From 0d8e5d965f2585e6ed151a9e92d83ee63df6172a Mon Sep 17 00:00:00 2001 From: Zachary Snow Date: Fri, 18 Dec 2020 12:59:08 -0700 Subject: [PATCH] Sign extend port connections where necessary - Signed cell outputs are sign extended when bound to larger wires - Signed connections are sign extended when bound to larger cell inputs - Sign extension is performed in hierarchy and flatten phases - genrtlil indirects signed constants through signed wires - Other phases producing RTLIL may need to be updated to preserve signedness information - Resolves #1418 - Resolves #2265 --- frontends/ast/genrtlil.cc | 26 ++++++++++- passes/hierarchy/hierarchy.cc | 8 +++- passes/techmap/flatten.cc | 5 +- tests/various/port_sign_extend.v | 76 +++++++++++++++++++++++++++++++ tests/various/port_sign_extend.ys | 22 +++++++++ 5 files changed, 132 insertions(+), 5 deletions(-) create mode 100644 tests/various/port_sign_extend.v create mode 100644 tests/various/port_sign_extend.ys diff --git a/frontends/ast/genrtlil.cc b/frontends/ast/genrtlil.cc index e878d0dd2..500ccf8c0 100644 --- a/frontends/ast/genrtlil.cc +++ b/frontends/ast/genrtlil.cc @@ -106,6 +106,7 @@ static RTLIL::SigSpec binop2rtlil(AstNode *that, IdString type, int result_width RTLIL::Wire *wire = current_module->addWire(cell->name.str() + "_Y", result_width); wire->attributes[ID::src] = stringf("%s:%d.%d-%d.%d", that->filename.c_str(), that->location.first_line, that->location.first_column, that->location.last_line, that->location.last_column); + wire->is_signed = that->is_signed; for (auto &attr : that->attributes) { if (attr.second->type != AST_CONSTANT) @@ -1721,8 +1722,29 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint) } if (child->type == AST_ARGUMENT) { RTLIL::SigSpec sig; - if (child->children.size() > 0) - sig = child->children[0]->genRTLIL(); + if (child->children.size() > 0) { + AstNode *arg = child->children[0]; + int local_width_hint = -1; + bool local_sign_hint = false; + // don't inadvertently attempt to detect the width of interfaces + if (arg->type != AST_IDENTIFIER || !arg->id2ast || arg->id2ast->type != AST_CELL) + arg->detectSignWidth(local_width_hint, local_sign_hint); + sig = arg->genRTLIL(local_width_hint, local_sign_hint); + log_assert(local_sign_hint == arg->is_signed); + if (sig.is_wire()) { + // if the resulting SigSpec is a wire, its + // signedness should match that of the AstNode + log_assert(arg->is_signed == sig.as_wire()->is_signed); + } else if (arg->is_signed) { + // non-trivial signed nodes are indirected through + // signed wires to enable sign extension + RTLIL::IdString wire_name = NEW_ID; + RTLIL::Wire *wire = current_module->addWire(wire_name, arg->bits.size()); + wire->is_signed = true; + current_module->connect(wire, sig); + sig = wire; + } + } if (child->str.size() == 0) { char buf[100]; snprintf(buf, 100, "$%d", ++port_counter); diff --git a/passes/hierarchy/hierarchy.cc b/passes/hierarchy/hierarchy.cc index 225e1feae..3372687e1 100644 --- a/passes/hierarchy/hierarchy.cc +++ b/passes/hierarchy/hierarchy.cc @@ -1233,14 +1233,18 @@ struct HierarchyPass : public Pass { { int n = GetSize(conn.second) - GetSize(w); if (!w->port_input && w->port_output) - module->connect(sig.extract(GetSize(w), n), Const(0, n)); + { + RTLIL::SigSpec out = sig.extract(0, GetSize(w)); + out.extend_u0(GetSize(sig), w->is_signed); + module->connect(sig.extract(GetSize(w), n), out.extract(GetSize(w), n)); + } sig.remove(GetSize(w), n); } else { int n = GetSize(w) - GetSize(conn.second); if (w->port_input && !w->port_output) - sig.append(Const(0, n)); + sig.extend_u0(GetSize(w), sig.is_wire() && sig.as_wire()->is_signed); else sig.append(module->addWire(NEW_ID, n)); } diff --git a/passes/techmap/flatten.cc b/passes/techmap/flatten.cc index 08978f446..ec5f83fb0 100644 --- a/passes/techmap/flatten.cc +++ b/passes/techmap/flatten.cc @@ -180,12 +180,15 @@ struct FlattenWorker RTLIL::Wire *tpl_wire = tpl->wire(port_name); RTLIL::SigSig new_conn; + bool is_signed = false; if (tpl_wire->port_output && !tpl_wire->port_input) { new_conn.first = port_it.second; new_conn.second = tpl_wire; + is_signed = tpl_wire->is_signed; } else if (!tpl_wire->port_output && tpl_wire->port_input) { new_conn.first = tpl_wire; new_conn.second = port_it.second; + is_signed = new_conn.second.is_wire() && new_conn.second.as_wire()->is_signed; } else { SigSpec sig_tpl = tpl_wire, sig_mod = port_it.second; for (int i = 0; i < GetSize(sig_tpl) && i < GetSize(sig_mod); i++) { @@ -204,7 +207,7 @@ struct FlattenWorker if (new_conn.second.size() > new_conn.first.size()) new_conn.second.remove(new_conn.first.size(), new_conn.second.size() - new_conn.first.size()); if (new_conn.second.size() < new_conn.first.size()) - new_conn.second.append(RTLIL::SigSpec(RTLIL::State::S0, new_conn.first.size() - new_conn.second.size())); + new_conn.second.extend_u0(new_conn.first.size(), is_signed); log_assert(new_conn.first.size() == new_conn.second.size()); if (sigmap(new_conn.first).has_const()) diff --git a/tests/various/port_sign_extend.v b/tests/various/port_sign_extend.v new file mode 100644 index 000000000..055f20ad8 --- /dev/null +++ b/tests/various/port_sign_extend.v @@ -0,0 +1,76 @@ +module GeneratorSigned1(out); + output wire signed out; + assign out = 1; +endmodule + +module GeneratorUnsigned1(out); + output wire out; + assign out = 1; +endmodule + +module GeneratorSigned2(out); + output wire signed [1:0] out; + assign out = 2; +endmodule + +module GeneratorUnsigned2(out); + output wire [1:0] out; + assign out = 2; +endmodule + +module PassThrough(a, b); + input wire [3:0] a; + output wire [3:0] b; + assign b = a; +endmodule + +module act(o1, o2, o3, o4, o5, yay1, nay1, yay2, nay2); + output wire [3:0] o1, o2, o3, o4, o5; + + // unsigned constant + PassThrough pt1(1'b1, o1); + + // unsigned wire + wire tmp2; + assign tmp2 = 1'sb1; + PassThrough pt2(tmp2, o2); + + // signed constant + PassThrough pt3(1'sb1, o3); + + // signed wire + wire signed tmp4; + assign tmp4 = 1'sb1; + PassThrough pt4(tmp4, o4); + + // signed expressions + wire signed [1:0] tmp5a = 2'b11; + wire signed [1:0] tmp5b = 2'b01; + PassThrough pt5(tmp5a ^ tmp5b, o5); + + output wire [2:0] yay1, nay1; + GeneratorSigned1 os1(yay1); + GeneratorUnsigned1 ou1(nay1); + + output wire [2:0] yay2, nay2; + GeneratorSigned2 os2(yay2); + GeneratorUnsigned2 ou2(nay2); +endmodule + +module ref(o1, o2, o3, o4, o5, yay1, nay1, yay2, nay2); + output wire [3:0] o1, o2, o3, o4, o5; + + assign o1 = 4'b0001; + assign o2 = 4'b0001; + assign o3 = 4'b1111; + assign o4 = 4'b1111; + assign o5 = 4'b1110; + + output wire [2:0] yay1, nay1; + assign yay1 = 3'b111; + assign nay1 = 3'b001; + + output wire [2:0] yay2, nay2; + assign yay2 = 3'b110; + assign nay2 = 3'b010; +endmodule diff --git a/tests/various/port_sign_extend.ys b/tests/various/port_sign_extend.ys new file mode 100644 index 000000000..0a6a93810 --- /dev/null +++ b/tests/various/port_sign_extend.ys @@ -0,0 +1,22 @@ +read_verilog port_sign_extend.v +hierarchy +flatten +equiv_make ref act equiv +equiv_simple +equiv_status -assert + +delete + +read_verilog port_sign_extend.v +flatten +equiv_make ref act equiv +equiv_simple +equiv_status -assert + +delete + +read_verilog port_sign_extend.v +hierarchy +equiv_make ref act equiv +prep -flatten -top equiv +equiv_status -assert