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/*
** ARM instruction emitter.
** Copyright (C) 2005-2011 Mike Pall. See Copyright Notice in luajit.h
*/
/* -- Constant encoding --------------------------------------------------- */
static uint8_t emit_invai[16] = {
/* AND */ (ARMI_AND^ARMI_BIC) >> 21,
/* EOR */ 0,
/* SUB */ (ARMI_SUB^ARMI_ADD) >> 21,
/* RSB */ 0,
/* ADD */ (ARMI_ADD^ARMI_SUB) >> 21,
/* ADC */ (ARMI_ADC^ARMI_SBC) >> 21,
/* SBC */ (ARMI_SBC^ARMI_ADC) >> 21,
/* RSC */ 0,
/* TST */ 0,
/* TEQ */ 0,
/* CMP */ (ARMI_CMP^ARMI_CMN) >> 21,
/* CMN */ (ARMI_CMN^ARMI_CMP) >> 21,
/* ORR */ 0,
/* MOV */ (ARMI_MOV^ARMI_MVN) >> 21,
/* BIC */ (ARMI_BIC^ARMI_AND) >> 21,
/* MVN */ (ARMI_MVN^ARMI_MOV) >> 21
};
/* Encode constant in K12 format for data processing instructions. */
static uint32_t emit_isk12(ARMIns ai, int32_t n)
{
uint32_t invai, i, m = (uint32_t)n;
/* K12: unsigned 8 bit value, rotated in steps of two bits. */
for (i = 0; i < 4096; i += 256, m = lj_rol(m, 2))
if (m <= 255) return ARMI_K12|m|i;
/* Otherwise try negation/complement with the inverse instruction. */
invai = emit_invai[((ai >> 21) & 15)];
if (!invai) return 0; /* Failed. No inverse instruction. */
m = ~(uint32_t)n;
if (invai == ((ARMI_SUB^ARMI_ADD) >> 21) ||
invai == (ARMI_CMP^ARMI_CMN) >> 21) m++;
for (i = 0; i < 4096; i += 256, m = lj_rol(m, 2))
if (m <= 255) return ARMI_K12|(invai<<21)|m|i;
return 0; /* Failed. */
}
/* -- Emit basic instructions --------------------------------------------- */
static void emit_dnm(ASMState *as, ARMIns ai, Reg rd, Reg rn, Reg rm)
{
*--as->mcp = ai | ARMF_D(rd) | ARMF_N(rn) | ARMF_M(rm);
}
static void emit_dm(ASMState *as, ARMIns ai, Reg rd, Reg rm)
{
*--as->mcp = ai | ARMF_D(rd) | ARMF_M(rm);
}
static void emit_dn(ASMState *as, ARMIns ai, Reg rd, Reg rn)
{
*--as->mcp = ai | ARMF_D(rd) | ARMF_N(rn);
}
static void emit_nm(ASMState *as, ARMIns ai, Reg rn, Reg rm)
{
*--as->mcp = ai | ARMF_N(rn) | ARMF_M(rm);
}
static void emit_d(ASMState *as, ARMIns ai, Reg rd)
{
*--as->mcp = ai | ARMF_D(rd);
}
static void emit_n(ASMState *as, ARMIns ai, Reg rn)
{
*--as->mcp = ai | ARMF_N(rn);
}
static void emit_m(ASMState *as, ARMIns ai, Reg rm)
{
*--as->mcp = ai | ARMF_M(rm);
}
static void emit_lsox(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
{
lua_assert(ofs >= -255 && ofs <= 255);
if (ofs < 0) ofs = -ofs; else ai |= ARMI_LS_U;
*--as->mcp = ai | ARMI_LS_P | ARMI_LSX_I | ARMF_D(rd) | ARMF_N(rn) |
((ofs & 0xf0) << 4) | (ofs & 0x0f);
}
static void emit_lso(ASMState *as, ARMIns ai, Reg rd, Reg rn, int32_t ofs)
{
lua_assert(ofs >= -4095 && ofs <= 4095);
/* Combine LDR/STR pairs to LDRD/STRD. */
if (*as->mcp == (ai|ARMI_LS_P|ARMI_LS_U|ARMF_D(rd^1)|ARMF_N(rn)|(ofs^4)) &&
(ai & ~(ARMI_LDR^ARMI_STR)) == ARMI_STR && rd != rn &&
(uint32_t)ofs <= 252 && !(ofs & 3) && !((rd ^ (ofs >>2)) & 1) &&
as->mcp != as->mcloop) {
as->mcp++;
emit_lsox(as, ai == ARMI_LDR ? ARMI_LDRD : ARMI_STRD, rd&~1, rn, ofs&~4);
return;
}
if (ofs < 0) ofs = -ofs; else ai |= ARMI_LS_U;
*--as->mcp = ai | ARMI_LS_P | ARMF_D(rd) | ARMF_N(rn) | ofs;
}
/* -- Emit loads/stores --------------------------------------------------- */
/* Prefer spills of BASE/L. */
#define emit_canremat(ref) ((ref) < ASMREF_L)
/* Try to find a one step delta relative to another constant. */
static int emit_kdelta1(ASMState *as, Reg d, int32_t i)
{
RegSet work = ~as->freeset & RSET_GPR;
while (work) {
Reg r = rset_picktop(work);
IRRef ref = regcost_ref(as->cost[r]);
lua_assert(r != d);
if (emit_canremat(ref)) {
int32_t delta = i - (ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i);
uint32_t k = emit_isk12(ARMI_ADD, delta);
if (k) {
if (k == ARMI_K12)
emit_dm(as, ARMI_MOV, d, r);
else
emit_dn(as, ARMI_ADD^k, d, r);
return 1;
}
}
rset_clear(work, r);
}
return 0; /* Failed. */
}
/* Try to find a two step delta relative to another constant. */
static int emit_kdelta2(ASMState *as, Reg d, int32_t i)
{
RegSet work = ~as->freeset & RSET_GPR;
while (work) {
Reg r = rset_picktop(work);
IRRef ref = regcost_ref(as->cost[r]);
lua_assert(r != d);
if (emit_canremat(ref)) {
int32_t delta = i - (ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i);
uint32_t sh, inv = 0, k2, k;
if (delta < 0) { delta = -delta; inv = ARMI_ADD^ARMI_SUB; }
sh = lj_ffs(delta) & ~1;
k2 = emit_isk12(0, delta & (255 << sh));
k = emit_isk12(0, delta & ~(255 << sh));
if (k) {
emit_dn(as, ARMI_ADD^k2^inv, d, d);
emit_dn(as, ARMI_ADD^k^inv, d, r);
return 1;
}
}
rset_clear(work, r);
}
return 0; /* Failed. */
}
/* Load a 32 bit constant into a GPR. */
static void emit_loadi(ASMState *as, Reg r, int32_t i)
{
uint32_t k = emit_isk12(ARMI_MOV, i);
lua_assert(rset_test(as->freeset, r) || r == RID_TMP);
if (k) {
/* Standard K12 constant. */
emit_d(as, ARMI_MOV^k, r);
} else if ((as->flags & JIT_F_ARMV6T2) && (uint32_t)i < 0x00010000u) {
/* 16 bit loword constant for ARMv6T2. */
emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), r);
} else if (emit_kdelta1(as, r, i)) {
/* One step delta relative to another constant. */
} else if ((as->flags & JIT_F_ARMV6T2)) {
/* 32 bit hiword/loword constant for ARMv6T2. */
emit_d(as, ARMI_MOVT|((i>>16) & 0x0fff)|(((i>>16) & 0xf000)<<4), r);
emit_d(as, ARMI_MOVW|(i & 0x0fff)|((i & 0xf000)<<4), r);
} else if (emit_kdelta2(as, r, i)) {
/* Two step delta relative to another constant. */
} else {
/* Otherwise construct the constant with up to 4 instructions. */
/* NYI: use mvn+bic, use pc-relative loads. */
for (;;) {
uint32_t sh = lj_ffs(i) & ~1;
int32_t m = i & (255 << sh);
i &= ~(255 << sh);
if (i == 0) {
emit_d(as, ARMI_MOV ^ emit_isk12(0, m), r);
break;
}
emit_dn(as, ARMI_ORR ^ emit_isk12(0, m), r, r);
}
}
}
#define emit_loada(as, r, addr) emit_loadi(as, (r), i32ptr((addr)))
static Reg ra_allock(ASMState *as, int32_t k, RegSet allow);
/* Get/set from constant pointer. */
static void emit_lsptr(ASMState *as, ARMIns ai, Reg r, void *p)
{
int32_t i = i32ptr(p);
emit_lso(as, ai, r, ra_allock(as, (i & ~4095), rset_exclude(RSET_GPR, r)),
(i & 4095));
}
/* Get/set global_State fields. */
#define emit_getgl(as, r, field) \
emit_lsptr(as, ARMI_LDR, (r), (void *)&J2G(as->J)->field)
#define emit_setgl(as, r, field) \
emit_lsptr(as, ARMI_STR, (r), (void *)&J2G(as->J)->field)
/* Trace number is determined from pc of exit instruction. */
#define emit_setvmstate(as, i) UNUSED(i)
/* -- Emit control-flow instructions -------------------------------------- */
/* Label for internal jumps. */
typedef MCode *MCLabel;
/* Return label pointing to current PC. */
#define emit_label(as) ((as)->mcp)
static void emit_branch(ASMState *as, ARMIns ai, MCode *target)
{
MCode *p = as->mcp;
ptrdiff_t delta = (target - p) - 1;
lua_assert(((delta + 0x00800000) >> 24) == 0);
*--p = ai | ((uint32_t)delta & 0x00ffffffu);
as->mcp = p;
}
static void emit_call(ASMState *as, void *target)
{
MCode *p = --as->mcp;
ptrdiff_t delta = ((char *)target - (char *)p) - 8;
if ((((delta>>2) + 0x00800000) >> 24) == 0) {
if ((delta & 1))
*p = ARMI_BLX | ((uint32_t)(delta>>2) & 0x00ffffffu) | ((delta&2) << 27);
else
*p = ARMI_BL | ((uint32_t)(delta>>2) & 0x00ffffffu);
} else { /* Target out of range: need indirect call. But don't use R0-R3. */
Reg r = ra_allock(as, i32ptr(target), RSET_RANGE(RID_R4, RID_R12+1));
*p = ARMI_BLXr | ARMF_M(r);
}
}
/* -- Emit generic operations --------------------------------------------- */
/* Generic move between two regs. */
static void emit_movrr(ASMState *as, IRIns *ir, Reg dst, Reg src)
{
lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
if (as->mcp != as->mcloop) { /* Swap early registers for loads/stores. */
MCode ins = *as->mcp, swp = (src^dst);
if ((ins & 0x0c000000) == 0x04000000 && (ins & 0x02000010) != 0x02000010) {
if (!((ins ^ (dst << 16)) & 0x000f0000))
*as->mcp = ins ^ (swp << 16); /* Swap N in load/store. */
if (!(ins & 0x00100000) && !((ins ^ (dst << 12)) & 0x0000f000))
*as->mcp = ins ^ (swp << 12); /* Swap D in store. */
}
}
emit_dm(as, ARMI_MOV, dst, src);
}
/* Generic load of register from stack slot. */
static void emit_spload(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
{
lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
emit_lso(as, ARMI_LDR, r, RID_SP, ofs);
}
/* Generic store of register to stack slot. */
static void emit_spstore(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
{
lua_assert(!irt_isnum(ir->t)); UNUSED(ir);
emit_lso(as, ARMI_STR, r, RID_SP, ofs);
}
/* Emit an arithmetic/logic operation with a constant operand. */
static void emit_opk(ASMState *as, ARMIns ai, Reg dest, Reg src,
int32_t i, RegSet allow)
{
uint32_t k = emit_isk12(ai, i);
if (k)
emit_dn(as, ai^k, dest, src);
else
emit_dnm(as, ai, dest, src, ra_allock(as, i, allow));
}
/* Add offset to pointer. */
static void emit_addptr(ASMState *as, Reg r, int32_t ofs)
{
if (ofs)
emit_opk(as, ARMI_ADD, r, r, ofs, rset_exclude(RSET_GPR, r));
}
#define emit_spsub(as, ofs) emit_addptr(as, RID_SP, -(ofs))
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