Bad code generated for *x = 0 where x is an xdata short ptr

Thomas Sailer — Tue, 08 Aug 2006 15:13:41 -0000

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

Recent changes to 1181: Bad code generated for *x = 0 where x is an xdata short ptr

Bad code generated for *x = 0 where x is an xdata short ptr