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lj_record.c
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lj_record.c
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/*
** Trace recorder (bytecode -> SSA IR).
** Copyright (C) 2005-2017 Mike Pall. See Copyright Notice in luajit.h
*/
#define lj_record_c
#define LUA_CORE
#include "lj_obj.h"
#if LJ_HASJIT
#include "lj_err.h"
#include "lj_str.h"
#include "lj_tab.h"
#include "lj_meta.h"
#include "lj_frame.h"
#if LJ_HASFFI
#include "lj_ctype.h"
#endif
#include "lj_bc.h"
#include "lj_ff.h"
#if LJ_HASPROFILE
#include "lj_debug.h"
#endif
#include "lj_ir.h"
#include "lj_jit.h"
#include "lj_ircall.h"
#include "lj_iropt.h"
#include "lj_trace.h"
#include "lj_record.h"
#include "lj_ffrecord.h"
#include "lj_snap.h"
#include "lj_dispatch.h"
#include "lj_vm.h"
/* Some local macros to save typing. Undef'd at the end. */
#define IR(ref) (&J->cur.ir[(ref)])
/* Pass IR on to next optimization in chain (FOLD). */
#define emitir(ot, a, b) (lj_ir_set(J, (ot), (a), (b)), lj_opt_fold(J))
/* Emit raw IR without passing through optimizations. */
#define emitir_raw(ot, a, b) (lj_ir_set(J, (ot), (a), (b)), lj_ir_emit(J))
/* -- Sanity checks ------------------------------------------------------- */
#ifdef LUA_USE_ASSERT
/* Sanity check the whole IR -- sloooow. */
static void rec_check_ir(jit_State *J)
{
IRRef i, nins = J->cur.nins, nk = J->cur.nk;
lj_assertJ(nk <= REF_BIAS && nins >= REF_BIAS && nins < 65536,
"inconsistent IR layout");
for (i = nk; i < nins; i++) {
IRIns *ir = IR(i);
uint32_t mode = lj_ir_mode[ir->o];
IRRef op1 = ir->op1;
IRRef op2 = ir->op2;
const char *err = NULL;
switch (irm_op1(mode)) {
case IRMnone:
if (op1 != 0) err = "IRMnone op1 used";
break;
case IRMref:
if (op1 < nk || (i >= REF_BIAS ? op1 >= i : op1 <= i))
err = "IRMref op1 out of range";
break;
case IRMlit: break;
case IRMcst:
if (i >= REF_BIAS) { err = "constant in IR range"; break; }
if (irt_is64(ir->t) && ir->o != IR_KNULL)
i++;
continue;
}
switch (irm_op2(mode)) {
case IRMnone:
if (op2) err = "IRMnone op2 used";
break;
case IRMref:
if (op2 < nk || (i >= REF_BIAS ? op2 >= i : op2 <= i))
err = "IRMref op2 out of range";
break;
case IRMlit: break;
case IRMcst: err = "IRMcst op2"; break;
}
if (!err && ir->prev) {
if (ir->prev < nk || (i >= REF_BIAS ? ir->prev >= i : ir->prev <= i))
err = "chain out of range";
else if (ir->o != IR_NOP && IR(ir->prev)->o != ir->o)
err = "chain to different op";
}
lj_assertJ(!err, "bad IR %04d op %d(%04d,%04d): %s",
i-REF_BIAS,
ir->o,
irm_op1(mode) == IRMref ? op1-REF_BIAS : op1,
irm_op2(mode) == IRMref ? op2-REF_BIAS : op2,
err);
}
}
/* Compare stack slots and frames of the recorder and the VM. */
static void rec_check_slots(jit_State *J)
{
BCReg s, nslots = J->baseslot + J->maxslot;
int32_t depth = 0;
cTValue *base = J->L->base - J->baseslot;
lj_assertJ(J->baseslot >= 1+LJ_FR2, "bad baseslot");
lj_assertJ(J->baseslot == 1+LJ_FR2 || (J->slot[J->baseslot-1] & TREF_FRAME),
"baseslot does not point to frame");
lj_assertJ(nslots <= LJ_MAX_JSLOTS, "slot overflow");
for (s = 0; s < nslots; s++) {
TRef tr = J->slot[s];
if (tr) {
cTValue *tv = &base[s];
IRRef ref = tref_ref(tr);
IRIns *ir = NULL; /* Silence compiler. */
lj_assertJ(tv < J->L->top, "slot %d above top of Lua stack", s);
if (!LJ_FR2 || ref || !(tr & (TREF_FRAME | TREF_CONT))) {
lj_assertJ(ref >= J->cur.nk && ref < J->cur.nins,
"slot %d ref %04d out of range", s, ref - REF_BIAS);
ir = IR(ref);
lj_assertJ(irt_t(ir->t) == tref_t(tr), "slot %d IR type mismatch", s);
}
if (s == 0) {
lj_assertJ(tref_isfunc(tr), "frame slot 0 is not a function");
#if LJ_FR2
} else if (s == 1) {
lj_assertJ((tr & ~TREF_FRAME) == 0, "bad frame slot 1");
#endif
} else if ((tr & TREF_FRAME)) {
GCfunc *fn = gco2func(frame_gc(tv));
BCReg delta = (BCReg)(tv - frame_prev(tv));
#if LJ_FR2
lj_assertJ(!ref || ir_knum(ir)->u64 == tv->u64,
"frame slot %d PC mismatch", s);
tr = J->slot[s-1];
ir = IR(tref_ref(tr));
#endif
lj_assertJ(tref_isfunc(tr),
"frame slot %d is not a function", s-LJ_FR2);
lj_assertJ(!tref_isk(tr) || fn == ir_kfunc(ir),
"frame slot %d function mismatch", s-LJ_FR2);
lj_assertJ(s > delta + LJ_FR2 ? (J->slot[s-delta] & TREF_FRAME)
: (s == delta + LJ_FR2),
"frame slot %d broken chain", s-LJ_FR2);
depth++;
} else if ((tr & TREF_CONT)) {
#if LJ_FR2
lj_assertJ(!ref || ir_knum(ir)->u64 == tv->u64,
"cont slot %d continuation mismatch", s);
#else
lj_assertJ(ir_kptr(ir) == gcrefp(tv->gcr, void),
"cont slot %d continuation mismatch", s);
#endif
lj_assertJ((J->slot[s+1+LJ_FR2] & TREF_FRAME),
"cont slot %d not followed by frame", s);
depth++;
} else {
/* Number repr. may differ, but other types must be the same. */
lj_assertJ(tvisnumber(tv) ? tref_isnumber(tr) :
itype2irt(tv) == tref_type(tr),
"slot %d type mismatch: stack type %d vs IR type %d",
s, itypemap(tv), tref_type(tr));
if (tref_isk(tr)) { /* Compare constants. */
TValue tvk;
lj_ir_kvalue(J->L, &tvk, ir);
lj_assertJ((tvisnum(&tvk) && tvisnan(&tvk)) ?
(tvisnum(tv) && tvisnan(tv)) :
lj_obj_equal(tv, &tvk),
"slot %d const mismatch: stack %016llx vs IR %016llx",
s, tv->u64, tvk.u64);
}
}
}
}
lj_assertJ(J->framedepth == depth,
"frame depth mismatch %d vs %d", J->framedepth, depth);
}
#endif
/* -- Type handling and specialization ------------------------------------ */
/* Note: these functions return tagged references (TRef). */
/* Specialize a slot to a specific type. Note: slot can be negative! */
static TRef sloadt(jit_State *J, int32_t slot, IRType t, int mode)
{
/* Caller may set IRT_GUARD in t. */
TRef ref = emitir_raw(IRT(IR_SLOAD, t), (int32_t)J->baseslot+slot, mode);
J->base[slot] = ref;
return ref;
}
/* Specialize a slot to the runtime type. Note: slot can be negative! */
static TRef sload(jit_State *J, int32_t slot)
{
IRType t = itype2irt(&J->L->base[slot]);
TRef ref = emitir_raw(IRTG(IR_SLOAD, t), (int32_t)J->baseslot+slot,
IRSLOAD_TYPECHECK);
if (irtype_ispri(t)) ref = TREF_PRI(t); /* Canonicalize primitive refs. */
J->base[slot] = ref;
return ref;
}
/* Get TRef from slot. Load slot and specialize if not done already. */
#define getslot(J, s) (J->base[(s)] ? J->base[(s)] : sload(J, (int32_t)(s)))
/* Get TRef for current function. */
static TRef getcurrf(jit_State *J)
{
if (J->base[-1-LJ_FR2])
return J->base[-1-LJ_FR2];
/* Non-base frame functions ought to be loaded already. */
lj_assertJ(J->baseslot == 1+LJ_FR2, "bad baseslot");
return sloadt(J, -1-LJ_FR2, IRT_FUNC, IRSLOAD_READONLY);
}
/* Compare for raw object equality.
** Returns 0 if the objects are the same.
** Returns 1 if they are different, but the same type.
** Returns 2 for two different types.
** Comparisons between primitives always return 1 -- no caller cares about it.
*/
int lj_record_objcmp(jit_State *J, TRef a, TRef b, cTValue *av, cTValue *bv)
{
int diff = !lj_obj_equal(av, bv);
if (!tref_isk2(a, b)) { /* Shortcut, also handles primitives. */
IRType ta = tref_isinteger(a) ? IRT_INT : tref_type(a);
IRType tb = tref_isinteger(b) ? IRT_INT : tref_type(b);
if (ta != tb) {
/* Widen mixed number/int comparisons to number/number comparison. */
if (ta == IRT_INT && tb == IRT_NUM) {
a = emitir(IRTN(IR_CONV), a, IRCONV_NUM_INT);
ta = IRT_NUM;
} else if (ta == IRT_NUM && tb == IRT_INT) {
b = emitir(IRTN(IR_CONV), b, IRCONV_NUM_INT);
} else {
return 2; /* Two different types are never equal. */
}
}
emitir(IRTG(diff ? IR_NE : IR_EQ, ta), a, b);
}
return diff;
}
/* Constify a value. Returns 0 for non-representable object types. */
TRef lj_record_constify(jit_State *J, cTValue *o)
{
if (tvisgcv(o))
return lj_ir_kgc(J, gcV(o), itype2irt(o));
else if (tvisint(o))
return lj_ir_kint(J, intV(o));
else if (tvisnum(o))
return lj_ir_knumint(J, numV(o));
else if (tvisbool(o))
return TREF_PRI(itype2irt(o));
else
return 0; /* Can't represent lightuserdata (pointless). */
}
/* -- Record loop ops ----------------------------------------------------- */
/* Loop event. */
typedef enum {
LOOPEV_LEAVE, /* Loop is left or not entered. */
LOOPEV_ENTERLO, /* Loop is entered with a low iteration count left. */
LOOPEV_ENTER /* Loop is entered. */
} LoopEvent;
/* Canonicalize slots: convert integers to numbers. */
static void canonicalize_slots(jit_State *J)
{
BCReg s;
if (LJ_DUALNUM) return;
for (s = J->baseslot+J->maxslot-1; s >= 1; s--) {
TRef tr = J->slot[s];
if (tref_isinteger(tr)) {
IRIns *ir = IR(tref_ref(tr));
if (!(ir->o == IR_SLOAD && (ir->op2 & IRSLOAD_READONLY)))
J->slot[s] = emitir(IRTN(IR_CONV), tr, IRCONV_NUM_INT);
}
}
}
/* Stop recording. */
void lj_record_stop(jit_State *J, TraceLink linktype, TraceNo lnk)
{
#ifdef LUAJIT_ENABLE_TABLE_BUMP
if (J->retryrec)
lj_trace_err(J, LJ_TRERR_RETRY);
#endif
lj_trace_end(J);
J->cur.linktype = (uint8_t)linktype;
J->cur.link = (uint16_t)lnk;
/* Looping back at the same stack level? */
if (lnk == J->cur.traceno && J->framedepth + J->retdepth == 0) {
if ((J->flags & JIT_F_OPT_LOOP)) /* Shall we try to create a loop? */
goto nocanon; /* Do not canonicalize or we lose the narrowing. */
if (J->cur.root) /* Otherwise ensure we always link to the root trace. */
J->cur.link = J->cur.root;
}
canonicalize_slots(J);
nocanon:
/* Note: all loop ops must set J->pc to the following instruction! */
lj_snap_add(J); /* Add loop snapshot. */
J->needsnap = 0;
J->mergesnap = 1; /* In case recording continues. */
}
/* Search bytecode backwards for a int/num constant slot initializer. */
static TRef find_kinit(jit_State *J, const BCIns *endpc, BCReg slot, IRType t)
{
/* This algorithm is rather simplistic and assumes quite a bit about
** how the bytecode is generated. It works fine for FORI initializers,
** but it won't necessarily work in other cases (e.g. iterator arguments).
** It doesn't do anything fancy, either (like backpropagating MOVs).
*/
const BCIns *pc, *startpc = proto_bc(J->pt);
for (pc = endpc-1; pc > startpc; pc--) {
BCIns ins = *pc;
BCOp op = bc_op(ins);
/* First try to find the last instruction that stores to this slot. */
if (bcmode_a(op) == BCMbase && bc_a(ins) <= slot) {
return 0; /* Multiple results, e.g. from a CALL or KNIL. */
} else if (bcmode_a(op) == BCMdst && bc_a(ins) == slot) {
if (op == BC_KSHORT || op == BC_KNUM) { /* Found const. initializer. */
/* Now try to verify there's no forward jump across it. */
const BCIns *kpc = pc;
for (; pc > startpc; pc--)
if (bc_op(*pc) == BC_JMP) {
const BCIns *target = pc+bc_j(*pc)+1;
if (target > kpc && target <= endpc)
return 0; /* Conditional assignment. */
}
if (op == BC_KSHORT) {
int32_t k = (int32_t)(int16_t)bc_d(ins);
return t == IRT_INT ? lj_ir_kint(J, k) : lj_ir_knum(J, (lua_Number)k);
} else {
cTValue *tv = proto_knumtv(J->pt, bc_d(ins));
if (t == IRT_INT) {
int32_t k = numberVint(tv);
if (tvisint(tv) || numV(tv) == (lua_Number)k) /* -0 is ok here. */
return lj_ir_kint(J, k);
return 0; /* Type mismatch. */
} else {
return lj_ir_knum(J, numberVnum(tv));
}
}
}
return 0; /* Non-constant initializer. */
}
}
return 0; /* No assignment to this slot found? */
}
/* Load and optionally convert a FORI argument from a slot. */
static TRef fori_load(jit_State *J, BCReg slot, IRType t, int mode)
{
int conv = (tvisint(&J->L->base[slot]) != (t==IRT_INT)) ? IRSLOAD_CONVERT : 0;
return sloadt(J, (int32_t)slot,
t + (((mode & IRSLOAD_TYPECHECK) ||
(conv && t == IRT_INT && !(mode >> 16))) ?
IRT_GUARD : 0),
mode + conv);
}
/* Peek before FORI to find a const initializer. Otherwise load from slot. */
static TRef fori_arg(jit_State *J, const BCIns *fori, BCReg slot,
IRType t, int mode)
{
TRef tr = J->base[slot];
if (!tr) {
tr = find_kinit(J, fori, slot, t);
if (!tr)
tr = fori_load(J, slot, t, mode);
}
return tr;
}
/* Return the direction of the FOR loop iterator.
** It's important to exactly reproduce the semantics of the interpreter.
*/
static int rec_for_direction(cTValue *o)
{
return (tvisint(o) ? intV(o) : (int32_t)o->u32.hi) >= 0;
}
/* Simulate the runtime behavior of the FOR loop iterator. */
static LoopEvent rec_for_iter(IROp *op, cTValue *o, int isforl)
{
lua_Number stopv = numberVnum(&o[FORL_STOP]);
lua_Number idxv = numberVnum(&o[FORL_IDX]);
lua_Number stepv = numberVnum(&o[FORL_STEP]);
if (isforl)
idxv += stepv;
if (rec_for_direction(&o[FORL_STEP])) {
if (idxv <= stopv) {
*op = IR_LE;
return idxv + 2*stepv > stopv ? LOOPEV_ENTERLO : LOOPEV_ENTER;
}
*op = IR_GT; return LOOPEV_LEAVE;
} else {
if (stopv <= idxv) {
*op = IR_GE;
return idxv + 2*stepv < stopv ? LOOPEV_ENTERLO : LOOPEV_ENTER;
}
*op = IR_LT; return LOOPEV_LEAVE;
}
}
/* Record checks for FOR loop overflow and step direction. */
static void rec_for_check(jit_State *J, IRType t, int dir,
TRef stop, TRef step, int init)
{
if (!tref_isk(step)) {
/* Non-constant step: need a guard for the direction. */
TRef zero = (t == IRT_INT) ? lj_ir_kint(J, 0) : lj_ir_knum_zero(J);
emitir(IRTG(dir ? IR_GE : IR_LT, t), step, zero);
/* Add hoistable overflow checks for a narrowed FORL index. */
if (init && t == IRT_INT) {
if (tref_isk(stop)) {
/* Constant stop: optimize check away or to a range check for step. */
int32_t k = IR(tref_ref(stop))->i;
if (dir) {
if (k > 0)
emitir(IRTGI(IR_LE), step, lj_ir_kint(J, (int32_t)0x7fffffff-k));
} else {
if (k < 0)
emitir(IRTGI(IR_GE), step, lj_ir_kint(J, (int32_t)0x80000000-k));
}
} else {
/* Stop+step variable: need full overflow check. */
TRef tr = emitir(IRTGI(IR_ADDOV), step, stop);
emitir(IRTI(IR_USE), tr, 0); /* ADDOV is weak. Avoid dead result. */
}
}
} else if (init && t == IRT_INT && !tref_isk(stop)) {
/* Constant step: optimize overflow check to a range check for stop. */
int32_t k = IR(tref_ref(step))->i;
k = (int32_t)(dir ? 0x7fffffff : 0x80000000) - k;
emitir(IRTGI(dir ? IR_LE : IR_GE), stop, lj_ir_kint(J, k));
}
}
/* Record a FORL instruction. */
static void rec_for_loop(jit_State *J, const BCIns *fori, ScEvEntry *scev,
int init)
{
BCReg ra = bc_a(*fori);
cTValue *tv = &J->L->base[ra];
TRef idx = J->base[ra+FORL_IDX];
IRType t = idx ? tref_type(idx) :
(init || LJ_DUALNUM) ? lj_opt_narrow_forl(J, tv) : IRT_NUM;
int mode = IRSLOAD_INHERIT +
((!LJ_DUALNUM || tvisint(tv) == (t == IRT_INT)) ? IRSLOAD_READONLY : 0);
TRef stop = fori_arg(J, fori, ra+FORL_STOP, t, mode);
TRef step = fori_arg(J, fori, ra+FORL_STEP, t, mode);
int tc, dir = rec_for_direction(&tv[FORL_STEP]);
lj_assertJ(bc_op(*fori) == BC_FORI || bc_op(*fori) == BC_JFORI,
"bad bytecode %d instead of FORI/JFORI", bc_op(*fori));
scev->t.irt = t;
scev->dir = dir;
scev->stop = tref_ref(stop);
scev->step = tref_ref(step);
rec_for_check(J, t, dir, stop, step, init);
scev->start = tref_ref(find_kinit(J, fori, ra+FORL_IDX, IRT_INT));
tc = (LJ_DUALNUM &&
!(scev->start && irref_isk(scev->stop) && irref_isk(scev->step) &&
tvisint(&tv[FORL_IDX]) == (t == IRT_INT))) ?
IRSLOAD_TYPECHECK : 0;
if (tc) {
J->base[ra+FORL_STOP] = stop;
J->base[ra+FORL_STEP] = step;
}
if (!idx)
idx = fori_load(J, ra+FORL_IDX, t,
IRSLOAD_INHERIT + tc + (J->scev.start << 16));
if (!init)
J->base[ra+FORL_IDX] = idx = emitir(IRT(IR_ADD, t), idx, step);
J->base[ra+FORL_EXT] = idx;
scev->idx = tref_ref(idx);
setmref(scev->pc, fori);
J->maxslot = ra+FORL_EXT+1;
}
/* Record FORL/JFORL or FORI/JFORI. */
static LoopEvent rec_for(jit_State *J, const BCIns *fori, int isforl)
{
BCReg ra = bc_a(*fori);
TValue *tv = &J->L->base[ra];
TRef *tr = &J->base[ra];
IROp op;
LoopEvent ev;
TRef stop;
IRType t;
if (isforl) { /* Handle FORL/JFORL opcodes. */
TRef idx = tr[FORL_IDX];
if (mref(J->scev.pc, const BCIns) == fori && tref_ref(idx) == J->scev.idx) {
t = J->scev.t.irt;
stop = J->scev.stop;
idx = emitir(IRT(IR_ADD, t), idx, J->scev.step);
tr[FORL_EXT] = tr[FORL_IDX] = idx;
} else {
ScEvEntry scev;
rec_for_loop(J, fori, &scev, 0);
t = scev.t.irt;
stop = scev.stop;
}
} else { /* Handle FORI/JFORI opcodes. */
BCReg i;
lj_meta_for(J->L, tv);
t = (LJ_DUALNUM || tref_isint(tr[FORL_IDX])) ? lj_opt_narrow_forl(J, tv) :
IRT_NUM;
for (i = FORL_IDX; i <= FORL_STEP; i++) {
if (!tr[i]) sload(J, ra+i);
lj_assertJ(tref_isnumber_str(tr[i]), "bad FORI argument type");
if (tref_isstr(tr[i]))
tr[i] = emitir(IRTG(IR_STRTO, IRT_NUM), tr[i], 0);
if (t == IRT_INT) {
if (!tref_isinteger(tr[i]))
tr[i] = emitir(IRTGI(IR_CONV), tr[i], IRCONV_INT_NUM|IRCONV_CHECK);
} else {
if (!tref_isnum(tr[i]))
tr[i] = emitir(IRTN(IR_CONV), tr[i], IRCONV_NUM_INT);
}
}
tr[FORL_EXT] = tr[FORL_IDX];
stop = tr[FORL_STOP];
rec_for_check(J, t, rec_for_direction(&tv[FORL_STEP]),
stop, tr[FORL_STEP], 1);
}
ev = rec_for_iter(&op, tv, isforl);
if (ev == LOOPEV_LEAVE) {
J->maxslot = ra+FORL_EXT+1;
J->pc = fori+1;
} else {
J->maxslot = ra;
J->pc = fori+bc_j(*fori)+1;
}
lj_snap_add(J);
emitir(IRTG(op, t), tr[FORL_IDX], stop);
if (ev == LOOPEV_LEAVE) {
J->maxslot = ra;
J->pc = fori+bc_j(*fori)+1;
} else {
J->maxslot = ra+FORL_EXT+1;
J->pc = fori+1;
}
J->needsnap = 1;
return ev;
}
/* Record ITERL/JITERL. */
static LoopEvent rec_iterl(jit_State *J, const BCIns iterins)
{
BCReg ra = bc_a(iterins);
if (!tref_isnil(getslot(J, ra))) { /* Looping back? */
J->base[ra-1] = J->base[ra]; /* Copy result of ITERC to control var. */
J->maxslot = ra-1+bc_b(J->pc[-1]);
J->pc += bc_j(iterins)+1;
return LOOPEV_ENTER;
} else {
J->maxslot = ra-3;
J->pc++;
return LOOPEV_LEAVE;
}
}
/* Record LOOP/JLOOP. Now, that was easy. */
static LoopEvent rec_loop(jit_State *J, BCReg ra)
{
if (ra < J->maxslot) J->maxslot = ra;
J->pc++;
return LOOPEV_ENTER;
}
/* Check if a loop repeatedly failed to trace because it didn't loop back. */
static int innerloopleft(jit_State *J, const BCIns *pc)
{
ptrdiff_t i;
for (i = 0; i < PENALTY_SLOTS; i++)
if (mref(J->penalty[i].pc, const BCIns) == pc) {
if ((J->penalty[i].reason == LJ_TRERR_LLEAVE ||
J->penalty[i].reason == LJ_TRERR_LINNER) &&
J->penalty[i].val >= 2*PENALTY_MIN)
return 1;
break;
}
return 0;
}
/* Handle the case when an interpreted loop op is hit. */
static void rec_loop_interp(jit_State *J, const BCIns *pc, LoopEvent ev)
{
if (J->parent == 0 && J->exitno == 0) {
if (pc == J->startpc && J->framedepth + J->retdepth == 0) {
/* Same loop? */
if (ev == LOOPEV_LEAVE) /* Must loop back to form a root trace. */
lj_trace_err(J, LJ_TRERR_LLEAVE);
lj_record_stop(J, LJ_TRLINK_LOOP, J->cur.traceno); /* Looping trace. */
} else if (ev != LOOPEV_LEAVE) { /* Entering inner loop? */
/* It's usually better to abort here and wait until the inner loop
** is traced. But if the inner loop repeatedly didn't loop back,
** this indicates a low trip count. In this case try unrolling
** an inner loop even in a root trace. But it's better to be a bit
** more conservative here and only do it for very short loops.
*/
if (bc_j(*pc) != -1 && !innerloopleft(J, pc))
lj_trace_err(J, LJ_TRERR_LINNER); /* Root trace hit an inner loop. */
if ((ev != LOOPEV_ENTERLO &&
J->loopref && J->cur.nins - J->loopref > 24) || --J->loopunroll < 0)
lj_trace_err(J, LJ_TRERR_LUNROLL); /* Limit loop unrolling. */
J->loopref = J->cur.nins;
}
} else if (ev != LOOPEV_LEAVE) { /* Side trace enters an inner loop. */
J->loopref = J->cur.nins;
if (--J->loopunroll < 0)
lj_trace_err(J, LJ_TRERR_LUNROLL); /* Limit loop unrolling. */
} /* Side trace continues across a loop that's left or not entered. */
}
/* Handle the case when an already compiled loop op is hit. */
static void rec_loop_jit(jit_State *J, TraceNo lnk, LoopEvent ev)
{
if (J->parent == 0 && J->exitno == 0) { /* Root trace hit an inner loop. */
/* Better let the inner loop spawn a side trace back here. */
lj_trace_err(J, LJ_TRERR_LINNER);
} else if (ev != LOOPEV_LEAVE) { /* Side trace enters a compiled loop. */
J->instunroll = 0; /* Cannot continue across a compiled loop op. */
if (J->pc == J->startpc && J->framedepth + J->retdepth == 0)
lj_record_stop(J, LJ_TRLINK_LOOP, J->cur.traceno); /* Form extra loop. */
else
lj_record_stop(J, LJ_TRLINK_ROOT, lnk); /* Link to the loop. */
} /* Side trace continues across a loop that's left or not entered. */
}
/* -- Record profiler hook checks ----------------------------------------- */
#if LJ_HASPROFILE
/* Need to insert profiler hook check? */
static int rec_profile_need(jit_State *J, GCproto *pt, const BCIns *pc)
{
GCproto *ppt;
lj_assertJ(J->prof_mode == 'f' || J->prof_mode == 'l',
"bad profiler mode %c", J->prof_mode);
if (!pt)
return 0;
ppt = J->prev_pt;
J->prev_pt = pt;
if (pt != ppt && ppt) {
J->prev_line = -1;
return 1;
}
if (J->prof_mode == 'l') {
BCLine line = lj_debug_line(pt, proto_bcpos(pt, pc));
BCLine pline = J->prev_line;
J->prev_line = line;
if (pline != line)
return 1;
}
return 0;
}
static void rec_profile_ins(jit_State *J, const BCIns *pc)
{
if (J->prof_mode && rec_profile_need(J, J->pt, pc)) {
emitir(IRTG(IR_PROF, IRT_NIL), 0, 0);
lj_snap_add(J);
}
}
static void rec_profile_ret(jit_State *J)
{
if (J->prof_mode == 'f') {
emitir(IRTG(IR_PROF, IRT_NIL), 0, 0);
J->prev_pt = NULL;
lj_snap_add(J);
}
}
#endif
/* -- Record calls and returns -------------------------------------------- */
/* Specialize to the runtime value of the called function or its prototype. */
static TRef rec_call_specialize(jit_State *J, GCfunc *fn, TRef tr)
{
TRef kfunc;
if (isluafunc(fn)) {
GCproto *pt = funcproto(fn);
/* Too many closures created? Probably not a monomorphic function. */
if (pt->flags >= PROTO_CLC_POLY) { /* Specialize to prototype instead. */
TRef trpt = emitir(IRT(IR_FLOAD, IRT_PGC), tr, IRFL_FUNC_PC);
emitir(IRTG(IR_EQ, IRT_PGC), trpt, lj_ir_kptr(J, proto_bc(pt)));
(void)lj_ir_kgc(J, obj2gco(pt), IRT_PROTO); /* Prevent GC of proto. */
return tr;
}
} else {
/* Don't specialize to non-monomorphic builtins. */
switch (fn->c.ffid) {
case FF_coroutine_wrap_aux:
case FF_string_gmatch_aux:
/* NYI: io_file_iter doesn't have an ffid, yet. */
{ /* Specialize to the ffid. */
TRef trid = emitir(IRT(IR_FLOAD, IRT_U8), tr, IRFL_FUNC_FFID);
emitir(IRTG(IR_EQ, IRT_INT), trid, lj_ir_kint(J, fn->c.ffid));
}
return tr;
default:
/* NYI: don't specialize to non-monomorphic C functions. */
break;
}
}
/* Otherwise specialize to the function (closure) value itself. */
kfunc = lj_ir_kfunc(J, fn);
emitir(IRTG(IR_EQ, IRT_FUNC), tr, kfunc);
return kfunc;
}
/* Record call setup. */
static void rec_call_setup(jit_State *J, BCReg func, ptrdiff_t nargs)
{
RecordIndex ix;
TValue *functv = &J->L->base[func];
TRef kfunc, *fbase = &J->base[func];
ptrdiff_t i;
(void)getslot(J, func); /* Ensure func has a reference. */
for (i = 1; i <= nargs; i++)
(void)getslot(J, func+LJ_FR2+i); /* Ensure all args have a reference. */
if (!tref_isfunc(fbase[0])) { /* Resolve __call metamethod. */
ix.tab = fbase[0];
copyTV(J->L, &ix.tabv, functv);
if (!lj_record_mm_lookup(J, &ix, MM_call) || !tref_isfunc(ix.mobj))
lj_trace_err(J, LJ_TRERR_NOMM);
for (i = ++nargs; i > LJ_FR2; i--) /* Shift arguments up. */
fbase[i+LJ_FR2] = fbase[i+LJ_FR2-1];
#if LJ_FR2
fbase[2] = fbase[0];
#endif
fbase[0] = ix.mobj; /* Replace function. */
functv = &ix.mobjv;
}
kfunc = rec_call_specialize(J, funcV(functv), fbase[0]);
#if LJ_FR2
fbase[0] = kfunc;
fbase[1] = TREF_FRAME;
#else
fbase[0] = kfunc | TREF_FRAME;
#endif
J->maxslot = (BCReg)nargs;
}
/* Record call. */
void lj_record_call(jit_State *J, BCReg func, ptrdiff_t nargs)
{
rec_call_setup(J, func, nargs);
/* Bump frame. */
J->framedepth++;
J->base += func+1+LJ_FR2;
J->baseslot += func+1+LJ_FR2;
if (J->baseslot + J->maxslot >= LJ_MAX_JSLOTS)
lj_trace_err(J, LJ_TRERR_STACKOV);
}
/* Record tail call. */
void lj_record_tailcall(jit_State *J, BCReg func, ptrdiff_t nargs)
{
rec_call_setup(J, func, nargs);
if (frame_isvarg(J->L->base - 1)) {
BCReg cbase = (BCReg)frame_delta(J->L->base - 1);
if (--J->framedepth < 0)
lj_trace_err(J, LJ_TRERR_NYIRETL);
J->baseslot -= (BCReg)cbase;
J->base -= cbase;
func += cbase;
}
/* Move func + args down. */
if (LJ_FR2 && J->baseslot == 2)
J->base[func+1] = TREF_FRAME;
memmove(&J->base[-1-LJ_FR2], &J->base[func], sizeof(TRef)*(J->maxslot+1+LJ_FR2));
/* Note: the new TREF_FRAME is now at J->base[-1] (even for slot #0). */
/* Tailcalls can form a loop, so count towards the loop unroll limit. */
if (++J->tailcalled > J->loopunroll)
lj_trace_err(J, LJ_TRERR_LUNROLL);
}
/* Check unroll limits for down-recursion. */
static int check_downrec_unroll(jit_State *J, GCproto *pt)
{
IRRef ptref;
for (ptref = J->chain[IR_KGC]; ptref; ptref = IR(ptref)->prev)
if (ir_kgc(IR(ptref)) == obj2gco(pt)) {
int count = 0;
IRRef ref;
for (ref = J->chain[IR_RETF]; ref; ref = IR(ref)->prev)
if (IR(ref)->op1 == ptref)
count++;
if (count) {
if (J->pc == J->startpc) {
if (count + J->tailcalled > J->param[JIT_P_recunroll])
return 1;
} else {
lj_trace_err(J, LJ_TRERR_DOWNREC);
}
}
}
return 0;
}
static TRef rec_cat(jit_State *J, BCReg baseslot, BCReg topslot);
/* Record return. */
void lj_record_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
{
TValue *frame = J->L->base - 1;
ptrdiff_t i;
for (i = 0; i < gotresults; i++)
(void)getslot(J, rbase+i); /* Ensure all results have a reference. */
while (frame_ispcall(frame)) { /* Immediately resolve pcall() returns. */
BCReg cbase = (BCReg)frame_delta(frame);
if (--J->framedepth <= 0)
lj_trace_err(J, LJ_TRERR_NYIRETL);
lj_assertJ(J->baseslot > 1+LJ_FR2, "bad baseslot for return");
gotresults++;
rbase += cbase;
J->baseslot -= (BCReg)cbase;
J->base -= cbase;
J->base[--rbase] = TREF_TRUE; /* Prepend true to results. */
frame = frame_prevd(frame);
J->needsnap = 1; /* Stop catching on-trace errors. */
}
/* Return to lower frame via interpreter for unhandled cases. */
if (J->framedepth == 0 && J->pt && bc_isret(bc_op(*J->pc)) &&
(!frame_islua(frame) ||
(J->parent == 0 && J->exitno == 0 &&
!bc_isret(bc_op(J->cur.startins))))) {
/* NYI: specialize to frame type and return directly, not via RET*. */
for (i = 0; i < (ptrdiff_t)rbase; i++)
J->base[i] = 0; /* Purge dead slots. */
J->maxslot = rbase + (BCReg)gotresults;
lj_record_stop(J, LJ_TRLINK_RETURN, 0); /* Return to interpreter. */
return;
}
if (frame_isvarg(frame)) {
BCReg cbase = (BCReg)frame_delta(frame);
if (--J->framedepth < 0) /* NYI: return of vararg func to lower frame. */
lj_trace_err(J, LJ_TRERR_NYIRETL);
lj_assertJ(J->baseslot > 1+LJ_FR2, "bad baseslot for return");
rbase += cbase;
J->baseslot -= (BCReg)cbase;
J->base -= cbase;
frame = frame_prevd(frame);
}
if (frame_islua(frame)) { /* Return to Lua frame. */
BCIns callins = *(frame_pc(frame)-1);
ptrdiff_t nresults = bc_b(callins) ? (ptrdiff_t)bc_b(callins)-1 :gotresults;
BCReg cbase = bc_a(callins);
GCproto *pt = funcproto(frame_func(frame - (cbase+1+LJ_FR2)));
if ((pt->flags & PROTO_NOJIT))
lj_trace_err(J, LJ_TRERR_CJITOFF);
if (J->framedepth == 0 && J->pt && frame == J->L->base - 1) {
if (check_downrec_unroll(J, pt)) {
J->maxslot = (BCReg)(rbase + gotresults);
lj_snap_purge(J);
lj_record_stop(J, LJ_TRLINK_DOWNREC, J->cur.traceno); /* Down-rec. */
return;
}
lj_snap_add(J);
}
for (i = 0; i < nresults; i++) /* Adjust results. */
J->base[i-1-LJ_FR2] = i < gotresults ? J->base[rbase+i] : TREF_NIL;
J->maxslot = cbase+(BCReg)nresults;
if (J->framedepth > 0) { /* Return to a frame that is part of the trace. */
J->framedepth--;
lj_assertJ(J->baseslot > cbase+1+LJ_FR2, "bad baseslot for return");
J->baseslot -= cbase+1+LJ_FR2;
J->base -= cbase+1+LJ_FR2;
} else if (J->parent == 0 && J->exitno == 0 &&
!bc_isret(bc_op(J->cur.startins))) {
/* Return to lower frame would leave the loop in a root trace. */
lj_trace_err(J, LJ_TRERR_LLEAVE);
} else if (J->needsnap) { /* Tailcalled to ff with side-effects. */
lj_trace_err(J, LJ_TRERR_NYIRETL); /* No way to insert snapshot here. */
} else { /* Return to lower frame. Guard for the target we return to. */
TRef trpt = lj_ir_kgc(J, obj2gco(pt), IRT_PROTO);
TRef trpc = lj_ir_kptr(J, (void *)frame_pc(frame));
emitir(IRTG(IR_RETF, IRT_PGC), trpt, trpc);
J->retdepth++;
J->needsnap = 1;
lj_assertJ(J->baseslot == 1+LJ_FR2, "bad baseslot for return");
/* Shift result slots up and clear the slots of the new frame below. */
memmove(J->base + cbase, J->base-1-LJ_FR2, sizeof(TRef)*nresults);
memset(J->base-1-LJ_FR2, 0, sizeof(TRef)*(cbase+1+LJ_FR2));
}
} else if (frame_iscont(frame)) { /* Return to continuation frame. */
ASMFunction cont = frame_contf(frame);
BCReg cbase = (BCReg)frame_delta(frame);
if ((J->framedepth -= 2) < 0)
lj_trace_err(J, LJ_TRERR_NYIRETL);
J->baseslot -= (BCReg)cbase;
J->base -= cbase;
J->maxslot = cbase-(2<<LJ_FR2);
if (cont == lj_cont_ra) {
/* Copy result to destination slot. */
BCReg dst = bc_a(*(frame_contpc(frame)-1));
J->base[dst] = gotresults ? J->base[cbase+rbase] : TREF_NIL;
if (dst >= J->maxslot) {
J->maxslot = dst+1;
}
} else if (cont == lj_cont_nop) {
/* Nothing to do here. */
} else if (cont == lj_cont_cat) {
BCReg bslot = bc_b(*(frame_contpc(frame)-1));
TRef tr = gotresults ? J->base[cbase+rbase] : TREF_NIL;
if (bslot != J->maxslot) { /* Concatenate the remainder. */
TValue *b = J->L->base, save; /* Simulate lower frame and result. */
J->base[J->maxslot] = tr;
copyTV(J->L, &save, b-(2<<LJ_FR2));
if (gotresults)
copyTV(J->L, b-(2<<LJ_FR2), b+rbase);
else
setnilV(b-(2<<LJ_FR2));
J->L->base = b - cbase;
tr = rec_cat(J, bslot, cbase-(2<<LJ_FR2));
b = J->L->base + cbase; /* Undo. */
J->L->base = b;
copyTV(J->L, b-(2<<LJ_FR2), &save);
}
if (tr) { /* Store final result. */
BCReg dst = bc_a(*(frame_contpc(frame)-1));
J->base[dst] = tr;
if (dst >= J->maxslot) {
J->maxslot = dst+1;
}
} /* Otherwise continue with another __concat call. */
} else {
/* Result type already specialized. */
lj_assertJ(cont == lj_cont_condf || cont == lj_cont_condt,
"bad continuation type");
}
} else {
lj_trace_err(J, LJ_TRERR_NYIRETL); /* NYI: handle return to C frame. */
}
lj_assertJ(J->baseslot >= 1+LJ_FR2, "bad baseslot for return");
}
/* -- Metamethod handling ------------------------------------------------- */
/* Prepare to record call to metamethod. */
static BCReg rec_mm_prep(jit_State *J, ASMFunction cont)
{
BCReg s, top = cont == lj_cont_cat ? J->maxslot : curr_proto(J->L)->framesize;
#if LJ_FR2
J->base[top] = lj_ir_k64(J, IR_KNUM, u64ptr(contptr(cont)));
J->base[top+1] = TREF_CONT;
#else
J->base[top] = lj_ir_kptr(J, contptr(cont)) | TREF_CONT;
#endif
J->framedepth++;
for (s = J->maxslot; s < top; s++)
J->base[s] = 0; /* Clear frame gap to avoid resurrecting previous refs. */
return top+1+LJ_FR2;
}
/* Record metamethod lookup. */
int lj_record_mm_lookup(jit_State *J, RecordIndex *ix, MMS mm)
{
RecordIndex mix;
GCtab *mt;
if (tref_istab(ix->tab)) {
mt = tabref(tabV(&ix->tabv)->metatable);
mix.tab = emitir(IRT(IR_FLOAD, IRT_TAB), ix->tab, IRFL_TAB_META);
} else if (tref_isudata(ix->tab)) {
int udtype = udataV(&ix->tabv)->udtype;
mt = tabref(udataV(&ix->tabv)->metatable);
/* The metatables of special userdata objects are treated as immutable. */
if (udtype != UDTYPE_USERDATA) {
cTValue *mo;
if (LJ_HASFFI && udtype == UDTYPE_FFI_CLIB) {
/* Specialize to the C library namespace object. */
emitir(IRTG(IR_EQ, IRT_PGC), ix->tab, lj_ir_kptr(J, udataV(&ix->tabv)));
} else {
/* Specialize to the type of userdata. */
TRef tr = emitir(IRT(IR_FLOAD, IRT_U8), ix->tab, IRFL_UDATA_UDTYPE);
emitir(IRTGI(IR_EQ), tr, lj_ir_kint(J, udtype));
}
immutable_mt:
mo = lj_tab_getstr(mt, mmname_str(J2G(J), mm));
if (!mo || tvisnil(mo))
return 0; /* No metamethod. */
/* Treat metamethod or index table as immutable, too. */
if (!(tvisfunc(mo) || tvistab(mo)))
lj_trace_err(J, LJ_TRERR_BADTYPE);
copyTV(J->L, &ix->mobjv, mo);
ix->mobj = lj_ir_kgc(J, gcV(mo), tvisfunc(mo) ? IRT_FUNC : IRT_TAB);