polserver/testsuite/escript/opt/opt005-stopped-optimizing-early.src at sqlite - mmo-ref/polserver - Forgejo: Beyond coding. We forge.

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Eric Swanson cc1b0c6ee3 fix optimizer bug: can stop optimizing prematurely if pre- or post-decrement operators are present

optimize_token() is meant to return true only if it performs an optimization.

By returning true when it did not, it makes the optimizer stop trying.

A script like this can trigger the condition:

var i := 3;
var ii;

ii := 1 - (--i);
print(i);
print(ii);

Notice that line 4 does not optimize to an 'assign-consume' and therefore does not optimize to 'assign global`

Listfile before (see instructions 6-12):

/vagrant/testsuite/escript/opt/opt005-stopped-optimizing-early.src, Line 1
var i := 3;
0: decl global #0
1: 3L
2: :=
3: #
var ii;
4: decl global #1
5: #
ii := 1 - (--i);
6: global #1
7: 1L
8: global #0
9: unary --
10: -
11: :=
12: #
print(i);
13: global #0
14: Func(1,0): Print
15: #
print(ii);
16: global #1
17: Func(1,0): Print
18: #
19: progend

Listfile after (see instructions 6-10):

/vagrant/testsuite/escript/opt/opt005-stopped-optimizing-early.src, Line 1
var i := 3;
0: decl global #0
1: 3L
2: :=
3: #
var ii;
4: decl global #1
5: #
ii := 1 - (--i);
6: 1L
7: global #0
8: unary --
9: -
10: global1 :=
print(i);
11: global #0
12: Func(1,0): Print
13: #
print(ii);
14: global #1
15: Func(1,0): Print
16: #
17: progend

2020-07-29 20:42:07 -07:00

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 var i := 3;
 var ii;
 // The OG optimizer had a bug where would exit early
 // after not optimizing (ii-), and so it would
 // not optimize the global assignment + consume.
 ii := 1 - (--i);
 print(i);
 print(ii);