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optimization control
--------------------
could be done with labels or blocks:
some_label:
for (int i : [0..10]) {
code.opt.something(some_label);
j += f(i);
}
codeblock some_block {
for (int i : [0..10]) {
code.opt.something(some_block);
j += f(i);
}
}
move out
--------
loops:
for (int i : [0..i-1]) {
for (int j : [0..j-1]) {
code.opt.move_out_var(loops, [a]);
if (a == 0) c += f(i, j);
else if (a == 1) c += f(j, i);
else c += f(i, i-j);
}
}
or
// won't work. the code doesn't say which code should be moved out.
// it could be if, if+for or if+for+for
loops:
for (int i : [0..i-1]) {
for (int j : [0..j-1]) {
if (a == 0) { code.opt.move_out(loops); c += f(i, j); }
else if (a == 1) { code.opt.move_out(loops); c += f(j, i); }
else { code.opt.move_out(loops); c += f(i, i-j); }
}
}
produces:
if (a == 0) {
for (int i : [0..i-1]) {
for (int j : [0..j-1]) {
c += f(i, j);
}
}
} else if (a == 1) {
for (int i : [0..i-1]) {
for (int j : [0..j-1]) {
c += f(j, i);
}
}
} else {
...
}
split_here
----------
loops:
for (int i : [0..i-1]) {
for (int j : [0..j-1]) {
lots();
of();
_code();
code.opt.split_here(loops);
even();
more();
_code();
}
}
produces:
loops:
for (int i : [0..i-1]) {
for (int j : [0..j-1]) {
lots();
of();
_code();
}
}
for (int i : [0..i-1]) {
for (int j : [0..j-1]) {
even();
more();
_code();
}
}
enforced tail call optimization
--------------------------------
int f(int x, int y)
{
if y <= 0 return x;
else continue f(x+y, y-1);
}
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