Exceptions in ARM

[Johannes Pfau]

On Saturday, 1 March 2014 at 09:24:40 UTC, Mike wrote:
> On Saturday, 1 March 2014 at 08:56:26 UTC, Timo Sintonen wrote:
>> There is nothing interesting in the assembly, only this wrong
>> call.
>> This form of instruction is just missing in M4 and it gives an
>> invalid instruction fault. So what are we arguing about?
>>
>> If this is so hard for us to find, no wonder the compiler 
>> writers
>> have not noticed this.
>
> Well, I yield then to the compiler folks.  Hopefully Iain or
> Johannes can provide some insight.

AFAIK the call to _Unwind_RaiseException [1] is just a normal 
function call [2] to a extern(C) function in a different 
compilation unit. It's not even a builtin so it doesn't look like 
a gdc bug. GCC bug is more likely but I wonder what exactly makes 
this case special? Why does this not happen for every function 
call to a extern(C) function?

Please try the following:
* Verify your --with-cpu, --with-arch, --with-tune flags for gcc 
configure. Also make sure that binutils is configured with the 
correct flags.
* Have a look at the build log how gcc/deh.d is compiled. Use the 
same compile command, but generate assembly via -S. Then look at 
the asm code to check whether the compiler or the 
assembler/linker is to blame.
* Try to reduce the example / understand why exactly this happens 
only in this case.
* When you have a reduced example, try to port it to C and see if 
GCC handles it correctly.


[1] 
https://github.com/D-Programming-GDC/GDC/blob/master/libphobos/libdruntime/gcc/deh.d#L151
[2] 
https://github.com/D-Programming-GDC/GDC/blob/master/libphobos/libdruntime/gcc/unwind/arm.d#L191