CMake improvements! (#468)

* CMake improvements:
* Static linking is not the default anymore.
* Platform Wheel Tag is now configurable via cmake variable.
* Updated documentation
* CI config file updated accordingly
* Added support for Win64 builds on Visual Studio 2017
* Windows C++ Simulator now links with a prebuilt version of
  OpenBLAS (64 bits), so there's no need to link against
  LAPACK anymore
* cmake added as a dependency
* Restored --static-libgcc flag for static MacOS builds so gcc
  can create *semi* static executables again. Clang doesn't have
  static compilation.

* Remove default WHEEL_TAG value so if not specified, the tag is
choosen by the wheel module

.travis.yml

@@ -51,7 +51,7 @@ stage_linux: &stage_linux
   dist: trusty
   language: python
   python: 3.5
-  env: CMAKE_FLAGS="-D CMAKE_CXX_COMPILER=g++-5 -D ENABLE_TARGETS_QA=False"
+  env: CMAKE_FLAGS="-D CMAKE_CXX_COMPILER=g++-5 -D ENABLE_TARGETS_QA=False -D WHEEL_TAG=-pmanylinux1_x86_64 -D STATIC_LINKING=True"
   addons:
     apt:
       sources:
@@ -66,7 +66,7 @@ stage_osx: &stage_osx
   os: osx
   osx_image: xcode9.2
   language: generic
-  env: CMAKE_FLAGS="-D CMAKE_CXX_COMPILER=g++-6 -D ENABLE_TARGETS_QA=False"
+  env: CMAKE_FLAGS="-D CMAKE_CXX_COMPILER=g++-6 -D ENABLE_TARGETS_QA=False -D STATIC_LINKING=True"
   before_install:
     # Travis does not provide support for Python 3 under osx - it needs to be
     # installed manually.

CONTRIBUTING.rst

@@ -83,6 +83,65 @@ more info about where to find libphreads.a for later building. Furthermore,
 we are forcing CMake to generate MingGW makefiles, because we don't support
 other toolchain at the moment.
 
+Useful CMake flags
+------------------
+
+There are some useful flags that can be set during cmake command invocation and
+will help you change some default behavior. To make use of them, you just need to
+pass them right after ``-D`` cmake argument. Example:
+.. code::
+
+    qiskit-sdk-py/out$ cmake -DUSEFUL_FLAG=Value ..
+
+Flags:
+
+USER_LIB_PATH
+    This flag tells CMake to look for libraries that are needed by some of the native
+    components to be built, but they are not in a common place where CMake could find
+    it automatically.
+    Values: An absolute path with file included.
+    Default: No value.
+    Example: ``cmake -DUSER_LIB_PATH=C:\path\to\mingw64\lib\libpthreads.a ..``
+
+STATIC_LINKING
+    Tells the build system whether to create static versions of the programs being built or not.
+    Notes: On MacOS static linking is not fully working for all versions of GNU G++/Clang
+    compilers, so enable this flag in this platform could cause errors.
+    Values: True|False
+    Default: False
+    Example: ``cmake -DSTATIC_LINKING=True ..``
+
+CMAKE_BUILD_TYPE
+    Tells the build system to create executables/libraries for debugging purposes
+    or highly optimized binaries ready for distribution.
+    Values: Debug|Release
+    Default: "Release"
+    Example: ``cmake -DCMAKE_BUILD_TYPE="Debug" ..``
+
+ENABLE_TARGETS_NON_PYTHON
+    We can enable or disable non-python code generation by setting this flag to True or False
+    respectively. This is mostly used in our CI systems so they can launch some fast tests
+    for the Python code (which is currently a majority).
+    Values: True|False
+    Default: True
+    Example: ``cmake -DENABLE_TARGETS_NON_PYTHON=True ..``
+
+ENABLE_TARGETS_QA
+    We can enable or disable QA stuff (lintering, styling and testing) by setting this flag to
+    True or False respectively. This is mostly used in our CI systems so they can run light
+    stages pretty fast, and fail fast if they found any issues within the code.
+    Values: True|False
+    Default: True
+    Example: ``cmake -DENABLE_TARGETS_QA=True ..``
+
+WHEEL_TAG
+    This is used to force platform specific tag name generation when creating wheels package
+    for Pypi.
+    Values: "-pWhateverTagName"
+    Default: No value.
+    Example: ``cmake -DWHEEL_TAG="-pmanylinux1_x86_64" ..``
+
+
 Test
 ~~~~
 

cmake/defaults.cmake

@@ -1,9 +1,14 @@
 # Default values for global scope variables.
 # They can be overriden by passing -DVARIABLE=Value to cmake, like:
-#     out$ cmake -DSTATIC_LINKING=False ..
+#     out$ cmake -DSTATIC_LINKING=True ..
 #
 
 set(CMAKE_BUILD_TYPE "Release")
-set(STATIC_LINKING True CACHE BOOL "Static linking of executables")
+set(STATIC_LINKING False CACHE BOOL "Static linking of executables")
 set(ENABLE_TARGETS_NON_PYTHON True CACHE BOOL "Enable targets for non Python code")
 set(ENABLE_TARGETS_QA True CACHE BOOL "Enable targets for QA targets")
+if(CMAKE_SIZEOF_VOID_P EQUAL 8)
+    set(ARCH64 True CACHE BOOL "We are on a 64 bits platform")
+elseif(CMAKE_SIZEOF_VOID_P EQUAL 4)
+	set(ARCH32 True CACHE BOOL "We are on a 32 bits platform")
+endif()

cmake/python-build.cmake

@@ -23,11 +23,11 @@ function(add_pypi_package_target TARGET_NAME PACKAGE_TYPE)
 
 	if(PACKAGE_TYPE STREQUAL "both")
 		set(PIP_PACKAGE_SOURCE_DIST sdist --dist-dir ${CMAKE_CURRENT_BINARY_DIR}/dist)
-		set(PIP_PACKAGE_PLATFORM_WHEELS bdist_wheel -p manylinux1_x86_64 --dist-dir ${CMAKE_CURRENT_BINARY_DIR}/dist)
+		set(PIP_PACKAGE_PLATFORM_WHEELS bdist_wheel ${WHEEL_TAG} --dist-dir ${CMAKE_CURRENT_BINARY_DIR}/dist)
 	elseif(PACKAGE_TYPE STREQUAL "sdist")
 		set(PIP_PACKAGE_SOURCE_DIST sdist --dist-dir ${CMAKE_CURRENT_BINARY_DIR}/dist)
 	elseif(PACKAGE_TYPE STREQUAL "bdist_wheel")
-		set(PIP_PACKAGE_PLATFORM_WHEELS bdist_wheel -p manylinux1_x86_64 --dist-dir ${CMAKE_CURRENT_BINARY_DIR}/dist)
+		set(PIP_PACKAGE_PLATFORM_WHEELS bdist_wheel ${WHEEL_TAG} --dist-dir ${CMAKE_CURRENT_BINARY_DIR}/dist)
 	endif()
 
 	# For ' make clean' target

requirements.txt

@@ -6,3 +6,4 @@ ply==3.10
 scipy>=0.19,<1.1
 sympy>=1.0
 pillow>=4.2.1
+cmake>=3.11,<3.12

src/qasm-simulator-cpp/CMakeLists.txt

@@ -39,35 +39,40 @@ set_target_properties(qasm_simulator_cpp PROPERTIES LINKER_LANGUAGE CXX)
 # Toolchain options
 set_property(TARGET qasm_simulator_cpp PROPERTY CXX_STANDARD 11)
 
-# Compiler flags
-enable_cxx_compiler_flag_if_supported("-O3")
-enable_cxx_compiler_flag_if_supported("-march=native")
-enable_cxx_compiler_flag_if_supported("-fopenmp")
-
-# We force static linking on Windows
-if(STATIC_LINKING OR MINGW)
+if(STATIC_LINKING)
 	# Hack: Seems like enable_cxx_compiler_flag_if_supported() is not properly
 	# working on MacOS, when a flag is not supported, it cascades errors
 	# to the rest of the flags being tested... and -static compilation on Mac
 	# with gcc is failing...
-	if(NOT APPLE)
-		enable_cxx_compiler_flag_if_supported("-static")
-    	enable_cxx_compiler_flag_if_supported("-static-libgcc")        
+	if(APPLE AND CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+	    message(WARNING "Clang on MacOS doesn't support some -static-* flags. Switching to dyn compilation...")
+	else()
+	    # MacOS compilers don't support -static flag either
+	    if(NOT APPLE)
+	        enable_cxx_compiler_flag_if_supported("-static")
+	    endif()
+	    # This is enough to build a semi-static executable on Mac
+	    enable_cxx_compiler_flag_if_supported("-static-libgcc")
+	    enable_cxx_compiler_flag_if_supported("-static-libstdc++")
 	endif()
-	enable_cxx_compiler_flag_if_supported("-static-libstdc++")
 endif()
 
-# Warnings and Errors
-enable_cxx_compiler_flag_if_supported("-pedantic")
-enable_cxx_compiler_flag_if_supported("-Wall")
-enable_cxx_compiler_flag_if_supported("-Wfloat-equal")
-enable_cxx_compiler_flag_if_supported("-Wundef")
-enable_cxx_compiler_flag_if_supported("-Wcast-align")
-enable_cxx_compiler_flag_if_supported("-Wwrite-strings")
-enable_cxx_compiler_flag_if_supported("-Wmissing-declarations")
-enable_cxx_compiler_flag_if_supported("-Wredundant-decls")
-enable_cxx_compiler_flag_if_supported("-Wshadow")
-enable_cxx_compiler_flag_if_supported("-Woverloaded-virtual")
+if(NOT MSVC)
+	# Compiler flags
+	enable_cxx_compiler_flag_if_supported("-O3")
+	enable_cxx_compiler_flag_if_supported("-march=native")
+	# Warnings and Errors
+	enable_cxx_compiler_flag_if_supported("-pedantic")
+	enable_cxx_compiler_flag_if_supported("-Wall")
+	enable_cxx_compiler_flag_if_supported("-Wfloat-equal")
+	enable_cxx_compiler_flag_if_supported("-Wundef")
+	enable_cxx_compiler_flag_if_supported("-Wcast-align")
+	enable_cxx_compiler_flag_if_supported("-Wwrite-strings")
+	enable_cxx_compiler_flag_if_supported("-Wmissing-declarations")
+	enable_cxx_compiler_flag_if_supported("-Wredundant-decls")
+	enable_cxx_compiler_flag_if_supported("-Wshadow")
+	enable_cxx_compiler_flag_if_supported("-Woverloaded-virtual")
+endif()
 
 target_include_directories(qasm_simulator_cpp PRIVATE ${QASM_SIMULATOR_CPP_SRC_DIR})
 target_include_directories(qasm_simulator_cpp PRIVATE ${QASM_SIMULATOR_CPP_SRC_DIR}/backends)
@@ -76,12 +81,21 @@ target_include_directories(qasm_simulator_cpp PRIVATE ${QASM_SIMULATOR_CPP_SRC_D
 target_include_directories(qasm_simulator_cpp PRIVATE ${QASM_SIMULATOR_CPP_SRC_DIR}/third-party/headers)
 
 # For header only libraries
-SET(CMAKE_FIND_LIBRARY_PREFIXES ${CMAKE_FIND_LIBRARY_PREFIXES} "")
+SET(CMAKE_FIND_LIBRARY_PREFIXES "" ${CMAKE_FIND_LIBRARY_PREFIXES})
 SET(CMAKE_FIND_LIBRARY_SUFFIXES ${CMAKE_FIND_LIBRARY_SUFFIXES} .hpp)
 
-# We force static linking on Windows
-if(STATIC_LINKING OR MINGW)
-    SET(CMAKE_FIND_LIBRARY_SUFFIXES .a .lib ${CMAKE_FIND_LIBRARY_SUFFIXES})
+if(STATIC_LINKING)
+    SET(CMAKE_FIND_LIBRARY_SUFFIXES .a ${CMAKE_FIND_LIBRARY_SUFFIXES})
+    if(WIN32)
+        SET(CMAKE_FIND_LIBRARY_SUFFIXES .lib ${CMAKE_FIND_LIBRARY_SUFFIXES})
+    endif()
+endif()
+
+find_package(OpenMP)
+if (OPENMP_FOUND)
+    set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
+    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
+    set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${OpenMP_EXE_LINKER_FLAGS}")
 endif()
 
 # Looking for external libraries
@@ -94,44 +108,33 @@ if(NOT LIB_JSON)
     message(FATAL_ERROR "JSON library not found!. Please provide with a USER_LIB_PATH to CMake so it can be searched there")
 endif()
 
-find_library(LIB_LAPACK
-	NAMES lapack
+find_library(BLAS_LIB
+	NAMES openblas mkl blas
 	PATHS ${QASM_SIMULATOR_CPP_EXTERNAL_LIBS})
-if(NOT LIB_LAPACK)
-    message(FATAL_ERROR "LAPACK library not found!. Please provide with a USER_LIB_PATH to CMake so it can be searched there")
+if(NOT BLAS_LIB)
+	message(FATAL_ERROR "BLAS library not found!. Please provide with a USER_LIB_PATH to CMake so it can be searched there")
 endif()
 
-find_library(LIB_BLAS
-	NAMES blas
-	PATHS ${QASM_SIMULATOR_CPP_EXTERNAL_LIBS})
-if(NOT LIB_BLAS)
-    message(FATAL_ERROR "BLAS library not found!. Please provide with a USER_LIB_PATH to CMake so it can be searched there")
-endif()
-
-find_library(LIB_THREADS
-	NAMES pthread
-	PATHS ${QASM_SIMULATOR_CPP_EXTERNAL_LIBS})
-if(NOT LIB_THREADS)
-    message(FATAL_ERROR "Pthreads library not found!. Please provide with a USER_LIB_PATH to CMake so it can be searched there")
-endif()
-
-set(LIBRARIES PRIVATE ${LIB_BLAS}
-                      ${LIB_LAPACK}
-					  ${LIB_THREADS})
-
+set(LIBRARIES PRIVATE ${BLAS_LIB})
+				  
 # Linking
 target_link_libraries(qasm_simulator_cpp ${LIBRARIES})
 
 set(QASM_SIMULATOR_CPP_OUTPUT_DIR $<TARGET_FILE_DIR:qasm_simulator_cpp>
 	CACHE INTERNAL "Output directory for building QISKit C++ Simulator")
 
-if(MINGW)
-	set(QASM_SIMULATOR_CPP_THIRD_PARTY_DLLS
-		"${QASM_SIMULATOR_CPP_SRC_DIR}/third-party/win64/dll/libblas.dll"
-		"${QASM_SIMULATOR_CPP_SRC_DIR}/third-party/win64/dll/libgfortran_64-3.dll"
-		"${QASM_SIMULATOR_CPP_SRC_DIR}/third-party/win64/dll/libquadmath_64-0.dll"
-		CACHE INTERNAL "Third-party C++ Simulator DLLs")
+# TODO Windows 32 bits builds are not supported yet
+set(ARCH_BITS "64")
+if(ARCH32)
+	set(ARCH_BITS "32")
+endif()
 
+# Copying necessary .dll files to output
+# TODO look into "install()" CMake function
+if(WIN32) # Windows 64 bits is also true here
+	set(QASM_SIMULATOR_CPP_THIRD_PARTY_DLLS
+		"${QASM_SIMULATOR_CPP_SRC_DIR}/third-party/win${ARCH_BITS}/dll/openblas.dll"
+		CACHE INTERNAL "Third-party C++ Simulator DLLs")
 	foreach(dll_file ${QASM_SIMULATOR_CPP_THIRD_PARTY_DLLS})
 		add_custom_command(
 			TARGET qasm_simulator_cpp
@@ -146,7 +149,7 @@ if(MINGW)
 				${QASM_SIMULATOR_CPP_OUTPUT_DIR}/${FINAL_FILE})
 	endforeach()
 endif()
-
+	
 # Tests
 # TODO: Enable them when ready
 #add_subdirectory(${QASM_SIMULATOR_CPP_DIR}/test)

src/qasm-simulator-cpp/src/backends/ideal_backend.hpp

@@ -28,6 +28,8 @@ limitations under the License.
 #include <complex>
 #include <string>
 #include <vector>
+#define _USE_MATH_DEFINES
+#include <math.h>
 
 #include "base_backend.hpp"
 #include "qubit_vector.hpp"