Add flooring modulo operator
authorXiretza <xiretza@xiretza.xyz>
Wed, 8 Apr 2020 17:30:47 +0000 (19:30 +0200)
committerXiretza <xiretza@xiretza.xyz>
Thu, 28 May 2020 20:59:03 +0000 (22:59 +0200)
The $div and $mod cells use truncating division semantics (rounding
towards 0), as defined by e.g. Verilog. Another rounding mode, flooring
(rounding towards negative infinity), can be used in e.g. VHDL. The
new $modfloor cell provides this flooring modulo (also known as "remainder"
in several languages, but this name is ambiguous).

This commit also fixes the handling of $mod in opt_expr, which was
previously optimized as if it was $modfloor.

23 files changed:
backends/btor/btor.cc
backends/btor/test_cells.sh
backends/firrtl/firrtl.cc
backends/smt2/smt2.cc
backends/smv/smv.cc
backends/smv/test_cells.sh
backends/verilog/verilog_backend.cc
kernel/calc.cc
kernel/celledges.cc
kernel/celltypes.h
kernel/rtlil.cc
kernel/rtlil.h
kernel/satgen.h
manual/PRESENTATION_Prog.tex
passes/cmds/stat.cc
passes/memory/memory_share.cc
passes/opt/opt_expr.cc
passes/opt/opt_share.cc
passes/opt/share.cc
passes/opt/wreduce.cc
passes/tests/test_cell.cc
techlibs/common/simlib.v
techlibs/common/techmap.v

index 14c8484e8b57581f1132ee08e7fb253180b1fa37..2816d32465c9bd6a9086fe13e362cd11ae32fe05 100644 (file)
@@ -266,20 +266,26 @@ struct BtorWorker
                        goto okay;
                }
 
-               if (cell->type.in(ID($div), ID($mod)))
+               if (cell->type.in(ID($div), ID($mod), ID($modfloor)))
                {
+                       bool a_signed = cell->hasParam(ID::A_SIGNED) ? cell->getParam(ID::A_SIGNED).as_bool() : false;
+                       bool b_signed = cell->hasParam(ID::B_SIGNED) ? cell->getParam(ID::B_SIGNED).as_bool() : false;
+
                        string btor_op;
                        if (cell->type == ID($div)) btor_op = "div";
+                       // "rem" = truncating modulo
                        if (cell->type == ID($mod)) btor_op = "rem";
+                       // "mod" = flooring modulo
+                       if (cell->type == ID($modfloor)) {
+                               // "umod" doesn't exist because it's the same as "urem"
+                               btor_op = a_signed || b_signed ? "mod" : "rem";
+                       }
                        log_assert(!btor_op.empty());
 
                        int width = GetSize(cell->getPort(ID::Y));
                        width = std::max(width, GetSize(cell->getPort(ID::A)));
                        width = std::max(width, GetSize(cell->getPort(ID::B)));
 
-                       bool a_signed = cell->hasParam(ID::A_SIGNED) ? cell->getParam(ID::A_SIGNED).as_bool() : false;
-                       bool b_signed = cell->hasParam(ID::B_SIGNED) ? cell->getParam(ID::B_SIGNED).as_bool() : false;
-
                        int nid_a = get_sig_nid(cell->getPort(ID::A), width, a_signed);
                        int nid_b = get_sig_nid(cell->getPort(ID::B), width, b_signed);
 
index e0f1a05140045f61916d879156788b67d3760538..e8d35acf8b1a2c78a0929a8d713f3b955bbf8eb4 100644 (file)
@@ -6,7 +6,7 @@ rm -rf test_cells.tmp
 mkdir -p test_cells.tmp
 cd test_cells.tmp
 
-../../../yosys -p 'test_cell -n 5 -w test all /$alu /$fa /$lcu /$lut /$sop /$macc /$mul /$div /$mod'
+../../../yosys -p 'test_cell -n 5 -w test all /$alu /$fa /$lcu /$lut /$sop /$macc /$mul /$div /$mod /$modfloor'
 
 for fn in test_*.il; do
        ../../../yosys -p "
index a90b0b87af1284cea2c487ff825855fcaa8d094b..b1d8500bb5b2204b0f189d7b19a1d015a88c6044 100644 (file)
@@ -585,6 +585,7 @@ struct FirrtlWorker
                                        firrtl_is_signed = a_signed | b_signed;
                                        firrtl_width = a_width;
                                } else if (cell->type == ID($mod)) {
+                                       // "rem" = truncating modulo
                                        primop = "rem";
                                        firrtl_width = min(a_width, b_width);
                                } else if (cell->type.in(ID($and), ID($_AND_))) {
index 3e67e55f2840d27de2656fb9eb0473f84a3ce5a0..26f17bcb3ba5cd882fbbeec856753db01fb21adb 100644 (file)
@@ -590,7 +590,17 @@ struct Smt2Worker
                        if (cell->type == ID($sub)) return export_bvop(cell, "(bvsub A B)");
                        if (cell->type == ID($mul)) return export_bvop(cell, "(bvmul A B)");
                        if (cell->type == ID($div)) return export_bvop(cell, "(bvUdiv A B)", 'd');
+                       // "rem" = truncating modulo
                        if (cell->type == ID($mod)) return export_bvop(cell, "(bvUrem A B)", 'd');
+                       // "mod" = flooring modulo
+                       if (cell->type == ID($modfloor)) {
+                               // bvumod doesn't exist because it's the same as bvurem
+                               if (cell->getParam(ID::A_SIGNED).as_bool()) {
+                                       return export_bvop(cell, "(bvsmod A B)", 'd');
+                               } else {
+                                       return export_bvop(cell, "(bvurem A B)", 'd');
+                               }
+                       }
 
                        if (cell->type.in(ID($reduce_and), ID($reduce_or), ID($reduce_bool)) &&
                                        2*GetSize(cell->getPort(ID::A).chunks()) < GetSize(cell->getPort(ID::A))) {
index 7113ebc97f0bfe89a76d0cf266fdd6389ef5d29d..2fc7099f4f6363372aeb8a8adbacd84a396b5e5b 100644 (file)
@@ -358,7 +358,8 @@ struct SmvWorker
                                continue;
                        }
 
-                       if (cell->type.in(ID($div), ID($mod)))
+                       // SMV has a "mod" operator, but its semantics don't seem to be well-defined - to be safe, don't generate it at all
+                       if (cell->type.in(ID($div)/*, ID($mod), ID($modfloor)*/))
                        {
                                int width_y = GetSize(cell->getPort(ID::Y));
                                int width = max(width_y, GetSize(cell->getPort(ID::A)));
@@ -366,7 +367,7 @@ struct SmvWorker
                                string expr_a, expr_b, op;
 
                                if (cell->type == ID($div))  op = "/";
-                               if (cell->type == ID($mod))  op = "mod";
+                               //if (cell->type == ID($mod))  op = "mod";
 
                                if (cell->getParam(ID::A_SIGNED).as_bool())
                                {
index 63de465c05c1c0ec972c22af644b0b6351539d93..ae832ce0080bce0e9ab5b2fede69589f2a7d2881 100644 (file)
@@ -7,8 +7,8 @@ mkdir -p test_cells.tmp
 cd test_cells.tmp
 
 # don't test $mul to reduce runtime
-# don't test $div and $mod to reduce runtime and avoid "div by zero" message
-../../../yosys -p 'test_cell -n 5 -w test all /$alu /$fa /$lcu /$lut /$macc /$mul /$div /$mod'
+# don't test $div/$mod/$modfloor to reduce runtime and avoid "div by zero" message
+../../../yosys -p 'test_cell -n 5 -w test all /$alu /$fa /$lcu /$lut /$macc /$mul /$div /$mod /$modfloor'
 
 cat > template.txt << "EOT"
 %module main
index 11b2ae10f27c6645debfcea0215dd38653c8ae0e..368b76793b075ee7b3f1437cbfd5ac17dd17c58a 100644 (file)
@@ -740,6 +740,40 @@ bool dump_cell_expr(std::ostream &f, std::string indent, RTLIL::Cell *cell)
 #undef HANDLE_UNIOP
 #undef HANDLE_BINOP
 
+       if (cell->type == ID($modfloor))
+       {
+               // wire truncated = $signed(A) % $signed(B);
+               // assign Y = (A[-1] == B[-1]) || truncated == 0 ? truncated : $signed(B) + $signed(truncated);
+
+               if (cell->getParam(ID::A_SIGNED).as_bool() && cell->getParam(ID::B_SIGNED).as_bool()) {
+                       SigSpec sig_a = cell->getPort(ID::A);
+                       SigSpec sig_b = cell->getPort(ID::B);
+
+                       std::string temp_id = next_auto_id();
+                       f << stringf("%s" "wire [%d:0] %s = ", indent.c_str(), GetSize(cell->getPort(ID::A))-1, temp_id.c_str());
+                       dump_cell_expr_port(f, cell, "A", true);
+                       f << stringf(" %% ");
+                       dump_attributes(f, "", cell->attributes, ' ');
+                       dump_cell_expr_port(f, cell, "B", true);
+                       f << stringf(";\n");
+
+                       f << stringf("%s" "assign ", indent.c_str());
+                       dump_sigspec(f, cell->getPort(ID::Y));
+                       f << stringf(" = (");
+                       dump_sigspec(f, sig_a.extract(sig_a.size()-1));
+                       f << stringf(" == ");
+                       dump_sigspec(f, sig_b.extract(sig_b.size()-1));
+                       f << stringf(") || %s == 0 ? %s : ", temp_id.c_str(), temp_id.c_str());
+                       dump_cell_expr_port(f, cell, "B", true);
+                       f << stringf(" + $signed(%s);\n", temp_id.c_str());
+                       return true;
+               } else {
+                       // same as truncating modulo
+                       dump_cell_expr_binop(f, indent, cell, "%");
+                       return true;
+               }
+       }
+
        if (cell->type == ID($shift))
        {
                f << stringf("%s" "assign ", indent.c_str());
index 4a48407717f0342ba8f5d7d70528e7856b20b177..38a529128eccb320ffcd1ec1b5f1361daf839251 100644 (file)
@@ -489,6 +489,7 @@ RTLIL::Const RTLIL::const_mul(const RTLIL::Const &arg1, const RTLIL::Const &arg2
        return big2const(y, result_len >= 0 ? result_len : max(arg1.bits.size(), arg2.bits.size()), min(undef_bit_pos, 0));
 }
 
+// truncating division
 RTLIL::Const RTLIL::const_div(const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len)
 {
        int undef_bit_pos = -1;
@@ -502,6 +503,7 @@ RTLIL::Const RTLIL::const_div(const RTLIL::Const &arg1, const RTLIL::Const &arg2
        return big2const(result_neg ? -(a / b) : (a / b), result_len >= 0 ? result_len : max(arg1.bits.size(), arg2.bits.size()), min(undef_bit_pos, 0));
 }
 
+// truncating modulo
 RTLIL::Const RTLIL::const_mod(const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len)
 {
        int undef_bit_pos = -1;
@@ -515,6 +517,29 @@ RTLIL::Const RTLIL::const_mod(const RTLIL::Const &arg1, const RTLIL::Const &arg2
        return big2const(result_neg ? -(a % b) : (a % b), result_len >= 0 ? result_len : max(arg1.bits.size(), arg2.bits.size()), min(undef_bit_pos, 0));
 }
 
+RTLIL::Const RTLIL::const_modfloor(const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len)
+{
+       int undef_bit_pos = -1;
+       BigInteger a = const2big(arg1, signed1, undef_bit_pos);
+       BigInteger b = const2big(arg2, signed2, undef_bit_pos);
+       if (b.isZero())
+               return RTLIL::Const(RTLIL::State::Sx, result_len);
+
+       BigInteger::Sign a_sign = a.getSign();
+       BigInteger::Sign b_sign = b.getSign();
+       a = a_sign == BigInteger::negative ? -a : a;
+       b = b_sign == BigInteger::negative ? -b : b;
+       BigInteger truncated = a_sign == BigInteger::negative ? -(a % b) : (a % b);
+       BigInteger modulo;
+
+       if (truncated == 0 || (a_sign == b_sign)) {
+               modulo = truncated;
+       } else {
+               modulo = b_sign == BigInteger::negative ? truncated - b : truncated + b;
+       }
+       return big2const(modulo, result_len >= 0 ? result_len : max(arg1.bits.size(), arg2.bits.size()), min(undef_bit_pos, 0));
+}
+
 RTLIL::Const RTLIL::const_pow(const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len)
 {
        int undef_bit_pos = -1;
index 54e0168e255f3bc61b6b100919e2f311907ef836..488ee9d02313d16d316af88ab630e3bcdeac7c23 100644 (file)
@@ -187,7 +187,7 @@ bool YOSYS_NAMESPACE_PREFIX AbstractCellEdgesDatabase::add_edges_from_cell(RTLIL
                return true;
        }
 
-       // FIXME: $mul $div $mod $slice $concat
+       // FIXME: $mul $div $mod $modfloor $slice $concat
        // FIXME: $lut $sop $alu $lcu $macc $fa
 
        return false;
index 450865ce90ae8f2539d7f0fd940e86ca223ec4fc..37c251f7ef899aebd09ac1ababec67a09f263bd7 100644 (file)
@@ -114,7 +114,7 @@ struct CellTypes
                        ID($and), ID($or), ID($xor), ID($xnor),
                        ID($shl), ID($shr), ID($sshl), ID($sshr), ID($shift), ID($shiftx),
                        ID($lt), ID($le), ID($eq), ID($ne), ID($eqx), ID($nex), ID($ge), ID($gt),
-                       ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($pow),
+                       ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($modfloor), ID($pow),
                        ID($logic_and), ID($logic_or), ID($concat), ID($macc)
                };
 
@@ -304,6 +304,7 @@ struct CellTypes
                HANDLE_CELL_TYPE(mul)
                HANDLE_CELL_TYPE(div)
                HANDLE_CELL_TYPE(mod)
+               HANDLE_CELL_TYPE(modfloor)
                HANDLE_CELL_TYPE(pow)
                HANDLE_CELL_TYPE(pos)
                HANDLE_CELL_TYPE(neg)
index 196e301b6c04e20fd449f197cf0cafd96467f230..f2480ba5a33e1280e54075b613188a5f220079b2 100644 (file)
@@ -948,7 +948,7 @@ namespace {
                                return;
                        }
 
-                       if (cell->type.in(ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($pow))) {
+                       if (cell->type.in(ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($modfloor), ID($pow))) {
                                param_bool(ID::A_SIGNED);
                                param_bool(ID::B_SIGNED);
                                port(ID::A, param(ID::A_WIDTH));
@@ -1949,6 +1949,7 @@ DEF_METHOD(Sub,      max(sig_a.size(), sig_b.size()), ID($sub))
 DEF_METHOD(Mul,      max(sig_a.size(), sig_b.size()), ID($mul))
 DEF_METHOD(Div,      max(sig_a.size(), sig_b.size()), ID($div))
 DEF_METHOD(Mod,      max(sig_a.size(), sig_b.size()), ID($mod))
+DEF_METHOD(ModFloor, max(sig_a.size(), sig_b.size()), ID($modfloor))
 DEF_METHOD(LogicAnd, 1, ID($logic_and))
 DEF_METHOD(LogicOr,  1, ID($logic_or))
 #undef DEF_METHOD
index 423c0b4bdf3be25be0bdd7d9f38147cfbbde5f33..6bb7599280144322496859d32ebdb94723d6b80b 100644 (file)
@@ -466,6 +466,7 @@ namespace RTLIL
        RTLIL::Const const_sub         (const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len);
        RTLIL::Const const_mul         (const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len);
        RTLIL::Const const_div         (const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len);
+       RTLIL::Const const_modfloor    (const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len);
        RTLIL::Const const_mod         (const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len);
        RTLIL::Const const_pow         (const RTLIL::Const &arg1, const RTLIL::Const &arg2, bool signed1, bool signed2, int result_len);
 
@@ -1204,6 +1205,7 @@ public:
        RTLIL::Cell* addMul (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, const RTLIL::SigSpec &sig_y, bool is_signed = false, const std::string &src = "");
        RTLIL::Cell* addDiv (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, const RTLIL::SigSpec &sig_y, bool is_signed = false, const std::string &src = "");
        RTLIL::Cell* addMod (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, const RTLIL::SigSpec &sig_y, bool is_signed = false, const std::string &src = "");
+       RTLIL::Cell* addModFloor (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, const RTLIL::SigSpec &sig_y, bool is_signed = false, const std::string &src = "");
        RTLIL::Cell* addPow (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, const RTLIL::SigSpec &sig_y, bool a_signed = false, bool b_signed = false, const std::string &src = "");
 
        RTLIL::Cell* addLogicNot (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_y, bool is_signed = false, const std::string &src = "");
@@ -1303,6 +1305,7 @@ public:
        RTLIL::SigSpec Mul (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, bool is_signed = false, const std::string &src = "");
        RTLIL::SigSpec Div (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, bool is_signed = false, const std::string &src = "");
        RTLIL::SigSpec Mod (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, bool is_signed = false, const std::string &src = "");
+       RTLIL::SigSpec ModFloor (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, bool is_signed = false, const std::string &src = "");
        RTLIL::SigSpec Pow (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, const RTLIL::SigSpec &sig_b, bool a_signed = false, bool b_signed = false, const std::string &src = "");
 
        RTLIL::SigSpec LogicNot (RTLIL::IdString name, const RTLIL::SigSpec &sig_a, bool is_signed = false, const std::string &src = "");
index 88b84b7e60459df07fa18299ad62c2b1d61e4fba..1d257aa2cdcd428f43c174b758cce32fcaa919e7 100644 (file)
@@ -279,7 +279,7 @@ struct SatGen
                bool arith_undef_handled = false;
                bool is_arith_compare = cell->type.in(ID($lt), ID($le), ID($ge), ID($gt));
 
-               if (model_undef && (cell->type.in(ID($add), ID($sub), ID($mul), ID($div), ID($mod)) || is_arith_compare))
+               if (model_undef && (cell->type.in(ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($modfloor)) || is_arith_compare))
                {
                        std::vector<int> undef_a = importUndefSigSpec(cell->getPort(ID::A), timestep);
                        std::vector<int> undef_b = importUndefSigSpec(cell->getPort(ID::B), timestep);
@@ -293,7 +293,7 @@ struct SatGen
                        int undef_any_b = ez->expression(ezSAT::OpOr, undef_b);
                        int undef_y_bit = ez->OR(undef_any_a, undef_any_b);
 
-                       if (cell->type.in(ID($div), ID($mod))) {
+                       if (cell->type.in(ID($div), ID($mod), ID($modfloor))) {
                                std::vector<int> b = importSigSpec(cell->getPort(ID::B), timestep);
                                undef_y_bit = ez->OR(undef_y_bit, ez->NOT(ez->expression(ezSAT::OpOr, b)));
                        }
@@ -935,7 +935,7 @@ struct SatGen
                        return true;
                }
 
-               if (cell->type.in(ID($div), ID($mod)))
+               if (cell->type.in(ID($div), ID($mod), ID($modfloor)))
                {
                        std::vector<int> a = importDefSigSpec(cell->getPort(ID::A), timestep);
                        std::vector<int> b = importDefSigSpec(cell->getPort(ID::B), timestep);
@@ -970,16 +970,28 @@ struct SatGen
                        }
 
                        std::vector<int> y_tmp = ignore_div_by_zero ? yy : ez->vec_var(y.size());
+
+                       // modulo calculation
+                       std::vector<int> modulo_trunc;
+                       int floored_eq_trunc;
+                       if (cell->parameters[ID::A_SIGNED].as_bool() && cell->parameters[ID::B_SIGNED].as_bool()) {
+                               modulo_trunc = ez->vec_ite(a.back(), ez->vec_neg(chain_buf), chain_buf);
+                               // floor == trunc when sgn(a) == sgn(b) or trunc == 0
+                               floored_eq_trunc = ez->OR(ez->IFF(a.back(), b.back()), ez->NOT(ez->expression(ezSAT::OpOr, modulo_trunc)));
+                       } else {
+                               modulo_trunc = chain_buf;
+                               floored_eq_trunc = ez->CONST_TRUE;
+                       }
+
                        if (cell->type == ID($div)) {
                                if (cell->parameters[ID::A_SIGNED].as_bool() && cell->parameters[ID::B_SIGNED].as_bool())
                                        ez->assume(ez->vec_eq(y_tmp, ez->vec_ite(ez->XOR(a.back(), b.back()), ez->vec_neg(y_u), y_u)));
                                else
                                        ez->assume(ez->vec_eq(y_tmp, y_u));
-                       } else {
-                               if (cell->parameters[ID::A_SIGNED].as_bool() && cell->parameters[ID::B_SIGNED].as_bool())
-                                       ez->assume(ez->vec_eq(y_tmp, ez->vec_ite(a.back(), ez->vec_neg(chain_buf), chain_buf)));
-                               else
-                                       ez->assume(ez->vec_eq(y_tmp, chain_buf));
+                       } else if (cell->type == ID($mod)) {
+                               ez->assume(ez->vec_eq(y_tmp, modulo_trunc));
+                       } else if (cell->type == ID($modfloor)) {
+                               ez->assume(ez->vec_eq(y_tmp, ez->vec_ite(floored_eq_trunc, modulo_trunc, ez->vec_add(modulo_trunc, b))));
                        }
 
                        if (ignore_div_by_zero) {
@@ -996,7 +1008,8 @@ struct SatGen
                                                div_zero_result.insert(div_zero_result.end(), cell->getPort(ID::A).size(), ez->CONST_TRUE);
                                                div_zero_result.insert(div_zero_result.end(), y.size() - div_zero_result.size(), ez->CONST_FALSE);
                                        }
-                               } else {
+                               } else if (cell->type.in(ID($mod), ID($modfloor))) {
+                                       // a mod 0 = a
                                        int copy_a_bits = min(cell->getPort(ID::A).size(), cell->getPort(ID::B).size());
                                        div_zero_result.insert(div_zero_result.end(), a.begin(), a.begin() + copy_a_bits);
                                        if (cell->parameters[ID::A_SIGNED].as_bool() && cell->parameters[ID::B_SIGNED].as_bool())
index b85eda89272b0cb1cbb3fd059c55fab22c0588cb..4652731e93b718cf6dafc775efa8c8b320389805 100644 (file)
@@ -307,7 +307,7 @@ cell name from the internal cell library:
 \begin{lstlisting}[xleftmargin=1cm, basicstyle=\ttfamily\fontsize{6pt}{7pt}\selectfont]
 $not $pos $neg $and $or $xor $xnor $reduce_and $reduce_or $reduce_xor $reduce_xnor
 $reduce_bool $shl $shr $sshl $sshr $lt $le $eq $ne $eqx $nex $ge $gt $add $sub $mul $div $mod
-$pow $logic_not $logic_and $logic_or $mux $pmux $slice $concat $lut $assert $sr $dff
+$modfloor $pow $logic_not $logic_and $logic_or $mux $pmux $slice $concat $lut $assert $sr $dff
 $dffsr $adff $dlatch $dlatchsr $memrd $memwr $mem $fsm $_NOT_ $_AND_ $_OR_ $_XOR_ $_MUX_ $_SR_NN_
 $_SR_NP_ $_SR_PN_ $_SR_PP_ $_DFF_N_ $_DFF_P_ $_DFF_NN0_ $_DFF_NN1_ $_DFF_NP0_ $_DFF_NP1_ $_DFF_PN0_
 $_DFF_PN1_ $_DFF_PP0_ $_DFF_PP1_ $_DFFSR_NNN_ $_DFFSR_NNP_ $_DFFSR_NPN_ $_DFFSR_NPP_ $_DFFSR_PNN_
index 6c4bc0e5b28ef07b63f31c71995894e4d872c758..e979685e09ae4bfdc62c08dbf21de4790e28a548 100644 (file)
@@ -109,7 +109,7 @@ struct statdata_t
                                                ID($lut), ID($and), ID($or), ID($xor), ID($xnor),
                                                ID($shl), ID($shr), ID($sshl), ID($sshr), ID($shift), ID($shiftx),
                                                ID($lt), ID($le), ID($eq), ID($ne), ID($eqx), ID($nex), ID($ge), ID($gt),
-                                               ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($pow), ID($alu))) {
+                                               ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($modfloor), ID($pow), ID($alu))) {
                                        int width_a = cell->hasPort(ID::A) ? GetSize(cell->getPort(ID::A)) : 0;
                                        int width_b = cell->hasPort(ID::B) ? GetSize(cell->getPort(ID::B)) : 0;
                                        int width_y = cell->hasPort(ID::Y) ? GetSize(cell->getPort(ID::Y)) : 0;
index 477246687e347185ac3a09875c620d86e651f73c..c9ac03a6ad4429664cdda553b902e0495df43ed4 100644 (file)
@@ -715,6 +715,7 @@ struct MemoryShareWorker
                cone_ct.cell_types.erase(ID($mul));
                cone_ct.cell_types.erase(ID($mod));
                cone_ct.cell_types.erase(ID($div));
+               cone_ct.cell_types.erase(ID($modfloor));
                cone_ct.cell_types.erase(ID($pow));
                cone_ct.cell_types.erase(ID($shl));
                cone_ct.cell_types.erase(ID($shr));
index 777a24777f3cc005771751b9ed2d2a778c4cd251..1b33435b15acde115e610b6f2ce04a171d041934 100644 (file)
@@ -864,7 +864,7 @@ void replace_const_cells(RTLIL::Design *design, RTLIL::Module *module, bool cons
 skip_fine_alu:
 
                if (cell->type.in(ID($reduce_xor), ID($reduce_xnor), ID($shift), ID($shiftx), ID($shl), ID($shr), ID($sshl), ID($sshr),
-                                       ID($lt), ID($le), ID($ge), ID($gt), ID($neg), ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($pow)))
+                                       ID($lt), ID($le), ID($ge), ID($gt), ID($neg), ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($modfloor), ID($pow)))
                {
                        RTLIL::SigSpec sig_a = assign_map(cell->getPort(ID::A));
                        RTLIL::SigSpec sig_b = cell->hasPort(ID::B) ? assign_map(cell->getPort(ID::B)) : RTLIL::SigSpec();
@@ -883,7 +883,7 @@ skip_fine_alu:
                        if (0) {
                found_the_x_bit:
                                cover_list("opt.opt_expr.xbit", "$reduce_xor", "$reduce_xnor", "$shl", "$shr", "$sshl", "$sshr", "$shift", "$shiftx",
-                                               "$lt", "$le", "$ge", "$gt", "$neg", "$add", "$sub", "$mul", "$div", "$mod", "$pow", cell->type.str());
+                                               "$lt", "$le", "$ge", "$gt", "$neg", "$add", "$sub", "$mul", "$div", "$mod", "$modfloor", "$pow", cell->type.str());
                                if (cell->type.in(ID($reduce_xor), ID($reduce_xnor), ID($lt), ID($le), ID($ge), ID($gt)))
                                        replace_cell(assign_map, module, cell, "x-bit in input", ID::Y, RTLIL::State::Sx);
                                else
@@ -1469,6 +1469,7 @@ skip_identity:
                FOLD_2ARG_CELL(mul)
                FOLD_2ARG_CELL(div)
                FOLD_2ARG_CELL(mod)
+               FOLD_2ARG_CELL(modfloor)
                FOLD_2ARG_CELL(pow)
 
                FOLD_1ARG_CELL(pos)
@@ -1583,9 +1584,11 @@ skip_identity:
                        }
                }
 
-               if (!keepdc && cell->type.in(ID($div), ID($mod)))
+               if (!keepdc && cell->type.in(ID($div), ID($mod), ID($modfloor)))
                {
+                       bool a_signed = cell->parameters[ID::A_SIGNED].as_bool();
                        bool b_signed = cell->parameters[ID::B_SIGNED].as_bool();
+                       SigSpec sig_a = assign_map(cell->getPort(ID::A));
                        SigSpec sig_b = assign_map(cell->getPort(ID::B));
                        SigSpec sig_y = assign_map(cell->getPort(ID::Y));
 
@@ -1628,11 +1631,13 @@ skip_identity:
                                                        cell->setPort(ID::B, new_b);
                                                        cell->check();
                                                }
-                                               else
+                                               else if (cell->type.in(ID($mod), ID($modfloor)))
                                                {
                                                        cover("opt.opt_expr.mod_mask");
 
-                                                       log_debug("Replacing modulo-by-%d cell `%s' in module `%s' with bitmask.\n",
+                                                       bool is_truncating = cell->type == ID($mod);
+                                                       log_debug("Replacing %s-modulo-by-%d cell `%s' in module `%s' with bitmask.\n",
+                                                                       is_truncating ? "truncating" : "flooring",
                                                                        b_val, cell->name.c_str(), module->name.c_str());
 
                                                        std::vector<RTLIL::SigBit> new_b = RTLIL::SigSpec(State::S1, i);
@@ -1643,6 +1648,24 @@ skip_identity:
                                                        cell->type = ID($and);
                                                        cell->parameters[ID::B_WIDTH] = GetSize(new_b);
                                                        cell->setPort(ID::B, new_b);
+
+                                                       // truncating modulo has the same masked bits as flooring modulo, but
+                                                       // the sign bits are those of A (except when R=0)
+                                                       if (is_truncating && a_signed) {
+                                                               Wire *flooring = module->addWire(NEW_ID, sig_y.size());
+                                                               cell->setPort(ID::Y, flooring);
+                                                               SigSpec truncating = SigSpec(flooring).extract(0, i);
+
+                                                               Wire *rem_nonzero = module->addWire(NEW_ID);
+                                                               module->addReduceOr(NEW_ID, truncating, rem_nonzero);
+                                                               SigSpec a_sign = sig_a[sig_a.size()-1];
+                                                               Wire *extend_bit = module->addWire(NEW_ID);
+                                                               module->addAnd(NEW_ID, a_sign, rem_nonzero, extend_bit);
+
+                                                               truncating.append(extend_bit);
+                                                               module->addPos(NEW_ID, truncating, sig_y, true);
+                                                       }
+
                                                        cell->check();
                                                }
 
index 1f69c98f49d9c6e37b01465d1eefd5d19ec4cfcf..b08a8172f7a46687c409fe446b997f8bb9413c38 100644 (file)
@@ -103,7 +103,7 @@ bool cell_supported(RTLIL::Cell *cell)
 
                if (sig_bi.is_fully_const() && sig_ci.is_fully_const() && sig_bi == sig_ci)
                        return true;
-       } else if (cell->type.in(LOGICAL_OPS, SHIFT_OPS, BITWISE_OPS, RELATIONAL_OPS, ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($concat))) {
+       } else if (cell->type.in(LOGICAL_OPS, SHIFT_OPS, BITWISE_OPS, RELATIONAL_OPS, ID($add), ID($sub), ID($mul), ID($div), ID($mod), ID($modfloor), ID($concat))) {
                return true;
        }
 
@@ -130,7 +130,7 @@ bool mergeable(RTLIL::Cell *a, RTLIL::Cell *b)
 
 RTLIL::IdString decode_port_semantics(RTLIL::Cell *cell, RTLIL::IdString port_name)
 {
-       if (cell->type.in(ID($lt), ID($le), ID($ge), ID($gt), ID($div), ID($mod), ID($concat), SHIFT_OPS) && port_name == ID::B)
+       if (cell->type.in(ID($lt), ID($le), ID($ge), ID($gt), ID($div), ID($mod), ID($modfloor), ID($concat), SHIFT_OPS) && port_name == ID::B)
                return port_name;
 
        return "";
index 2839507b0f80bfa9759ba2c41c670dc1698c8718..1c8942df0d9866f4f9be66dca8120985fff2261c 100644 (file)
@@ -376,7 +376,7 @@ struct ShareWorker
                                continue;
                        }
 
-                       if (cell->type.in(ID($mul), ID($div), ID($mod))) {
+                       if (cell->type.in(ID($mul), ID($div), ID($mod), ID($modfloor))) {
                                if (config.opt_aggressive || cell->parameters.at(ID::Y_WIDTH).as_int() >= 4)
                                        shareable_cells.insert(cell);
                                continue;
@@ -1133,6 +1133,7 @@ struct ShareWorker
                cone_ct.cell_types.erase(ID($mul));
                cone_ct.cell_types.erase(ID($mod));
                cone_ct.cell_types.erase(ID($div));
+               cone_ct.cell_types.erase(ID($modfloor));
                cone_ct.cell_types.erase(ID($pow));
                cone_ct.cell_types.erase(ID($shl));
                cone_ct.cell_types.erase(ID($shr));
@@ -1512,6 +1513,7 @@ struct SharePass : public Pass {
                config.generic_bin_ops.insert(ID($sub));
                config.generic_bin_ops.insert(ID($div));
                config.generic_bin_ops.insert(ID($mod));
+               config.generic_bin_ops.insert(ID($modfloor));
                // config.generic_bin_ops.insert(ID($pow));
 
                config.generic_uni_ops.insert(ID($logic_not));
index 195400bf0005ecb30860441fd0b25cb2fdc8d77c..17b957d23a236bf4533217a3c0b665a1f08d1e37 100644 (file)
@@ -37,7 +37,7 @@ struct WreduceConfig
                        ID($and), ID($or), ID($xor), ID($xnor),
                        ID($shl), ID($shr), ID($sshl), ID($sshr), ID($shift), ID($shiftx),
                        ID($lt), ID($le), ID($eq), ID($ne), ID($eqx), ID($nex), ID($ge), ID($gt),
-                       ID($add), ID($sub), ID($mul), // ID($div), ID($mod), ID($pow),
+                       ID($add), ID($sub), ID($mul), // ID($div), ID($mod), ID($modfloor), ID($pow),
                        ID($mux), ID($pmux),
                        ID($dff), ID($adff)
                });
@@ -545,7 +545,7 @@ struct WreducePass : public Pass {
                                        }
                                }
 
-                               if (c->type.in(ID($div), ID($mod), ID($pow)))
+                               if (c->type.in(ID($div), ID($mod), ID($modfloor), ID($pow)))
                                {
                                        SigSpec A = c->getPort(ID::A);
                                        int original_a_width = GetSize(A);
index cdbe922b216d405fc9c9d096a7214890689aa6fe..bc5ff598ee38ec53ae3d42cb20e136baeca08ef2 100644 (file)
@@ -264,7 +264,7 @@ static void create_gold_module(RTLIL::Design *design, RTLIL::IdString cell_type,
                cell->setPort(ID::Y, wire);
        }
 
-       if (muxdiv && cell_type.in(ID($div), ID($mod))) {
+       if (muxdiv && cell_type.in(ID($div), ID($mod), ID($modfloor))) {
                auto b_not_zero = module->ReduceBool(NEW_ID, cell->getPort(ID::B));
                auto div_out = module->addWire(NEW_ID, GetSize(cell->getPort(ID::Y)));
                module->addMux(NEW_ID, RTLIL::SigSpec(0, GetSize(div_out)), div_out, b_not_zero, cell->getPort(ID::Y));
@@ -839,6 +839,7 @@ struct TestCellPass : public Pass {
                cell_types[ID($mul)] = "ABSY";
                cell_types[ID($div)] = "ABSY";
                cell_types[ID($mod)] = "ABSY";
+               cell_types[ID($modfloor)] = "ABSY";
                // cell_types[ID($pow)] = "ABsY";
 
                cell_types[ID($logic_not)] = "ASY";
index 2cdddeabb840247b2072265bd86c6c6425fb49f2..57fc07caa8045a1852cdf8cf3074ab0169fc4126 100644 (file)
@@ -1021,6 +1021,14 @@ endmodule
 
 // --------------------------------------------------------
 
+//  |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+//-
+//-     $mod (A, B, Y)
+//-
+//- Modulo/remainder of division with truncated result (rounded towards 0).
+//-
+//- Invariant: $div(A, B) * B + $mod(A, B) == A
+//-
 module \$mod (A, B, Y);
 
 parameter A_SIGNED = 0;
@@ -1043,6 +1051,46 @@ endgenerate
 
 endmodule
 
+// --------------------------------------------------------
+
+//  |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+//-
+//-     $modfloor (A, B, Y)
+//-
+//- Modulo/remainder of division with floored result (rounded towards negative infinity).
+//-
+//- Invariant: $divfloor(A, B) * B + $modfloor(A, B) == A
+//-
+module \$modfloor (A, B, Y);
+
+parameter A_SIGNED = 0;
+parameter B_SIGNED = 0;
+parameter A_WIDTH = 0;
+parameter B_WIDTH = 0;
+parameter Y_WIDTH = 0;
+
+input [A_WIDTH-1:0] A;
+input [B_WIDTH-1:0] B;
+output [Y_WIDTH-1:0] Y;
+
+generate
+       if (A_SIGNED && B_SIGNED) begin:BLOCK1
+               localparam WIDTH = B_WIDTH >= Y_WIDTH ? B_WIDTH : Y_WIDTH;
+               wire [WIDTH-1:0] B_buf, Y_trunc;
+               assign B_buf = $signed(B);
+               assign Y_trunc = $signed(A) % $signed(B);
+               // flooring mod is the same as truncating mod for positive division results (A and B have
+               // the same sign), as well as when there's no remainder.
+               // For all other cases, they behave as `floor - trunc = B`
+               assign Y = (A[A_WIDTH-1] == B[B_WIDTH-1]) || Y_trunc == 0 ? Y_trunc : $signed(B_buf) + $signed(Y_trunc);
+       end else begin:BLOCK2
+               // no difference between truncating and flooring for unsigned
+               assign Y = A % B;
+       end
+endgenerate
+
+endmodule
+
 // --------------------------------------------------------
 `ifndef SIMLIB_NOPOW
 
index c1efc378b1f89bb0b2527e1cc082b6f0fdf803e3..95223180de355b6ce9b1ed53e7d2e54eabf9314d 100644 (file)
@@ -364,7 +364,8 @@ module \$__div_mod_u (A, B, Y, R);
        end endgenerate
 endmodule
 
-module \$__div_mod (A, B, Y, R);
+// truncating signed division/modulo
+module \$__div_mod_trunc (A, B, Y, R);
        parameter A_SIGNED = 0;
        parameter B_SIGNED = 0;
        parameter A_WIDTH = 1;
@@ -420,7 +421,7 @@ module _90_div (A, B, Y);
        (* force_downto *)
        output [Y_WIDTH-1:0] Y;
 
-       \$__div_mod #(
+       \$__div_mod_trunc #(
                .A_SIGNED(A_SIGNED),
                .B_SIGNED(B_SIGNED),
                .A_WIDTH(A_WIDTH),
@@ -448,7 +449,79 @@ module _90_mod (A, B, Y);
        (* force_downto *)
        output [Y_WIDTH-1:0] Y;
 
-       \$__div_mod #(
+       \$__div_mod_trunc #(
+               .A_SIGNED(A_SIGNED),
+               .B_SIGNED(B_SIGNED),
+               .A_WIDTH(A_WIDTH),
+               .B_WIDTH(B_WIDTH),
+               .Y_WIDTH(Y_WIDTH)
+       ) div_mod (
+               .A(A),
+               .B(B),
+               .R(Y)
+       );
+endmodule
+
+// flooring signed division/modulo
+module \$__div_mod_floor (A, B, Y, R);
+       parameter A_SIGNED = 0;
+       parameter B_SIGNED = 0;
+       parameter A_WIDTH = 1;
+       parameter B_WIDTH = 1;
+       parameter Y_WIDTH = 1;
+
+       localparam WIDTH =
+                       A_WIDTH >= B_WIDTH && A_WIDTH >= Y_WIDTH ? A_WIDTH :
+                       B_WIDTH >= A_WIDTH && B_WIDTH >= Y_WIDTH ? B_WIDTH : Y_WIDTH;
+
+       input [A_WIDTH-1:0] A;
+       input [B_WIDTH-1:0] B;
+       output [Y_WIDTH-1:0] Y, R;
+
+       wire [WIDTH-1:0] A_buf, B_buf;
+       \$pos #(.A_SIGNED(A_SIGNED), .A_WIDTH(A_WIDTH), .Y_WIDTH(WIDTH)) A_conv (.A(A), .Y(A_buf));
+       \$pos #(.A_SIGNED(B_SIGNED), .A_WIDTH(B_WIDTH), .Y_WIDTH(WIDTH)) B_conv (.A(B), .Y(B_buf));
+
+       wire [WIDTH-1:0] A_buf_u, B_buf_u, Y_u, R_u, R_s;
+       assign A_buf_u = A_SIGNED && A_buf[WIDTH-1] ? -A_buf : A_buf;
+       assign B_buf_u = B_SIGNED && B_buf[WIDTH-1] ? -B_buf : B_buf;
+
+       \$__div_mod_u #(
+               .WIDTH(WIDTH)
+       ) div_mod_u (
+               .A(A_buf_u),
+               .B(B_buf_u),
+               .Y(Y_u),
+               .R(R_u)
+       );
+
+       // For negative results, if there was a remainder, subtract one to turn
+       // the round towards 0 into a round towards -inf
+       assign Y = A_SIGNED && B_SIGNED && (A_buf[WIDTH-1] != B_buf[WIDTH-1]) ? (R_u == 0 ? -Y_u : -Y_u-1) : Y_u;
+
+       // truncating modulo
+       assign R_s = A_SIGNED && B_SIGNED && A_buf[WIDTH-1] ? -R_u : R_u;
+       // Flooring modulo differs from truncating modulo only if it is nonzero and
+       // A and B have different signs - then `floor - trunc = B`
+       assign R = (R_s != 0) && A_SIGNED && B_SIGNED && (A_buf[WIDTH-1] != B_buf[WIDTH-1]) ? $signed(B_buf) + $signed(R_s) : R_s;
+endmodule
+
+(* techmap_celltype = "$modfloor" *)
+module _90_modfloor (A, B, Y);
+       parameter A_SIGNED = 0;
+       parameter B_SIGNED = 0;
+       parameter A_WIDTH = 1;
+       parameter B_WIDTH = 1;
+       parameter Y_WIDTH = 1;
+
+       (* force_downto *)
+       input [A_WIDTH-1:0] A;
+       (* force_downto *)
+       input [B_WIDTH-1:0] B;
+       (* force_downto *)
+       output [Y_WIDTH-1:0] Y;
+
+       \$__div_mod_floor #(
                .A_SIGNED(A_SIGNED),
                .B_SIGNED(B_SIGNED),
                .A_WIDTH(A_WIDTH),