codegen.cpp

// Copyright Contributors to the Open Shading Language project.
// SPDX-License-Identifier: BSD-3-Clause
// https://github.com/AcademySoftwareFoundation/OpenShadingLanguage

#include <iostream>
#include <string>
#include <vector>

#include "oslcomp_pvt.h"

#include <OpenImageIO/strutil.h>
namespace Strutil = OIIO::Strutil;


OSL_NAMESPACE_BEGIN
namespace pvt {  // OSL::pvt



size_t
OSLCompilerImpl::add_op_args(size_t nargs, Symbol** args)
{
    size_t n = m_opargs.size();
    for (size_t i = 0; i < nargs; ++i) {
        OSL_DASSERT(args[i]);
        m_opargs.push_back(args[i]->dealias());
    }
    return n;
}



void
OSLCompilerImpl::codegen_method(ustring method)
{
    m_codegenmethod = method;
    if (method == main_method_name())
        m_main_method_start = next_op_label();
}



ustring
OSLCompilerImpl::main_method_name()
{
    static ustring name("___main___");
    return name;
}



int
OSLCompilerImpl::emitcode(const char* opname, size_t nargs, Symbol** args,
                          ASTNode* node)
{
    // Reduce to a call to insert_code at the end of the ops
    return insert_code((int)m_ircode.size(), opname, nargs, args, node);
}



int
OSLCompilerImpl::insert_code(int opnum, const char* opname, size_t nargs,
                             Symbol** args, ASTNode* node)
{
    Opcode op(ustring(opname), m_codegenmethod, m_opargs.size(), nargs);
    if (node)
        op.source(node->sourcefile(), node->sourceline());
    m_ircode.insert(m_ircode.begin() + opnum, op);
    add_op_args(nargs, args);

    // Unless we were inserting at the end, we may need to adjust
    // the jump addresses of other ops and the param init ranges.
    if (opnum < (int)m_ircode.size() - 1) {
        // Adjust jump offsets
        for (auto& c : m_ircode) {
            for (int j = 0; j < (int)Opcode::max_jumps && c.jump(j) >= 0; ++j) {
                if (c.jump(j) > opnum) {
                    c.jump(j) = c.jump(j) + 1;
                    // std::cerr << "Adjusting jump target at op " << n << "\n";
                }
            }
        }
        // Adjust param init ranges
        for (auto&& s : symtab()) {
            if (s->symtype() == SymTypeParam
                || s->symtype() == SymTypeOutputParam) {
                if (s->initbegin() > opnum)
                    s->initbegin(s->initbegin() + 1);
                if (s->initend() > opnum)
                    s->initend(s->initend() + 1);
            }
        }
    }

    return opnum;
}



Symbol*
OSLCompilerImpl::make_temporary(const TypeSpec& type)
{
    ustring name = ustring::fmtformat("$tmp{}", ++m_next_temp);
    Symbol* s    = new Symbol(name, type, SymTypeTemp);
    symtab().insert(s);

    // A struct really makes several subvariables
    if (type.is_structure() || type.is_structure_array()) {
        // Add the fields as individual declarations
        add_struct_fields(type.structspec(), name, SymTypeTemp,
                          type.arraylength());
    }

    return s;
}



void
OSLCompilerImpl::add_struct_fields(StructSpec* structspec, ustring basename,
                                   SymType symtype, int arraylen, ASTNode* node,
                                   ASTNode* init)
{
    if (init) {
        if (init->nodetype() == ASTNode::variable_ref_node)
            init = NULL;  // So we don't register whole-struct assignment
        else if (init->nodetype() == ASTNode::compound_initializer_node)
            init = ((ASTcompound_initializer*)init)->initlist().get();
    }
    // arraylen is the length of the array of the surrounding data type
    for (int i = 0; i < (int)structspec->numfields(); ++i) {
        const StructSpec::FieldSpec& field(structspec->field(i));
        ustring fieldname = ustring::fmtformat("{}.{}", basename, field.name);
        TypeSpec type     = field.type;
        int arr           = type.arraylength();
        if (arr && arraylen) {
            errorfmt(
                node ? node->sourcefile() : ustring(),
                node ? node->sourceline() : 1,
                "Nested structs with >1 levels of arrays are not allowed: {}",
                structspec->name());
        }
        if (arraylen || arr) {
            // Translate an outer array into an inner array
            arr = std::max(1, arraylen) * std::max(1, arr);
            type.make_array(arr);
        }
        Symbol* sym = new Symbol(fieldname, type, symtype, node);
        sym->fieldid(i);
        symtab().insert(sym);
        if (field.type.is_structure() || field.type.is_structure_array()) {
            // nested structures -- recurse!
            add_struct_fields(type.structspec(), fieldname, symtype, arr, node,
                              arr ? NULL : init);
        } else {
            if (node && init && !arr) {
                // Remember the pairing of this field and the initial expr.
                ((ASTvariable_declaration*)node)
                    ->register_struct_init(fieldname, init);
            }
        }
        if (init)
            init = init->nextptr();
    }
}



Symbol*
OSLCompilerImpl::make_constant(ustring val)
{
    for (auto&& sym : m_const_syms) {
        if (sym->typespec().is_string() && sym->get_string() == val)
            return sym;
    }
    // It's not a constant we've added before
    ustring name      = ustring::fmtformat("$const{}", ++m_next_const);
    ConstantSymbol* s = new ConstantSymbol(name, val);
    symtab().insert(s);
    m_const_syms.push_back(s);
    return s;
}



Symbol*
OSLCompilerImpl::make_constant(TypeDesc type, const void* val)
{
    size_t typesize = type.size();
    for (auto&& sym : m_const_syms) {
        if (sym->typespec().simpletype() == type
            && !memcmp(val, sym->dataptr(), typesize))
            return sym;
    }
    // It's not a constant we've added before
    ustring name      = ustring::fmtformat("$const{}", ++m_next_const);
    ConstantSymbol* s = new ConstantSymbol(name, type);
    memcpy(s->dataptr(), val, typesize);
    symtab().insert(s);
    m_const_syms.push_back(s);
    return s;
}



Symbol*
OSLCompilerImpl::make_constant(int val)
{
    for (auto&& sym : m_const_syms) {
        if (sym->typespec().is_int() && sym->get_int() == val)
            return sym;
    }
    // It's not a constant we've added before
    ustring name      = ustring::fmtformat("$const{}", ++m_next_const);
    ConstantSymbol* s = new ConstantSymbol(name, val);
    symtab().insert(s);
    m_const_syms.push_back(s);
    return s;
}



Symbol*
OSLCompilerImpl::make_constant(float val)
{
    for (auto&& sym : m_const_syms) {
        if (sym->typespec().is_float() && sym->floatval() == val)
            return sym;
    }
    // It's not a constant we've added before
    ustring name      = ustring::fmtformat("$const{}", ++m_next_const);
    ConstantSymbol* s = new ConstantSymbol(name, val);
    symtab().insert(s);
    m_const_syms.push_back(s);
    return s;
}



Symbol*
OSLCompilerImpl::make_constant(TypeDesc type, float x, float y, float z)
{
    Vec3 val(x, y, z);
    for (auto&& sym : m_const_syms) {
        if (sym->typespec().simpletype() == type && sym->get_vec3() == val)
            return sym;
    }
    // It's not a constant we've added before
    ustring name      = ustring::fmtformat("$const{}", ++m_next_const);
    ConstantSymbol* s = new ConstantSymbol(name, type, x, y, z);
    symtab().insert(s);
    m_const_syms.push_back(s);
    return s;
}



int
ASTNode::emitcode(const char* opname, Symbol* arg0, Symbol* arg1, Symbol* arg2,
                  Symbol* arg3)
{
    Symbol* args[4] = { arg0, arg1, arg2, arg3 };
    size_t nargs    = (arg0 != NULL) + (arg1 != NULL) + (arg2 != NULL)
                   + (arg3 != NULL);
    return m_compiler->emitcode(opname, nargs, args, this);
}



int
ASTNode::emitcode(const char* opname, size_t nargs, Symbol** args)
{
    return m_compiler->emitcode(opname, nargs, args, this);
}



Symbol*
ASTNode::coerce(Symbol* sym, const TypeSpec& type, bool acceptfloat)
{
    if (equivalent(sym->typespec(), type))
        return sym;  // No coercion necessary

    if (type.is_closure())
        return sym;  // No coercion necessary

    if (acceptfloat && sym->typespec().is_float())
        return sym;

    if (type.is_unsized_array() && sym->typespec().is_array()
        && equivalent(sym->typespec().elementtype(), type.elementtype())) {
        // coercion not necessary to pass known length array to
        // array parameter of unspecified length.
        return sym;
    }

    if (sym->symtype() == SymTypeConst && sym->typespec().is_int()
        && type.is_float_based() && !type.is_array()) {
        // It's not only the wrong type, it's a constant of the wrong
        // type. We need a new constant of the right type.
        ConstantSymbol* constsym = (ConstantSymbol*)sym;
        sym = m_compiler->make_constant(constsym->floatval());
        if (type.is_float() || acceptfloat)
            return sym;
    }

    Symbol* t = m_compiler->make_temporary(type);
    emitcode("assign", t, sym);
    return t;
}



Symbol*
ASTNode::codegen(Symbol* /*dest*/)
{
    OSL_ASSERT_MSG(0, "Unimplemented codegen for %s (%s)", nodetypename(),
                   opname() ? opname() : "");
    return nullptr;
}



void
ASTNode::codegen_children()
{
    for (auto&& c : m_children) {
        codegen_list(c);
    }
}



Symbol*
ASTNode::codegen_list(ref node, Symbol* dest)
{
    Symbol* sym = NULL;
    while (node) {
        bool last = (node->nextptr() == NULL);
        sym       = node->codegen(last ? dest : NULL);
        node      = node->next();
    }
    return sym;
}



Symbol*
ASTNode::codegen_int(Symbol*, bool boolify, bool invert)
{
    Symbol* dest  = codegen();
    TypeSpec type = dest->typespec();
    if (!type.is_int() || boolify || invert) {
        // If they're not using an int as the condition, then it's an
        // implied comparison to zero.
        Symbol* tempvar = m_compiler->make_temporary(TypeInt);
        Symbol* zerovar = NULL;
        if (type.is_closure())
            zerovar = m_compiler->make_constant((int)0);
        else if (type.is_string())
            zerovar = m_compiler->make_constant(ustring(""));
        else if (type.is_int())
            zerovar = m_compiler->make_constant((int)0);
        else
            zerovar = m_compiler->make_constant(0.0f);
        emitcode(invert ? "eq" : "neq", tempvar, dest, zerovar);
        dest = tempvar;
    }
    return dest;
}



Symbol*
ASTshader_declaration::codegen(Symbol*)
{
    for (ref f = formals(); f; f = f->next()) {
        OSL_DASSERT(f->nodetype() == ASTNode::variable_declaration_node);
        ASTvariable_declaration* v = (ASTvariable_declaration*)f.get();
        OSL_DASSERT(v->init());  // Shader formals MUST have initializers
        // If the initializer is a literal and we output it as a
        // constant in the symbol definition, no need for ops.
        std::string out;
        if (!v->param_default_literals(v->sym(), v->init().get(), out))
            v->codegen();
    }

    m_compiler->codegen_method(m_compiler->main_method_name());
    codegen_list(statements());
    return NULL;
}



Symbol*
ASTreturn_statement::codegen(Symbol* dest)
{
    FunctionSymbol* myfunc = m_compiler->current_function();
    if (myfunc) {
        // If it's a user function (as opposed to a main shader body)...
        if (expr()) {
            // If we are returning a value, generate code for the value,
            // try to put it in the designated function return location,
            // but if that's not possible, let it go wherever and then
            // copy it.
            OSL_DASSERT(myfunc->return_location() != NULL);
            Symbol* retloc = myfunc->return_location();
            dest           = expr()->codegen(retloc);
            if (dest != retloc) {
                if (retloc->typespec().is_structure()) {
                    StructSpec* structspec = retloc->typespec().structspec();
                    OSL_DASSERT(dest && structspec);
                    codegen_assign_struct(structspec,
                                          ustring(retloc->mangled()),
                                          ustring(dest->mangled()), NULL, true,
                                          0, false /*not a shader param init*/);
                } else {
                    // Simple type
                    emitcode("assign", myfunc->return_location(), dest);
                }
            }
        }
        // Unless this was the unconditional last statement of the
        // function, emit a "return" op.
        if (this->nextptr() != NULL || myfunc->nesting_level() > 0)
            emitcode("return");
    } else {
        // Must be return from the main shader body -- exit from the shader
        emitcode("exit");
    }
    return NULL;
}



Symbol*
ASTcompound_initializer::codegen(Symbol* sym)
{
    if (canconstruct())
        return ASTtype_constructor::codegen(sym);

    if (m_typespec.is_structure_based()) {
        if (!sym)
            sym = m_compiler->make_temporary(m_typespec);
        return codegen_struct_initializers(initlist(), sym,
                                           true /*is_constructor*/);
    }

    if (m_typespec.is_sized_array()) {
        if (!sym)
            sym = m_compiler->make_temporary(m_typespec);
        codegen_initlist(initlist(), m_typespec, sym);
        return sym;
    }

    errorfmt("Possible compiler bug: compound_initializer codegen does not "
             "know how to handle type {}",
             typespec());
    return nullptr;
}



Symbol*
ASTassign_expression::codegen(Symbol* dest)
{
    ASTindex* index = NULL;
    Symbol *ind = NULL, *ind2 = NULL, *ind3 = NULL;

    if (var()->nodetype() == index_node) {
        // Assigning to an individual component or array element
        index = (ASTindex*)var().get();
        dest  = NULL;
    } else if (var()->nodetype() == structselect_node) {
        if (!((ASTstructselect*)var().get())->compindex())
            dest = var()->codegen();
        // ^^ N.B. don't do the extra codegen of the destination if this
        // is the kind of structselect that is really an assignment to a
        // named component (P.x = ...).
    } else {
        dest = var()->codegen();
    }

    // For compound assignments (+=, *=, etc.), read the current LHS value,
    // apply the binary op, and use the result as the operand for plain assign.
    // Index expressions are evaluated once and reused for the write because they
    // are the only ones at the moment that could have side effects.
    Symbol* operand;
    if (m_op != Assign) {
        Symbol* lhs_read;
        if (index) {
            lhs_read = index->codegen(NULL, ind, ind2, ind3);
        } else {
            lhs_read = var()->codegen();
        }
        Symbol* rhs = expr()->codegen();
        operand     = m_compiler->make_temporary(typespec());
        emitcode(opword(), operand, lhs_read, rhs);
    } else {
        operand = expr()->codegen(dest);
    }
    OSL_DASSERT(operand != NULL);

    if (typespec().is_structure_array()) {
        // Assign entire array-of-struct to another array-of-struct
        if (operand != dest) {
            StructSpec* structspec = typespec().structspec();
            codegen_assign_struct(structspec, ustring(dest->mangled()),
                                  ustring(operand->mangled()), NULL, true, 0,
                                  false /*not a shader param init*/);
        }
        return dest;
    }

    if (typespec().is_structure()) {
        // Assignment of struct copies each element individually
        if (operand != dest) {
            StructSpec* structspec = typespec().structspec();
            Symbol* arrayindex = index ? (ind ? ind : index->index()->codegen())
                                       : NULL;
            if (arrayindex) {
                // Special case -- assignment to a element of an array of
                // structs.  Beware the temp that may have been created above,
                // instead refer back to the original.
                Symbol* v = index->lvalue()->codegen();
                codegen_assign_struct(structspec, ustring(v->mangled()),
                                      ustring(operand->mangled()), arrayindex,
                                      false, -1 /* means we don't know */,
                                      false /*not a shader param init*/);
            } else {
                // Assignment of one scalar struct to another scalar struct
                OSL_DASSERT(dest);
                codegen_assign_struct(structspec, ustring(dest->mangled()),
                                      ustring(operand->mangled()), NULL, true,
                                      0, false /*not a shader param init*/);
            }
        }
        return dest;
    }

    if (var()->nodetype() == structselect_node) {
        ASTstructselect* ss = (ASTstructselect*)var().get();
        ss->codegen_assign(dest, operand);
        return dest;
    }

    if (index) {
        index->codegen_assign(operand, ind, ind2, ind3);
        dest = operand;  // so transitive assignment works for array refs
    } else if (operand != dest) {
        emitcode(typespec().is_array() ? "arraycopy" : "assign", dest, operand);
    }
    return dest;
}



void
ASTNode::codegen_assign_struct(StructSpec* structspec, ustring dstsym,
                               ustring srcsym, Symbol* arrayindex,
                               bool copywholearrays, int intindex,
                               bool paraminit)
{
    for (int i = 0; i < (int)structspec->numfields(); ++i) {
        const TypeSpec& fieldtype(structspec->field(i).type);
        if (fieldtype.is_structure()) {
            // struct within struct -- recurse
            ustring fieldname(structspec->field(i).name);
            codegen_assign_struct(fieldtype.structspec(),
                                  ustring::fmtformat("{}.{}", dstsym, fieldname),
                                  ustring::fmtformat("{}.{}", srcsym, fieldname),
                                  arrayindex, copywholearrays, 0, paraminit);
            continue;
        }

        if (fieldtype.is_structure_array() && !arrayindex) {
            // struct array within struct -- loop over indices and recurse
            OSL_ASSERT(!arrayindex && "two levels of arrays not allowed");
            ustring fieldname(structspec->field(i).name);
            ustring dstfield = ustring::fmtformat("{}.{}", dstsym, fieldname);
            ustring srcfield = ustring::fmtformat("{}.{}", srcsym, fieldname);
            for (int i = 0; i < fieldtype.arraylength(); ++i) {
                codegen_assign_struct(fieldtype.structspec(), dstfield,
                                      srcfield, m_compiler->make_constant(i),
                                      copywholearrays, i, paraminit);
            }
            continue;
        }

        Symbol *dfield, *ofield;
        m_compiler->struct_field_pair(structspec, i, dstsym, srcsym, dfield,
                                      ofield);
        if (paraminit) {
            m_compiler->codegen_method(ustring(dfield->mangled()));
            dfield->initbegin(m_compiler->next_op_label());
        }
        if (arrayindex) {
            // field is a scalar, but we're assigning to one element of
            // an array of structs.
            if (ofield->typespec().is_array()) {
                // Both are arrays
                TypeSpec elemtype = dfield->typespec().elementtype();
                if (copywholearrays && intindex >= 0) {
                    // Copying whole arrays -- instead of element by
                    // element, do an arraycopy when we're on element 0,
                    // and "skip" the other elements.
                    if (intindex == 0)
                        emitcode("arraycopy", dfield, ofield);
                } else {
                    // Copying a partial array
                    Symbol* tmp = m_compiler->make_temporary(elemtype);
                    emitcode("aref", tmp, ofield, arrayindex);
                    emitcode("aassign", dfield, arrayindex, tmp);
                }
            } else {
                // Only the destination is an array
                emitcode("aassign", dfield, arrayindex, ofield);
            }
        } else if (dfield->typespec().is_array()) {
            // field is an array
            emitcode("arraycopy", dfield, ofield);
        } else {
            // field is a scalar, struct is a scalar
            emitcode("assign", dfield, ofield);
        }
        if (paraminit)
            dfield->initend(m_compiler->next_op_label());
    }
}



bool
ASTNode::one_default_literal(const Symbol* sym, ASTNode* init, std::string& out,
                             string_view sep) const
{
    // FIXME -- this only works for single values or arrays made of
    // literals.  Needs to be seriously beefed up.
    bool islit      = init && init->nodetype() == ASTNode::literal_node;
    ASTliteral* lit = static_cast<ASTliteral*>(init);
    bool completed  = true;  // have we output the full initialization?
    TypeSpec type   = sym->typespec().elementtype();
    if (type.is_closure()) {
        // this clause avoid trouble and assertions if the following
        // is_int(), i_float(), etc, encounter a closure.
        completed = islit;
    } else if (type.is_structure()) {
        // No initializers for struct
        completed = false;
    } else if (type.is_int()) {
        if (islit && lit->typespec().is_int())
            out += fmtformat("{}", lit->intval());
        else {
            out += "0";  // FIXME?
            completed = false;
        }
    } else if (type.is_float()) {
        if (islit && lit->typespec().is_int())
            out += fmtformat("{}", lit->intval());
        else if (islit && lit->typespec().is_float())
            out += fmtformat("{:.9g}", lit->floatval());
        else {
            out += "0";  // FIXME?
            completed = false;
        }
    } else if (type.is_triple()) {
        if (islit && lit->typespec().is_int()) {
            float f = lit->intval();
            out += fmtformat("{:.9g}{}{:.9g}{}{:.9g}", f, sep, f, sep, f);
        } else if (islit && lit->typespec().is_float()) {
            float f = lit->floatval();
            out += fmtformat("{:.9g}{}{:.9g}{}{:.9g}", f, sep, f, sep, f);
        } else if (init && init->typespec() == type
                   && (init->nodetype() == ASTNode::type_constructor_node
                       || (init->nodetype() == ASTNode::compound_initializer_node
                           && static_cast<ASTcompound_initializer*>(init)
                                  ->canconstruct()))) {
            ASTtype_constructor* ctr = (ASTtype_constructor*)init;
            ASTNode::ref val         = ctr->args();
            float f[3];
            int nargs = 0;
            if (val.get() && val->nodetype() == ASTNode::literal_node
                && val->typespec().is_string()) {  // "space" name case
                val       = val->next();
                completed = false;
            }
            bool one_arg = (val && !val->nextptr());
            for (int c = 0; c < 3; ++c) {
                if (val.get())
                    ++nargs;
                if (val.get() && val->nodetype() == ASTNode::literal_node) {
                    f[c] = ((ASTliteral*)val.get())->floatval();
                    val  = val->next();
                } else if (c > 0 && one_arg) {
                    f[c] = f[0];
                } else {
                    f[c]      = 0;
                    completed = false;
                }
            }
            if (nargs == 1)
                out += fmtformat("{:.9g}{}{:.9g}{}{:.9g}", f[0], sep, f[0], sep,
                                 f[0]);
            else
                out += fmtformat("{:.9g}{}{:.9g}{}{:.9g}", f[0], sep, f[1], sep,
                                 f[2]);
        } else {
            out += fmtformat("0{}0{}0", sep, sep);
            completed = false;
        }
    } else if (type.is_matrix()) {
        if (islit && lit->typespec().is_int()) {
            float f = lit->intval();
            for (int c = 0; c < 16; ++c)
                out += fmtformat("{:.9g}{}", (c / 4) == (c % 4) ? f : 0.0f,
                                 c < 15 ? sep : "");
        } else if (islit && lit->typespec().is_float()) {
            float f = lit->floatval();
            for (int c = 0; c < 16; ++c)
                out += fmtformat("{:.9g}{}", (c / 4) == (c % 4) ? f : 0.0f,
                                 c < 15 ? sep : "");
        } else if (init && init->typespec() == type
                   && init->nodetype() == ASTNode::type_constructor_node) {
            ASTtype_constructor* ctr = (ASTtype_constructor*)init;
            ASTNode::ref val         = ctr->args();
            float f[16];
            int nargs = 0;
            OSL_DASSERT(val.get());
            if (val->nodetype() == ASTNode::literal_node
                && val->typespec().is_string()) {
                val       = val->next();
                completed = false;
            }
            for (int c = 0; c < 16; ++c) {
                if (val.get())
                    ++nargs;
                if (val.get() && val->nodetype() == ASTNode::literal_node) {
                    f[c] = ((ASTliteral*)val.get())->floatval();
                    val  = val->next();
                    if (!val.get())  // we're done -- no more args
                        break;
                } else {
                    f[c]      = 0;
                    completed = false;
                }
            }
            if (nargs == 1) {
                for (int c = 0; c < 16; ++c)
                    out += fmtformat("{:.9g}{}",
                                     (c / 4) == (c % 4) ? f[0] : 0.0f,
                                     c < 15 ? sep : "");
            } else {
                for (int c = 0; c < 16; ++c)
                    out += fmtformat("{:.9g}{}", f[c], c < 15 ? sep : "");
            }
        } else {
            for (int c = 0; c < 16; ++c)
                out += fmtformat("0{}", c < 15 ? sep : "");
            completed = false;
        }
    } else if (type.is_string()) {
        if (islit && lit->typespec().is_string())
            out += fmtformat("\"{}\"", Strutil::escape_chars(lit->strval()));
        else {
            out += "\"\"";  // FIXME?
            completed = false;
        }
    } else {
        OSL_ASSERT(0 && "help with initializer");
    }
    return completed;
}



bool
ASTvariable_declaration::param_default_literals(const Symbol* sym,
                                                ASTNode* init, std::string& out,
                                                string_view separator) const
{
    out.clear();

    if (sym->typespec().is_structure()
        || sym->typespec().is_structure_array()) {
        // Structures are just placeholders, they don't get initialized.
        // The defaults will get associated with their individual member
        // fields.
        return false;
    }

    if (sym->fieldid() >= 0) {
        // A structure field has already had its individual init stashed in
        // the node that defined its parameter (i.e., *this). Look in that
        // list for the initializer for this specific field.
        init = NULL;
        for (auto&& n : m_struct_field_inits) {
            if (n.first == sym->name()) {
                init = n.second;
                break;
            }
        }
    }

    bool compound = (init && init->nodetype() == compound_initializer_node);
    if (compound) {
        compound = !static_cast<ASTcompound_initializer*>(init)->canconstruct();
        if (compound)
            init = ((ASTcompound_initializer*)init)->initlist().get();
    }

    bool completed = true;  // have we output the full initialization?
    for (int i = 0; i == 0 || init; ++i, init = init->nextptr()) {
        if (i)
            out += separator;
        completed &= one_default_literal(sym, init, out, separator);
        if (!compound || !init)
            break;
    }
    return completed;
}



Symbol*
ASTvariable_declaration::codegen(Symbol* /*dst*/)
{
    if (init())
        codegen_initializer(init(), m_sym);
    return m_sym;
}



void
ASTvariable_declaration::codegen_initializer(ref init, Symbol* sym)
{
    // Cases: simple, struct (go field by field), array (go element by element)
    if (typespec().is_structure()) {
        codegen_struct_initializers(init, sym);
    } else if (typespec().is_array()) {
        OSL_DASSERT(init->nodetype() == compound_initializer_node);
        init = ((ASTcompound_initializer*)init.get())->initlist();
        codegen_initlist(init, typespec(), sym);
    } else {
        if (init->nodetype() == compound_initializer_node) {
            ASTcompound_initializer* cinit
                = static_cast<ASTcompound_initializer*>(init.get());
            init = cinit->initlist();
            if (cinit->canconstruct()) {
                bool paraminit
                    = (m_compiler->codegen_method()
                           != m_compiler->main_method_name()
                       && (m_sym->symtype() == SymTypeParam
                           || m_sym->symtype() == SymTypeOutputParam));
                if (paraminit) {
                    // For parameter initialization, don't really generate ops if it
                    // can be statically initialized.
                    m_compiler->codegen_method(sym->name());
                    sym->initbegin(m_compiler->next_op_label());
                }

                Symbol* dest = cinit->codegen(sym);
                if (dest != sym)
                    emitcode("assign", sym, dest);

                if (paraminit)
                    sym->initend(m_compiler->next_op_label());
                return;
            }
        }
        codegen_initlist(init, m_typespec, m_sym);
    }
}


Symbol*
ASTNode::codegen_aassign(TypeSpec elemtype, Symbol* src, Symbol* lval,
                         Symbol* ind, int i)
{
    const TypeSpec& srctype = src->typespec();
    if (!equivalent(elemtype, srctype)) {
        // Allow floatarray[ind] = int or intarray[ind] = float, but otherwise
        // A[ind] = x is only allowed if the type of x is equivalent to that of
        // A's elements.
        // You can't for example, do colorarray[ind] = int.
        if (elemtype.is_closure() || !elemtype.is_scalarnum()
            || srctype.is_closure() || !srctype.is_scalarnum()) {
            //  Convert through a temp.
            Symbol* tmp = m_compiler->make_temporary(elemtype);
            emitcode("assign", tmp, src);
            src = tmp;
        }
    }

    if (!ind)
        ind = m_compiler->make_constant(i);

    emitcode("aassign", lval, ind, src);

    return src;
}


void
ASTNode::codegen_initlist(ref init, TypeSpec type, Symbol* sym)
{
    // If we're doing this initialization for shader params for their
    // init ops, we need to take care to set the codegen method names
    // properly.
    bool paraminit = (m_compiler->codegen_method()
                          != m_compiler->main_method_name()
                      && (sym->symtype() == SymTypeParam
                          || sym->symtype() == SymTypeOutputParam));

    if (type.is_structure()) {
        // Special case -- structure : Recurse to handle each field
        // individually.
        StructSpec* structspec(type.structspec());
        for (int i = 0; init && i < structspec->numfields();
             init  = init->next(), ++i) {
            const StructSpec::FieldSpec& field(structspec->field(i));
            ustring fieldname = ustring::fmtformat("{}.{}", sym->mangled(),
                                                   field.name);
            Symbol* fieldsym  = m_compiler->symtab().find_exact(fieldname);
            if (paraminit) {
                OSL_DASSERT(nodetype() == variable_declaration_node);
                ASTvariable_declaration* v = (ASTvariable_declaration*)this;
                std::string out;
                if (v->param_default_literals(fieldsym, init.get(), out))
                    continue;  // Skip if we had a static initializer
            }
            codegen_initlist(init, fieldsym->typespec(), fieldsym);
        }
        return;
    }

    if (paraminit) {
        // Warn early about struct array parameters.
        // Handling this will likely need changes to oso format.
        if (type.is_structure_array()) {
            errorfmt("array of struct are not allowed as parameters");
            return;
        }
        // For parameter initialization, don't really generate ops if it
        // can be statically initialized.
        m_compiler->codegen_method(sym->name());
        sym->initbegin(m_compiler->next_op_label());
    }

    // Special case for arrays initialized by only constants of the
    // right type.
    OSL_DASSERT(sym->typespec() == type);
    if (type.is_array() && !type.is_closure_based()
        && !type.is_structure_array()) {
        TypeDesc elemtype = type.simpletype().elementtype();
        bool all_const    = true;
        int length        = 0;
        for (ref i = init; i; i = i->next(), ++length) {
            // It's not a constant if the initializer isn't a literal
            if (i->nodetype() != ASTNode::literal_node) {
                all_const = false;
                break;
            }
            // Also check that the initializer type is equivalent to the
            // element type of the array, but allow for float arrays with
            // int literal initializers.
            TypeDesc itype = i->typespec().simpletype();
            if (itype != elemtype
                && !(itype == TypeDesc::INT && elemtype == TypeDesc::FLOAT)) {
                all_const = false;
                break;
            }
        }
        if (all_const && init) {
            std::vector<char> arrayvals(type.simpletype().size());
            for (int i = 0; init; init = init->next(), ++i) {
                ASTliteral* lit = (ASTliteral*)init.get();
                if (elemtype == TypeDesc::INT)
                    ((int*)&arrayvals[0])[i] = lit->intval();
                else if (elemtype == TypeDesc::FLOAT)
                    ((float*)&arrayvals[0])[i] = lit->floatval();
                else if (elemtype == TypeDesc::STRING)
                    ((ustring*)&arrayvals[0])[i] = lit->ustrval();
                else {
                    OSL_DASSERT(0);
                }
            }
            Symbol* c = m_compiler->make_constant(type.simpletype(),
                                                  &arrayvals[0]);
            emitcode("assign", sym, c);
            // Tag end of init ops because of the early return
            if (paraminit)
                sym->initend(m_compiler->next_op_label());
            return;
        }
    } else if (type.is_structure_array()) {
        for (int i = 0; init && i < type.arraylength(); ++i) {
            ASTNode* expr = init.get();
            bool ctor     = false;
            Symbol* dest  = sym;
            switch (expr->nodetype()) {
            case function_call_node: {
                ASTfunction_call* fcall = static_cast<ASTfunction_call*>(expr);
                if ((ctor = fcall->is_struct_ctr())) {
                    expr = fcall->args().get();
                    OSL_DASSERT(expr != nullptr);
                }
            } break;
            case compound_initializer_node:
                ctor = static_cast<ASTcompound_initializer*>(expr)
                           ->canconstruct();
                break;
            default: break;
            }
            codegen_struct_initializers(expr, dest, ctor,
                                        m_compiler->make_constant(i));

            init = init->next();
        }
        if (paraminit)
            sym->initend(m_compiler->next_op_label());
        return;
    } else if (init->nodetype() == compound_initializer_node)
        init = ((ASTcompound_initializer*)init.get())->initlist();

    // Loop over a list of initializers (it's just 1 if not an array)...
    for (int i = 0; init; init = init->next(), ++i) {
        if (sym->typespec().is_structure()
            && init->nodetype() == compound_initializer_node) {
            // Nested structure
            ASTNode::ref finit
                = ((ASTcompound_initializer*)init.get())->initlist();
            codegen_struct_initializers(finit, sym);
            break;
        }

        Symbol* dest = init->codegen(sym);
        if (dest != sym) {
            if (sym->typespec().is_array()) {
                // Array variable -- assign to the i-th element
                dest = codegen_aassign(sym->typespec().elementtype(), dest, sym,
                                       nullptr, i);
            } else {
                // Non-array variable, just a simple assignment
                emitcode("assign", sym, dest);
            }
        }
        if (!sym->typespec().is_array())  // non-array type shouldn't loop
            break;                        //  even if init is a list
    }

    if (paraminit)
        sym->initend(m_compiler->next_op_label());
}



Symbol*
ASTNode::codegen_struct_initializers(ref init, Symbol* sym, bool is_constructor,
                                     Symbol* arrayindex)
{
    // If we're doing this initialization for shader params for their
    // init ops, we need to take care to set the codegen method names
    // properly.
    bool paraminit = (m_compiler->codegen_method()
                          != m_compiler->main_method_name()
                      && (sym->symtype() == SymTypeParam
                          || sym->symtype() == SymTypeOutputParam));

    OSL_ASSERT(sym->typespec().is_structure_based());
    if (init->nodetype() != compound_initializer_node && !is_constructor) {
        // Just one initializer, it's a whole struct of the right type.
        Symbol* initsym = init->codegen(sym);
        if (initsym != sym) {
            StructSpec* structspec(sym->typespec().structspec());
            codegen_assign_struct(structspec, ustring(sym->mangled()),
                                  ustring(initsym->mangled()), arrayindex, true,
                                  0, paraminit);
        }
        return sym;
    }

    // General case -- per-field initializers
    if (!is_constructor && init->nodetype() == compound_initializer_node) {
        init = ((ASTcompound_initializer*)init.get())->initlist();
    }
    StructSpec* structspec(sym->typespec().structspec());
    for (int i = 0; init && i < structspec->numfields();
         init  = init->next(), ++i) {
        // Structure element -- assign to the i-th member field
        const StructSpec::FieldSpec& field(structspec->field(i));
        ustring fieldname = ustring::fmtformat("{}.{}", sym->mangled(),
                                               field.name);
        Symbol* fieldsym  = m_compiler->symtab().find_exact(fieldname);
        if (fieldsym->typespec().is_structure_based()
            && (init->nodetype() == type_constructor_node
                || init->nodetype() == compound_initializer_node)) {
            bool ctor = init->nodetype() == type_constructor_node
                            ? true
                            : static_cast<ASTcompound_initializer*>(init.get())
                                  ->canconstruct();
            // The field is itself a nested struct, so recurse
            codegen_struct_initializers(init, fieldsym, ctor, arrayindex);
            continue;
        }

        if (paraminit && nodetype() == variable_declaration_node) {
            // For parameter initialization, don't really generate ops if it
            // can be statically initialized.
            std::string out;
            ASTvariable_declaration* v = (ASTvariable_declaration*)this;
            if (v->param_default_literals(fieldsym, init.get(), out))
                continue;
        }
        if (paraminit) {
            // Delineate and remember the init ops for this field individually
            m_compiler->codegen_method(fieldname);
            fieldsym->initbegin(m_compiler->next_op_label());
        }

        if (init->nodetype() == compound_initializer_node
            && !((ASTcompound_initializer*)init.get())->canconstruct()) {
            // Initialize the field with a compound initializer
            codegen_initlist(((ASTcompound_initializer*)init.get())->initlist(),
                             field.type, fieldsym);
        } else if (init->nodetype() == function_call_node
                   && static_cast<ASTfunction_call*>(init.get())
                          ->is_struct_ctr()) {
            codegen_struct_initializers(
                static_cast<ASTfunction_call*>(init.get())->args(), fieldsym,
                true, arrayindex);
        } else {
            // Initialize the field with a scalar initializer
            Symbol* dest = init->codegen(fieldsym);
            if (dest != fieldsym) {
                if (!arrayindex)
                    emitcode("assign", fieldsym, dest);
                else {
                    dest = codegen_aassign(fieldsym->typespec().elementtype(),
                                           dest, fieldsym, arrayindex);
                }
            }
        }

        if (paraminit)
            fieldsym->initend(m_compiler->next_op_label());
    }
    return sym;
}



Symbol*
ASTvariable_ref::codegen(Symbol*)
{
    return m_sym;
}



Symbol*
ASTpreincdec::codegen(Symbol*)
{
    Symbol* sym = var()->codegen();
    Symbol* one = sym->typespec().is_int() ? m_compiler->make_constant(1)
                                           : m_compiler->make_constant(1.0f);
    emitcode(m_op == Incr ? "add" : "sub", sym, sym, one);
    // FIXME -- what if it's an indexed lvalue, like v[i]?
    return sym;
}



Symbol*
ASTpostincdec::codegen(Symbol* dest)
{
    Symbol* sym = var()->codegen();
    Symbol* one = sym->typespec().is_int() ? m_compiler->make_constant(1)
                                           : m_compiler->make_constant(1.0f);
    if (!dest)
        dest = m_compiler->make_temporary(sym->typespec());
    emitcode("assign", dest, sym);
    emitcode(m_op == Incr ? "add" : "sub", sym, sym, one);
    // FIXME -- what if it's an indexed lvalue, like v[i]?
    return dest;
}



Symbol*
ASTindex::codegen(Symbol* dest)
{
    // All heavy lifting is done by the version that stores index symbols.
    Symbol *ind = NULL, *ind2 = NULL, *ind3 = NULL;
    return codegen(dest, ind, ind2, ind3);
}



Symbol*
ASTindex::codegen(Symbol* dest, Symbol*& ind, Symbol*& ind2, Symbol*& ind3)
{
    Symbol* lv = lvalue()->codegen();
    ind        = index()->codegen();
    ind2       = index2() ? index2()->codegen() : NULL;
    ind3       = index3() ? index3()->codegen() : NULL;
    // Make a destination if not given one, or if it's the wrong type
    if (!dest || !equivalent(dest->typespec(), typespec()))
        dest = m_compiler->make_temporary(typespec());
    if (lv->typespec().is_array()) {
        if (index3()) {
            // matrixarray[a][c][r]
            Symbol* tmp = m_compiler->make_temporary(
                lv->typespec().elementtype());
            emitcode("aref", tmp, lv, ind);
            emitcode("mxcompref", dest, tmp, ind2, ind3);
        } else if (index2()) {
            // colorarray[a][c]
            Symbol* tmp = m_compiler->make_temporary(
                lv->typespec().elementtype());
            emitcode("aref", tmp, lv, ind);
            emitcode("compref", dest, tmp, ind2);
        } else if (lv->typespec().is_structure_array()) {
            // arrayofstruct[a] -- this is tricky, we have no way to
            // directly address a struct (or a single array element, for
            // that matter), so we bite the bullet and copy the whole
            // struct element by element.
            codegen_copy_struct_array_element(lv->typespec().structspec(),
                                              ustring(dest->mangled()),
                                              ustring(lv->mangled()), ind);
        } else {
            // regulararray[a]
            emitcode("aref", dest, lv, ind);
        }
    } else if (lv->typespec().is_triple()) {
        emitcode("compref", dest, lv, ind);
    } else if (lv->typespec().is_matrix()) {
        emitcode("mxcompref", dest, lv, ind, ind2);
    } else {
        OSL_ASSERT(0);
    }
    return dest;
}



void
ASTindex::codegen_copy_struct_array_element(StructSpec* structspec,
                                            ustring destname, ustring srcname,
                                            Symbol* index)
{
    for (int fi = 0; fi < (int)structspec->numfields(); ++fi) {
        const StructSpec::FieldSpec& field(structspec->field(fi));
        const TypeSpec& type(field.type);
        if (type.is_structure()) {
            // struct within struct -- recurse!
            codegen_copy_struct_array_element(
                type.structspec(),
                ustring::fmtformat("{}.{}", destname, field.name),
                ustring::fmtformat("{}.{}", srcname, field.name), index);
        } else {
            OSL_ASSERT(!type.is_array());
            Symbol *dfield, *sfield;
            m_compiler->struct_field_pair(structspec, fi, destname, srcname,
                                          dfield, sfield);
            emitcode("aref", dfield, sfield, index);
        }
    }
}



void
ASTindex::codegen_assign(Symbol* src, Symbol* ind, Symbol* ind2, Symbol* ind3)
{
    Symbol* lv = lvalue()->codegen();
    if (!ind)
        ind = index()->codegen();
    if (!ind2)
        ind2 = index2() ? index2()->codegen() : NULL;
    if (!ind3)
        ind3 = index3() ? index3()->codegen() : NULL;
    if (lv->typespec().is_array()) {
        TypeSpec elemtype = lv->typespec().elementtype();
        if (ind3 && elemtype.is_matrix()) {
            // Component of matrix array, e.g., matrixarray[i][c][r] = float
            Symbol* temp = m_compiler->make_temporary(elemtype);
            emitcode("aref", temp, lv, ind);
            emitcode("mxcompassign", temp, ind2, ind3, src);
            emitcode("aassign", lv, ind, temp);
        } else if (ind2 && elemtype.is_triple()) {
            // Component of triple array, e.g., colorarray[i][c] = float
            Symbol* temp = m_compiler->make_temporary(elemtype);
            emitcode("aref", temp, lv, ind);
            emitcode("compassign", temp, ind2, src);
            emitcode("aassign", lv, ind, temp);
        } else {
            src = codegen_aassign(elemtype, src, lv, ind);
        }
    } else if (lv->typespec().is_triple()) {
        emitcode("compassign", lv, ind, src);
    } else if (lv->typespec().is_matrix()) {
        emitcode("mxcompassign", lv, ind, ind2, src);
    } else {
        OSL_ASSERT(0);
    }
}



Symbol*
ASTstructselect::codegen(Symbol* dest)
{
    if (compindex()) {
        // Redirected codegen to ASTIndex for named component (e.g., point.x)
        return compindex()->codegen(dest);
    }

    // Must account for array indices farther up the chain.
    Symbol* indexsym = codegen_index();

    if (indexsym) {
        Symbol* tmp = m_compiler->make_temporary(typespec());
        emitcode("aref", tmp, m_fieldsym, indexsym);
        return tmp;
    } else {
        return m_fieldsym;
    }
}



void
ASTstructselect::codegen_assign(Symbol* dest, Symbol* src)
{
    OSL_DASSERT(src);

    if (compindex()) {
        // Redirected codegen to ASTIndex for named component (e.g., point.x)
        compindex()->codegen_assign(src);
        return;
    }

    src = coerce(src, typespec());

    // Must account for array indices farther up the chain.
    Symbol* indexsym = codegen_index();

    if (indexsym)
        emitcode("aassign", m_fieldsym, indexsym, src);
    else
        emitcode("assign", dest, src);
}



// A struct select needs to decipher whether there is an array index
// necessary in the chain of events.  The only kind of assignment that
// makes sense is a series of struct field selections, array indexings,
// or (last) a direct variable reference (for the top level struct).
// This function generates code for the index and returns the resulting
// symbol, or returns NULL if no dereference is necessary.
Symbol*
ASTstructselect::codegen_index()
{
    // Must account for array indices farther up the chain.
    ASTNode* node    = this;
    Symbol* indexsym = NULL;
    while (node) {
        if (node->nodetype() == variable_ref_node) {
            // Hit final variable ref -- done
            break;
        } else if (node->nodetype() == structselect_node) {
            // Hit another struct select -- recurse up
            node = ((ASTstructselect*)node)->lvalue().get();
        } else if (node->nodetype() == index_node) {
            // Hit an array index node -- find the index and recurse
            ASTindex* arrayref = (ASTindex*)node;
            indexsym           = arrayref->index()->codegen();
            // FIXME -- to allow multiple levels of array indexing,
            // this should "append", i.e. multiply, the old index
            // with the new one.
            node = arrayref->lvalue().get();
        } else {
            OSL_ASSERT(0);
        }
    }

    return indexsym;
}



Symbol*
ASTconditional_statement::codegen(Symbol*)
{
    Symbol* condvar = cond()->codegen_int();

    // Generate the op for the 'if' itself.  Record its label, so that we
    // can go back and patch it with the jump destinations.
    int ifop = emitcode("if", condvar);
    // "if" is unusual in that it doesn't write its first argument
    m_compiler->lastop().argread(0, true);
    m_compiler->lastop().argwrite(0, false);

    // Generate the code for the 'true' and 'false' code blocks, recording
    // the jump destinations for 'else' and the next op after the if.
    m_compiler->push_nesting(false);
    codegen_list(truestmt());
    int falselabel = m_compiler->next_op_label();
    codegen_list(falsestmt());
    int donelabel = m_compiler->next_op_label();
    m_compiler->pop_nesting(false);

    // Fix up the 'if' to have the jump destinations.
    m_compiler->ircode(ifop).set_jump(falselabel, donelabel);

    return NULL;
}



// while (cond) statement
// do statement while (cond);
// for (init; cond; iter);
Symbol*
ASTloop_statement::codegen(Symbol*)
{
    // Generate the op for the loop itself.  Record its label, so that we
    // can go back and patch it with the jump destinations.
    int loop_op = emitcode(opname());
    // Loop ops read their first arg, not write it
    m_compiler->lastop().argread(0, true);
    m_compiler->lastop().argwrite(0, false);

    m_compiler->push_nesting(true);
    codegen_list(init());

    int condlabel   = m_compiler->next_op_label();
    Symbol* condvar = cond()->codegen_int(/*dest=*/nullptr,
                                          /*boolify=*/true);

    // Retroactively add the argument
    size_t argstart = m_compiler->add_op_args(1, &condvar);
    m_compiler->ircode(loop_op).set_args(argstart, 1);
    // N.B. the arg is both read and written -- already the default state

    int bodylabel = m_compiler->next_op_label();
    codegen_list(stmt());
    int iterlabel = m_compiler->next_op_label();
    codegen_list(iter());
    int donelabel = m_compiler->next_op_label();
    m_compiler->pop_nesting(true);

    // Fix up the loop op to have the jump destinations.
    m_compiler->ircode(loop_op).set_jump(condlabel, bodylabel, iterlabel,
                                         donelabel);

    // FIXME -- account for the fact that the first argument, unlike
    // almost all other ops, is read, not written
    return NULL;
}



Symbol*
ASTloopmod_statement::codegen(Symbol*)
{
    emitcode(opname());
    return NULL;
}



Symbol*
ASTunary_expression::codegen(Symbol* dest)
{
    // Code generation for unary expressions (-x, !x, etc.)

    if (m_function_overload) {
        // A little crazy, but we temporarily construct an ASTfunction_call
        // in order to codegen this overloaded operator.
        ustring funcname = ustring::fmtformat("__operator__{}__", opword());
        ASTfunction_call fc(m_compiler, funcname, expr().get(),
                            m_function_overload);
        fc.typecheck(typespec());
        return dest = fc.codegen(dest);
    }

    if (m_op == Not) {
        // Special case for logical ops
        return expr()->codegen_int(NULL, true /*boolify*/, true /*invert*/);
    }

    // Generate the code for our expression
    Symbol* esym = expr()->codegen();

    if (m_op == Add) {
        // Special case: +x just returns x.
        return esym;
    }

    // If we were not given a requested destination, or if it is not of
    // the right type, make a temporary.
    if (dest == NULL || !equivalent(dest->typespec(), typespec()))
        dest = m_compiler->make_temporary(typespec());

    // Negation of closures: turn into multiplication by -1.0
    if (esym->typespec().is_closure()) {
        OSL_DASSERT(m_op == Sub);
        emitcode("mul", dest, esym, m_compiler->make_constant(-1.0f));
        return dest;
    }

    // Generate the opcode
    emitcode(opword(), dest, esym);

    return dest;
}



Symbol*
ASTbinary_expression::codegen(Symbol* dest)
{
    if (m_function_overload) {
        // A little crazy, but we temporarily construct an ASTfunction_call
        // in order to codegen this overloaded operator. Slightly tricky
        // is that we need to concatenate our left and right arguments into
        // an arg list.
        ustring funcname = ustring::fmtformat("__operator__{}__", opword());
        if (left()->nextptr() || right()->nextptr()) {
            errorfmt("Overloaded %s cannot be passed arguments {} and {}",
                     funcname, left()->nodetypename(), right()->nodetypename());
            return dest;
        }
        ref args = left();
        args->append(right().get());
        ASTfunction_call fc(m_compiler, funcname, args.get(),
                            m_function_overload);
        fc.typecheck(typespec());
        dest = fc.codegen(dest);
        // now put things back the way we found them
        left()->detach_next();
        return dest;
    }

    // Special case for logic ops that short-circuit
    if (m_op == And || m_op == Or)
        return codegen_logic(dest);

    Symbol* lsym = left()->codegen();
    Symbol* rsym = right()->codegen();
    if (dest == NULL || !equivalent(dest->typespec(), typespec()))
        dest = m_compiler->make_temporary(typespec());

    // Special case for closure operations
    if (typespec().is_closure()) {
        OSL_DASSERT(m_op == Mul || m_op == Div || m_op == Add);
        if (m_op == Mul || m_op == Div) {
            // Need to coerce the weight into a color.
            // N.B. The typecheck always reorders c=k*c into c=c*k.
            rsym = coerce(rsym, TypeColor, true);
        }
        emitcode(opword(), dest, lsym, rsym);
        return dest;
    }

    // Promote ints to float-like types, for mixed arithmetic
    if ((m_op == Mul || m_op == Div || m_op == Add || m_op == Sub)) {
        if (lsym->typespec().is_float_based() && rsym->typespec().is_int()) {
            if (rsym->symtype() == SymTypeConst) {
                float val = ((ConstantSymbol*)rsym)->floatval();
                rsym      = m_compiler->make_constant(val);
            } else {
                Symbol* tmp = rsym;
                rsym        = m_compiler->make_temporary(lsym->typespec());
                emitcode("assign", rsym, tmp);  // type coercion
            }
        } else if (lsym->typespec().is_int()
                   && rsym->typespec().is_float_based()) {
            if (lsym->symtype() == SymTypeConst) {
                float val = ((ConstantSymbol*)lsym)->floatval();
                lsym      = m_compiler->make_constant(val);
            } else {
                Symbol* tmp = lsym;
                lsym        = m_compiler->make_temporary(rsym->typespec());
                emitcode("assign", lsym, tmp);  // type coercion
            }
        }
    }

    emitcode(opword(), dest, lsym, rsym);
    return dest;
}



Symbol*
ASTbinary_expression::codegen_logic(Symbol* dest)
{
    dest = left()->codegen_int(NULL, true);

    int ifop = emitcode("if", dest);
    // "if" is unusual in that it doesn't write its first argument
    m_compiler->lastop().argread(0, true);
    m_compiler->lastop().argwrite(0, false);
    int falselabel;
    m_compiler->push_nesting(false);

    if (m_op == And) {
        Symbol* rsym = right()->codegen_int(dest, true);
        if (rsym != dest)
            emitcode("assign", dest, rsym);
        falselabel = m_compiler->next_op_label();
    } else { /* Or */
        falselabel   = m_compiler->next_op_label();
        Symbol* rsym = right()->codegen_int(dest, true);
        if (rsym != dest)
            emitcode("assign", dest, rsym);
    }

    int donelabel = m_compiler->next_op_label();
    m_compiler->pop_nesting(false);
    m_compiler->ircode(ifop).set_jump(falselabel, donelabel);
    return dest;
}



Symbol*
ASTternary_expression::codegen(Symbol* dest)
{
    if (!dest)
        dest = m_compiler->make_temporary(typespec());

    Symbol* condvar = cond()->codegen_int();

    // Generate the op for the 'if' itself.  Record its label, so that we
    // can go back and patch it with the jump destinations.
    int ifop = emitcode("if", condvar);
    // "if" is unusual in that it doesn't write its first argument
    m_compiler->lastop().argread(0, true);
    m_compiler->lastop().argwrite(0, false);

    // Generate the code for the 'true' and 'false' code blocks, recording
    // the jump destinations for 'else' and the next op after the if.
    m_compiler->push_nesting(false);
    Symbol* trueval = trueexpr()->codegen(dest);
    if (trueval != dest)
        emitcode("assign", dest, trueval);

    int falselabel = m_compiler->next_op_label();

    m_compiler->push_nesting(false);
    Symbol* falseval = falseexpr()->codegen(dest);
    if (falseval != dest)
        emitcode("assign", dest, falseval);

    int donelabel = m_compiler->next_op_label();
    m_compiler->pop_nesting(false);

    // Fix up the 'if' to have the jump destinations.
    m_compiler->ircode(ifop).set_jump(falselabel, donelabel);

    return dest;
}



Symbol*
ASTcomma_operator::codegen(Symbol* dest)
{
    return codegen_list(expr(), dest);
    // N.B. codegen_list already returns the type of the LAST node in
    // the list, just like the comma operator is supposed to do.
}



Symbol*
ASTtypecast_expression::codegen(Symbol* dest)
{
    Symbol* e = expr()->codegen(dest);

    // If the cast is a null operation -- they are already the same types,
    // or we're converting one triple to another -- just pass the expression.
    if (equivalent(typespec(), e->typespec()))
        return e;

    // Some actual conversion is necessary.  Generally, our "assign"
    // op can handle it all easily.
    if (dest == NULL || !equivalent(dest->typespec(), typespec()))
        dest = m_compiler->make_temporary(typespec());
    emitcode("assign", dest, e);
    return dest;
}



Symbol*
ASTtype_constructor::codegen(Symbol* dest)
{
    if (dest == NULL || !equivalent(dest->typespec(), typespec()))
        dest = m_compiler->make_temporary(typespec());

    // Handle simple case of a triple constructed from 3 float literals
    if (typespec().is_triple()) {
        bool all_literals = true;
        ASTNode::ref val  = args();
        float f[3];
        for (int c = 0; c < 3; ++c) {
            if (val->nodetype() == ASTNode::literal_node
                && (val->typespec().is_float() || val->typespec().is_int()))
                f[c] = ((ASTliteral*)val.get())->floatval();
            else
                all_literals = false;
            if (val->next())
                val = val->next();
        }
        if (all_literals)
            return m_compiler->make_constant(typespec().simpletype(), f[0],
                                             f[1], f[2]);
        // Doesn't fit the pattern, drop to the usual case...
    }

    // Special case: construct float(float_expr) -- just put it directly
    // in the dest.
    Symbol* argevaldest = nullptr;
    if (dest && typespec().is_float() && nchildren() == 1
        && child(0)->typespec().is_float()) {
        argevaldest = dest;
    }

    std::vector<Symbol*> argdest;
    argdest.push_back(dest);
    int nargs = 0;
    for (ref a = args(); a; a = a->next(), ++nargs) {
        Symbol* argval = a->codegen(argevaldest);
        if (argval->typespec().is_int() && !typespec().is_int()) {
            // Coerce to float if it's an int
            if (a->nodetype() == literal_node) {
                // It's a literal int, so let's make a literal float
                int i  = ((ASTliteral*)a.get())->intval();
                argval = m_compiler->make_constant((float)i);
            } else {
                // General case
                Symbol* tmp = argval;
                argval = m_compiler->make_temporary(TypeSpec(TypeDesc::FLOAT));
                emitcode("assign", argval, tmp);
            }
        }
        argdest.push_back(argval);
    }
    if (nargs == 1 && argdest.size() == 2 && argdest[1] == dest) {
        // Don't have to do anything, we already coaxed the one argument
        // to show up in the requested destination. This can happen for
        //    foo = float(float_expr)
        // to avoid the extra needless copy.
    } else if (nargs == 1) {
        emitcode("assign", argdest.size(),
                 (argdest.size()) ? &argdest[0] : NULL);
    } else
        emitcode(typespec().string().c_str(), argdest.size(),
                 (argdest.size()) ? &argdest[0] : NULL);
    return dest;
}



bool
ASTfunction_call::argread(int arg) const
{
    if (is_user_function()) {
        // assume all are readable except return value
        if (!typespec().is_void() && arg == 0)
            return false;
        else
            return true;
    } else {  // built-in function
        return (arg < 32) ? (m_argread & (1 << arg)) : true;
    }
}



bool
ASTfunction_call::argwrite(int arg) const
{
    if (is_user_function()) {
        // assume all are readable except return value
        if (typespec().is_void()) {
            ASTvariable_declaration* formal
                = (ASTvariable_declaration*)list_nth(user_function()->formals(),
                                                     arg);
            return formal->is_output();
        } else {
            if (arg == 0)
                return true;  // return value always writes
            ASTvariable_declaration* formal
                = (ASTvariable_declaration*)list_nth(user_function()->formals(),
                                                     arg - 1);
            return formal->is_output();
        }
    } else {  // built-in function
        return (arg < 32) ? (m_argwrite & (1 << arg)) : false;
    }
}



Symbol*
ASTfunction_call::codegen(Symbol* dest)
{
    if (is_struct_ctr()) {
        // Looks like function call, but is actually struct constructor
        if (!dest)
            dest = m_compiler->make_temporary(typespec());
        codegen_struct_initializers(args(), dest, true /*is_constructor*/);
        return dest;
    }

    // Set up a return destination if not passed one (or not the right type)
    if (!typespec().is_void()) {
        if (dest == NULL || !equivalent(dest->typespec(), typespec()))
            dest = m_compiler->make_temporary(typespec());
    }

    std::vector<TypeSpec> polyargs;
    const char* param_argcodes = func()->argcodes().c_str();
    int len;
    TypeSpec::type_from_code(param_argcodes, &len);  // skip ret type
    TypeSpec::typespecs_from_codes(param_argcodes + len, polyargs);

    // Generate code for all the individual arguments.  Remember the
    // individual indices for arguments that are array elements or
    // vector/color/matrix components.
    SymbolPtrVec argdest, index, index2, index3;
    bool indexed_output_params = false;
    int argdest_return_offset  = 0;
    ASTNode* a                 = args().get();

    int returnarg = !typespec().is_void();
    ASTNode* form = is_user_function() ? user_function()->formals().get()
                                       : NULL;
    for (int i = 0; a; a = a->nextptr(), ++i) {
        TypeSpec formaltype = (i < (int)polyargs.size())
                                  ? polyargs[i]
                                  : TypeSpec(TypeDesc::UNKNOWN);
        bool writearg       = argwrite(i + returnarg);
        codegen_arg(argdest, index, index2, index3, i, a, form, formaltype,
                    writearg, indexed_output_params);
        if (form)
            form = form->nextptr();
    }

    if (is_user_function()) {
        // Record the return location
        func()->return_location(typespec().is_void() ? NULL : dest);

        // Alias each function formal parameter to the symbol holding
        // the corresponding actual parameter.
        ASTNode* form = user_function()->formals().get();
        ASTNode* a    = args().get();
        for (int i = 0; a; a = a->nextptr(), form = form->nextptr(), ++i) {
            ASTvariable_declaration* f = (ASTvariable_declaration*)form;
            const TypeSpec& ftype(f->sym()->typespec());
            if (ftype.is_structure() || ftype.is_structure_array()) {
                // If the formal parameter is a struct, we also need to
                // alias each of the fields
                if (a->nodetype() == variable_ref_node
                    || a->nodetype() == function_call_node
                    || a->nodetype() == compound_initializer_node
                    || a->nodetype() == binary_expression_node
                    || a->nodetype() == unary_expression_node) {
                    // Passed a variable that is a struct ; make the struct
                    // fields of the formal param alias to the struct fields
                    // of the actual param. Exact same logic if passed the
                    // result location of a call to a function that returns
                    // a struct.
                    struct_pair_all_fields(ftype.structspec(),
                                           ustring(f->sym()->mangled()),
                                           ustring(argdest[i]->mangled()));
                } else if (a->nodetype() == structselect_node) {
                    // Passed a field of a struct, which is itself a struct.
                    // This is very similar to the variable_ref_node case.
                    struct_pair_all_fields(
                        ftype.structspec(), ustring(f->sym()->mangled()),
                        ustring(((ASTstructselect*)a)->fieldsym()->mangled()));
                } else if (a->nodetype() == index_node) {
                    // Passed one struct in an array of structs.  That throws
                    // us for a spin.  Not much to do but *copy* the struct
                    // elements.
                    ASTindex* ind      = (ASTindex*)a;
                    Symbol* arrayindex = ind->index()->codegen();
                    struct_pair_all_fields(ftype.structspec(),
                                           ustring(f->sym()->mangled()),
                                           ustring(argdest[i]->mangled()),
                                           arrayindex);
                } else {
                    OSL_ASSERT(0 && "unhandled structure designation");
                }
            }
            f->sym()->alias(argdest[i]);
        }

        // Return statements inside the middle of a function (not the
        // last statement in the function, or inside a conditional)
        // require special care, since we don't have a general "jump"
        // instruction.  Instead, we wrap the function call inside a
        // "functioncall" op that marks the range.
        int loop_op = emitcode("functioncall",
                               m_compiler->make_constant(m_name));

        // Generate the code for the function body
        m_compiler->push_function(func());
        codegen_list(user_function()->statements());
        m_compiler->pop_function();

        // Go back and mark the "functioncall" with the right jump address
        m_compiler->ircode(loop_op).argread(0, true);    // read
        m_compiler->ircode(loop_op).argwrite(0, false);  // not written
        int endlabel = m_compiler->next_op_label();
        m_compiler->ircode(loop_op).set_jump(endlabel);

    } else {
        bool isclosure = func() && func()->typespec().is_closure();
        if (isclosure) {
            Symbol* clname = m_compiler->make_constant(m_name);
            argdest.insert(argdest.begin(), clname);
            argdest_return_offset++;
        }
        // Built-in function
        if (!typespec().is_void()) {  // Insert the return dest if non-void
            argdest.insert(argdest.begin(), dest);
            argdest_return_offset++;
        }
        // Emit the actual op
        emitcode(isclosure ? "closure" : m_name.c_str(), argdest.size(),
                 (argdest.size()) ? &argdest[0] : NULL);
        // Propagate derivative-taking info to the opcode
        m_compiler->lastop().set_argbits(m_argread, m_argwrite,
                                         m_argtakesderivs);
    }

    if (indexed_output_params) {
        // Second half of the element/component-passed-as-output-param
        // issue -- restore the written values to the right spots.
        a = args().get();
        for (int i = 0; a; a = a->nextptr(), ++i) {
            if (index[i]) {
                OSL_ASSERT(a->nodetype() == ASTNode::index_node
                           || a->nodetype() == ASTNode::structselect_node);
                ASTindex* indexnode
                    = (a->nodetype() == index_node)
                          ? static_cast<ASTindex*>(a)
                          : static_cast<ASTstructselect*>(a)->compindex();
                indexnode->codegen_assign(argdest[i + argdest_return_offset],
                                          index[i], index2[i], index3[i]);
            }
        }
    }

    return dest;
}



/// Generate code for one argument to the function, appending its value
/// symbol to argdest and any indexing arguments to index, index2,
/// index3.  If the argument a struct, recurse.
void
ASTfunction_call::codegen_arg(SymbolPtrVec& argdest, SymbolPtrVec& index1,
                              SymbolPtrVec& index2, SymbolPtrVec& index3,
                              int argnum, ASTNode* arg, ASTNode* form,
                              const TypeSpec& formaltype, bool writearg,
                              bool& indexed_output_params)
{
    Symbol* thisarg = NULL;
    Symbol *ind1 = NULL, *ind2 = NULL, *ind3 = NULL;  // array/component indices

    bool is_struct = arg->typespec().is_structure();
    if (is_struct) {
        // Structure arguments
        thisarg = arg->codegen();
    } else if (arg && writearg
               && (arg->nodetype() == index_node
                   || (arg->nodetype() == structselect_node
                       && ((ASTstructselect*)arg)->compindex()))) {
        // Special case for individual array elements or vec/col/matrix
        // components being passed as output params of the function --
        // these aren't really lvalues, so we need to restore their
        // values.  We save the indices we genearate code for here...
        ASTindex* indexnode
            = (arg->nodetype() == index_node)
                  ? static_cast<ASTindex*>(arg)
                  : static_cast<ASTstructselect*>(arg)->compindex();
        thisarg               = indexnode->codegen(NULL, ind1, ind2, ind3);
        indexed_output_params = true;
    } else {
        // Anything else
        thisarg = arg->codegen();
    }
    // Handle type coercion of the argument
    if (!is_struct && formaltype.simpletype() != TypeDesc(TypeDesc::UNKNOWN)
        && formaltype.simpletype() != TypeDesc(TypeDesc::UNKNOWN, -1)) {
        Symbol* origarg = thisarg;
        thisarg         = coerce(thisarg, formaltype);
        // Error to type-coerce an output -- where would the result go?
        if (thisarg != origarg && form
            && !equivalent(origarg->typespec(), form->typespec())
            && form->nodetype() == variable_declaration_node
            && ((ASTvariable_declaration*)form)->is_output()) {
            errorfmt("Cannot pass '{} {}' as argument {} to {}\n\t"
                     "because it is an output parameter that must be a %s",
                     origarg->typespec(), origarg->name(), argnum + 1,
                     user_function()->func()->name(), form->typespec());
        }
    }
    if (thisarg) {
        argdest.push_back(thisarg);
        index1.push_back(ind1);
        index2.push_back(ind2);
        index3.push_back(ind3);
    } else
        arg->errorfmt("Invalid argument to function");
}



void
ASTfunction_call::struct_pair_all_fields(StructSpec* structspec, ustring formal,
                                         ustring actual, Symbol* arrayindex)
{
    for (int fi = 0; fi < (int)structspec->numfields(); ++fi) {
        const StructSpec::FieldSpec& field(structspec->field(fi));
        const TypeSpec& type(field.type);
        if (type.is_structure() || type.is_structure_array()) {
            // struct within struct -- recurse!
            struct_pair_all_fields(
                type.structspec(),
                ustring::fmtformat("{}.{}", formal, field.name),
                ustring::fmtformat("{}.{}", actual, field.name), arrayindex);
        } else {
            Symbol *fsym, *asym;
            m_compiler->struct_field_pair(structspec, fi, formal, actual, fsym,
                                          asym);
            fsym->alias(asym);
        }
    }
}



Symbol*
ASTliteral::codegen(Symbol* /*dest*/)
{
    TypeSpec t = typespec();
    if (t.is_string())
        return m_compiler->make_constant(ustring(strval()));
    if (t.is_int())
        return m_compiler->make_constant(intval());
    if (t.is_float())
        return m_compiler->make_constant(floatval());
    OSL_DASSERT(0 && "Don't know how to generate code for this literal");
    return nullptr;
}



};  // namespace pvt

OSL_NAMESPACE_END