path: root/src/t_x86-64_sysv.c

#include "t_x86-64.h"

static int classify(uchar cls[2], const TypeData *td, uint off);

static void
clsscalar(uchar cls[2], uint off, Type ty)
{
   if (iscomplex(ty)) {
      classify(cls, &typedata[complex2struct(ty).dat], off);
      return;
   }
   enum irclass k = type2cls[scalartypet(ty)];
   uchar *fcls = &cls[off/8];
   if (isflt(ty)) { /* SSE */
      if (!*fcls || (*fcls == KF32 && k > *fcls))
         *fcls = k;
   } else { /* INTEGER */
      assert(isint(ty) || ty.t == TYPTR);
      if (cls2siz[*fcls] < cls2siz[k])
         *fcls = k == KPTR ? KI64 : k;
   }
   if (off % 8 >= 4 && cls2siz[*fcls] < 8)
      *fcls = kisint(*fcls) ? KI64 : KF64;
}

static int
classifyarr(uchar cls[2], Type ty, uint off)
{
   Type chld = typechild(ty);
   uint n = typearrlen(ty), siz = typesize(chld);
   assert(n > 0);
   for (uint i = 0; i < n; ++i) {
      uint offx = off + i * siz;
      if (isagg(chld)) {
         if (!classify(cls, &typedata[chld.dat], offx))
            return cls[0] = cls[1] = 0;
      } else if (chld.t == TYARRAY) {
         if (!classifyarr(cls, chld, offx))
            return cls[0] = cls[1] = 0;
      } else {
         clsscalar(cls, offx, chld);
      }
   }
   return !!cls[0] + !!cls[1];
}

/* XXX types with alignment >= 16 */

static int
classify(uchar cls[2], const TypeData *td, uint off)
{
   uint siz = alignup(td->siz, 4);
   if (siz > 16) /* MEMORY */
      return 0;
   assert(isaggt(td->t));
   for (int i = 0; i < td->nmemb; ++i) {
      FieldData *fld = &td->fld[i].f;
      uint align = typealign(fld->t);
      if (alignup(fld->off, align) != fld->off) /* unaligned field -> MEMORY */
         return cls[0] = cls[1] = 0;
      if (isagg(fld->t)) {
         if (!classify(cls, &typedata[fld->t.dat], off + fld->off))
            return cls[0] = cls[1] = 0;
      } else if (fld->t.t == TYARRAY) {
         if (isincomplete(fld->t)) continue;
         if (!classifyarr(cls, fld->t, off + fld->off))
            return cls[0] = cls[1] = 0;
      } else {
         clsscalar(cls, fld->off + off, fld->t);
      }
   }
   return !!cls[0] + !!cls[1];
}

static int
abiarg(short r[2], uchar cls[2], uchar *r2off, int *ni, int *nf, int *ns, IRType typ)
{
   static const uchar intregs[] = { RDI, RSI, RDX, RCX, R8, R9 };
   enum { NINT = countof(intregs), NFLT = 8 };

   if (!typ.isagg) {
      if (kisflt(cls[0] = typ.cls) && *nf < NFLT) {
         r[0] = XMM0 + (*nf)++;
      } else if (kisint(cls[0]) && *ni < NINT) {
         r[0] = intregs[(*ni)++];
      } else {
         r[0] = *ns;
         *ns += 8;
         return 0; /* MEMORY */
      }
      return 1;
   }
   cls[0] = cls[1] = 0;
   int ret = classify(cls, &typedata[typ.dat], 0);
   if (!ret) { /*MEMORY*/
      r[0] = *ns;
      *ns = alignup(*ns + typedata[typ.dat].siz, 8);
      return 0;
   }
   assert(ret <= 2);
   int ni_save = *ni, nf_save = *nf;
   *r2off = 8;
   for (int i = 0; i < ret; ++i) {
      assert(cls[i]);
      if (kisflt(cls[i]) && *nf < NFLT)
         r[i] = XMM0 + (*nf)++;
      else if (kisint(cls[i]) && *ni < NINT)
         r[i] = intregs[(*ni)++];
      else { /* MEMORY */
         *ni = ni_save, *nf = nf_save;
         r[0] = *ns;
         *ns = alignup(*ns + typedata[typ.dat].siz, 8);
         r[1] = -1;
         return cls[0] = cls[1] = 0;
      }
   }
   return ret;
}

static int
abiret(short r[2], uchar cls[2], uchar *r2off, int *ni, IRType typ)
{
   if (!typ.isagg) {
      r[0] = kisflt(cls[0] = typ.cls) ? XMM0 : RAX;
      return 1;
   }

   cls[0] = cls[1] = 0;
   int ret = classify(cls, &typedata[typ.dat], 0);
   if (!ret) { /* MEMORY */
      assert(*ni == 0);
      r[0] = RAX; /* on return should contain result location address */
      r[1] = RDI; /* register for caller-owned result location argument */
      ++*ni;
      return 0;
   }
   assert(ret <= 2);
   *r2off = 8;
   for (int i = 0, ni = 0, nf = 0; i < ret; ++i) {
      assert(cls[i]);
      if (kisflt(cls[i])) /* SSE (XMM0, XMM1) */
         r[i] = XMM0 + nf++;
      else if (kisint(cls[i])) /* INTEGER (RAX, RDX) */
         r[i] = ni++ == 0 ? RAX : RDX;
      else assert(0);
   }
   return ret;
}

/* Layout of va_list:
 * struct {
 *    ( 0) unsigned int gp_offset;
 *    ( 4) unsigned int fp_offset;
 *    ( 8) void *overflow_arg_area;
 *    (16) void *reg_save_area;
 * }
 * Layout of register save area (align 16):
 *    reg  off
 *    rdi   0
 *    rsi   8
 *    rdx  16
 *    rcx  24
 *    r8   32
 *    r9   40
 *    xmm0 48
 *    xmm1 64
 *    ...
 *  in x86_64/emit xvaprologue generates the code to save the registers to a stack slot
 *  there only needs to be one xvaprologue if there's any vastart instrs, and it has to be
 *  at the beginning of the function (before IR generated by regalloc can touch any registers)
 *  then vastart can initialize va_list.reg_save_area with a pointer to that
 */

static void
vastart(Function *fn, Block *blk, int *curi)
{
   Ref rsave; /* register save area */
   int gpr0 = 0, fpr0 = 0, stk0 = 0;
   Instr *ins = &instrtab[blk->ins.p[*curi]];
   Ref ap = ins->l, src, dst;
   assert(ins->op == Ovastart);
   /* add xvaprologue if not there yet, which must be the first
    * real instruction in the function (following alloca) */
   if (fn->entry->ins.n > 1 && instrtab[fn->entry->ins.p[1]].op == Oxvaprologue) {
      rsave = mkref(RTMP, fn->entry->ins.p[0]); /* alloca instruction */
      assert(instrtab[rsave.i].op == Oalloca16);
   } else {
      rsave = insertinstr(fn->entry, 0, mkalloca(192, 16));
      insertinstr(fn->entry, 1, (Instr){Oxvaprologue, 0, .keep=1, .l=rsave});
   }
   /* find first unnamed gpr and fpr */
   for (int i = 0; i < fn->nabiarg; ++i) {
      ABIArg abi = fn->abiarg[i];
      if (!abi.isstk){
         if (abi.reg < XMM0) ++gpr0;
         else ++fpr0;
      } else {
         stk0 = abi.stk+8;
      }
   }
   /* set ap->reg_save_area */
   *ins = mkinstr2(Oadd, KPTR, ap, mkref(RICON, 16));
   dst = mkref(RTMP, ins - instrtab);
   int i = *curi + 1;
   insertinstr(blk, i++, mkinstr2(Ostorei64, 0, dst, rsave));
   /* set ap->overflow_arg_area */
   src = insertinstr(blk, i++, mkinstr1(Ocopy, KPTR, mkref(RSTACK, -stk0-8)));
   dst = insertinstr(blk, i++, mkinstr2(Oadd, KPTR, ap, mkref(RICON, 8)));
   insertinstr(blk, i++, mkinstr2(Ostorei64, 0, dst, src));
   /* set ap->gp_offset */
   insertinstr(blk, i++, mkinstr2(Ostorei32, 0, ap, mkref(RICON, gpr0*8)));
   /* set ap->fp_offset */
   dst = insertinstr(blk, i++, mkinstr2(Oadd, KPTR, ap, mkref(RICON, 4)));
   insertinstr(blk, i++, mkinstr2(Ostorei32, 0, dst, mkref(RICON, 6*8 + fpr0*16)));
   *curi = i-1;
}

static void
vaarg(Function *fn, Block *blk, int *curi)
{
   short r[2];
   uchar cls[2];
   Ref tmp;
   int ni = 0, nf = 0, ns = 0;
   uchar r2off;
   int var = blk->ins.p[*curi];
   Ref ap = instrtab[var].l;
   IRType ty = ref2type(instrtab[var].r);

   assert(instrtab[var].op == Ovaarg);
   blk->ins.p[*curi] = newinstr(blk, (Instr){Onop});

   int ret = abiarg(r, cls, &r2off, &ni, &nf, &ns, ty);

   if (ret == 2) assert(!"nyi");
   else if (ret == 1) {
      Block *merge;
      Ref phi, phiargs[2];
      /* int: l->gp_offset < 48 - num_gp * 8 */
      /* sse: l->fp_offset < 304 - num_gp * 16 (why 304? ... 176) */
      tmp = ni ? ap : insertinstr(blk, (*curi)++, mkinstr2(Oadd, KPTR, ap, mkref(RICON, 4)));
      tmp = insertinstr(blk, (*curi)++, mkinstr1(Oloadu32, KI32, tmp));
      tmp = insertinstr(blk, (*curi)++, mkinstr2(Oulte, KI32, tmp, mkref(RICON, ni ? 48 - ni*8 : 176 - nf*16)));
      merge = blksplitafter(fn, blk, *curi);
      blk->jmp.t = 0;
      useblk(fn, blk);
      putcondbranch(fn, tmp, newblk(fn), newblk(fn));
      useblk(fn, blk->s1);
      {
         /* phi0: &l->reg_save_area[l->gp/fp_offset] */
         Ref sav = addinstr(fn, mkinstr1(Oloadi64, KPTR, irbinop(fn, Oadd, KPTR, ap, mkref(RICON, 16))));
         Ref roff = addinstr(fn, mkinstr1(Oloadu32, KI32, irbinop(fn, Oadd, KPTR, ap, mkref(RICON, ni ? 0 : 4))));
         phiargs[0] = irbinop(fn, Oadd, KPTR, sav, roff);
         /* l->gp/fp_offset += num_gp/fp * 8(16) */
         roff = irbinop(fn, Oadd, KI32, roff, mkref(RICON, ni ? ni * 8 : nf * 16));
         addinstr(fn, mkinstr2(Ostorei32, 0, irbinop(fn, Oadd, KPTR, ap, mkref(RICON, ni ? 0 : 4)), roff));
         assert(merge->npred == 1);
         blkpred(merge, 0) = blk->s1;
         blk->s1->jmp.t = Jb;
         blk->s1->s1 = merge;
      }
      useblk(fn, blk->s2);
      {
         /* phi1: l->overflow_arg_area */
         Ref adr = irbinop(fn, Oadd, KPTR, ap, mkref(RICON, 8));
         Ref ovf = addinstr(fn, mkinstr1(Oloadi64, KPTR, adr));
         /* align no-op */
         
         phiargs[1] = ovf;
         /* update l->overflow_arg_area += size */
         int siz = 8;
         addinstr(fn, mkinstr2(Ostorei64, 0, adr, irbinop(fn, Oadd, KPTR, ovf, mkref(RICON, siz))));
         putbranch(fn, merge);
      }
      assert(merge->npred == 2);
      vpush(&merge->ins, 0);
      memmove(merge->ins.p+1, merge->ins.p, (merge->ins.n-1)*sizeof *merge->ins.p);
      merge->ins.p[0] = var;
      phi = insertphi(merge, KPTR);
      memcpy(phitab.p[instrtab[phi.i].l.i], phiargs, sizeof phiargs);
      if (!ty.isagg) {
         instrtab[var] = mkinstr1(cls2load[cls[0]], cls[0], phi);
      } else {
         instrtab[var] = mkalloca(8, 8);
         tmp = insertinstr(merge, 1, mkinstr1(Oloadi64, KI64, phi));
         insertinstr(merge, 2, mkinstr2(Ostorei64, 0, mkref(RTMP, var), tmp));
      }
      fn->prop &= ~FNUSE;
   } else {
      assert(!"nyi");
   }
}

static const char x86_64_rnames[][6] = {
#define R(r) #r,
   LIST_REGS(R)
#undef R
};

const MCTarg t_x86_64_sysv = {
   .gpr0 = RAX, .ngpr = R15 - RAX + 1,
   .gprscratch = R11, .fprscratch = XMM15,
   .fpr0 = XMM0, .nfpr = XMM15 - XMM0 + 1,
   .rcallee = 1<<RBX | 1<<R12 | 1<<R13 | 1<<R14 | 1<<R15,
   .rglob = 1<<RSP | 1<<RBP,
   .rnames = x86_64_rnames,
   .objkind = OBJELF,
   .abiret = abiret,
   .abiarg = abiarg,
   .vastart = vastart,
   .vaarg = vaarg,
   .isel = x86_64_isel,
   .emit = x86_64_emit
};

/* vim:set ts=3 sw=3 expandtab: */