tuned makefile flags

Author: DiamonDinoia

CMakeLists.txt

@@ -12,15 +12,13 @@ if (CMAKE_CXX_COMPILER_ID IN_LIST GNU_LIKE_FRONTENDS)
     set(FINUFFT_CXX_FLAGS_RELEASE -O3
             -funroll-loops
             -ffp-contract=fast
-            -fexcess-precision=fast
             -fno-math-errno
             -fno-signed-zeros
             -fno-trapping-math
             -fassociative-math
             -freciprocal-math
             -fmerge-all-constants
             -ftree-vectorize
-
     )
     # if -fimplicit-constexpr is supported, add it to the list of flags
     check_cxx_compiler_flag("-fimplicit-constexpr" COMPILER_SUPPORTS_FIMPLICIT_CONSTEXPR)

makefile

@@ -27,7 +27,11 @@ PYTHON = python3
 # Notes: 1) -Ofast breaks isfinite() & isnan(), so use -O3 which now is as fast
 #        2) -fcx-limited-range for fortran-speed complex arith in C++
 #        3) we use simply-expanded (:=) makefile variables, otherwise confusing
-CFLAGS := -O3 -funroll-loops -march=native -fcx-limited-range -ffp-contract=fast $(CFLAGS)
+# 		 4) the extra math flags are for speed, but they do not impact accuracy
+#           they allow gcc to vectorize the code more effectively
+CFLAGS := -O3 -funroll-loops -march=native -fcx-limited-range -ffp-contract=fast\
+		  -fno-math-errno -fno-signed-zeros -fno-trapping-math -fassociative-math\
+		  -freciprocal-math -fmerge-all-constants -ftree-vectorize $(CFLAGS)
 FFLAGS := $(CFLAGS) $(FFLAGS)
 CXXFLAGS := $(CFLAGS) $(CXXFLAGS)
 # FFTW base name, and math linking...