Removed optimization for «if ... then goto»
That optimization was too complex and caused some weird traces when
debugging. The more common case «if ... then break» was kept.
diff --git a/lparser.c b/lparser.c
index fb7a126..77813a7 100644
--- a/lparser.c
+++ b/lparser.c
@@ -1623,59 +1623,21 @@
}
-/*
-** Check whether next instruction is a single jump (a 'break', a 'goto'
-** to a forward label, or a 'goto' to a backward label with no variable
-** to close). If so, set the name of the 'label' it is jumping to
-** ("break" for a 'break') or to where it is jumping to ('target') and
-** return true. If not a single jump, leave input unchanged, to be
-** handled as a regular statement.
-*/
-static int issinglejump (LexState *ls, TString **label, int *target) {
- if (testnext(ls, TK_BREAK)) { /* a break? */
- *label = luaS_newliteral(ls->L, "break");
- return 1;
- }
- else if (ls->t.token != TK_GOTO || luaX_lookahead(ls) != TK_NAME)
- return 0; /* not a valid goto */
- else {
- TString *lname = ls->lookahead.seminfo.ts; /* label's id */
- Labeldesc *lb = findlabel(ls, lname);
- if (lb) { /* a backward jump? */
- /* does it need to close variables? */
- if (luaY_nvarstack(ls->fs) > stacklevel(ls->fs, lb->nactvar))
- return 0; /* not a single jump; cannot optimize */
- *target = lb->pc;
- }
- else /* jump forward */
- *label = lname;
- luaX_next(ls); /* skip goto */
- luaX_next(ls); /* skip name */
- return 1;
- }
-}
-
-
static void test_then_block (LexState *ls, int *escapelist) {
/* test_then_block -> [IF | ELSEIF] cond THEN block */
BlockCnt bl;
- int line;
FuncState *fs = ls->fs;
- TString *jlb = NULL;
- int target = NO_JUMP;
expdesc v;
int jf; /* instruction to skip 'then' code (if condition is false) */
luaX_next(ls); /* skip IF or ELSEIF */
expr(ls, &v); /* read condition */
checknext(ls, TK_THEN);
- line = ls->linenumber;
- if (issinglejump(ls, &jlb, &target)) { /* 'if x then goto' ? */
- luaK_goiffalse(ls->fs, &v); /* will jump to label if condition is true */
+ if (ls->t.token == TK_BREAK) { /* 'if x then break' ? */
+ int line = ls->linenumber;
+ luaK_goiffalse(ls->fs, &v); /* will jump if condition is true */
+ luaX_next(ls); /* skip 'break' */
enterblock(fs, &bl, 0); /* must enter block before 'goto' */
- if (jlb != NULL) /* forward jump? */
- newgotoentry(ls, jlb, line, v.t); /* will be resolved later */
- else /* backward jump */
- luaK_patchlist(fs, v.t, target); /* jump directly to 'target' */
+ newgotoentry(ls, luaS_newliteral(ls->L, "break"), line, v.t);
while (testnext(ls, ';')) {} /* skip semicolons */
if (block_follow(ls, 0)) { /* jump is the entire block? */
leaveblock(fs);
@@ -1684,7 +1646,7 @@
else /* must skip over 'then' part if condition is false */
jf = luaK_jump(fs);
}
- else { /* regular case (not a jump) */
+ else { /* regular case (not a break) */
luaK_goiftrue(ls->fs, &v); /* skip over block if condition is false */
enterblock(fs, &bl, 0);
jf = v.f;
diff --git a/testes/code.lua b/testes/code.lua
index 34b0466..1f971cd 100644
--- a/testes/code.lua
+++ b/testes/code.lua
@@ -392,28 +392,6 @@
end,
'TEST', 'JMP', 'TEST', 'JMP', 'ADDI', 'MMBINI', 'JMP', 'RETURN0')
-checkequal(
-function (a) while a < 10 do a = a + 1 end end,
-function (a)
- ::loop::
- if not (a < 10) then goto exit end
- a = a + 1
- goto loop
-::exit::
-end
-)
-
-checkequal(
-function (a) repeat local x = a + 1; a = x until a > 0 end,
-function (a)
- ::loop:: do
- local x = a + 1
- a = x
- end
- if not (a > 0) then goto loop end
-end
-)
-
checkequal(function () return 6 or true or nil end,
function () return k6 or kTrue or kNil end)
