GDC 9 and ARM Cortex-M

[Timo Sintonen]

On Sunday, 7 July 2019 at 09:57:33 UTC, Iain Buclaw wrote:
> On Sun, 7 Jul 2019 at 08:25, Timo Sintonen via D.gnu 
> <d.gnu at puremagic.com> wrote:
>>
>> My little test program is nearly working now.
>> Some funny things I have found:
>>
>> - When not using -O2 4 extra bytes appear in front of tdata 
>> init values. With -O2 they disappear.
>
> Don't think that has anything to do with gdc.
>
>> - I have my own calloc where I first allocate a block with 
>> malloc and then use memset to zero it. GCC can see this and 
>> replaces these two calls with a call to calloc...
>>
>
> Use -fno-builtin to disable C function recognition.
>
>> >
>> > There were big changes in exception handling code about 2 
>> > years ago and my exception code stopped to work. What was 
>> > changed back then? How can I get my code to work again? 
>> > Could this be some struct alignment problem like some years 
>> > ago?
>>
>> The program dies somewhere in unwinding code. It looks like 
>> the stack pointer is moved incorrectly and values are popped 
>> to wrong registers in function return. There might be a size 
>> mismatch between c and d side when function arguments are 
>> passed in stack. Any idea where to look?
>>
>
> The only recent change that would have affected ABI is the 
> addition of the general-regs-only attribute added for ARM EABI.
>  As far as I still know - and I have done testing on my phone 
> that sports a Cortex-A53 - the unwind routines for gdc work 
> well.  I'm not aware of there being any differences between ARM 
> targets regarding type sizes.
>
> Function and type definitions are in gcc/unwind/arm_commond.d, 
> and that has been translated from 
> gcc/ginclude/unwind-arm-common.h.

Am I picking the right value in gcc/unwind/arm.d line 54 and does 
that matter?

With hex dump of the stack and map file I was able to manually 
create trace:
_d_dynamic cast
gcc.deh.actionTableLookup
gcc.deh.scan
gcc.deh.__gdc_personality
__gdc_personality_v0
__gnu_unwind_raiseException
unwind_raiseException
_d_throw
myThrowingFunction
main