1. When the last statement of a function is a RETURN statement which is syntactically required, it could still be deleted.
2. The child of a RETURN statement could be removed if the statement was not executed.
This commit fixes both issues.
Bug report and test case provided by @Tonaie. Fixes#14.
E.g. llSubStringIndex(...) > -1 was converted into !~llSubStringIndex(...) which is incorrect. We even had a test case for it... with a wrong expected response file.
Bug report and test case by Sinha Hynes (thanks!)
vector * quaternion: Simplified by precalculating the repeated products and removing math.fsum.
quaternion * quaternion: Add more F32's to get a result closer to SL's (still not there, but we're definitively closer now).
We left out quaternion/quaternion in the tests, and the q*q test was not general enough (had many zeros). Remedied that.
The algorithm for adding parentheses around unary operators was not working properly. It converted a * (-b) * c into a * -b * c, which LSL handles as a * -(b * c).
Fix and add test cases for that. One of the test cases shows an example where the difference matters: 0 * (-1e20) * 1e20 should result in 0.0, but if wrongly parenthesized, it gives NaN, because 1e20*1e20 gives infinity due to float overflow, and minus infinity times 0 is indeterminate.
The addition of parentheses has been improved, but it still does not eliminate every redundant parenthesis.
Also fix the horrendous typo of using "operands" where it should be "operators".
In the same places as state changes are allowed, i.e. in places where a parent of the AST node is a WHILE/DO/FOR or an IF without ELSE, it's allowed to use return statements with expressions that return void, e.g. llDie(), provided the function itself is declared as returning void.
The construction, when found, is rewritten to '{<void expression>; return;}' because the optimizer is not designed to deal with these monsters.
We've renamed the variable SuspiciousStSw to PruneBug, because it's used for both purposes now, though a better name might have been PruneBugPendingChecks, because these are only errors if the IF has an ELSE. We've also added the exception to raise as part of the data stored in the list.
Per report by Tonaie Resident.
Revert "Add support for C11-style _Pragma operator on processpre".
Revert "Add unit test for the _Pragma operator".
This reverts commits 31fcb331c7 and e261ac2121.
This should rather be the job of the preprocessor, which should generate #pragma lines. gcc does that.
A minor difference is that strings and whitespace are parsed according to LSL rules, not to C rules, since this processing is performed in the lexer.
This could be fixed, but is it worth the trouble?
This is a first try at redundant jump removal (jumps that target the very next instruction). It's too basic in several ways.
- The statement is replaced by a ';' instead of removed.
- If the jump was the only statement in an if, when the if becomes empty, it's not folded.
- Jumps that are last in the 'then' branch of if+else are not visible. This would need either to track multiple last statements, or to have some means to anticipate what the next statement is at every statement. A Control Flow Graph would help a lot.
- When a label is immediately followed by a jump, all jumps to that label should target the destination of that jump if it's in scope. Added to TODO.
- It misses some optimizations when not expanding WHILE and FOR into IF/JUMP.
Moving everything to an earlier stage would help with some of these, especially with ';' and 'if' folding. Unconditionally expanding WHILE and FOR would also help.
SymbolReplacedOrDeleted had an "emergency fix" that disabled several kinds of substitutions, because they generated code that didn't compile. The cause was actually elsewhere.
The actual problem was the marking of function parameters as being written to by function calls. This is true in a sense, but there's a big scope change that totally destroys the possibility of substituting identifiers, for example.
We were not removing the function parameters, anyway, therefore that code has just been disabled.
Note that removal of function parameters may be impossible if one parameter has side effects. Consider this:
f(string x, integer y, string z)
{
llOwnerSay(x + z);
}
integer n = 2;
default{state_entry(){
f("a" + (string)n, n=llSetRegionPos(<100,100,100>), "c" + (string)n);
}}
Even worse if the expression for the x argument has side effects too and x and y need to be performed in the right order.
Fortunately, such case is highly unlikely. But if we ever implement removal of function parameters, that's an additional difficulty to take care of.
This allows optimizing, for example:
integer a = 1;
integer b = a;
llOwnerSay((string)b);
which wasn't done before. This case is prone to happen with inlined functions, e.g. using the result of an inlined function as a parameter to another.
It was an awful name but we couldn't think of anything better. That's what we have come up with as a substitute, which is not entirely accurate but it is MUCH more descriptive of what it actually does.
It's set in a variable local to that module. There's currently no way to enable it except by editing the code, but since it's mostly for internal purposes, it's OK like that.
