Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Pass ancilla buffer to XACC even if user passes multiple qregs #259

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Pass ancilla buffer to XACC even if user passes multiple qregs #259

wants to merge 1 commit into from

Commits on Dec 2, 2022

  1. Pass ancilla buffer to XACC even if user passes multiple qregs 

    This is an attempt to address the Quantum++ backend receiving
out-of-range qubit indices in some cases. For example, due to using a
different code path, this code works (thanks to Akihiro for both
examples):

    #include <qcor_arithmetic>

    __qpu__ void CUa(qreg x, int a, int N) {
        // c = |1>
        qreg c = qalloc(1);
        X(c[0]);
        // x = |3>
        X(x[0]);
        X(x[1]);
        mul_integer_mod_in_place::ctrl(c, x, a, N);
        Measure(x);
    }

    int main() {
        set_verbose(true);
        int a = 1;
        int N = 2;
        set_shots(2);
        auto x = qalloc(2);
        CUa(x, a, N);
        x.print();
    }

Yet this code throws a runtime error:

    #include <qcor_arithmetic>

    __qpu__ void CUa(qreg x, qreg c, int a, int N) {
        // c = |1>
        X(c[0]);
        // x = |3>
        X(x[0]);
        X(x[1]);
        mul_integer_mod_in_place::ctrl(c, x, a, N);
        Measure(x);
    }

    int main() {
        set_verbose(true);
        int a = 1;
        int N = 2;
        set_shots(2);
        auto x = qalloc(2);
        auto c = qalloc(1);
        CUa(x, c, a, N);
        x.print();
    }

Specifically, the error was:

    terminate called after throwing an instance of 'qpp::exception::MatrixMismatchSubsys'
      what():  In qpp::apply(): Matrix mismatch subsystems!

Or with XACC built with debug mode, the following assertion is tripped
beforehand:

    .../xacc/quantum/plugins/qpp/accelerator/QppVisitor.cpp:96: qpp::idx xacc::quantum::QppVisitor::xaccIdxToQppIdx(size_t) const: Assertion `in_idx < m_buffer->size()' failed.

With this change, this issue no longer occurs because the ancilla buffer
is passed for xacc::internal_compiler::execute(). Before,
xacc::internal_compiler::execute() noticed that some instructions were
referencing an AcceleratorBuffer `aux_temp_buffer` not in the list of
buffers passed to it and tried to recreate one, but that apparently
failed to prevent some misbehavior in this case.
    @ausbin
    ausbin committed Dec 2, 2022
    Configuration menu
    Copy the full SHA
    2410ac8 View commit details
    Browse the repository at this point in the history