[Oberon] O-7 code generation

[Jan de Kruyf]

Ok,
I did find the answer:
It gets patched in Modules.Load

j.


On Mon, Nov 23, 2015 at 5:24 PM, Jan de Kruyf <jan.de.kruyf at gmail.com>
wrote:

> Hallo,
>
> I stumbled onto something I do not understand, but perhaps there is a
> compiler specialist.
>
> Here it is:
> MODULE Test1;
> VAR t : INTEGER;
> BEGIN
>    t := 9;
> END Test1.
>
>
> code
>    0     4EE90004       SUB SP SP      4
>    1     AFE00000       STR  LNK SP       0
>    2     40000009       MOV  R0  R0      9
>    3     8D000003       LDR SB  R0       3
>    4     A0D00000       STR   R0 SB       0
>    5     8FE00000       LDR LNK SP       0
>    6     4EE80004       ADD SP SP      4
>    7     C700000F       B LNK
>
>
> So I assign '9' to 'local' global variable 't'.
>
> In line 2 constant 9 is moved into R0
> in line 3 SB is loaded with the data from [R0 + 3]
> in line 4 R0 is stored in [SB + 3]
>
> So R0 is overwritten, unless this is patched by the module loader.
>
> But the book says that line 3 was designed to read:
>
> LDR SB R12  3      ;(section 12.7.9 -- 2nd last paragraph)
>
>
> Does anyone know what is up here?
>
> Thanks,
>
> j.
>
>
>
>
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