3 ms·
To handle this case some SSA implementations add a concept of "pi" nodes, which are used to artificially split variables on branches that establish some useful
by nikic 10y ago
To handle this case some SSA implementations add a concept of "pi" nodes, which are used to artificially split variables on branches that establish some useful data flow property.
x1 = ...
if (x1 > 0) {
x2 = pi(x1 & RANGE[1..])
use(x2)
} else {
x3 = pi(x1 & RANGE[..0])
use(x3)
}
x4 = phi(x2, x3) // if used
I have placed the pi nodes in the blocks, but semantically they are placed along the control edge.
Ref e.g. e-SSA in the ABCD value range inference algorithm.