Fixed small issue with constant propagation
Constants directly assigned to other constants were not propagating:
For instance, in
local <const> k1 = 10
local <const> k2 = k1
'k2' were not treated as a compile-time constant.
diff --git a/lcode.c b/lcode.c
index 40efcff..c2b5fc6 100644
--- a/lcode.c
+++ b/lcode.c
@@ -68,6 +68,15 @@
/*
+** Get the constant value from a constant expression
+*/
+static TValue *const2val (FuncState *fs, const expdesc *e) {
+ lua_assert(e->k == VCONST);
+ return &fs->ls->dyd->actvar.arr[e->u.info].k;
+}
+
+
+/*
** If expression is a constant, fills 'v' with its value
** and returns 1. Otherwise, returns 0.
*/
@@ -85,6 +94,10 @@
setsvalue(fs->ls->L, v, e->u.strval);
return 1;
}
+ case VCONST: {
+ setobj(fs->ls->L, v, const2val(fs, e));
+ return 1;
+ }
default: return tonumeral(e, v);
}
}
@@ -730,14 +743,13 @@
/*
-** Ensure that expression 'e' is not a variable.
+** Ensure that expression 'e' is not a variable (nor a constant).
** (Expression still may have jump lists.)
*/
void luaK_dischargevars (FuncState *fs, expdesc *e) {
switch (e->k) {
case VCONST: {
- TValue *val = &fs->ls->dyd->actvar.arr[e->u.info].k;
- const2exp(val, e);
+ const2exp(const2val(fs, e), e);
break;
}
case VLOCAL: { /* already in a register */
diff --git a/testes/code.lua b/testes/code.lua
index b509145..57923b1 100644
--- a/testes/code.lua
+++ b/testes/code.lua
@@ -8,7 +8,8 @@
print "testing code generation and optimizations"
-- to test constant propagation
-local <const> k0 = 0
+local <const> k0aux = 0
+local <const> k0 = k0aux
local <const> k1 = 1
local <const> k3 = 3
local <const> k6 = k3 + (k3 << k0)
@@ -410,8 +411,9 @@
do -- string constants
+ local <const> k0 = "00000000000000000000000000000000000000000000000000"
local function f1 ()
- local <const> k = "00000000000000000000000000000000000000000000000000"
+ local <const> k = k0
return function ()
return function () return k end
end
@@ -419,8 +421,8 @@
local f2 = f1()
local f3 = f2()
- assert(f3() == string.rep("0", 50))
- checkK(f3, f3())
+ assert(f3() == k0)
+ checkK(f3, k0)
-- string is not needed by other functions
assert(T.listk(f1)[1] == nil)
assert(T.listk(f2)[1] == nil)
