Valid chunk choices

gistfile1.cpp

f(v0, v1) = v0*v1
g(v2, v3, v4) = f(v2, v3)
h(v5, v6) = g(v5, v6, 0) + g(v5, v6, 1)

h.root() // h is output, so this is implicit
// this means:
[allocate h]
for all v6:
  for all v5:
    h[v5,v6] = g(v5,v6,0) + g(v5,v6,1)

// this leaves the variable list: v6, v5 for choices at which g could be evaluated.

g.chunk(v6)
// this means:
for all v6:
  [allocate and evaluate as much of g as needed by all calls below here]
  for all v5:
    h[v5,v6] = g[...] + g[...]

// the evaluation block actually expands to:
for all v6:
  [allocate g for range needed by h over all values of v5 below]
  for all v4 required by h(v6,*):
    for all v3 required by h(v6,*):
      for all v2 required by h(v6,*):
        g[v2,v3,v4] = f(v2,v3)
  for all v5:
    h[v5,v6] = g[v5,v6,0] + v[v5,v6,1]

// So now for f...
// The variable list when g was scheduled was: v6, v5
// g was chunked under v6. This eliminated v5 from the list for where f is called.
// (if you look above, you can clearly see f *isn't called within the v5 loop*)
// f is called by g, so it can also be chunked under any of the variables of g's domain.
// Now the variable list for f is: v6, v4, v3, v2
// Notice that this is the same as the ordered set of loops above where f is "called"

f.chunk(v4)
// this means
for all v6:
  [allocate g for range needed by h over all values of v5 below]
  for all v4 required by h(v6,*):
    [allocate f for the range needed by g over all values of v2,v3 below]
    for all v1 required by g(v4,*,*):
      for all v0 required by g(v4,*,*):
        f[v0,v1] = v0+v1
    for all v3 required by h(v6,*):
      for all v2 required by h(v6,*):
        g[v2,v3,v4] = f(v2,v3)
  for all v5:
    h[v5,v6] = g[v5,v6,0] + v[v5,v6,1]