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/* Source code for RCC-Legacy.
Copyright (C) 2026 Richard Qin
This file is part of RCC.
RCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3, or (at your option) any later
version.
RCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with RCC; see the file LICENSE. If not see
<http://www.gnu.org/licenses/>. */
/// @file fold.cc
/// @brief Constant folding utilities -- called by GVN (dedupins / assoccon), no standalone driver.
///
/// See docs/fold.md for architectural notes.
#include "rcc/all.h"
#include <cstdint>
#include <cstring>
namespace rcc {
namespace {
inline bool iscon(const Con* c, int w, uint64_t k) {
if (c->type != Con::CBits)
return false;
int64_t v = w ? c->bits.i : static_cast<int32_t>(c->bits.i);
return static_cast<uint64_t>(v) == (w ? k : static_cast<uint32_t>(k));
}
union Bits64 {
int64_t s;
uint64_t u;
float fs;
double fd;
};
inline Bits64 read_bits(const Con* c) {
Bits64 b;
b.s = c->bits.i;
return b;
}
int addr_combine(int op, const Con* cl, const Con* cr, int* typ_out, Sym* sym_out) {
int ctyp = Con::CBits;
Sym sym;
std::memset(&sym, 0, sizeof sym);
bool al = (cl->type == Con::CAddr);
bool ar = (cr->type == Con::CAddr);
if (op == Oadd) {
if (al && ar)
return 1;
if (al || ar) {
ctyp = Con::CAddr;
sym = al ? cl->sym : cr->sym;
}
} else if (op == Osub) {
if (al && ar) {
if (!symeq(cl->sym, cr->sym))
return 1;
// Subtract same sym.
} else if (al) {
ctyp = Con::CAddr;
sym = cl->sym;
} else if (ar) {
return 1; // Number - address is invalid
}
} else if (op == Ocast) {
if (al) {
ctyp = Con::CAddr;
sym = cl->sym;
}
} else if (al || ar) {
return 1;
}
*typ_out = ctyp;
*sym_out = sym;
return 0;
}
uint64_t foldcmp_int(int cmp, int w, Bits64 l, Bits64 r) {
if (!w) {
l.u = static_cast<uint64_t>(static_cast<int32_t>(l.u));
r.u = static_cast<uint64_t>(static_cast<int32_t>(r.u));
}
switch (cmp) {
case Cieq:
return l.u == r.u;
case Cine:
return l.u != r.u;
case Ciule:
return l.u <= r.u;
case Ciult:
return l.u < r.u;
case Ciuge:
return l.u >= r.u;
case Ciugt:
return l.u > r.u;
case Cisle:
return l.s <= r.s;
case Cislt:
return l.s < r.s;
case Cisge:
return l.s >= r.s;
case Cisgt:
return l.s > r.s;
default:
die("foldcmp_int: bad cmp %d", cmp);
}
}
template <typename F>
uint64_t foldcmp_flt(int cmp, F l, F r) {
switch (cmp) {
case Cfeq:
return l == r;
case Cfne:
return l != r;
case Cfle:
return l <= r;
case Cflt:
return l < r;
case Cfge:
return l >= r;
case Cfgt:
return l > r;
case Cfo:
return (l < r) || (l >= r);
case Cfuo:
return !((l < r) || (l >= r));
default:
die("foldcmp_flt: bad cmp %d", cmp);
}
}
void foldflt(Con* res, int op, int w, const Con* cl, const Con* cr) {
if (cl->type != Con::CBits || cr->type != Con::CBits)
err(const_cast<char*>("invalid address operand for '%s'"), optab[op].name);
res->type = Con::CBits;
res->sym = Sym{};
std::memset(&res->bits, 0, sizeof res->bits);
res->flt = 0;
if (w) {
double ld = cl->bits.d, rd = cr->bits.d, xd;
switch (op) {
case Oadd:
xd = ld + rd;
break;
case Osub:
xd = ld - rd;
break;
case Oneg:
xd = -ld;
break;
case Odiv:
xd = ld / rd;
break;
case Omul:
xd = ld * rd;
break;
case Oswtof:
xd = static_cast<double>(static_cast<int32_t>(cl->bits.i));
break;
case Ouwtof:
xd = static_cast<double>(static_cast<uint32_t>(cl->bits.i));
break;
case Osltof:
xd = static_cast<double>(static_cast<int64_t>(cl->bits.i));
break;
case Oultof:
xd = static_cast<double>(static_cast<uint64_t>(cl->bits.i));
break;
case Oexts:
xd = static_cast<double>(cl->bits.s);
break;
case Ocast:
xd = ld;
break;
default:
die("foldflt: bad op Kd %d", op);
}
res->bits.d = xd;
res->flt = 2;
} else {
float ls = cl->bits.s, rs = cr->bits.s, xs;
switch (op) {
case Oadd:
xs = ls + rs;
break;
case Osub:
xs = ls - rs;
break;
case Oneg:
xs = -ls;
break;
case Odiv:
xs = ls / rs;
break;
case Omul:
xs = ls * rs;
break;
case Oswtof:
xs = static_cast<float>(static_cast<int32_t>(cl->bits.i));
break;
case Ouwtof:
xs = static_cast<float>(static_cast<uint32_t>(cl->bits.i));
break;
case Osltof:
xs = static_cast<float>(static_cast<int64_t>(cl->bits.i));
break;
case Oultof:
xs = static_cast<float>(static_cast<uint64_t>(cl->bits.i));
break;
case Otruncd:
xs = static_cast<float>(cl->bits.d);
break;
case Ocast:
xs = ls;
break;
default:
die("foldflt: bad op Ks %d", op);
}
res->bits.s = xs;
res->flt = 1;
}
}
} // namespace
int foldint(Con* res, int op, int w, Con* cl, Con* cr) {
// Address combination check.
int ctyp;
Sym sym;
if (addr_combine(op, cl, cr, &ctyp, &sym))
return 1;
Bits64 l = read_bits(cl);
Bits64 r = read_bits(cr);
// Div / rem.
if (op == Odiv || op == Orem || op == Oudiv || op == Ourem) {
if (iscon(cr, w, 0))
return 1;
if (op == Odiv || op == Orem) {
uint64_t intmin = w ? static_cast<uint64_t>(INT64_MIN)
: static_cast<uint64_t>(static_cast<uint32_t>(INT32_MIN));
if (iscon(cr, w, static_cast<uint64_t>(-1)) && iscon(cl, w, intmin))
return 1;
}
}
// Dispatch.
uint64_t x;
if (op >= Ocmpw && op <= Ocmpw1) {
x = foldcmp_int(op - Ocmpw, /*w=*/0, l, r);
} else if (op >= Ocmpl && op <= Ocmpl1) {
x = foldcmp_int(op - Ocmpl, /*w=*/1, l, r);
} else if (op >= Ocmps && op <= Ocmps1) {
x = foldcmp_flt<float>(op - Ocmps, cl->bits.s, cr->bits.s);
} else if (op >= Ocmpd && op <= Ocmpd1) {
x = foldcmp_flt<double>(op - Ocmpd, cl->bits.d, cr->bits.d);
} else {
// Shift count mask.
const uint64_t shmask = static_cast<uint64_t>(31 | (w << 5));
switch (op) {
case Oadd:
x = l.u + r.u;
break;
case Osub:
x = l.u - r.u;
break;
case Oneg:
x = -l.u;
break;
case Omul:
x = l.u * r.u;
break;
case Odiv:
x = w ? static_cast<uint64_t>(l.s / r.s)
: static_cast<uint64_t>(static_cast<int32_t>(l.s) /
static_cast<int32_t>(r.s));
break;
case Orem:
x = w ? static_cast<uint64_t>(l.s % r.s)
: static_cast<uint64_t>(static_cast<int32_t>(l.s) %
static_cast<int32_t>(r.s));
break;
case Oudiv:
x = w ? l.u / r.u : static_cast<uint32_t>(l.u) / static_cast<uint32_t>(r.u);
break;
case Ourem:
x = w ? l.u % r.u : static_cast<uint32_t>(l.u) % static_cast<uint32_t>(r.u);
break;
case Oand:
x = l.u & r.u;
break;
case Oor:
x = l.u | r.u;
break;
case Oxor:
x = l.u ^ r.u;
break;
// Signed right shift.
case Osar:
x = static_cast<uint64_t>((w ? l.s : static_cast<int32_t>(l.s)) >> (r.u & shmask));
break;
case Oshr:
x = (w ? l.u : static_cast<uint32_t>(l.u)) >> (r.u & shmask);
break;
case Oshl:
x = l.u << (r.u & shmask);
break;
case Oextsb:
x = static_cast<uint64_t>(static_cast<int8_t>(l.u));
break;
case Oextub:
x = static_cast<uint8_t>(l.u);
break;
case Oextsh:
x = static_cast<uint64_t>(static_cast<int16_t>(l.u));
break;
case Oextuh:
x = static_cast<uint16_t>(l.u);
break;
case Oextsw:
x = static_cast<uint64_t>(static_cast<int32_t>(l.u));
break;
case Oextuw:
x = static_cast<uint32_t>(l.u);
break;
case Ostosi:
x = w ? static_cast<uint64_t>(static_cast<int64_t>(cl->bits.s))
: static_cast<uint64_t>(static_cast<int32_t>(cl->bits.s));
break;
case Ostoui:
x = w ? static_cast<uint64_t>(cl->bits.s)
: static_cast<uint64_t>(static_cast<uint32_t>(cl->bits.s));
break;
case Odtosi:
x = w ? static_cast<uint64_t>(static_cast<int64_t>(cl->bits.d))
: static_cast<uint64_t>(static_cast<int32_t>(cl->bits.d));
break;
case Odtoui:
x = w ? static_cast<uint64_t>(cl->bits.d)
: static_cast<uint64_t>(static_cast<uint32_t>(cl->bits.d));
break;
case Ocast:
x = l.u;
break;
default:
die("foldint: unsupported op %d", op);
}
}
// Write back.
res->type = static_cast<decltype(res->type)>(ctyp);
res->sym = sym;
std::memset(&res->bits, 0, sizeof res->bits);
res->bits.i = static_cast<int64_t>(x);
res->flt = 0;
return 0;
}
namespace {
Ref opfold(Ctx* ctx, int op, int cls, Con* cl, Con* cr, Fn* fn) {
Con c;
std::memset(&c, 0, sizeof c);
if (cls == Kw || cls == Kl) {
if (foldint(&c, op, cls == Kl, cl, cr))
return Ref::none();
} else {
foldflt(&c, op, cls == Kd, cl, cr);
}
if (!KWIDE(cls))
c.bits.i &= 0xffffffff;
Ref r = newcon(ctx, &c, fn);
assert((cls != Ks && cls != Kd) || c.flt);
return r;
}
} // namespace
Ref foldref(Ctx* ctx, Fn* fn, Ins* i) {
if (rtype(i->to) != RTmp)
return Ref::none();
if (!optab[i->op].canfold)
return Ref::none();
if (rtype(i->arg[0]) != RCon)
return Ref::none();
Ref rr = i->arg[1];
if (req(rr, Ref::none()))
rr = Ref::con_z();
if (rtype(rr) != RCon)
return Ref::none();
Con* cl = &fn->con[i->arg[0].val];
Con* cr = &fn->con[rr.val];
return opfold(ctx, i->op, i->cls, cl, cr, fn);
}
} // namespace rcc
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