gcc version 2.96 (CVS, from 20000203, Linux): Bug with -O1

[Daniel Lauer]

Hello,

the compiler
	GNU C version 2.96 (CVS version from Feb 3, 2000)
makes wrong assembler code when compiling the following C-Code with -O1.
There is no error compiling it with -O0.

This error does NOT occur when compiling with
     -	gcc version 2.95.2 19991024 (release)
 or  -	gcc version 2.8.1
 or  -	gcc version 2.7.2.3
 or  -	gcc version 2.7.2.1

Daniel Lauer,
Bonn, Germany, 2000, Feb 09

Appendix:
 - C source 'bug.c'
 - output of verison '-O1'
 - output of verison '-O0'


-- C source 'bug.c' -----------------------------------------------------

unsigned int buggy (unsigned int *param) {
    unsigned int accu, zero=0, borrow;    
    accu    = - *param;
    borrow  = - (accu > zero);
    *param += accu;
    return borrow;
}
int main (int i, char **c) {
    unsigned int param = 1;
    printf ("Value must be zero: %ld\n", 1 + buggy( &param ) );
    return 0;
}

-------------------------------------------------------------------------

-- output of 'gcc -v -O1 bug.c; a.out' ----------------------------------
Reading specs from
	/usr/local/gcc-20000203/lib/gcc-lib/i586-pc-linux-gnu/2.96/specs
gcc version 2.96 20000203 (experimental)
[...]
Value must be zero: 1

-------------------------------------------------------------------------

-- output of 'gcc -v -O0 bug.c; a.out' ----------------------------------
Reading specs from
	/usr/local/gcc-20000203/lib/gcc-lib/i586-pc-linux-gnu/2.96/specs
gcc version 2.96 20000203 (experimental)
[...]
Value must be zero: 0

-------------------------------------------------------------------------