Choose BLAS library path (#543)

* Search blas library under specified dir (-DBLAS_LIB_PATH)
* BLAS_LIB_PATH flag explanation

CHANGELOG.md

@@ -21,6 +21,8 @@ Changelog](http://keepachangelog.com/en/1.0.0/).
 Added
 -----
 - Added high level pulse simulator tests (\#379)
+- CMake BLAS_LIB_PATH flag to set path to look for BLAS lib (\#543) 
+
 Changed
 -------
 

CMakeLists.txt

@@ -26,6 +26,7 @@ option(BUILD_TESTS "Specify whether we want to build tests or not" FALSE)
 include(CTest)
 include(compiler_utils)
 include(Linter)
+include(findBLASInSpecificPath)
 
 # Get version information
 get_version(${VERSION_NUM})
@@ -156,25 +157,26 @@ if(STATIC_LINKING)
 	set(BLA_STATIC TRUE)
 endif()
 
-if(APPLE)
-	message(STATUS "Looking for Apple BLAS library...")
-    set(BLA_VENDOR "Apple")
+if(BLAS_LIB_PATH)
+	find_BLAS_in_specific_path(${BLAS_LIB_PATH})
 else()
-	message(STATUS "Looking for OpenBLAS library...")
-    set(BLA_VENDOR "OpenBLAS")
-endif()
-
-if(WIN32)
-	message(STATUS "Uncompressing OpenBLAS static library...")
-	execute_process(COMMAND ${CMAKE_COMMAND} -E tar "xvfj" "${AER_SIMULATOR_CPP_SRC_DIR}/third-party/win64/lib/openblas.7z"
-		WORKING_DIRECTORY  "${AER_SIMULATOR_CPP_SRC_DIR}/third-party/win64/lib/")
-endif()
-
-find_package(BLAS QUIET)
-if(NOT BLAS_FOUND)
-	message(STATUS "OpenBLAS not found. Looking for any other BLAS library...")
-	unset(BLA_VENDOR)
-	find_package(BLAS REQUIRED)
+	if(APPLE)
+		message(STATUS  "Looking for Apple BLAS library...")
+		set(BLA_VENDOR "Apple")
+	else()
+		message(STATUS "Looking for OpenBLAS library...")
+		set(BLA_VENDOR "OpenBLAS")
+	endif()
+	if(WIN32)
+		message(STATUS "Uncompressing OpenBLAS static library...")
+		execute_process(COMMAND ${CMAKE_COMMAND} -E tar "xvfj" "${AER_SIMULATOR_CPP_SRC_DIR}/third-party/win64/lib/openblas.7z" WORKING_DIRECTORY  "${AER_SIMULATOR_CPP_SRC_DIR}/third-party/win64/lib/")
+	endif()
+	find_package(BLAS QUIET)
+	if(NOT BLAS_FOUND)
+		message(STATUS "OpenBLAS not found. Looking for any other BLAS library...")
+		unset(BLA_VENDOR)
+		find_package(BLAS REQUIRED)
+	endif()
 endif()
 
 message(STATUS "BLAS library found: ${BLAS_LIBRARIES}")

CONTRIBUTING.md

@@ -257,6 +257,14 @@ USER_LIB_PATH
     Default: No value.
     Example: ``cmake -DUSER_LIB_PATH=C:\path\to\openblas\libopenblas.so ..``
 
+BLAS_LIB_PATH
+    Tells CMake the directory to look for the BLAS library instead of the usual paths.
+    If no BLAS library is found under that directory, CMake will raise an error and stop.
+
+    Values: An absolute path with file included.
+    Default: No value.
+    Example: ``cmake -DBLAS_LIB_PATH=/path/to/look/for/blas/ ..``
+
 STATIC_LINKING
     Tells the build system whether to create static versions of the programs being built or not.
     NOTE: On MacOS static linking is not fully working for all versions of GNU G++/Clang
@@ -300,6 +308,18 @@ qiskit-aer$ python ./setup.py install
 qiskit-aer$ python -m unittest discover -s test -v
 ```
 
+Alternatively you can run the integration tests in parallel using `stestr`.
+```
+qiskit-aer$ stestr run --slowest
+```
+
+The `slowest` option will print the slowest tests at the end. 
+Manual for `stestr` can be found [here](https://stestr.readthedocs.io/en/latest/MANUAL.html#).
+You may need to install it:
+```
+qiskit-aer$ pip install stestr
+```
+
 The integration tests for Terra addon are included in: `test/terra`.
 
 

cmake/findBLASInSpecificPath.cmake

@@ -0,0 +1,54 @@
+function(find_blas_in_specific_path BLAS_LIB_PATH)
+
+    function(check_blas_lib_found BLAS_LIB_PATH BLAS_LIBS BLAS_FOUND)
+        # This function is intented to be called only from find_blas_in_specific_path
+        # Check if the lib has been found and if it was in a sub of the provided path.
+        # FindBLAS.cmake always search some standard paths so, if no lib is found
+        # below provided BLAS_LIB_PATH, it could have found the BLAS lib at some other place
+        # and not where the user specified
+        if(NOT BLAS_FOUND)
+            return()
+        endif()
+        list(GET BLAS_LIBS 0 FIRST_BLAS_PATH)
+        # Need to add final separator in order to check if BLAS_LIB_PATH is a
+        # parent directory for BLAS_LIBS
+        string(APPEND BLAS_LIB_PATH "/") # already in CMake format
+        file(TO_CMAKE_PATH ${FIRST_BLAS_PATH} FIRST_BLAS_PATH)
+        string(APPEND FIRST_BLAS_PATH "/") # already in CMake format
+        string(FIND ${FIRST_BLAS_PATH} ${BLAS_LIB_PATH} BLAS_DIR_MATCH)
+        if(NOT BLAS_FOUND OR NOT BLAS_DIR_MATCH STREQUAL "0")
+            set(BLAS_FOUND FALSE PARENT_SCOPE)
+        endif()
+    endfunction()
+
+    get_filename_component(BLAS_LIB_PATH ${BLAS_LIB_PATH} ABSOLUTE)
+    message(STATUS "Looking for BLAS library in user defined dir: ${BLAS_LIB_PATH}")
+    file(TO_CMAKE_PATH ${BLAS_LIB_PATH} BLAS_LIB_PATH)
+    if(NOT IS_DIRECTORY ${BLAS_LIB_PATH})
+        message(FATAL_ERROR "${BLAS_LIB_PATH} is not a valid directory")
+    endif()
+
+    # Modify CMAKE_PREFIX_PATH locally to only search in provided dir
+    # (though FindBLAS ALWAYS search certain system dirs)
+    set(CMAKE_PREFIX_PATH ${BLAS_LIB_PATH})
+
+    find_package(BLAS QUIET)
+    # Check if BLAS libs are under provided DIR
+    check_blas_lib_found(${BLAS_LIB_PATH} ${BLAS_LIBRARIES} ${BLAS_FOUND})
+
+    if(NOT BLAS_FOUND AND APPLE)
+        # We may need to search for specific APPLE framework
+        # Try again setting the BLA_VENDOR to APPLE
+        set(BLA_VENDOR "Apple")
+        find_package(BLAS QUIET)
+        check_blas_lib_found(${BLAS_LIB_PATH} ${BLAS_LIBRARIES} ${BLAS_FOUND})
+    endif()
+
+    if(NOT BLAS_FOUND)
+        message(FATAL_ERROR "BLAS library not found in dir: ${BLAS_LIB_PATH}")
+    endif()
+
+    set(BLAS_LIBRARIES ${BLAS_LIBRARIES} PARENT_SCOPE)
+    set(BLAS_FOUND ${BLAS_FOUND} PARENT_SCOPE)
+    set(BLAS_LINKER_FLAGS ${BLAS_LINKER_FLAGS} PARENT_SCOPE)
+endfunction()