I have a combiner pattern that converts a sub-cmp pattern to a cmp insn,
something like this -
"if (a-1 < 0)"
is converted to
"if (a<1)"
Now consider the following test case -
<snip>
f(long a){return (--a > 0);}
main(){if(f(0x80000000L)==0)abort();exit(0);}
</snip>
The compiler generates the following code for f()
cmp r0, 1 ;;canonicalized
mov r0,1
sub.le r0,r0,r0
This works fine under normal circumstances. However, in the testcase,
the least negative no. i.e. 0x80000000 (hereafer referred to as MIN) is
passed. When 1 is subtracted from MIN, by --a, it becomes positive and
the conditions get reversed thus leading to failure during execution.
Similar problem seems to arise when MAX is passed to a function that
does "return (++a < 0).
How do I tackle this problem? Anything I may be missing?
Thanks in advance.
Ashwin
