Merge pull request #4677 from ye-luo/custom-isnan

Introduce qmcplusplus::isnan

src/Platforms/CPU/CMakeLists.txt

@@ -2,14 +2,17 @@
 #// This file is distributed under the University of Illinois/NCSA Open Source License.
 #// See LICENSE file in top directory for details.
 #//
-#// Copyright (c) 2020 QMCPACK developers.
+#// Copyright (c) 2023 QMCPACK developers.
 #//
 #// File developed by: Ye Luo, yeluo@anl.gov, Argonne National Laboratory
 #//
 #// File created by: Ye Luo, yeluo@anl.gov, Argonne National Laboratory
 #//////////////////////////////////////////////////////////////////////////////////////
 
-add_library(platform_cpu_runtime INTERFACE)
+# To enable a custom qmcplusplus::isnan, remove fast-math. Only the file scope CMAKE_CXX_FLAGS gets affected.
+string(REPLACE " -ffast-math" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
+
+add_library(platform_cpu_runtime math.cpp)
 target_link_libraries(platform_cpu_runtime INTERFACE Math::scalar_vector_functions)
 
 set(CPU_SRCS BlasThreadingEnv.cpp OMPThreadCountProtectorLA.cpp)

src/Platforms/CPU/math.cpp

@@ -0,0 +1,19 @@
+//////////////////////////////////////////////////////////////////////////////////////
+// This file is distributed under the University of Illinois/NCSA Open Source License.
+// See LICENSE file in top directory for details.
+//
+// Copyright (c) 2023 QMCPACK developers.
+//
+// File developed by: Ye Luo, yeluo@anl.gov, Argonne National Laboratory
+//
+// File created by: Ye Luo, yeluo@anl.gov, Argonne National Laboratory
+//////////////////////////////////////////////////////////////////////////////////////
+
+#include <cmath>
+
+namespace qmcplusplus
+{
+// To make the customized qmcplusplus::isnan always effective, this file must be compiled without -ffast-math.
+bool isnan(float a) { return a != a; }
+bool isnan(double a) { return a != a; }
+} // namespace qmcplusplus

src/Platforms/CPU/math.hpp

@@ -98,6 +98,14 @@ inline bool iszero(T a)
   return std::fpclassify(a) == FP_ZERO;
 }
 
+/** return true if the value is NaN.
+ * std::isnan can be affected by compiler the -ffast-math option and return true constantly.
+ * The customized qmcplusplus::isnan should be always effective.
+ * This requires its definition compiled without -ffast-math.
+ */
+bool isnan(float);
+bool isnan(double);
+
 }
 
 #endif

src/Platforms/tests/CPU/CMakeLists.txt

@@ -13,7 +13,7 @@ set(SRC_DIR cpu)
 set(UTEST_EXE test_${SRC_DIR})
 set(UTEST_NAME deterministic-unit_test_${SRC_DIR})
 
-add_executable(${UTEST_EXE} test_aligned_allocator.cpp test_e2iphi.cpp)
+add_executable(${UTEST_EXE} test_aligned_allocator.cpp test_e2iphi.cpp test_math.cpp)
 target_link_libraries(${UTEST_EXE} platform_runtime catch_main)
 
 add_unit_test(${UTEST_NAME} 1 1 $<TARGET_FILE:${UTEST_EXE}>)

src/Platforms/tests/CPU/test_math.cpp

@@ -0,0 +1,38 @@
+//////////////////////////////////////////////////////////////////////////////////////
+// This file is distributed under the University of Illinois/NCSA Open Source License.
+// See LICENSE file in top directory for details.
+//
+// Copyright (c) 2023 QMCPACK developers.
+//
+// File developed by: Ye Luo, yeluo@anl.gov, Argonne National Laboratory
+//
+// File created by: Ye Luo, yeluo@anl.gov, Argonne National Laboratory
+//////////////////////////////////////////////////////////////////////////////////////
+
+
+#include "catch.hpp"
+
+#include <cmath>
+#include "CPU/math.hpp"
+
+namespace qmcplusplus
+{
+
+template<typename T>
+void test_isnan()
+{
+  const T one(1);
+  T a = std::sqrt(-one);
+  T b = -a;
+  CHECK(!qmcplusplus::isnan(one));
+  CHECK(qmcplusplus::isnan(a));
+  CHECK(qmcplusplus::isnan(b));
+}
+
+TEST_CASE("isnan", "[numerics]")
+{
+  test_isnan<float>();
+  test_isnan<double>();
+}
+
+} // namespace qmcplusplus

src/QMCTools/ppconvert/CMakeLists.txt

@@ -9,7 +9,7 @@ if(CMAKE_CXX_FLAGS_RELEASE)
   string(REPLACE "-DNDEBUG" "" CMAKE_CXX_FLAGS_RELEASE ${CMAKE_CXX_FLAGS_RELEASE})
 endif()
 
-string(REPLACE "-ffast-math" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
+string(REPLACE " -ffast-math" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
 
 if(CMAKE_CROSSCOMPILING)
   message(STATUS "Cannot run std::isnan tests when cross compiling. Setting ISNAN_WORKS to FALSE.")