MPI based implementation

.gitignore

@@ -0,0 +1,4 @@
+build
+build/*
+.cache
+.clang-format*

CMakeLists.txt

@@ -3,8 +3,7 @@ cmake_minimum_required(VERSION 3.21)
 project(CQ-SIMBE
   VERSION 0.1.0
   DESCRIPTION "CQ compliant simulated backend."
-  LANGUAGES C
-)
+  LANGUAGES C Fortran)
 
 # User configure options
 
@@ -41,19 +40,48 @@ option(
   OFF
 )
 
+option(
+  BUILD_WITH_MPI
+  "Build with MPI-based communication. Turned ON by default." 
+  OFF
+)
+message(STATUS "BUILD_WITH_MPI turned ${BUILD_WITH_MPI}.")
+
+option(
+  QUEST_BUILT_WITH_MPI
+  "Flag to define if QuEST was built with MPI. This will affect how we do the communication." 
+  OFF
+)
+message(STATUS "QUEST_BUILT_WITH_MPI turned ${QUEST_BUILT_WITH_MPI}.")
+
 # Dependencies
 
 find_package(Threads REQUIRED)
-find_package(QuEST 4.0 REQUIRED)
+find_package(QuEST REQUIRED)
 
 # CQ-SimBE Library
 
 add_library(cq-simbe)
 add_library(CQ-SIMBE::cq-simbe ALIAS cq-simbe)
 
+if (BUILD_WITH_MPI)
+  find_package(MPI COMPONENTS Fortran C REQUIRED)
+  include_directories(SYSTEM ${MPI_INCLUDE_PATH})
+  target_compile_definitions(cq-simbe PUBLIC
+    CQ_WITH_MPI_COMMS=1
+    $<$<CONFIG:Debug>:DEBUG_MODE>
+  )
+endif()
+
+if (BUILD_WITH_MPI AND QUEST_BUILT_WITH_MPI)
+    target_compile_definitions(cq-simbe PRIVATE CQ_CONF_QUEST_WITH_MPI=1)
+endif()
+
+
 target_compile_features(cq-simbe PRIVATE c_std_99)
 target_compile_options(cq-simbe PRIVATE -Wall)
 
+
 target_include_directories(cq-simbe
   PUBLIC
   $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
@@ -64,6 +92,10 @@ target_include_directories(cq-simbe
 
 target_link_libraries(cq-simbe PRIVATE Threads::Threads QuEST::QuEST)
 
+if (BUILD_WITH_MPI)
+    target_link_libraries(cq-simbe PRIVATE ${MPI_C_LIBRARIES})
+endif()
+
 if (BUILD_FORTRAN_INTERFACE)
   enable_language(Fortran)
 

examples/fortran/CMakeLists.txt

@@ -11,7 +11,11 @@ target_link_libraries(zero-qft
   ${MATHS_LIBRARY}
 )
 
-set_target_properties(zero-qft PROPERTIES Fortran_PREPROCESS ON)
+set_target_properties(zero-qft
+  PROPERTIES
+  Fortran_PREPROCESS ON
+  Fortran_MODULE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/mod/zero-qft"
+)
 
 add_executable(plus-qft
   plus_qft.f90
@@ -24,4 +28,28 @@ target_link_libraries(plus-qft
   ${MATHS_LIBRARY}
 )
 
-set_target_properties(plus-qft PROPERTIES Fortran_PREPROCESS ON)
+set_target_properties(plus-qft
+  PROPERTIES
+  Fortran_PREPROCESS ON
+  Fortran_MODULE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/mod/plus-qft"
+)
+
+if (BUILD_WITH_MPI)
+  add_executable(mpi-plus-qft
+    mpi_plus_qft.f90
+    utils.f90
+  )
+
+  target_link_libraries(mpi-plus-qft
+    PRIVATE
+    CQ-SIMBE::cq-simbe
+    ${MATHS_LIBRARY}
+    ${MPI_Fortran_LIBRARIES}
+  )
+
+  set_target_properties(mpi-plus-qft
+    PROPERTIES
+    Fortran_PREPROCESS ON
+    Fortran_MODULE_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/mod/mpi-plus-qft"
+  )
+endif()

examples/fortran/mpi_plus_qft.f90

@@ -0,0 +1,129 @@
+program plus_qft
+use mpi
+use cq
+#include "cqf.h"
+use example_utils
+implicit none
+
+integer :: ireturn, freturn, alloc_status, free_status, reg_status, qrun_status, ierr
+integer(kind=8) :: NQUBITS, NSHOTS, NMEASURE
+type(qubit) :: qrc
+integer(kind=2), allocatable, target :: cr(:)
+
+integer :: id, nproc, split_cond, cq_comm
+
+call MPI_Init(ierr)
+call MPI_Comm_size(MPI_COMM_WORLD, nproc, ierr)
+call MPI_Comm_rank(MPI_COMM_WORLD, id, ierr)
+
+if (id >= 3) then
+  split_cond = 1
+else 
+  split_cond = 0
+end if 
+
+call MPI_Comm_split(MPI_COMM_WORLD, split_cond, id, cq_comm, ierr)
+
+NQUBITS = 10
+NSHOTS = 10
+NMEASURE = NQUBITS
+
+write(*,'(A)') 'before init'
+
+if (split_cond == 1) then
+ireturn = cq_init_custom_mpi_comm(cq_comm, 1)
+
+write(*,'(A,I4)') 'cq_init returned: ',ireturn
+
+reg_status = cq_register_qkern(plus_state_qft)
+
+write(*,'(A,I4)') 'after register_qkern: ', reg_status
+
+CQ_PROG_BEGIN()
+
+alloc_status = cq_alloc_qureg(qrc, NQUBITS)
+
+write(*,'(A,I4)') 'alloc_qureg returned: ', alloc_status
+
+allocate(cr(NMEASURE * NSHOTS))
+
+CALL cq_init_creg(NMEASURE * NSHOTS, -1, cr)
+
+write(*,'(A)') 'after init_creg'
+
+qrun_status = cq_sm_qrun(plus_state_qft, qrc, NQUBITS, cr, NMEASURE, NSHOTS)
+
+write(*,'(A,I4)') 'after sm_qrun: ', qrun_status
+
+CALL report_results(cr, NMEASURE, NSHOTS)
+
+write(*,'(A)') 'after report results'
+
+free_status = cq_free_qureg(qrc)
+
+write(*,'(A,I4)') 'free_status returned: ', free_status
+
+CQ_PROG_END()
+
+freturn = cq_finalise(0)
+
+write(*,'(A,I4)') 'cq_finalise returned: ',freturn
+
+write(*,'(A)') 'after finalise'
+
+end if
+
+if (split_cond ==  0) then
+  write(*,*) 'I am user-owned rank doing something unrelated to CQ'
+end if
+
+call MPI_Barrier(MPI_COMM_WORLD, ierr)
+call MPI_Finalize(ierr)
+
+contains
+
+  subroutine qft(NQUBITS, qr)
+    implicit none
+    integer(kind=8), value :: NQUBITS
+    type(qubit), value :: qr
+    integer(kind=8) :: i, j
+    integer :: status
+    real(8), parameter :: PI = 3.1415926535897932384626433832795028841971694
+    real(8) :: angle
+
+    do i = 0, NQUBITS - 1
+      status = cq_hadamard(qr, i)
+      do j = i + 1, NQUBITS - 1 
+        angle = PI / (2.0 ** j)
+        status = cq_cphase(qr, j, i, angle)
+      end do
+    end do
+
+    do i = 0, (NQUBITS / 2) - 1
+      j = NQUBITS - (i + 1)
+      status = cq_swap(qr, i, j)
+    end do
+  end subroutine qft 
+
+  function plus_state_qft(NQUBITS, qr, NMEASURE, cr, reg) bind(C) result(status)
+    implicit none
+    integer(kind=8), value :: NQUBITS
+    type(qubit), value :: qr
+    integer(kind=8), value :: NMEASURE
+    integer(kind=2), intent(inout) :: cr(0:NMEASURE)
+    type(qkern_map), value :: reg
+    integer(kind=8) :: i
+    integer :: status
+    integer(kind=8) :: STATE_IDX = 0
+    CQ_REGISTER_KERNEL("plus_state_qft", reg)
+    status = cq_set_qureg(qr, STATE_IDX, NQUBITS)
+
+    do i = 0, NQUBITS-1
+      status = cq_hadamard(qr, i)
+    end do
+
+    call qft(NQUBITS, qr)
+    status = cq_measure_qureg(qr, NQUBITS, cr)
+  end function plus_state_qft
+
+end program

examples/fortran/plus_qft.f90

@@ -19,6 +19,12 @@ program plus_qft
 
 write(*,'(A,I4)') 'cq_init returned: ',ireturn
 
+reg_status = cq_register_qkern(plus_state_qft)
+
+write(*,'(A,I4)') 'after register_qkern: ', reg_status
+
+CQ_PROG_BEGIN()
+
 alloc_status = cq_alloc_qureg(qrc, NQUBITS)
 
 write(*,'(A,I4)') 'alloc_qureg returned: ', alloc_status
@@ -29,10 +35,6 @@ program plus_qft
 
 write(*,'(A)') 'after init_creg'
 
-reg_status = cq_register_qkern(plus_state_qft)
-
-write(*,'(A,I4)') 'after register_qkern: ', reg_status
-
 qrun_status = cq_sm_qrun(plus_state_qft, qrc, NQUBITS, cr, NMEASURE, NSHOTS)
 
 write(*,'(A,I4)') 'after sm_qrun: ', qrun_status
@@ -45,6 +47,8 @@ program plus_qft
 
 write(*,'(A,I4)') 'free_status returned: ', free_status
 
+CQ_PROG_END()
+
 freturn = cq_finalise(0)
 
 write(*,'(A,I4)') 'cq_finalise returned: ',freturn

examples/fortran/zero_qft.f90

@@ -15,10 +15,16 @@ program zero_qft
 
 write(*,'(A)') 'before init'
 
-ireturn = cq_init(0)
+ireturn = cq_init(1)
 
 write(*,'(A,I4)') 'cq_init returned: ',ireturn
 
+reg_status = cq_register_qkern(zero_state_qft)
+
+write(*,'(A,I4)') 'after register_qkern: ', reg_status
+
+CQ_PROG_BEGIN()
+
 alloc_status = cq_alloc_qureg(qrc, NQUBITS)
 
 write(*,'(A,I4)') 'alloc_qureg returned: ', alloc_status
@@ -29,11 +35,6 @@ program zero_qft
 
 write(*,'(A)') 'after init_creg'
 
-
-reg_status = cq_register_qkern(zero_state_qft)
-
-write(*,'(A,I4)') 'after register_qkern: ', reg_status
-
 qrun_status = cq_sm_qrun(zero_state_qft, qrc, NQUBITS, cr, NMEASURE, NSHOTS)
 
 write(*,'(A,I4)') 'after sm_qrun: ', qrun_status
@@ -46,7 +47,9 @@ program zero_qft
 
 write(*,'(A,I4)') 'free_status returned: ', free_status
 
-freturn = cq_finalise(0)
+CQ_PROG_END()
+
+freturn = cq_finalise(1)
 
 write(*,'(A,I4)') 'cq_finalise returned: ',freturn
 

examples/qft/CMakeLists.txt

@@ -22,4 +22,20 @@ target_link_libraries(aqft
   PRIVATE
   CQ-SIMBE::cq-simbe
   ${MATHS_LIBRARY}
-)
+)
+
+if (BUILD_WITH_MPI)
+  add_executable(mpi_aqft
+    mpi_aqft.c
+    qft-utils.c
+  )
+
+  find_library(MATHS_LIBRARY m REQUIRED)
+
+  target_link_libraries(mpi_aqft 
+    PRIVATE
+    CQ-SIMBE::cq-simbe
+    ${MATHS_LIBRARY}
+    ${MPI_C_LIBRARIES}
+  )
+endif()