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Implement down-recursion.

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This commit is contained in:
Mike Pall 2010-03-01 06:45:30 +01:00
parent 69ea553024
commit e7b737aa12
7 changed files with 114 additions and 13 deletions
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8
src/lj_asm.c
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@ -3212,8 +3212,14 @@ static void asm_tail_link(ASMState *as)
if (as->T->link == TRACE_INTERP) {
/* Setup fixed registers for exit to interpreter. */
const BCIns *pc = snap_pc(as->T->snapmap[snap->mapofs + snap->nent]);
if (bc_op(*pc) == BC_JLOOP) { /* NYI: find a better way to do this. */
BCIns *retpc = &as->J->trace[bc_d(*pc)]->startins;
if (bc_isret(bc_op(*retpc)))
pc = retpc;
}
emit_loada(as, RID_DISPATCH, J2GG(as->J)->dispatch);
emit_loada(as, RID_PC, snap_pc(as->T->snapmap[snap->mapofs + snap->nent]));
emit_loada(as, RID_PC, pc);
} else if (baseslot) {
/* Save modified BASE for linking to trace with higher start frame. */
emit_setgl(as, RID_BASE, jit_base);

5
src/lj_bc.h
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@ -245,6 +245,11 @@ typedef enum {
(BCM##ma|(BCM##mb<<3)|(BCM##mc<<7)|(MM_##mm<<11)),
#define BCMODE_FF 0
static LJ_AINLINE int bc_isret(BCOp op)
{
return (op == BC_RETM || op == BC_RET || op == BC_RET0 || op == BC_RET1);
}
LJ_DATA const uint16_t lj_bc_mode[];
LJ_DATA const uint16_t lj_bc_ofs[];

5
src/lj_dispatch.c
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@ -380,11 +380,8 @@ void LJ_FASTCALL lj_dispatch_ins(lua_State *L, const BCIns *pc)
L->top = L->base + slots; /* Fix top again. */
}
}
if ((g->hookmask & LUA_MASKRET)) {
BCOp op = bc_op(pc[-1]);
if (op == BC_RETM || op == BC_RET || op == BC_RET0 || op == BC_RET1)
if ((g->hookmask & LUA_MASKRET) && bc_isret(bc_op(pc[-1])))
callhook(L, LUA_HOOKRET, -1);
}
}
/* Initialize call. Ensure stack space and clear missing parameters. */

3
src/lj_jit.h
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@ -287,6 +287,9 @@ typedef struct jit_State {
TraceNo parent; /* Parent of current side trace (0 for root traces). */
ExitNo exitno; /* Exit number in parent of current side trace. */
BCIns *patchpc; /* PC for pending re-patch. */
BCIns patchins; /* Instruction for pending re-patch. */
TValue errinfo; /* Additional info element for trace errors. */
MCode *mcarea; /* Base of current mcode area. */

41
src/lj_record.c
View File

@ -522,6 +522,29 @@ static void rec_tailcall(jit_State *J, BCReg func, ptrdiff_t nargs)
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;
}
/* Record return. */
static void rec_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
{
@ -545,6 +568,15 @@ static void rec_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
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)));
if (J->pt && frame == J->L->base - 1) {
if (J->framedepth == 0 && check_downrec_unroll(J, pt)) {
J->maxslot = rbase + nresults;
rec_stop(J, J->curtrace); /* Down-recursion. */
return;
}
lj_snap_add(J);
}
for (i = 0; i < nresults; i++) /* Adjust results. */
J->base[i-1] = i < gotresults ? J->base[rbase+i] : TREF_NIL;
J->maxslot = cbase+(BCReg)nresults;
@ -553,11 +585,10 @@ static void rec_ret(jit_State *J, BCReg rbase, ptrdiff_t gotresults)
lua_assert(J->baseslot > cbase+1);
J->baseslot -= cbase+1;
J->base -= cbase+1;
} else if (J->parent == 0) {
} else if (J->parent == 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 { /* Return to lower frame. Guard for the target we return to. */
GCproto *pt = funcproto(frame_func(frame - (cbase+1)));
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_PTR), trpt, trpc);
@ -2285,6 +2316,12 @@ static const BCIns *rec_setup_root(jit_State *J)
J->maxslot = ra;
pc++;
break;
case BC_RET:
case BC_RET0:
case BC_RET1:
/* No bytecode range check for down-recursive root traces. */
J->maxslot = ra + bc_d(ins);
break;
case BC_FUNCF:
/* No bytecode range check for root traces started by a hot call. */
J->maxslot = J->pt->numparams;

62
src/lj_trace.c
View File

@ -357,6 +357,8 @@ static void trace_start(jit_State *J)
if ((J->pt->flags & PROTO_NO_JIT)) { /* JIT disabled for this proto? */
if (J->parent == 0) {
/* Lazy bytecode patching to disable hotcount events. */
lua_assert(bc_op(*J->pc) == BC_FORL || bc_op(*J->pc) == BC_ITERL ||
bc_op(*J->pc) == BC_LOOP || bc_op(*J->pc) == BC_FUNCF);
setbc_op(J->pc, (int)bc_op(*J->pc)+(int)BC_ILOOP-(int)BC_LOOP);
J->pt->flags |= PROTO_HAS_ILOOP;
}
@ -416,10 +418,16 @@ static void trace_stop(jit_State *J)
/* Patch bytecode of starting instruction in root trace. */
setbc_op(pc, (int)op+(int)BC_JLOOP-(int)BC_LOOP);
setbc_d(pc, J->curtrace);
addroot:
/* Add to root trace chain in prototype. */
J->cur.nextroot = pt->trace;
pt->trace = (TraceNo1)J->curtrace;
break;
case BC_RET:
case BC_RET0:
case BC_RET1:
*pc = BCINS_AD(BC_JLOOP, J->cur.snap[0].nslots, J->curtrace);
goto addroot;
case BC_JMP:
/* Patch exit branch in parent to side trace entry. */
lua_assert(J->parent != 0 && J->cur.root != 0);
@ -450,6 +458,21 @@ static void trace_stop(jit_State *J)
);
}
/* Start a new root trace for down-recursion. */
static int trace_downrec(jit_State *J)
{
/* Restart recording at the return instruction. */
lua_assert(J->pt != NULL);
lua_assert(bc_isret(bc_op(*J->pc)));
if (bc_op(*J->pc) == BC_RETM)
return 0; /* NYI: down-recursion with RETM. */
J->parent = 0;
J->exitno = 0;
J->state = LJ_TRACE_RECORD;
trace_start(J);
return 1;
}
/* Abort tracing. */
static int trace_abort(jit_State *J)
{
@ -463,7 +486,7 @@ static int trace_abort(jit_State *J)
return 1; /* Retry ASM with new MCode area. */
}
/* Penalize or blacklist starting bytecode instruction. */
if (J->parent == 0)
if (J->parent == 0 && !bc_isret(bc_op(J->cur.startins)))
penalty_pc(J, &gcref(J->cur.startpt)->pt, (BCIns *)J->startpc, e);
if (J->curtrace) { /* Is there anything to abort? */
ptrdiff_t errobj = savestack(L, L->top-1); /* Stack may be resized. */
@ -493,17 +516,29 @@ static int trace_abort(jit_State *J)
J->curtrace = 0;
}
L->top--; /* Remove error object */
if (e == LJ_TRERR_MCODEAL)
if (e == LJ_TRERR_DOWNREC)
return trace_downrec(J);
else if (e == LJ_TRERR_MCODEAL)
lj_trace_flushall(L);
return 0;
}
/* Perform pending re-patch of a bytecode instruction. */
static LJ_AINLINE void trace_pendpatch(jit_State *J, int force)
{
if (LJ_UNLIKELY(J->patchpc) && (force || J->chain[IR_RETF])) {
*J->patchpc = J->patchins;
J->patchpc = NULL;
}
}
/* State machine for the trace compiler. Protected callback. */
static TValue *trace_state(lua_State *L, lua_CFunction dummy, void *ud)
{
jit_State *J = (jit_State *)ud;
UNUSED(dummy);
do {
retry:
switch (J->state) {
case LJ_TRACE_START:
J->state = LJ_TRACE_RECORD; /* trace_start() may change state. */
@ -512,6 +547,7 @@ static TValue *trace_state(lua_State *L, lua_CFunction dummy, void *ud)
break;
case LJ_TRACE_RECORD:
trace_pendpatch(J, 0);
setvmstate(J2G(J), RECORD);
lj_vmevent_send(L, RECORD,
setintV(L->top++, J->curtrace);
@ -523,6 +559,7 @@ static TValue *trace_state(lua_State *L, lua_CFunction dummy, void *ud)
break;
case LJ_TRACE_END:
trace_pendpatch(J, 1);
J->loopref = 0;
if ((J->flags & JIT_F_OPT_LOOP) &&
J->cur.link == J->curtrace && J->framedepth + J->retdepth == 0) {
@ -551,8 +588,9 @@ static TValue *trace_state(lua_State *L, lua_CFunction dummy, void *ud)
setintV(L->top++, (int32_t)LJ_TRERR_RECERR);
/* fallthrough */
case LJ_TRACE_ERR:
trace_pendpatch(J, 1);
if (trace_abort(J))
break; /* Retry. */
goto retry;
setvmstate(J2G(J), INTERP);
J->state = LJ_TRACE_IDLE;
lj_dispatch_update(J2G(J));
@ -627,6 +665,7 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
lua_State *L = J->L;
ExitDataCP exd;
int errcode;
const BCIns *pc;
exd.J = J;
exd.exptr = exptr;
errcode = lj_vm_cpcall(L, NULL, &exd, trace_exit_cp);
@ -651,8 +690,21 @@ int LJ_FASTCALL lj_trace_exit(jit_State *J, void *exptr)
}
);
trace_hotside(J, exd.pc);
setcframe_pc(cframe_raw(L->cframe), exd.pc);
pc = exd.pc;
trace_hotside(J, pc);
if (bc_op(*pc) == BC_JLOOP) {
BCIns *retpc = &J->trace[bc_d(*pc)]->startins;
if (bc_isret(bc_op(*retpc))) {
if (J->state == LJ_TRACE_RECORD) {
J->patchins = *pc;
J->patchpc = (BCIns *)pc;
*J->patchpc = *retpc;
} else {
pc = retpc;
}
}
}
setcframe_pc(cframe_raw(L->cframe), pc);
return 0;
}

1
src/lj_traceerr.h
View File

@ -22,6 +22,7 @@ TREDEF(LUNROLL, "loop unroll limit reached")
TREDEF(BADTYPE, "bad argument type")
TREDEF(CJITOFF, "call to JIT-disabled function")
TREDEF(CUNROLL, "call unroll limit reached")
TREDEF(DOWNREC, "down-recursion, restarting")
TREDEF(NYIVF, "NYI: vararg function")
TREDEF(NYICF, "NYI: C function %p")
TREDEF(NYIFF, "NYI: FastFunc %s")