src/lj_emit_ppc.h

   1 /*
   2 ** PPC 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_tab(ASMState *as, PPCIns pi, Reg rt, Reg ra, Reg rb)
   9 {
  10   *--as->mcp = pi | PPCF_T(rt) | PPCF_A(ra) | PPCF_B(rb);
  11 }
  12
  13 #define emit_asb(as, pi, ra, rs, rb)    emit_tab(as, (pi), (rs), (ra), (rb))
  14 #define emit_as(as, pi, ra, rs)         emit_tab(as, (pi), (rs), (ra), 0)
  15 #define emit_ab(as, pi, ra, rb)         emit_tab(as, (pi), 0, (ra), (rb))
  16
  17 static void emit_tai(ASMState *as, PPCIns pi, Reg rt, Reg ra, int32_t i)
  18 {
  19   *--as->mcp = pi | PPCF_T(rt) | PPCF_A(ra) | (i & 0xffff);
  20 }
  21
  22 #define emit_ti(as, pi, rt, i)          emit_tai(as, (pi), (rt), 0, (i))
  23 #define emit_ai(as, pi, ra, i)          emit_tai(as, (pi), 0, (ra), (i))
  24 #define emit_asi(as, pi, ra, rs, i)     emit_tai(as, (pi), (rs), (ra), (i))
  25
  26 #define emit_fab(as, pi, rf, ra, rb) \
  27   emit_tab(as, (pi), (rf)&31, (ra)&31, (rb)&31)
  28 #define emit_fb(as, pi, rf, rb)         emit_tab(as, (pi), (rf)&31, 0, (rb)&31)
  29 #define emit_fac(as, pi, rf, ra, rc) \
  30   emit_tab(as, (pi) | PPCF_C((rc) & 31), (rf)&31, (ra)&31, 0)
  31 #define emit_facb(as, pi, rf, ra, rc, rb) \
  32   emit_tab(as, (pi) | PPCF_C((rc) & 31), (rf)&31, (ra)&31, (rb)&31)
  33 #define emit_fai(as, pi, rf, ra, i)     emit_tai(as, (pi), (rf)&31, (ra), (i))
  34
  35 static void emit_rot(ASMState *as, PPCIns pi, Reg ra, Reg rs,
  36                      int32_t n, int32_t b, int32_t e)
  37 {
  38   *--as->mcp = pi | PPCF_T(rs) | PPCF_A(ra) | PPCF_B(n) |
  39                PPCF_MB(b) | PPCF_ME(e);
  40 }
  41
  42 static void emit_slwi(ASMState *as, Reg ra, Reg rs, int32_t n)
  43 {
  44   lua_assert(n >= 0 && n < 32);
  45   emit_rot(as, PPCI_RLWINM, ra, rs, n, 0, 31-n);
  46 }
  47
  48 static void emit_rotlwi(ASMState *as, Reg ra, Reg rs, int32_t n)
  49 {
  50   lua_assert(n >= 0 && n < 32);
  51   emit_rot(as, PPCI_RLWINM, ra, rs, n, 0, 31);
  52 }
  53
  54 /* -- Emit loads/stores --------------------------------------------------- */
  55
  56 /* Prefer rematerialization of BASE/L from global_State over spills. */
  57 #define emit_canremat(ref)      ((ref) <= REF_BASE)
  58
  59 /* Try to find a one step delta relative to another constant. */
  60 static int emit_kdelta1(ASMState *as, Reg t, int32_t i)
  61 {
  62   RegSet work = ~as->freeset & RSET_GPR;
  63   while (work) {
  64     Reg r = rset_picktop(work);
  65     IRRef ref = regcost_ref(as->cost[r]);
  66     lua_assert(r != t);
  67     if (ref < ASMREF_L) {
  68       int32_t delta = i - (ra_iskref(ref) ? ra_krefk(as, ref) : IR(ref)->i);
  69       if (checki16(delta)) {
  70         emit_tai(as, PPCI_ADDI, t, r, delta);
  71         return 1;
  72       }
  73     }
  74     rset_clear(work, r);
  75   }
  76   return 0;  /* Failed. */
  77 }
  78
  79 /* Load a 32 bit constant into a GPR. */
  80 static void emit_loadi(ASMState *as, Reg r, int32_t i)
  81 {
  82   if (checki16(i)) {
  83     emit_ti(as, PPCI_LI, r, i);
  84   } else {
  85     if ((i & 0xffff)) {
  86       int32_t jgl = i32ptr(J2G(as->J));
  87       if ((uint32_t)(i-jgl) < 65536) {
  88         emit_tai(as, PPCI_ADDI, r, RID_JGL, i-jgl-32768);
  89         return;
  90       } else if (emit_kdelta1(as, r, i)) {
  91         return;
  92       }
  93       emit_asi(as, PPCI_ORI, r, r, i);
  94     }
  95     emit_ti(as, PPCI_LIS, r, (i >> 16));
  96   }
  97 }
  98
  99 #define emit_loada(as, r, addr)         emit_loadi(as, (r), i32ptr((addr)))
 100
 101 static Reg ra_allock(ASMState *as, int32_t k, RegSet allow);
 102
 103 /* Get/set from constant pointer. */
 104 static void emit_lsptr(ASMState *as, PPCIns pi, Reg r, void *p, RegSet allow)
 105 {
 106   int32_t jgl = i32ptr(J2G(as->J));
 107   int32_t i = i32ptr(p);
 108   Reg base;
 109   if ((uint32_t)(i-jgl) < 65536) {
 110     i = i-jgl-32768;
 111     base = RID_JGL;
 112   } else {
 113     base = ra_allock(as, i-(int16_t)i, allow);
 114   }
 115   emit_tai(as, pi, r, base, i);
 116 }
 117
 118 #define emit_loadn(as, r, tv) \
 119   emit_lsptr(as, PPCI_LFD, ((r) & 31), (void *)(tv), RSET_GPR)
 120
 121 /* Get/set global_State fields. */
 122 static void emit_lsglptr(ASMState *as, PPCIns pi, Reg r, int32_t ofs)
 123 {
 124   emit_tai(as, pi, r, RID_JGL, ofs-32768);
 125 }
 126
 127 #define emit_getgl(as, r, field) \
 128   emit_lsglptr(as, PPCI_LWZ, (r), (int32_t)offsetof(global_State, field))
 129 #define emit_setgl(as, r, field) \
 130   emit_lsglptr(as, PPCI_STW, (r), (int32_t)offsetof(global_State, field))
 131
 132 /* Trace number is determined from per-trace exit stubs. */
 133 #define emit_setvmstate(as, i)          UNUSED(i)
 134
 135 /* -- Emit control-flow instructions -------------------------------------- */
 136
 137 /* Label for internal jumps. */
 138 typedef MCode *MCLabel;
 139
 140 /* Return label pointing to current PC. */
 141 #define emit_label(as)          ((as)->mcp)
 142
 143 static void emit_condbranch(ASMState *as, PPCIns pi, PPCCC cc, MCode *target)
 144 {
 145   MCode *p = as->mcp;
 146   ptrdiff_t delta = ((char *)target - (char *)p) + 4;
 147   lua_assert(((delta + 0x8000) >> 16) == 0);
 148   pi ^= (delta & 0x8000) * (PPCF_Y/0x8000);
 149   *--p = pi | PPCF_CC(cc) | ((uint32_t)delta & 0xffffu);
 150   as->mcp = p;
 151 }
 152
 153 static void emit_call(ASMState *as, void *target)
 154 {
 155   MCode *p = --as->mcp;
 156   ptrdiff_t delta = (char *)target - (char *)p;
 157   if ((((delta>>2) + 0x00800000) >> 24) == 0) {
 158     *p = PPCI_BL | (delta & 0x03fffffcu);
 159   } else {  /* Target out of range: need indirect call. Don't use arg reg. */
 160     RegSet allow = RSET_GPR & ~RSET_RANGE(RID_R0, REGARG_LASTGPR+1);
 161     Reg r = ra_allock(as, i32ptr(target), allow);
 162     *p = PPCI_BCTRL;
 163     p[-1] = PPCI_MTCTR | PPCF_T(r);
 164     as->mcp = p-1;
 165   }
 166 }
 167
 168 /* -- Emit generic operations --------------------------------------------- */
 169
 170 #define emit_mr(as, dst, src) \
 171   emit_asb(as, PPCI_MR, (dst), (src), (src))
 172
 173 /* Generic move between two regs. */
 174 static void emit_movrr(ASMState *as, IRIns *ir, Reg dst, Reg src)
 175 {
 176   UNUSED(ir);
 177   if (dst < RID_MAX_GPR)
 178     emit_mr(as, dst, src);
 179   else
 180     emit_fb(as, PPCI_FMR, dst, src);
 181 }
 182
 183 /* Generic load of register from stack slot. */
 184 static void emit_spload(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
 185 {
 186   if (r < RID_MAX_GPR)
 187     emit_tai(as, PPCI_LWZ, r, RID_SP, ofs);
 188   else
 189     emit_fai(as, irt_isnum(ir->t) ? PPCI_LFD : PPCI_LFS, r, RID_SP, ofs);
 190 }
 191
 192 /* Generic store of register to stack slot. */
 193 static void emit_spstore(ASMState *as, IRIns *ir, Reg r, int32_t ofs)
 194 {
 195   if (r < RID_MAX_GPR)
 196     emit_tai(as, PPCI_STW, r, RID_SP, ofs);
 197   else
 198     emit_fai(as, irt_isnum(ir->t) ? PPCI_STFD : PPCI_STFS, r, RID_SP, ofs);
 199 }
 200
 201 /* Emit a compare (for equality) with a constant operand. */
 202 static void emit_cmpi(ASMState *as, Reg r, int32_t k)
 203 {
 204   if (checki16(k)) {
 205     emit_ai(as, PPCI_CMPWI, r, k);
 206   } else if (checku16(k)) {
 207     emit_ai(as, PPCI_CMPLWI, r, k);
 208   } else {
 209     emit_ai(as, PPCI_CMPLWI, RID_TMP, k);
 210     emit_asi(as, PPCI_XORIS, RID_TMP, r, (k >> 16));
 211   }
 212 }
 213
 214 /* Add offset to pointer. */
 215 static void emit_addptr(ASMState *as, Reg r, int32_t ofs)
 216 {
 217   if (ofs) {
 218     emit_tai(as, PPCI_ADDI, r, r, ofs);
 219     if (!checki16(ofs))
 220       emit_tai(as, PPCI_ADDIS, r, r, (ofs + 32768) >> 16);
 221   }
 222 }
 223
 224 static void emit_spsub(ASMState *as, int32_t ofs)
 225 {
 226   if (ofs) {
 227     emit_tai(as, PPCI_STWU, RID_TMP, RID_SP, -ofs);
 228     emit_tai(as, PPCI_ADDI, RID_TMP, RID_SP,
 229              CFRAME_SIZE + (as->parent ? as->parent->spadjust : 0));
 230   }
 231 }
 232