src/lj_emit_mips.h

   1 /*
   2 ** MIPS instruction emitter.
   3 ** Copyright (C) 2005-2012 Mike Pall. See Copyright Notice in luajit.h
   4 */
   5
   6 /* -- Emit basic instructions --------------------------------------------- */
   7
   8 static void emit_dst(ASMState *as, MIPSIns mi, Reg rd, Reg rs, Reg rt)
   9 {
  10   *--as->mcp = mi | MIPSF_D(rd) | MIPSF_S(rs) | MIPSF_T(rt);
  11 }
  12
  13 static void emit_dta(ASMState *as, MIPSIns mi, Reg rd, Reg rt, uint32_t a)
  14 {
  15   *--as->mcp = mi | MIPSF_D(rd) | MIPSF_T(rt) | MIPSF_A(a);
  16 }
  17
  18 #define emit_ds(as, mi, rd, rs)         emit_dst(as, (mi), (rd), (rs), 0)
  19 #define emit_tg(as, mi, rt, rg)         emit_dst(as, (mi), (rg)&31, 0, (rt))
  20
  21 static void emit_tsi(ASMState *as, MIPSIns mi, Reg rt, Reg rs, int32_t i)
  22 {
  23   *--as->mcp = mi | MIPSF_T(rt) | MIPSF_S(rs) | (i & 0xffff);
  24 }
  25
  26 #define emit_ti(as, mi, rt, i)          emit_tsi(as, (mi), (rt), 0, (i))
  27 #define emit_hsi(as, mi, rh, rs, i)     emit_tsi(as, (mi), (rh) & 31, (rs), (i))
  28
  29 static void emit_fgh(ASMState *as, MIPSIns mi, Reg rf, Reg rg, Reg rh)
  30 {
  31   *--as->mcp = mi | MIPSF_F(rf&31) | MIPSF_G(rg&31) | MIPSF_H(rh&31);
  32 }
  33
  34 #define emit_fg(as, mi, rf, rg)         emit_fgh(as, (mi), (rf), (rg), 0)
  35
  36 static void emit_rotr(ASMState *as, Reg dest, Reg src, Reg tmp, uint32_t shift)
  37 {
  38   if ((as->flags & JIT_F_MIPS32R2)) {
  39     emit_dta(as, MIPSI_ROTR, dest, src, shift);
  40   } else {
  41     emit_dst(as, MIPSI_OR, dest, dest, tmp);
  42     emit_dta(as, MIPSI_SLL, dest, src, (-shift)&31);
  43     emit_dta(as, MIPSI_SRL, tmp, src, shift);
  44   }
  45 }
  46
  47 /* -- Emit loads/stores --------------------------------------------------- */
  48
  49 /* Prefer rematerialization of BASE/L from global_State over spills. */
  50 #define emit_canremat(ref)      ((ref) <= REF_BASE)
  51
  52 /* Try to find a one step delta relative to another constant. */
  53 static int emit_kdelta1(ASMState *as, Reg t, int32_t i)
  54 {
  55   RegSet work = ~as->freeset & RSET_GPR;
  56   while (work) {
  57     Reg r = rset_picktop(work);
  58     IRRef ref = regcost_ref(as->cost[r]);
  59     lua_assert(r != t);
  60     if (ref < ASMREF_L) {
  61       int32_t delta = i - (ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i);
  62       if (checki16(delta)) {
  63         emit_tsi(as, MIPSI_ADDIU, t, r, delta);
  64         return 1;
  65       }
  66     }
  67     rset_clear(work, r);
  68   }
  69   return 0;  /* Failed. */
  70 }
  71
  72 /* Load a 32 bit constant into a GPR. */
  73 static void emit_loadi(ASMState *as, Reg r, int32_t i)
  74 {
  75   if (checki16(i)) {
  76     emit_ti(as, MIPSI_LI, r, i);
  77   } else {
  78     if ((i & 0xffff)) {
  79       int32_t jgl = i32ptr(J2G(as->J));
  80       if ((uint32_t)(i-jgl) < 65536) {
  81         emit_tsi(as, MIPSI_ADDIU, r, RID_JGL, i-jgl-32768);
  82         return;
  83       } else if (emit_kdelta1(as, r, i)) {
  84         return;
  85       } else if ((i >> 16) == 0) {
  86         emit_tsi(as, MIPSI_ORI, r, RID_ZERO, i);
  87         return;
  88       }
  89       emit_tsi(as, MIPSI_ORI, r, r, i);
  90     }
  91     emit_ti(as, MIPSI_LUI, r, (i >> 16));
  92   }
  93 }
  94
  95 #define emit_loada(as, r, addr)         emit_loadi(as, (r), i32ptr((addr)))
  96
  97 static Reg ra_allock(ASMState *as, int32_t k, RegSet allow);
  98 static void ra_allockreg(ASMState *as, int32_t k, Reg r);
  99
 100 /* Get/set from constant pointer. */
 101 static void emit_lsptr(ASMState *as, MIPSIns mi, Reg r, void *p, RegSet allow)
 102 {
 103   int32_t jgl = i32ptr(J2G(as->J));
 104   int32_t i = i32ptr(p);
 105   Reg base;
 106   if ((uint32_t)(i-jgl) < 65536) {
 107     i = i-jgl-32768;
 108     base = RID_JGL;
 109   } else {
 110     base = ra_allock(as, i-(int16_t)i, allow);
 111   }
 112   emit_tsi(as, mi, r, base, i);
 113 }
 114
 115 #define emit_loadn(as, r, tv) \
 116   emit_lsptr(as, MIPSI_LDC1, ((r) & 31), (void *)(tv), RSET_GPR)
 117
 118 /* Get/set global_State fields. */
 119 static void emit_lsglptr(ASMState *as, MIPSIns mi, Reg r, int32_t ofs)
 120 {
 121   emit_tsi(as, mi, r, RID_JGL, ofs-32768);
 122 }
 123
 124 #define emit_getgl(as, r, field) \
 125   emit_lsglptr(as, MIPSI_LW, (r), (int32_t)offsetof(global_State, field))
 126 #define emit_setgl(as, r, field) \
 127   emit_lsglptr(as, MIPSI_SW, (r), (int32_t)offsetof(global_State, field))
 128
 129 /* Trace number is determined from per-trace exit stubs. */
 130 #define emit_setvmstate(as, i)          UNUSED(i)
 131
 132 /* -- Emit control-flow instructions -------------------------------------- */
 133
 134 /* Label for internal jumps. */
 135 typedef MCode *MCLabel;
 136
 137 /* Return label pointing to current PC. */
 138 #define emit_label(as)          ((as)->mcp)
 139
 140 static void emit_branch(ASMState *as, MIPSIns mi, Reg rs, Reg rt, MCode *target)
 141 {
 142   MCode *p = as->mcp;
 143   ptrdiff_t delta = target - p;
 144   lua_assert(((delta + 0x8000) >> 16) == 0);
 145   *--p = mi | MIPSF_S(rs) | MIPSF_T(rt) | ((uint32_t)delta & 0xffffu);
 146   as->mcp = p;
 147 }
 148
 149 static void emit_jmp(ASMState *as, MCode *target)
 150 {
 151   *--as->mcp = MIPSI_NOP;
 152   emit_branch(as, MIPSI_B, RID_ZERO, RID_ZERO, (target));
 153 }
 154
 155 static void emit_call(ASMState *as, void *target)
 156 {
 157   MCode *p = as->mcp;
 158   *--p = MIPSI_NOP;
 159   if ((((uintptr_t)target ^ (uintptr_t)p) >> 28) == 0)
 160     *--p = MIPSI_JAL | (((uintptr_t)target >>2) & 0x03ffffffu);
 161   else  /* Target out of range: need indirect call. */
 162     *--p = MIPSI_JALR | MIPSF_S(RID_CFUNCADDR);
 163   as->mcp = p;
 164   ra_allockreg(as, i32ptr(target), RID_CFUNCADDR);
 165 }
 166
 167 /* -- Emit generic operations --------------------------------------------- */
 168
 169 #define emit_move(as, dst, src) \
 170   emit_ds(as, MIPSI_MOVE, (dst), (src))
 171
 172 /* Generic move between two regs. */
 173 static void emit_movrr(ASMState *as, IRIns *ir, Reg dst, Reg src)
 174 {
 175   if (dst < RID_MAX_GPR)
 176     emit_move(as, dst, src);
 177   else
 178     emit_fg(as, irt_isnum(ir->t) ? MIPSI_MOV_D : MIPSI_MOV_S, dst, src);
 179 }
 180
 181 /* Generic load of register from stack slot. */
 182 static void emit_spload(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
 183 {
 184   if (r < RID_MAX_GPR)
 185     emit_tsi(as, MIPSI_LW, r, RID_SP, ofs);
 186   else
 187     emit_tsi(as, irt_isnum(ir->t) ? MIPSI_LDC1 : MIPSI_LWC1,
 188              (r & 31), RID_SP, ofs);
 189 }
 190
 191 /* Generic store of register to stack slot. */
 192 static void emit_spstore(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
 193 {
 194   if (r < RID_MAX_GPR)
 195     emit_tsi(as, MIPSI_SW, r, RID_SP, ofs);
 196   else
 197     emit_tsi(as, irt_isnum(ir->t) ? MIPSI_SDC1 : MIPSI_SWC1,
 198              (r&31), RID_SP, ofs);
 199 }
 200
 201 /* Add offset to pointer. */
 202 static void emit_addptr(ASMState *as, Reg r, int32_t ofs)
 203 {
 204   if (ofs) {
 205     lua_assert(checki16(ofs));
 206     emit_tsi(as, MIPSI_ADDIU, r, r, ofs);
 207   }
 208 }
 209
 210 #define emit_spsub(as, ofs)     emit_addptr(as, RID_SP, -(ofs))
 211