From 7ca3c40b50b385ead6b8bc4c54de97b61d11a12a Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Fri, 10 Jan 2025 13:54:51 -0300 Subject: Another way to compile goto's The compilation of a goto or a label just create an entry and generate boilerplate code for the gotos. As we don't know yet whether it needs a CLOSE, we code a jump followed by a CLOSE, which is then dead code. When a block ends (and then we know for sure whether there are variables that need to be closed), we check the goto's against the labels of that block. When closing a goto against a label, if it needs a CLOSE, the compiler swaps the order of the jump and the CLOSE, making the CLOSE active. --- testes/goto.lua | 35 +++++++++++++++++++++++++---------- 1 file changed, 25 insertions(+), 10 deletions(-) (limited to 'testes/goto.lua') diff --git a/testes/goto.lua b/testes/goto.lua index 4ac6d7d0..103cccef 100644 --- a/testes/goto.lua +++ b/testes/goto.lua @@ -250,21 +250,36 @@ assert(testG(3) == "3") assert(testG(4) == 5) assert(testG(5) == 10) -do - -- if x back goto out of scope of upvalue - local X +do -- test goto's around to-be-closed variable + + -- set 'var' and return an object that will reset 'var' when + -- it goes out of scope + local function newobj (var) + _ENV[var] = true + return setmetatable({}, {__close = function () + _ENV[var] = nil + end}) + end + goto L1 - ::L2:: goto L3 + ::L4:: assert(not X); goto L5 -- varX dead here - ::L1:: do - local a = setmetatable({}, {__close = function () X = true end}) - assert(X == nil) - if a then goto L2 end -- jumping back out of scope of 'a' - end + ::L1:: + local varX = newobj("X") + assert(X); goto L2 -- varX alive here - ::L3:: assert(X == true) -- checks that 'a' was correctly closed + ::L3:: + assert(X); goto L4 -- varX alive here + + ::L2:: assert(X); goto L3 -- varX alive here + + ::L5:: -- return end + + + +foo() -------------------------------------------------------------------------------- -- cgit v1.2.3-55-g6feb