Optimize empty 'else' sections

[Christian-W. Budde]

Considering the following code:

procedure FooBar(a: Float);
begin
  if a < 0.5 then
    if a < 0.3 then
      Console.log('Foobar')
    else
  else
end;

FooBar(0.4);

will compile to

function FooBar(a) {
   if (a<0.5) {
      if (a<0.3) {
         console.log("Foobar");
      } else {
         /* null */
      }
   } else {
      /* null */
   }
};
FooBar(0.4)

With two empty else sections.

When I enable the cgoOptimizeForSize option I might expect that at least the last empty 'else' section would be removed by the optimization. This is currently not the case. The code is:

function FooBar(a){if(a<0.5){if(a<0.3){console.log("Foobar")}else{}}else{}};FooBar(0.4)

While it could be just:

function FooBar(a){if(a<0.5){if(a<0.3){console.log("Foobar")}}};FooBar(0.4)

The priority is set to minor as it's not what happens often in the real world. I just want to write it down here.

[Eric Grange]

These cases should probably be optimized earlier than the codegen (in the compiler).

In regular code such "else" clauses are probably a sign of an incorrect code, but they could also happen in "normal" code through conditional ifdef'ing

[Christian-W. Budde]

In my case they are indeed a result of several IFDEFs. I am aware that I should probably improve the code to reduce the amount of conditional compilation, especially for sake of legibility, but so far I'm having quite a few sections with this "issue".

As I mentioned earlier, it's not critical. I just found it while looking through some already minified code.

In fact this sort of issue will get easily removed by the closure compiler, which runs at the build stage.

[Eric Grange]

Fixed #139 + test

→ <<cset 25127c00255f>>