ethminer/libserpent/compiler.cpp

#include <stdio.h>
#include <iostream>
#include <vector>
#include <map>
#include "util.h"
#include "bignum.h"
#include "opcodes.h"

// Auxiliary data that is gathered while compiling
struct programAux {
    std::map<std::string, std::string> vars;
    int nextVarMem;
    bool allocUsed;
    bool calldataUsed;
    int step;
    int labelLength;
};

// Auxiliary data that gets passed down vertically
// but not back up
struct programVerticalAux {
    int height;
    std::string innerScopeName;
    std::map<std::string, int> dupvars;
    std::map<std::string, int> funvars;
    std::vector<mss> scopes;
};

// Compilation result
struct programData {
    programAux aux;
    Node code;
    int outs;
};

programAux Aux() {
    programAux o;
    o.allocUsed = false;
    o.calldataUsed = false;
    o.step = 0;
    o.nextVarMem = 32;
    return o;
}

programVerticalAux verticalAux() {
    programVerticalAux o;
    o.height = 0;
    o.dupvars = std::map<std::string, int>();
    o.funvars = std::map<std::string, int>();
    o.scopes = std::vector<mss>();
    return o;
}

programData pd(programAux aux = Aux(), Node code=token("_"), int outs=0) {
    programData o;
    o.aux = aux;
    o.code = code;
    o.outs = outs;
    return o;
}

Node multiToken(Node nodes[], int len, Metadata met) {
    std::vector<Node> out;
    for (int i = 0; i < len; i++) {
        out.push_back(nodes[i]);
    }
    return astnode("_", out, met);
}

Node finalize(programData c);

Node popwrap(Node node) {
    Node nodelist[] = {
        node,
        token("POP", node.metadata)
    };
    return multiToken(nodelist, 2, node.metadata);
}

// Grabs variables
mss getVariables(Node node, mss cur=mss()) {
    Metadata m = node.metadata;
    // Tokens don't contain any variables
    if (node.type == TOKEN)
        return cur;
    // Don't descend into call fragments
    else if (node.val == "lll")
        return getVariables(node.args[1], cur);
    // At global scope get/set/ref also declare    
    else if (node.val == "get" || node.val == "set" || node.val == "ref") {
        if (node.args[0].type != TOKEN)
            err("Variable name must be simple token,"
                " not complex expression! " + printSimple(node.args[0]), m);
        if (!cur.count(node.args[0].val)) {
            cur[node.args[0].val] = utd(cur.size() * 32 + 32);
            //std::cerr << node.args[0].val << " " << cur[node.args[0].val] << "\n";
        }
    }
    // Recursively process children
    for (unsigned i = 0; i < node.args.size(); i++) {
        cur = getVariables(node.args[i], cur);
    }
    return cur;
}

// Turns LLL tree into tree of code fragments
programData opcodeify(Node node,
                      programAux aux=Aux(),
                      programVerticalAux vaux=verticalAux()) {
    std::string symb = "_"+mkUniqueToken();
    Metadata m = node.metadata;
    // Get variables
    if (!aux.vars.size()) {
        aux.vars = getVariables(node);
        aux.nextVarMem = aux.vars.size() * 32 + 32;
    }
    // Numbers
    if (node.type == TOKEN) {
        return pd(aux, nodeToNumeric(node), 1);
    }
    else if (node.val == "ref" || node.val == "get" || node.val == "set") {
        std::string varname = node.args[0].val;
        // Determine reference to variable
        Node varNode = tkn(aux.vars[varname], m);
        //std::cerr << varname << " " << printSimple(varNode) << "\n";
        // Set variable
        if (node.val == "set") {
            programData sub = opcodeify(node.args[1], aux, vaux);
            if (!sub.outs)
                err("Value to set variable must have nonzero arity!", m);
            // What if we are setting a stack variable?
            if (vaux.dupvars.count(node.args[0].val)) {
                int h = vaux.height - vaux.dupvars[node.args[0].val];
                if (h > 16) err("Too deep for stack variable (max 16)", m);
                Node nodelist[] = {
                    sub.code,
                    token("SWAP"+unsignedToDecimal(h), m),
                    token("POP", m)
                };
                return pd(sub.aux, multiToken(nodelist, 3, m), 0);                   
            }
            // Setting a memory variable
            else {
                Node nodelist[] = {
                    sub.code,
                    varNode,
                    token("MSTORE", m),
                };
                return pd(sub.aux, multiToken(nodelist, 3, m), 0);                   
            }
        }
        // Get variable
        else if (node.val == "get") {
            // Getting a stack variable
            if (vaux.dupvars.count(node.args[0].val)) {
                 int h = vaux.height - vaux.dupvars[node.args[0].val];
                if (h > 16) err("Too deep for stack variable (max 16)", m);
                return pd(aux, token("DUP"+unsignedToDecimal(h)), 1);                   
            }
            // Getting a memory variable
            else {
                Node nodelist[] = 
                     { varNode, token("MLOAD", m) };
                return pd(aux, multiToken(nodelist, 2, m), 1);
            }
        }
        // Refer variable
        else if (node.val == "ref") {
            if (vaux.dupvars.count(node.args[0].val))
                err("Cannot ref stack variable!", m);
            return pd(aux, varNode, 1);
        }
    }
    // Comments do nothing
    else if (node.val == "comment") {
        Node* nodelist = nullptr;
        return pd(aux, multiToken(nodelist, 0, m), 0);
    }
    // Custom operation sequence
    // eg. (ops bytez id msize swap1 msize add 0 swap1 mstore) == alloc
    if (node.val == "ops") {
        std::vector<Node>  subs2;
        int depth = 0;
        for (unsigned i = 0; i < node.args.size(); i++) {
            std::string op = upperCase(node.args[i].val);
            if (node.args[i].type == ASTNODE || opinputs(op) == -1) {
                programVerticalAux vaux2 = vaux;
                vaux2.height = vaux.height - i - 1 + node.args.size();
                programData sub = opcodeify(node.args[i], aux, vaux2);
                aux = sub.aux;
                depth += sub.outs;
                subs2.push_back(sub.code);
            }
            else {
                subs2.push_back(token(op, m));
                depth += opoutputs(op) - opinputs(op);
            }
        }
        if (depth < 0 || depth > 1) err("Stack depth mismatch", m);
        return pd(aux, astnode("_", subs2, m), 0);
    }
    // Code blocks
    if (node.val == "lll" && node.args.size() == 2) {
        if (node.args[1].val != "0") aux.allocUsed = true;
        std::vector<Node> o;
        o.push_back(finalize(opcodeify(node.args[0])));
        programData sub = opcodeify(node.args[1], aux, vaux);
        Node code = astnode("____CODE", o, m);
        Node nodelist[] = {
            token("$begincode"+symb+".endcode"+symb, m), token("DUP1", m),
            token("$begincode"+symb, m), sub.code, token("CODECOPY", m),
            token("$endcode"+symb, m), token("JUMP", m),
            token("~begincode"+symb, m), code, 
            token("~endcode"+symb, m), token("JUMPDEST", m)
        };
        return pd(sub.aux, multiToken(nodelist, 11, m), 1);
    }
    // Stack variables
    if (node.val == "with") {
        programData initial = opcodeify(node.args[1], aux, vaux);
        programVerticalAux vaux2 = vaux;
        vaux2.dupvars[node.args[0].val] = vaux.height;
        vaux2.height += 1;
        if (!initial.outs)
            err("Initial variable value must have nonzero arity!", m);
        programData sub = opcodeify(node.args[2], initial.aux, vaux2);
        Node nodelist[] = {
            initial.code,
            sub.code
        };
        programData o = pd(sub.aux, multiToken(nodelist, 2, m), sub.outs);
        if (sub.outs)
            o.code.args.push_back(token("SWAP1", m));
        o.code.args.push_back(token("POP", m));
        return o;
    }
    // Seq of multiple statements
    if (node.val == "seq") {
        std::vector<Node> children;
        int lastOut = 0;
        for (unsigned i = 0; i < node.args.size(); i++) {
            programData sub = opcodeify(node.args[i], aux, vaux);
            aux = sub.aux;
            if (sub.outs == 1) {
                if (i < node.args.size() - 1) sub.code = popwrap(sub.code);
                else lastOut = 1;
            }
            children.push_back(sub.code);
        }
        return pd(aux, astnode("_", children, m), lastOut);
    }
    // 2-part conditional (if gets rewritten to unless in rewrites)
    else if (node.val == "unless" && node.args.size() == 2) {
        programData cond = opcodeify(node.args[0], aux, vaux);
        programData action = opcodeify(node.args[1], cond.aux, vaux);
        aux = action.aux;
        if (!cond.outs) err("Condition of if/unless statement has arity 0", m);
        if (action.outs) action.code = popwrap(action.code);
        Node nodelist[] = {
            cond.code,
            token("$endif"+symb, m), token("JUMPI", m),
            action.code,
            token("~endif"+symb, m), token("JUMPDEST", m)
        };
        return pd(aux, multiToken(nodelist, 6, m), 0);
    }
    // 3-part conditional
    else if (node.val == "if" && node.args.size() == 3) {
        programData ifd = opcodeify(node.args[0], aux, vaux);
        programData thend = opcodeify(node.args[1], ifd.aux, vaux);
        programData elsed = opcodeify(node.args[2], thend.aux, vaux);
        aux = elsed.aux;
        if (!ifd.outs)
            err("Condition of if/unless statement has arity 0", m);
        // Handle cases where one conditional outputs something
        // and the other does not
        int outs = (thend.outs && elsed.outs) ? 1 : 0;
        if (thend.outs > outs) thend.code = popwrap(thend.code);
        if (elsed.outs > outs) elsed.code = popwrap(elsed.code);
        Node nodelist[] = {
            ifd.code,
            token("ISZERO", m),
            token("$else"+symb, m), token("JUMPI", m),
            thend.code,
            token("$endif"+symb, m), token("JUMP", m),
            token("~else"+symb, m), token("JUMPDEST", m),
            elsed.code,
            token("~endif"+symb, m), token("JUMPDEST", m)
        };
        return pd(aux, multiToken(nodelist, 12, m), outs);
    }
    // While (rewritten to this in rewrites)
    else if (node.val == "until") {
        programData cond = opcodeify(node.args[0], aux, vaux);
        programData action = opcodeify(node.args[1], cond.aux, vaux);
        aux = action.aux;
        if (!cond.outs)
            err("Condition of while/until loop has arity 0", m);
        if (action.outs) action.code = popwrap(action.code);
        Node nodelist[] = {
            token("~beg"+symb, m), token("JUMPDEST", m),
            cond.code,
            token("$end"+symb, m), token("JUMPI", m),
            action.code,
            token("$beg"+symb, m), token("JUMP", m),
            token("~end"+symb, m), token("JUMPDEST", m),
        };
        return pd(aux, multiToken(nodelist, 10, m));
    }
    // Memory allocations
    else if (node.val == "alloc") {
        programData bytez = opcodeify(node.args[0], aux, vaux);
        aux = bytez.aux;
        if (!bytez.outs)
            err("Alloc input has arity 0", m);
        aux.allocUsed = true;
        Node nodelist[] = {
            bytez.code,
            token("MSIZE", m), token("SWAP1", m), token("MSIZE", m),
            token("ADD", m), 
            token("0", m), token("SWAP1", m), token("MSTORE", m)
        };
        return pd(aux, multiToken(nodelist, 8, m), 1);
    }
    // All other functions/operators
    else {
        std::vector<Node>  subs2;
        int depth = opinputs(upperCase(node.val));
        if (depth == -1)
            err("Not a function or opcode: "+node.val, m);
        if ((int)node.args.size() != depth)
            err("Invalid arity for "+node.val, m);
        for (int i = node.args.size() - 1; i >= 0; i--) {
            programVerticalAux vaux2 = vaux;
            vaux2.height = vaux.height - i - 1 + node.args.size();
            programData sub = opcodeify(node.args[i], aux, vaux2);
            aux = sub.aux;
            if (!sub.outs)
                err("Input "+unsignedToDecimal(i)+" has arity 0", sub.code.metadata);
            subs2.push_back(sub.code);
        }
        subs2.push_back(token(upperCase(node.val), m));
        int outdepth = opoutputs(upperCase(node.val));
        return pd(aux, astnode("_", subs2, m), outdepth);
    }
}

// Adds necessary wrappers to a program
Node finalize(programData c) {
    std::vector<Node> bottom;
    Metadata m = c.code.metadata;
    // If we are using both alloc and variables, we need to pre-zfill
    // some memory
    if ((c.aux.allocUsed || c.aux.calldataUsed) && c.aux.vars.size() > 0) {
        Node nodelist[] = {
            token("0", m), 
            token(unsignedToDecimal(c.aux.nextVarMem - 1)),
            token("MSTORE8", m)
        };
        bottom.push_back(multiToken(nodelist, 3, m));
    }
    // The actual code
    bottom.push_back(c.code);
    return astnode("_", bottom, m);
}

//LLL -> code fragment tree
Node buildFragmentTree(Node node) {
    return finalize(opcodeify(node));
}


// Builds a dictionary mapping labels to variable names
programAux buildDict(Node program, programAux aux, int labelLength) {
    Metadata m = program.metadata;
    // Token
    if (program.type == TOKEN) {
        if (isNumberLike(program)) {
            aux.step += 1 + toByteArr(program.val, m).size();
        }
        else if (program.val[0] == '~') {
            aux.vars[program.val.substr(1)] = unsignedToDecimal(aux.step);
        }
        else if (program.val[0] == '$') {
            aux.step += labelLength + 1;
        }
        else aux.step += 1;
    }
    // A sub-program (ie. LLL)
    else if (program.val == "____CODE") {
        programAux auks = Aux();
        for (unsigned i = 0; i < program.args.size(); i++) {
            auks = buildDict(program.args[i], auks, labelLength);
        }
        for (std::map<std::string,std::string>::iterator it=auks.vars.begin();
             it != auks.vars.end();
             it++) {
            aux.vars[(*it).first] = (*it).second;
        }
        aux.step += auks.step;
    }
    // Normal sub-block
    else {
        for (unsigned i = 0; i < program.args.size(); i++) {
            aux = buildDict(program.args[i], aux, labelLength);
        }
    }
    return aux;
}

// Applies that dictionary
Node substDict(Node program, programAux aux, int labelLength) {
    Metadata m = program.metadata;
    std::vector<Node> out;
    std::vector<Node> inner;
    if (program.type == TOKEN) {
        if (program.val[0] == '$') {
            std::string tokStr = "PUSH"+unsignedToDecimal(labelLength);
            out.push_back(token(tokStr, m));
            int dotLoc = program.val.find('.');
            if (dotLoc == -1) {
                std::string val = aux.vars[program.val.substr(1)];
                inner = toByteArr(val, m, labelLength);
            }
            else {
                std::string start = aux.vars[program.val.substr(1, dotLoc-1)],
                            end = aux.vars[program.val.substr(dotLoc + 1)],
                            dist = decimalSub(end, start);
                inner = toByteArr(dist, m, labelLength);
            }
            out.push_back(astnode("_", inner, m));
        }
        else if (program.val[0] == '~') { }
        else if (isNumberLike(program)) {
            inner = toByteArr(program.val, m);
            out.push_back(token("PUSH"+unsignedToDecimal(inner.size())));
            out.push_back(astnode("_", inner, m));
        }
        else return program;
    }
    else {
        for (unsigned i = 0; i < program.args.size(); i++) {
            Node n = substDict(program.args[i], aux, labelLength);
            if (n.type == TOKEN || n.args.size()) out.push_back(n);
        }
    }
    return astnode("_", out, m);
}

// Compiled fragtree -> compiled fragtree without labels
Node dereference(Node program) {
    int sz = treeSize(program) * 4;
    int labelLength = 1;
    while (sz >= 256) { labelLength += 1; sz /= 256; }
    programAux aux = buildDict(program, Aux(), labelLength);
    return substDict(program, aux, labelLength);
}

// Dereferenced fragtree -> opcodes
std::vector<Node> flatten(Node derefed) {
    std::vector<Node> o;
    if (derefed.type == TOKEN) {
        o.push_back(derefed);
    }
    else {
        for (unsigned i = 0; i < derefed.args.size(); i++) {
            std::vector<Node> oprime = flatten(derefed.args[i]);
            for (unsigned j = 0; j < oprime.size(); j++) o.push_back(oprime[j]);
        }
    }
    return o;
}

// Opcodes -> bin
std::string serialize(std::vector<Node> codons) {
    std::string o;
    for (unsigned i = 0; i < codons.size(); i++) {
        int v;
        if (isNumberLike(codons[i])) {
            v = decimalToUnsigned(codons[i].val);
        }
        else if (codons[i].val.substr(0,4) == "PUSH") {
            v = 95 + decimalToUnsigned(codons[i].val.substr(4));
        }
        else {
            v = opcode(codons[i].val);
        }
        o += (char)v;
    }
    return o;
}

// Bin -> opcodes
std::vector<Node> deserialize(std::string ser) {
    std::vector<Node> o;
    int backCount = 0;
    for (unsigned i = 0; i < ser.length(); i++) {
        unsigned char v = (unsigned char)ser[i];
        std::string oper = op((int)v);
        if (oper != "" && backCount <= 0) o.push_back(token(oper));
        else if (v >= 96 && v < 128 && backCount <= 0) {
            o.push_back(token("PUSH"+unsignedToDecimal(v - 95)));
        }
        else o.push_back(token(unsignedToDecimal(v)));
        if (v >= 96 && v < 128 && backCount <= 0) {
            backCount = v - 95;
        }
        else backCount--;
    }
    return o;
}

// Fragtree -> bin
std::string assemble(Node fragTree) {
    return serialize(flatten(dereference(fragTree)));
}

// Fragtree -> tokens
std::vector<Node> prettyAssemble(Node fragTree) {
    return flatten(dereference(fragTree));
}

// LLL -> bin
std::string compileLLL(Node program) {
    return assemble(buildFragmentTree(program));
}

// LLL -> tokens
std::vector<Node> prettyCompileLLL(Node program) {
    return prettyAssemble(buildFragmentTree(program));
}

// Converts a list of integer values to binary transaction data
std::string encodeDatalist(std::vector<std::string> vals) {
    std::string o;
    for (unsigned i = 0; i < vals.size(); i++) {
        std::vector<Node> n = toByteArr(strToNumeric(vals[i]), Metadata(), 32);
        for (unsigned j = 0; j < n.size(); j++) {
            int v = decimalToUnsigned(n[j].val);
            o += (char)v;
        }
    }
    return o;
}

// Converts binary transaction data into a list of integer values
std::vector<std::string> decodeDatalist(std::string ser) {
    std::vector<std::string> out;
    for (unsigned i = 0; i < ser.length(); i+= 32) {
        std::string o = "0";
		for (unsigned j = i; j < i + 32; j++) {
            int vj = (int)(unsigned char)ser[j];
            o = decimalAdd(decimalMul(o, "256"), unsignedToDecimal(vj));
        }
        out.push_back(o);
    }
    return out;
}