Ion q transpiler (#68)

* fix gmpf::exp stability issue

* Fix typo

* Formatting

* Fix stability issue for gmpf::exp negative vals

* Create ionq files

* write IonQ transpiler; initial iteration

* remove references to M_PI

---------

Co-authored-by: Kevin Guo <[email protected]>

examples/ionq_test.qasm

@@ -0,0 +1,8 @@
+OPENQASM 2.0;
+include "qelib1.inc";
+
+qreg q[2];
+qreg a[2];
+
+tdg a[0];
+crz(2) a[1], q[0];

include/grid_synth/gmp_functions.hpp

@@ -210,14 +210,15 @@ inline mpf_class reduce_angle(const mpf_class& phi) {
 inline mpf_class sin(const mpf_class& theta) {
     long int initial_prec = theta.get_prec();
     long int tol_exp = std::log10(2) * initial_prec;
+    mpf_class eps(("1e-" + std::to_string(tol_exp)));
     mpf_class phi = reduce_angle(theta);
     mpz_class i(1);
     mpf_class lasts(0);
     mpf_class s = phi;
     mpf_class fact(1);
     mpf_class num(phi);
     mpf_class sign(1);
-    while (gmp_abs(s - lasts) > mpf_class("1e-" + std::to_string(tol_exp))) {
+    while (gmp_abs(s - lasts) > eps) {
         lasts = s;
         i += mpf_class("2");
         fact *= i * (i - mpf_class("1"));
@@ -231,14 +232,15 @@ inline mpf_class sin(const mpf_class& theta) {
 inline mpf_class cos(const mpf_class& theta) {
     // long int initial_prec = theta.get_prec();
     long int tol_exp = std::log10(2) * theta.get_prec();
+    mpf_class eps(("1e-" + std::to_string(tol_exp)));
     mpf_class phi = reduce_angle(theta);
     mpz_class i(0);
     mpf_class lasts(0);
     mpf_class s(1);
     mpf_class fact(1);
     mpf_class num(1);
     mpf_class sign(1);
-    while (gmp_abs(s - lasts) > mpf_class("1e-" + std::to_string(tol_exp))) {
+    while (gmp_abs(s - lasts) > eps) {
         lasts = s;
         i += mpf_class("2");
         fact *= i * (i - mpf_class("1"));
@@ -250,16 +252,19 @@ inline mpf_class cos(const mpf_class& theta) {
 }
 
 inline mpf_class exp(const mpf_class& x) {
-    // TODO: fix stability issue when x negative
+    if (x < 0)
+        return 1 / gmpf::exp(-x);
     long int tol_exp = std::log10(2) * x.get_prec();
-    mpz_class i = 0;
+    mpf_class eps(("1e-" + std::to_string(tol_exp)));
+    mpz_class i = 1;
     mpf_class s = 1;
-    mpf_class term = 1;
-    while (gmp_abs(term) > mpf_class("1e-" + std::to_string(tol_exp))) {
+    mpf_class term = x;
+    // Use Taylor's remainder theorem bound on error
+    while (gmp_abs(term*s) > eps) {
+        s += term;
         i += 1;
         term *= x;
         term /= i;
-        s += term;
     }
     return s;
 }

include/output/cirq.hpp

@@ -375,7 +375,7 @@ class CirqOutputter final : public ast::Visitor {
     }
 };
 
-/** \brief Writes an AST in Cirq format to a stdout */
+/** \brief Writes an AST in Cirq format to stdout */
 void output_cirq(ast::Program& prog) {
     CirqOutputter outputter(std::cout);
     outputter.run(prog);

include/output/ionq.hpp

@@ -0,0 +1,243 @@
+/*
+ * This file is part of staq.
+ *
+ * Copyright (c) 2019 - 2023 softwareQ Inc. All rights reserved.
+ *
+ * MIT License
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * \file output/ionq.hpp
+ * \brief IonQ outputter
+ */
+
+#ifndef OUTPUT_IONQ_HPP_
+#define OUTPUT_IONQ_HPP_
+
+#include <fstream>
+#include <iomanip>
+#include <typeinfo>
+
+#include "qasmtools/ast/ast.hpp"
+
+namespace staq {
+namespace output {
+
+namespace ast = qasmtools::ast;
+
+/** \brief Equivalent IonQ standard gates for qasm standard gates */
+std::unordered_map<std::string, std::string> qasmstd_to_ionq{
+    {"sdg", "si"}, {"tdg", "ti"}, {"u1", "rz"}};
+
+/**
+ * \class staq::output::IonQOutputter
+ * \brief Visitor for converting a QASM AST to IonQ
+ */
+class IonQOutputter final : public ast::Visitor {
+  public:
+    IonQOutputter(std::ostream& os) : Visitor(), os_(os) {}
+    ~IonQOutputter() = default;
+
+    void run(ast::Program& prog) {
+        prefix_ = "";
+        first_gate = true;
+
+        prog.accept(*this);
+    }
+
+    // Variables
+    void visit(ast::VarAccess& ap) {}
+
+    // Expressions
+    void visit(ast::BExpr& expr) {}
+
+    void visit(ast::UExpr& expr) {}
+
+    void visit(ast::PiExpr&) {}
+
+    void visit(ast::IntExpr& expr) {}
+
+    void visit(ast::RealExpr& expr) {}
+
+    void visit(ast::VarExpr& expr) {}
+
+    // Statements
+    void visit(ast::MeasureStmt& stmt) {}
+
+    void visit(ast::ResetStmt& stmt) {}
+
+    void visit(ast::IfStmt& stmt) {}
+
+    // Gates
+    void visit(ast::UGate& gate) {}
+
+    void visit(ast::CNOTGate& gate) {}
+
+    void visit(ast::BarrierGate&) {}
+
+    void visit(ast::DeclaredGate& gate) {
+        // JSON output: avoid outputting comma before first gate
+        if (first_gate) {
+            first_gate = false;
+        } else {
+            os_ << ",\n";
+        }
+
+        os_ << prefix_ << "{\n";
+        prefix_ += "    ";
+
+        std::string name = gate.name();
+        if (auto it = qasmstd_to_ionq.find(gate.name());
+            it != qasmstd_to_ionq.end())
+            name = it->second;
+
+        int cur_qarg = 0;
+        bool ctrl = false;
+        // Handle control gates
+        // Control is the first qarg, if applicable
+        if (name[0] == 'c') {
+            cur_qarg = 1;
+            ctrl = true;
+            name = name.substr(1);
+        }
+
+        // IonQ handles gates with multiple control args,
+        //  but the QE standard gates have at most one control arg.
+        if (ctrl) {
+            os_ << prefix_ << "\"control\": " << gate.qarg(0).offset().value()
+                << ",\n";
+        }
+
+        if (gate.num_qargs() - cur_qarg == 1) {
+            // Single target gate
+            os_ << prefix_
+                << "\"target\": " << gate.qarg(cur_qarg).offset().value()
+                << ",\n";
+        } else {
+            // Multi target gate
+            os_ << prefix_ << "\"targets\": [";
+            for (int i = cur_qarg; i < gate.num_qargs(); ++i) {
+                os_ << gate.qarg(i).offset().value();
+                if (i + 1 != gate.num_qargs())
+                    os_ << ",";
+            }
+
+            os_ << "],\n";
+        }
+
+        if (gate.num_cargs()) {
+            // TODO: assert that there is exactly one carg
+            // TODO: assert that this is a rotation gate
+            // TODO: Handle multiples of pi nicely
+            os_ << prefix_ << "\"angle\": " << std::fixed
+                << gate.carg(0).constant_eval().value() / qasmtools::utils::pi << ",\n";
+        }
+
+        os_ << prefix_ << "\"gate\": \"" << name << "\"\n"; // no comma
+
+        prefix_.resize(prefix_.size() - 4);
+        os_ << prefix_
+            << "}"; // Do not output newline for proper JSON formatting
+    }
+
+    // Declarations
+    void visit(ast::GateDecl& decl) {}
+
+    void visit(ast::OracleDecl& decl) {}
+
+    void visit(ast::RegisterDecl& decl) {
+        if (decl.is_quantum()) {
+            os_ << prefix_ << "\"qubits\": " << decl.size() << ",\n";
+        } else {
+            // should never occur
+        }
+    }
+
+    void visit(ast::AncillaDecl& decl) {}
+
+    // Program
+    void visit(ast::Program& prog) {
+        os_ << prefix_ << "{\n";
+        prefix_ += "    ";
+
+        os_ << prefix_ << "\"format\": \"ionq.circuit.v0\",\n";
+        os_ << prefix_ << "\"gateset\": \"qis\",\n";
+
+        // Print the qubit count line (global register decl)
+        prog.foreach_stmt([this](auto& stmt) {
+            if (typeid(stmt) == typeid(ast::RegisterDecl))
+                stmt.accept(*this);
+        });
+
+        os_ << prefix_ << "\"circuit\": [\n";
+        prefix_ += "    ";
+
+        // Program body
+        prog.foreach_stmt([this](auto& stmt) {
+            // Skip the gate declarations from qelib1.inc
+            // and the global register decl
+            if ((typeid(stmt) != typeid(ast::GateDecl)) &&
+                (typeid(stmt) != typeid(ast::RegisterDecl)))
+                stmt.accept(*this);
+        });
+
+        // Close circuit
+        os_ << "\n";
+        prefix_.resize(prefix_.size() - 4);
+        os_ << prefix_ << "]\n";
+
+        // Close input
+        prefix_.resize(prefix_.size() - 4);
+        os_ << prefix_ << "}\n";
+    }
+
+  private:
+    std::ostream& os_;
+
+    std::string prefix_ = "";
+    bool first_gate = true;
+};
+
+/** \brief Writes an AST in IonQ format to stdout */
+void output_ionq(ast::Program& prog) {
+    IonQOutputter outputter(std::cout);
+    outputter.run(prog);
+}
+
+/** \brief Writes an AST in IonQ format to a given output stream */
+void write_ionq(ast::Program& prog, std::string fname) {
+    std::ofstream ofs;
+    ofs.open(fname);
+
+    if (!ofs.good()) {
+        std::cerr << "Error: failed to open output file " << fname << "\n";
+    } else {
+        IonQOutputter outputter(ofs);
+        outputter.run(prog);
+    }
+
+    ofs.close();
+}
+
+} /* namespace output */
+} /* namespace staq */
+
+#endif /* OUTPUT_IONQ_HPP_ */

include/output/projectq.hpp

@@ -431,7 +431,7 @@ class ProjectQOutputter final : public ast::Visitor {
     }
 };
 
-/** \brief Writes an AST in ProjectQ format to a stdout */
+/** \brief Writes an AST in ProjectQ format to stdout */
 void output_projectq(ast::Program& prog) {
     ProjectQOutputter outputter(std::cout);
     outputter.run(prog);

include/output/qsharp.hpp

@@ -372,7 +372,7 @@ class QSharpOutputter final : public ast::Visitor {
     bool ambiguous_ = false;
 };
 
-/** \brief Writes an AST in Q# format to a stdout */
+/** \brief Writes an AST in Q# format to stdout */
 void output_qsharp(ast::Program& prog) {
     QSharpOutputter outputter(std::cout);
     outputter.run(prog);

include/output/quil.hpp

@@ -340,7 +340,7 @@ class QuilOutputter final : public ast::Visitor {
     std::unordered_map<ast::symbol, std::pair<int, int>> globals_{};
 };
 
-/** \brief Writes an AST in Quil format to a stdout */
+/** \brief Writes an AST in Quil format to stdout */
 void output_quil(ast::Program& prog) {
     QuilOutputter outputter(std::cout);
     outputter.run(prog);