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Improved width extension with regard to undef propagation

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This commit is contained in:
Clifford Wolf 2013-11-06 20:50:53 +01:00
parent f839b842a2
commit 6fcbc79b5c
4 changed files with 171 additions and 87 deletions
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69
frontends/ast/genrtlil.cc
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@ -83,6 +83,56 @@ static RTLIL::SigSpec uniop2rtlil(AstNode *that, std::string type, int result_wi
return sig;
}
// helper function for extending bit width (preferred over SigSpec::extend() because of correct undef propagation in ConstEval)
static void widthExtend(AstNode *that, RTLIL::SigSpec &sig, int width, bool is_signed)
{
if (width <= sig.width) {
sig.extend(width, is_signed);
return;
}
std::stringstream sstr;
sstr << "$extend" << "$" << that->filename << ":" << that->linenum << "$" << (RTLIL::autoidx++);
RTLIL::Cell *cell = new RTLIL::Cell;
cell->attributes["\\src"] = stringf("%s:%d", that->filename.c_str(), that->linenum);
cell->name = sstr.str();
cell->type = "$pos";
current_module->cells[cell->name] = cell;
RTLIL::Wire *wire = new RTLIL::Wire;
wire->attributes["\\src"] = stringf("%s:%d", that->filename.c_str(), that->linenum);
wire->name = cell->name + "_Y";
wire->width = width;
current_module->wires[wire->name] = wire;
RTLIL::SigChunk chunk;
chunk.wire = wire;
chunk.width = wire->width;
chunk.offset = 0;
RTLIL::SigSpec new_sig;
new_sig.chunks.push_back(chunk);
new_sig.width = chunk.width;
if (that != NULL)
for (auto &attr : that->attributes) {
if (attr.second->type != AST_CONSTANT)
log_error("Attribute `%s' with non-constant value at %s:%d!\n",
attr.first.c_str(), that->filename.c_str(), that->linenum);
cell->attributes[attr.first].str = attr.second->str;
cell->attributes[attr.first].bits = attr.second->bits;
}
cell->parameters["\\A_SIGNED"] = RTLIL::Const(is_signed);
cell->parameters["\\A_WIDTH"] = RTLIL::Const(sig.width);
cell->connections["\\A"] = sig;
cell->parameters["\\Y_WIDTH"] = width;
cell->connections["\\Y"] = new_sig;
sig = new_sig;
}
// helper function for creating RTLIL code for binary operations
static RTLIL::SigSpec binop2rtlil(AstNode *that, std::string type, int result_width, const RTLIL::SigSpec &left, const RTLIL::SigSpec &right)
{
@ -943,7 +993,7 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
int width = arg.width;
if (width_hint > 0) {
width = width_hint;
arg.extend(width, is_signed);
widthExtend(this, arg, width, is_signed);
}
return uniop2rtlil(this, type_name, width, arg);
}
@ -972,7 +1022,7 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
if (0) { case AST_REDUCE_XNOR: type_name = "$reduce_xnor"; }
{
RTLIL::SigSpec arg = children[0]->genRTLIL();
RTLIL::SigSpec sig = uniop2rtlil(this, type_name, 1, arg);
RTLIL::SigSpec sig = uniop2rtlil(this, type_name, std::max(width_hint, 1), arg);
return sig;
}
@ -981,7 +1031,7 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
if (0) { case AST_REDUCE_BOOL: type_name = "$reduce_bool"; }
{
RTLIL::SigSpec arg = children[0]->genRTLIL();
RTLIL::SigSpec sig = arg.width > 1 ? uniop2rtlil(this, type_name, 1, arg) : arg;
RTLIL::SigSpec sig = arg.width > 1 ? uniop2rtlil(this, type_name, std::max(width_hint, 1), arg) : arg;
return sig;
}
@ -1008,12 +1058,13 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
if (0) { case AST_GE: type_name = "$ge"; }
if (0) { case AST_GT: type_name = "$gt"; }
{
int width = std::max(width_hint, 1);
width_hint = -1, sign_hint = true;
children[0]->detectSignWidthWorker(width_hint, sign_hint);
children[1]->detectSignWidthWorker(width_hint, sign_hint);
RTLIL::SigSpec left = children[0]->genRTLIL(width_hint, sign_hint);
RTLIL::SigSpec right = children[1]->genRTLIL(width_hint, sign_hint);
RTLIL::SigSpec sig = binop2rtlil(this, type_name, 1, left, right);
RTLIL::SigSpec sig = binop2rtlil(this, type_name, width, left, right);
return sig;
}
@ -1054,14 +1105,14 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
{
RTLIL::SigSpec left = children[0]->genRTLIL();
RTLIL::SigSpec right = children[1]->genRTLIL();
return binop2rtlil(this, type_name, 1, left, right);
return binop2rtlil(this, type_name, std::max(width_hint, 1), left, right);
}
// generate cells for unary operations: $logic_not
case AST_LOGIC_NOT:
{
RTLIL::SigSpec arg = children[0]->genRTLIL();
return uniop2rtlil(this, "$logic_not", 1, arg);
return uniop2rtlil(this, "$logic_not", std::max(width_hint, 1), arg);
}
// generate multiplexer for ternary operator (aka ?:-operator)
@ -1079,8 +1130,8 @@ RTLIL::SigSpec AstNode::genRTLIL(int width_hint, bool sign_hint)
int width = std::max(val1.width, val2.width);
is_signed = children[1]->is_signed && children[2]->is_signed;
val1.extend(width, is_signed);
val2.extend(width, is_signed);
widthExtend(this, val1, width, is_signed);
widthExtend(this, val2, width, is_signed);
return mux2rtlil(this, cond, val1, val2);
}
@ -1271,7 +1322,7 @@ RTLIL::SigSpec AstNode::genWidthRTLIL(int width, RTLIL::SigSpec *subst_from, RT
genRTLIL_subst_to = backup_subst_to;
if (width >= 0)
sig.extend(width, is_signed);
widthExtend(this, sig, width, is_signed);
return sig;
}