jfp@practic.com (John F. Peters) (01/08/90)
DESCRIPTION:
gcc-1.36(ns32k) running in Vax 4.3bsd-tahoe,
md -> ./config/ns32k.md, tm.h -> ./config/tm-sequent.h:
Dereferencing pointer in memory gives incorrect assembly code.
REPEAT-BY:
Run this script using your local name for ns32k gcc:
------------------------------------------------------------------------------
set -v
cat > badref.c <<"EOF"
char *cp;
main()
{
char ch;
ch = cp[0];
ch = cp[1];
}
EOF
gcc32k -v -g -S badref.c
cat badref.s
------------------------------------------------------------------------------
There is an incorrect address reference in the assembler output.
Reference to cp[0] yields "0(cp)", should be "0(cp(sb))".
Reference to cp[1] yields "1(cp(sb))" which is correct.
This is my script output, with the error marked:
------------------------------------------------------------------------------
cat > badref.c <<"EOF"
char *cp;
main()
{
char ch;
ch = cp[0];
ch = cp[1];
}
EOF
gcc32k -v -g -S badref.c
gcc version 1.36
/usr/gnu/lib32k/gcc-cpp -v -undef -D__GNUC__ -Dns32000 -Dsequent -Dunix -D__ns32000__ -D__sequent__ -D__unix__ badref.c /usr/tmp/cc001736.cpp
GNU CPP version 1.36
/usr/gnu/lib32k/gcc-cc1 /usr/tmp/cc001736.cpp -quiet -dumpbase badref.c -g -version -o badref.s
GNU C version 1.36 (32000, Sequent syntax) compiled by GNU C version 1.36.
default target switches: -m32081
cat badref.s
#NO_APP
gcc_compiled.:
.stabs "badref.c",100,0,0,Ltext
Ltext:
.stabs "int:t1=r1;-2147483648;2147483647;",128,0,0,0
.stabs "char:t2=r2;0;127;",128,0,0,0
.stabs "long int:t3=r1;-2147483648;2147483647;",128,0,0,0
.stabs "unsigned int:t4=r1;0;-1;",128,0,0,0
.stabs "long unsigned int:t5=r1;0;-1;",128,0,0,0
.stabs "short int:t6=r1;-32768;32767;",128,0,0,0
.stabs "long long int:t7=r1;0;-1;",128,0,0,0
.stabs "short unsigned int:t8=r1;0;65535;",128,0,0,0
.stabs "long long unsigned int:t9=r1;0;-1;",128,0,0,0
.stabs "signed char:t10=r1;-128;127;",128,0,0,0
.stabs "unsigned char:t11=r1;0;255;",128,0,0,0
.stabs "float:t12=r1;4;0;",128,0,0,0
.stabs "double:t13=r1;8;0;",128,0,0,0
.stabs "long double:t14=r1;8;0;",128,0,0,0
.stabs "void:t15=15",128,0,0,0
.text
.align 1
.globl _main
_main:
.stabd 68,0,4
enter [],4
LBB2:
.stabd 68,0,7
movb 0(_cp),-4(fp) <==WRONG
.stabd 68,0,8
movb 1(_cp(sb)),-4(fp) <==RIGHT
LBE2:
.stabd 68,0,9
L1:
exit []
ret 0
.stabs "main:F1",36,0,0,_main
.stabs "ch:2",128,0,0,-4
.stabn 192,0,0,LBB2
.stabn 224,0,0,LBE2
.stabs "cp:G16=*2",32,0,0,0
.comm _cp,4
------------------------------------------------------------------------------
jfp@practic.com