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New implementation for constants

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VLOCAL expressions keep a reference to their corresponding 'Vardesc',
and 'Upvaldesc' (for upvalues) has a field 'ro' (read-only). So, it is
easier to check whether a variable is read-only. The decoupling in
VLOCAL between 'vidx' ('Vardesc' index) and 'sidx' (stack index)
should also help the forthcoming implementation of compile-time
constant propagation.
This commit is contained in:
Roberto Ierusalimschy
2019-07-09 10:43:17 -03:00
parent e888976bc6
commit 54f7b46c1e
8 changed files with 125 additions and 131 deletions
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16
lparser.h
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@@ -33,8 +33,9 @@ typedef enum {
VKINT, /* integer constant; nval = numerical integer value */
VNONRELOC, /* expression has its value in a fixed register;
info = result register */
VLOCAL, /* local variable; var.idx = local register */
VUPVAL, /* upvalue variable; var.idx = index of upvalue in 'upvalues' */
VLOCAL, /* local variable; var.ridx = local register;
var.vidx = index in 'actvar.arr' */
VUPVAL, /* upvalue variable; info = index of upvalue in 'upvalues' */
VINDEXED, /* indexed variable;
ind.t = table register;
ind.idx = key's R index */
@@ -70,8 +71,9 @@ typedef struct expdesc {
short idx; /* index (R or "long" K) */
lu_byte t; /* table (register or upvalue) */
} ind;
struct { /* for local variables and upvalues */
lu_byte idx; /* index of the variable */
struct { /* for local variables */
lu_byte sidx; /* index in the stack */
unsigned short vidx; /* index in 'actvar.arr' */
} var;
} u;
int t; /* patch list of 'exit when true' */
@@ -81,9 +83,10 @@ typedef struct expdesc {
/* description of an active local variable */
typedef struct Vardesc {
TValue val; /* constant value (if variable is 'const') */
short idx; /* index of the variable in the Proto's 'locvars' array */
TValuefields; /* constant value (if variable is 'const') */
lu_byte ro; /* true if variable is 'const' */
lu_byte sidx; /* index of the variable in the stack */
short pidx; /* index of the variable in the Proto's 'locvars' array */
} Vardesc;
@@ -144,7 +147,6 @@ typedef struct FuncState {
} FuncState;
LUAI_FUNC Vardesc *luaY_getvardesc (FuncState **fs, const expdesc *e);
LUAI_FUNC LClosure *luaY_parser (lua_State *L, ZIO *z, Mbuffer *buff,
Dyndata *dyd, const char *name, int firstchar);