On 11/19/20 5:41 PM, Jakub Jelinek wrote:
Hi!
As mentioned in the PR, the previous PR91029 patch was testing
op2 >= 0 which is unnecessary, even negative op2 values will work the same,
furthermore, from if a % b > 0 we can deduce a > 0 rather than just a >= 0
(0 % b would be 0), and it actually valid even for other constants than 0,
a % b > 5 means a > 5 (a % b has the same sign as a and a in [0, 5] would
result in a % b in [0, 5]. Also, we can deduce a range for the other
operand, if we know
a % b >= 20, then b must be (in absolute value for signed modulo) > 20,
for a % [0, 20] the result would be [0, 19].
The following patch implements all of that, bootstrapped/regtested on
x86_64-linux and i686-linux, ok for trunk?
OK.
I was having a hard time keeping it all straight! the op1_range and
op2_range calculations can be real head spinners sometimes.
Andrew
