[sdcc-devel] [ sdcc-Bugs-1536762 ] Bad code generated for *x = 0 where x is an xdata short ptr

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Bugs item #1536762, was opened at 2006-08-08 17:13
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Category: msc51(8051) target
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Thomas Sailer (tsailer)
Assigned to: Nobody/Anonymous (nobody)
Summary: Bad code generated for *x = 0 where x is an xdata short ptr

Initial Comment:
sdcc svn4321, command line:
sdcc -c -mmcs51 --model-small --debug -I. --xram-size 
1024 --code-size 16384 -o t.rel t.c

See the attached test case. I could not slim it down 
more, as removing any of the remaining element 
apparently causes the register pressure to drop to 
the point where this bug is not exhibited.

The problem lies in the s.c->s = 0; statement, where 
the compiler stomps itself over the dptr (dpl) 
register.


                            119 ;       t.c:26: 
s.c->s = 0;
                            120 ;       genAssign
                            121 ;       genPlus
   0008 90s00r00            122         mov     
dptr,#_s
   000B E0                  123         movx    
a,@dptr
   000C 24 03               124         add     
a,#0x03
   000E F5 82               125         mov     dpl,a
   0010 A3                  126         inc     dptr
   0011 E0                  127         movx    
a,@dptr
   0012 34 00               128         addc    
a,#0x00
   0014 F5 83               129         mov     dph,a
                            130 ;       genPointerSet
                            131 ;     
genFarPointerSet
                            132 ;       Peephole 181    
changed mov to clr
   0016 E4                  133         clr     a
   0017 F0                  134         movx    
@dptr,a


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