nik/lush
1
1
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

First implementation of constant propagation

Browse Source 
Local constant variables initialized with compile-time constants
are optimized away from the code.
This commit is contained in:
Roberto Ierusalimschy
2019-07-12 11:38:42 -03:00
parent be8445d7e4
commit f6aab3ec1f
12 changed files with 249 additions and 119 deletions
Download Patch File Download Diff File Expand all files Collapse all files

113
lparser.c
View File

@@ -170,15 +170,16 @@ static void codename (LexState *ls, expdesc *e) {
** Register a new local variable in the active 'Proto' (for debug
** information).
*/
static int registerlocalvar (lua_State *L, FuncState *fs, TString *varname) {
static int registerlocalvar (LexState *ls, FuncState *fs, TString *varname) {
Proto *f = fs->f;
int oldsize = f->sizelocvars;
luaM_growvector(L, f->locvars, fs->ndebugvars, f->sizelocvars,
luaM_growvector(ls->L, f->locvars, fs->ndebugvars, f->sizelocvars,
LocVar, SHRT_MAX, "local variables");
while (oldsize < f->sizelocvars)
f->locvars[oldsize++].varname = NULL;
f->locvars[fs->ndebugvars].varname = varname;
luaC_objbarrier(L, f, varname);
f->locvars[fs->ndebugvars].startpc = fs->pc;
luaC_objbarrier(ls->L, f, varname);
return fs->ndebugvars++;
}
@@ -191,16 +192,13 @@ static Vardesc *new_localvar (LexState *ls, TString *name) {
FuncState *fs = ls->fs;
Dyndata *dyd = ls->dyd;
Vardesc *var;
int reg = registerlocalvar(L, fs, name);
checklimit(fs, dyd->actvar.n + 1 - fs->firstlocal,
MAXVARS, "local variables");
luaM_growvector(L, dyd->actvar.arr, dyd->actvar.n + 1,
dyd->actvar.size, Vardesc, USHRT_MAX, "local variables");
var = &dyd->actvar.arr[dyd->actvar.n++];
var->pidx = cast(short, reg);
var->ro = 0;
var->name = name;
setnilvalue(var);
var->vd.kind = VDKREG; /* default is a regular variable */
var->vd.name = name;
return var;
}
@@ -225,8 +223,8 @@ static Vardesc *getlocalvardesc (FuncState *fs, int i) {
static int stacklevel (FuncState *fs, int nvar) {
while (nvar > 0) {
Vardesc *vd = getlocalvardesc(fs, nvar - 1);
if (vdinstack(vd)) /* is in the stack? */
return vd->sidx + 1;
if (vd->vd.kind != RDKCTC) /* is in the stack? */
return vd->vd.sidx + 1;
else
nvar--; /* try previous variable */
}
@@ -247,10 +245,10 @@ int luaY_nvarstack (FuncState *fs) {
*/
static LocVar *localdebuginfo (FuncState *fs, int i) {
Vardesc *vd = getlocalvardesc(fs, i);
if (!vdinstack(vd))
if (vd->vd.kind == RDKCTC)
return NULL; /* no debug info. for constants */
else {
int idx = vd->pidx;
int idx = vd->vd.pidx;
lua_assert(idx < fs->ndebugvars);
return &fs->f->locvars[idx];
}
@@ -261,7 +259,7 @@ static void init_var (FuncState *fs, expdesc *e, int i) {
e->f = e->t = NO_JUMP;
e->k = VLOCAL;
e->u.var.vidx = i;
e->u.var.sidx = getlocalvardesc(fs, i)->sidx;
e->u.var.sidx = getlocalvardesc(fs, i)->vd.sidx;
}
@@ -269,15 +267,19 @@ static void check_readonly (LexState *ls, expdesc *e) {
FuncState *fs = ls->fs;
TString *varname = NULL; /* to be set if variable is const */
switch (e->k) {
case VCONST: {
varname = ls->dyd->actvar.arr[e->u.info].vd.name;
break;
}
case VLOCAL: {
Vardesc *vardesc = getlocalvardesc(fs, e->u.var.vidx);
if (vardesc->ro)
varname = vardesc->name;
if (vardesc->vd.kind != VDKREG) /* not a regular variable? */
varname = vardesc->vd.name;
break;
}
case VUPVAL: {
Upvaldesc *up = &fs->f->upvalues[e->u.info];
if (up->ro)
if (up->kind != VDKREG)
varname = up->name;
break;
}
@@ -302,8 +304,8 @@ static void adjustlocalvars (LexState *ls, int nvars) {
for (i = 0; i < nvars; i++) {
int varidx = fs->nactvar++;
Vardesc *var = getlocalvardesc(fs, varidx);
var->sidx = stklevel++;
fs->f->locvars[var->pidx].startpc = fs->pc;
var->vd.sidx = stklevel++;
var->vd.pidx = registerlocalvar(ls, fs, var->vd.name);
}
}
@@ -354,13 +356,13 @@ static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
if (v->k == VLOCAL) {
up->instack = 1;
up->idx = v->u.var.sidx;
up->ro = getlocalvardesc(prev, v->u.var.vidx)->ro;
lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->name));
up->kind = getlocalvardesc(prev, v->u.var.vidx)->vd.kind;
lua_assert(eqstr(name, getlocalvardesc(prev, v->u.var.vidx)->vd.name));
}
else {
up->instack = 0;
up->idx = cast_byte(v->u.info);
up->ro = prev->f->upvalues[v->u.info].ro;
up->kind = prev->f->upvalues[v->u.info].kind;
lua_assert(eqstr(name, prev->f->upvalues[v->u.info].name));
}
up->name = name;
@@ -373,11 +375,17 @@ static int newupvalue (FuncState *fs, TString *name, expdesc *v) {
** Look for an active local variable with the name 'n' in the
** function 'fs'.
*/
static int searchvar (FuncState *fs, TString *n) {
static int searchvar (FuncState *fs, TString *n, expdesc *var) {
int i;
for (i = cast_int(fs->nactvar) - 1; i >= 0; i--) {
if (eqstr(n, getlocalvardesc(fs, i)->name))
return i;
Vardesc *vd = getlocalvardesc(fs, i);
if (eqstr(n, vd->vd.name)) { /* found? */
if (vd->vd.kind == RDKCTC) /* compile-time constant? */
init_exp(var, VCONST, fs->firstlocal + i);
else /* real variable */
init_var(fs, var, i);
return var->k;
}
}
return -1; /* not found */
}
@@ -405,20 +413,19 @@ static void singlevaraux (FuncState *fs, TString *n, expdesc *var, int base) {
if (fs == NULL) /* no more levels? */
init_exp(var, VVOID, 0); /* default is global */
else {
int v = searchvar(fs, n); /* look up locals at current level */
int v = searchvar(fs, n, var); /* look up locals at current level */
if (v >= 0) { /* found? */
init_var(fs, var, v); /* variable is local */
if (!base)
if (v == VLOCAL && !base)
markupval(fs, var->u.var.vidx); /* local will be used as an upval */
}
else { /* not found as local at current level; try upvalues */
int idx = searchupvalue(fs, n); /* try existing upvalues */
if (idx < 0) { /* not found? */
singlevaraux(fs->prev, n, var, 0); /* try upper levels */
if (var->k == VVOID) /* not found? */
return; /* it is a global */
/* else was LOCAL or UPVAL */
idx = newupvalue(fs, n, var); /* will be a new upvalue */
if (var->k == VLOCAL || var->k == VUPVAL) /* local or upvalue? */
idx = newupvalue(fs, n, var); /* will be a new upvalue */
else /* it is a global or a constant */
return; /* don't need to do anything at this level */
}
init_exp(var, VUPVAL, idx); /* new or old upvalue */
}
@@ -483,7 +490,7 @@ static void adjust_assign (LexState *ls, int nvars, int nexps, expdesc *e) {
** local variable.
*/
static l_noret jumpscopeerror (LexState *ls, Labeldesc *gt) {
const char *varname = getstr(getlocalvardesc(ls->fs, gt->nactvar)->name);
const char *varname = getstr(getlocalvardesc(ls->fs, gt->nactvar)->vd.name);
const char *msg = "<goto %s> at line %d jumps into the scope of local '%s'";
msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line, varname);
luaK_semerror(ls, msg); /* raise the error */
@@ -1710,21 +1717,20 @@ static int getlocalattribute (LexState *ls) {
const char *attr = getstr(str_checkname(ls));
checknext(ls, '>');
if (strcmp(attr, "const") == 0)
return 1; /* read-only variable */
return RDKCONST; /* read-only variable */
else if (strcmp(attr, "toclose") == 0)
return 2; /* to-be-closed variable */
return RDKTOCLOSE; /* to-be-closed variable */
else
luaK_semerror(ls,
luaO_pushfstring(ls->L, "unknown attribute '%s'", attr));
}
return 0;
return VDKREG;
}
static void checktoclose (LexState *ls, int toclose) {
if (toclose != -1) { /* is there a to-be-closed variable? */
static void checktoclose (LexState *ls, int level) {
if (level != -1) { /* is there a to-be-closed variable? */
FuncState *fs = ls->fs;
int level = luaY_nvarstack(fs) + toclose;
markupval(fs, level + 1);
fs->bl->insidetbc = 1; /* in the scope of a to-be-closed variable */
luaK_codeABC(fs, OP_TBC, level, 0, 0);
@@ -1734,20 +1740,20 @@ static void checktoclose (LexState *ls, int toclose) {
static void localstat (LexState *ls) {
/* stat -> LOCAL ATTRIB NAME {',' ATTRIB NAME} ['=' explist] */
FuncState *fs = ls->fs;
int toclose = -1; /* index of to-be-closed variable (if any) */
Vardesc *var; /* last variable */
int nvars = 0;
int nexps;
expdesc e;
do {
int kind = getlocalattribute(ls);
Vardesc *var = new_localvar(ls, str_checkname(ls));
if (kind != 0) { /* is there an attribute? */
var->ro = 1; /* all attributes make variable read-only */
if (kind == 2) { /* to-be-closed? */
if (toclose != -1) /* one already present? */
luaK_semerror(ls, "multiple to-be-closed variables in local list");
toclose = nvars;
}
var = new_localvar(ls, str_checkname(ls));
var->vd.kind = kind;
if (kind == RDKTOCLOSE) { /* to-be-closed? */
if (toclose != -1) /* one already present? */
luaK_semerror(ls, "multiple to-be-closed variables in local list");
toclose = luaY_nvarstack(fs) + nvars;
}
nvars++;
} while (testnext(ls, ','));
@@ -1757,9 +1763,18 @@ static void localstat (LexState *ls) {
e.k = VVOID;
nexps = 0;
}
adjust_assign(ls, nvars, nexps, &e);
if (nvars == nexps && /* no adjustments? */
var->vd.kind == RDKCONST && /* last variable is const? */
luaK_exp2const(fs, &e, &var->k)) { /* compile-time constant? */
var->vd.kind = RDKCTC; /* variable is a compile-time constant */
adjustlocalvars(ls, nvars - 1); /* exclude last variable */
fs->nactvar++; /* but count it */
}
else {
adjust_assign(ls, nvars, nexps, &e);
adjustlocalvars(ls, nvars);
}
checktoclose(ls, toclose);
adjustlocalvars(ls, nvars);
}
@@ -1925,7 +1940,7 @@ static void mainfunc (LexState *ls, FuncState *fs) {
env = allocupvalue(fs); /* ...set environment upvalue */
env->instack = 1;
env->idx = 0;
env->ro = 0;
env->kind = VDKREG;
env->name = ls->envn;
luaX_next(ls); /* read first token */
statlist(ls); /* parse main body */