tet@UUNET.UU.NET (10/06/88)
PROBLEM: Gcc-1.28, (when not optimizing), produces
incorrect code for moves from an unsigned short
to either an int or an unsigned int.
With the optimizer on, the correct code is emitted.
Tom Tkacik
{umix!mcf, uunet!edsews}!rphroy!tetnix!tet
SYSTEM: AT&T UnixPC UNIX: SYSV.? (ver 3.5)
CONFIGURATION FILES: standard for the UnixPC
tm.h ----> tm-3b1.h
md ----> m68k.md
aux-output.c ----> output-m68k.c
COMMAND: gcc -v -S -gg bug.c
The -gg option is for aiding in reading the output file.
A program compiled with -gg cannot be assembled on the UnixPC.
VERSION:
gcc version 1.28
/usr/local/lib/gcc-cpp -v -undef -D__GNU__ -D__GNUC__ -Dmc68k -Dunix -Dunixpc bug.c /tmp/cca03586.cpp
GNU CPP version 1.28
/usr/local/lib/gcc-cc1 /tmp/cca03586.cpp -quiet -dumpbase bug.c -version -symout /tmp/cca03586.sym -o bug.s
GNU C version 1.28 (68k, SGS/AT&T unixpc syntax) compiled by GNU C version 1.28.
---------------------------------------------------------------
/* bug.c -- gcc makes two errors in this code */
unsigned int ui;
int i;
unsigned short us;
short s;
f()
{
i = s;
i = us; /* gcc gets this wrong */
ui = s;
ui = us; /* this also */
}
---------------------------------------------------------------
file "bug.c"
.text 0
.gdbbeg 0
.gdbbeg 1
Ltext: .stabs "bug.c",100,0,0,Ltext
.data 0
Ldata:
lcomm Lbss,0
.gdbsym Ldata,52
.gdbsym Lbss,56
text
even
global f
f:
.gdbbeg 2
.gdbline 0,9
link.w %a6,&0
mov.l %d2,-(%sp)
.gdbline 0,10
mov.w s,%a0 <---- short to int is correct
mov.l %a0,i
.gdbline 0,11
mov.w us,%d2 <---- unsigned short to int is wrong
clr.l i
mov.l i,%d0
mov.w %d2,%d0
mov.l %d0,%d0
.gdbline 0,12
mov.w s,%a0 <---- short to unsigned is correct
mov.l %a0,ui
.gdbline 0,13
mov.w us,%d2 <---- unsigned short to unsigned is wrong
clr.l ui
mov.l ui,%d0
mov.w %d2,%d0
mov.l %d0,%d0
.gdbline 0,14
L%1:
.gdbend 2
mov.l -4(%a6),%d2
unlk %a6
rts
.gdbblock 2,1188
comm s,2
comm us,2
comm i,4
comm ui,4
.text 0
.gdbend 0
.gdbblock 0,1328
.gdbend 1
.gdbblock 1,1864
.gdblinetab 0,2092