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codegen.c: eliminate loop if condition is constant.

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For example, `while false; ...; end` should be removed.
This commit is contained in:
Yukihiro "Matz" Matsumoto
2021-08-01 20:32:10 +09:00
parent 9dc801a798
commit 1315e8751e
1 changed files with 28 additions and 21 deletions
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mrbgems/mruby-compiler/core/codegen.c
+28 -21
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@@ -2096,33 +2096,40 @@ codegen(codegen_scope *s, node *tree, int val)
break;
case NODE_WHILE:
{
struct loopinfo *lp = loop_push(s, LOOP_NORMAL);
uint32_t pos;
if (!val) lp->acc = -1;
lp->pc0 = new_label(s);
codegen(s, tree->car, VAL);
pop();
pos = genjmp2_0(s, OP_JMPNOT, cursp(), NOVAL);
lp->pc1 = new_label(s);
codegen(s, tree->cdr, NOVAL);
genjmp(s, OP_JMP, lp->pc0);
dispatch(s, pos);
loop_pop(s, val);
}
break;
case NODE_UNTIL:
{
struct loopinfo *lp = loop_push(s, LOOP_NORMAL);
uint32_t pos;
uint32_t pos = JMPLINK_START;
if (!val) lp->acc = -1;
lp->pc0 = new_label(s);
codegen(s, tree->car, VAL);
pop();
pos = genjmp2_0(s, OP_JMPIF, cursp(), NOVAL);
switch (nint(tree->car->car)) {
case NODE_TRUE:
case NODE_INT:
case NODE_STR:
if (nt == NODE_UNTIL) {
if (val) genop_1(s, OP_LOADNIL, cursp());
goto exit;
}
break;
case NODE_FALSE:
case NODE_NIL:
if (nt == NODE_WHILE) {
if (val) genop_1(s, OP_LOADNIL, cursp());
goto exit;
}
break;
default:
codegen(s, tree->car, VAL);
pop();
if (nt == NODE_WHILE) {
pos = genjmp2_0(s, OP_JMPNOT, cursp(), NOVAL);
}
else {
pos = genjmp2_0(s, OP_JMPIF, cursp(), NOVAL);
}
break;
}
lp->pc1 = new_label(s);
codegen(s, tree->cdr, NOVAL);
genjmp(s, OP_JMP, lp->pc0);