[sdcc-devel] [ sdcc-Bugs-3419769 ] Z80: Function pointers results in unreachable code

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Bugs item #3419769, was opened at 2011-10-06 19:31
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Category: z80 port
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: mic_ ()
Assigned to: Nobody/Anonymous (nobody)
Summary: Z80: Function pointers results in unreachable code

Initial Comment:
I'm compiling the Petit FatFs source (attached) with the following command:

sdcc -mz80 --data-loc 0xC001 --no-std-crt0 --oldralloc --no-peep --code-loc 0x8000 pff.c

My SDCC version is:

mcs51/gbz80/z80/z180/ds390/pic16/pic14/TININative/ds400/hc08 3.0.5 #6899
(Oct 2 2011) (MINGW32)

When building the Petit FatFs code for the Z80 I decided to put some of the low-level disk I/O routines it uses in a separate bank.
So I replaced e.g. this prototype:

DSTATUS disk_initialize(void);

with a define like this:

#define disk_initialize ((DSTATUS (*)(void))0xD689)

(I generate these defines automatically from the map files with a tool)
After doing these changes the compiler incorrectly marks large portions of code as unreachable.

For example, it considers the following return to always be taken:

    if (disk_initialize() != 0) 
        return FR_NOT_READY;

even though that depends on the value returned by disk_initialize.

Attached the code in question.

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>Comment By: mic_ ()
Date: 2011-10-06 19:36

Message:
I should add that I've successfully used the same principle of defined
function pointers elsewhere (with the same version of SDCC).  I only ran
into these problems when using them in PFF.

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