%x", s.growth._data.length); // prints
>> 3ff0000000000000
>> }
>>
>> It doesn't happen with -O, or when compiled with LDC or GDC.
>
> Can't reproduce on Git master x86_64 linux. Prints 0 no matter what flags are used.

Oh wait no, sorry. It does print 3ff0000000000000 if I use 1.0 instead of 2.0

On Tuesday, 5 November 2013 at 09:34:47 UTC, John Colvin wrote:
>
> Can't reproduce on Git master x86_64 linux. Prints 0 no matter what flags are used.

Mac - OS X 10.9 (13A603)

dmd -v
DMD64 D Compiler v2.064
Copyright (c) 1999-2013 by Digital Mars written by Walter Bright


bash-3.2$ rdmd --chatty --force /Users/user@/tmp/init.d
stat /tmp/.rdmd-502
stat /tmp/.rdmd-502/rdmd-init.d-7C1A09D7F9F238EF000AE7814A586BCD
'dmd' '-v' '-o-' '/Users/user/tmp/init.d' '-I/Users/user/tmp'
read /tmp/.rdmd-502/rdmd-init.d-7C1A09D7F9F238EF000AE7814A586BCD/rdmd.deps
which dmd
stat /Users/user/bin/dmd
'dmd' '-of/tmp/.rdmd-502/rdmd-init.d-7C1A09D7F9F238EF000AE7814A586BCD/init' '-od/tmp/.rdmd-502/rdmd-init.d-7C1A09D7F9F238EF000AE7814A586BCD/objs' '-I/Users/user/tmp' '/Users/user/tmp/init.d'
stat /tmp/.rdmd-502/rdmd-init.d-7C1A09D7F9F238EF000AE7814A586BCD/objs
rmdirRecurse /tmp/.rdmd-502/rdmd-init.d-7C1A09D7F9F238EF000AE7814A586BCD/objs
'/tmp/.rdmd-502/rdmd-init.d-7C1A09D7F9F238EF000AE7814A586BCD/init'
Segmentation fault: 11

On Tuesday, 5 November 2013 at 00:16:11 UTC, deadalnix wrote:
>
> I'm not sure what DMD is trying to do, but the function call to writefln is clearly wrong.

Strange bug.

FWIW adding a constructor `this(immutable(int)[] data) { _data = data; }` seems to be a workaround.

Thanks
Dan

On Tuesday, 5 November 2013 at 00:16:11 UTC, deadalnix wrote:
>
> I'm not sure what DMD is trying to do, but the function call to writefln is clearly wrong.

Strange bug.

FWIW adding a constructor `this(immutable(int)[] data) { _data =
data; }` seems to be a workaround.

Thanks
Dan