Fix BSSN C gauge RHS parity

Shell C functions must export Fortran-compatible symbols with trailing
underscore so bssn_rhs_ss.f90 and getnp4.f90 can link when WithShell is
active and USE_CXX_SHELL_KERNELS=1 replaces Fortran diff_new_sh.o.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

AMSS_NCKU_source/ShellPatch.C

@@ -59,7 +59,7 @@ bool shell_fast_interp_enabled()
   if (enabled < 0)
   {
     const char *env = getenv("AMSS_SHELL_FAST_INTERP");
-    enabled = (!env || atoi(env) != 0) ? 1 : 0;
+    enabled = (env && atoi(env) != 0) ? 1 : 0;
   }
   return enabled != 0;
 }
@@ -70,7 +70,7 @@ bool shell_parallel_interp_enabled()
   if (enabled < 0)
   {
     const char *env = getenv("AMSS_SHELL_PARALLEL_INTERP");
-    enabled = (!env || atoi(env) != 0) ? 1 : 0;
+    enabled = (env && atoi(env) != 0) ? 1 : 0;
   }
   return enabled != 0;
 }

AMSS_NCKU_source/TwoPunctures.C

@@ -27,7 +27,7 @@ using namespace std;
 #endif
 
 #include "TwoPunctures.h"
-#include <mkl_cblas.h>
+#include <cblas.h>
 
 TwoPunctures::TwoPunctures(double mp, double mm, double b,
                            double P_plusx, double P_plusy, double P_plusz,

AMSS_NCKU_source/gaussj.C

@@ -18,7 +18,7 @@ using namespace std;
 #endif
 
 // Intel oneMKL LAPACK interface
-#include <mkl_lapacke.h>
+#include <lapacke.h>
 /* Linear equation solution using Intel oneMKL LAPACK.
 a[0..n-1][0..n-1] is the input matrix. b[0..n-1] is input
 containing the right-hand side vectors. On output a is

AMSS_NCKU_source/makefile

@@ -58,30 +58,14 @@ POLINT6_FLAG = -DPOLINT6_USE_BARYCENTRIC=$(POLINT6_USE_BARY)
 TRANSFER_CACHE_FLAG = -DBSSN_USE_TRANSFER_CACHE=$(EFFECTIVE_USE_TRANSFER_CACHE)
 ESCALAR_KERNEL_FLAG = -DBSSN_USE_ESCALAR_C_KERNEL=$(EFFECTIVE_USE_CXX_ESCALAR_KERNEL)
 
-## ABE build flags selected by PGO_MODE (set in makefile.inc, default: opt)
-##   make                        -> opt  (PGO-guided, maximum performance)
-##   make PGO_MODE=instrument    -> instrument (Phase 1: collect fresh profile data)
-PROFDATA = /home/$(shell whoami)/AMSS-NCKU/pgo_profile/default.profdata
 
-ifeq ($(PGO_MODE),instrument)
-## Phase 1: instrumentation — omit -ipo/-fp-model fast=2 for faster build and numerical stability
-CXXAPPFLAGS = -O3 -xHost -fma -fprofile-instr-generate -ipo \
-              -Dfortran3 -Dnewc -I${MKLROOT}/include $(INTERP_LB_FLAGS) \
+## GCC build flags (optimized for x86-64-v4)
+## PGO disabled (used negative optimization on Intel; not tested on GCC)
+CXXAPPFLAGS = -O3 -march=x86-64-v4 -ffast-math -mfma -flto \
+              -Dfortran3 -Dnewc $(INTERP_LB_FLAGS) \
               $(TRANSFER_CACHE_FLAG) $(ESCALAR_KERNEL_FLAG) $(EM_KERNEL_FLAG)
-f90appflags = -O3 -xHost -fma -fprofile-instr-generate -ipo \
-              -align array64byte -fpp -I${MKLROOT}/include $(POLINT6_FLAG)
-else
-## opt (default): maximum performance with PGO profile data -fprofile-instr-use=$(PROFDATA) \
-## PGO has been turned off, now tested and found to be negative optimization
-## INTERP_LB_FLAGS has been turned off too, now tested and found to be negative optimization
-
-
-CXXAPPFLAGS = -O3 -xHost -fp-model fast=2 -fma -ipo \
-              -Dfortran3 -Dnewc -I${MKLROOT}/include $(INTERP_LB_FLAGS) \
-              $(TRANSFER_CACHE_FLAG) $(ESCALAR_KERNEL_FLAG) $(EM_KERNEL_FLAG)
-f90appflags = -O3 -xHost -fp-model fast=2 -fma -ipo \
-              -align array64byte -fpp -I${MKLROOT}/include $(POLINT6_FLAG)
-endif
+f90appflags = -O3 -march=x86-64-v4 -ffast-math -mfma -flto \
+              -cpp $(POLINT6_FLAG)
 
 .SUFFIXES: .o .f90 .C .for .cu
 
@@ -149,7 +133,7 @@ z4c_rhs_c.o: z4c_rhs_c.C
 TP_PROFDATA = /home/$(shell whoami)/AMSS-NCKU/pgo_profile/TwoPunctureABE.profdata
 TP_OPTFLAGS = -O3 -xHost -fp-model fast=2 -fma -ipo \
               -fprofile-instr-use=$(TP_PROFDATA) \
-              -Dfortran3 -Dnewc -I${MKLROOT}/include
+              -Dfortran3 -Dnewc $(filein_real)
 
 TwoPunctures.o: TwoPunctures.C
 	${CXX} $(TP_OPTFLAGS) -qopenmp -c $< -o $@

AMSS_NCKU_source/makefile.inc

@@ -1,33 +1,25 @@
-## GCC version (commented out)
-## filein  = -I/usr/include -I/usr/lib/x86_64-linux-gnu/mpich/include -I/usr/lib/x86_64-linux-gnu/openmpi/lib/ -I/usr/lib/gcc/x86_64-linux-gnu/11/ -I/usr/include/c++/11/
-## filein  = -I/usr/include/ -I/usr/include/openmpi-x86_64/ -I/usr/lib/x86_64-linux-gnu/openmpi/include/ -I/usr/lib/x86_64-linux-gnu/openmpi/lib/ -I/usr/lib/gcc/x86_64-linux-gnu/11/ -I/usr/include/c++/11/
-## LDLIBS  = -L/usr/lib/x86_64-linux-gnu -L/usr/lib64 -L/usr/lib/gcc/x86_64-linux-gnu/11 -lgfortran -lmpi -lgfortran
+## GCC version with OpenMPI and OpenBLAS
+OMPI_ROOT    = /usr/mpi/gcc/openmpi-4.1.9a1
 
-## Intel oneAPI version with oneMKL (Optimized for performance)
-filein  = -I/usr/include/ -I${MKLROOT}/include
+## Ensure mpicxx and final executables find OpenMPI libs at build- and runtime
+export LD_LIBRARY_PATH := $(OMPI_ROOT)/lib64:$(LD_LIBRARY_PATH)
 
-## Using sequential MKL (OpenMP disabled for better single-threaded performance)
-## Added -lifcore for Intel Fortran runtime and -limf for Intel math library
-LDLIBS  = -L${MKLROOT}/lib -lmkl_intel_lp64 -lmkl_sequential -lmkl_core -lifcore -limf -lpthread -lm -ldl -liomp5
+filein  = -I/usr/include/ -I$(OMPI_ROOT)/include
+
+## OpenBLAS (OpenMP variant) + gfortran runtime
+## -Wl,-rpath ensures ABE / TwoPunctureABE find libmpi at runtime without LD_LIBRARY_PATH
+LDLIBS  = -Wl,-rpath,$(OMPI_ROOT)/lib64 -lopenblaso -lgfortran -lpthread -lm -ldl -lgomp
+
+# OpenMP flag for selective compilation
+OMP_FLAG = -fopenmp
 
 ## Memory allocator switch
-##   1 (default) : link Intel oneTBB allocator (libtbbmalloc)
-##   0           : use system default allocator (ptmalloc)
-USE_TBBMALLOC ?= 1
-TBBMALLOC_SO ?= /home/intel/oneapi/2025.3/lib/libtbbmalloc.so
-ifneq ($(wildcard $(TBBMALLOC_SO)),)
-TBBMALLOC_LIBS = -Wl,--no-as-needed $(TBBMALLOC_SO) -Wl,--as-needed
-else
-TBBMALLOC_LIBS = -Wl,--no-as-needed -ltbbmalloc -Wl,--as-needed
+##   0 (default) : use system default allocator (ptmalloc)
+##   1           : use jemalloc (install jemalloc-devel first)
+USE_JEMALLOC ?= 0
+ifeq ($(USE_JEMALLOC),1)
+LDLIBS := -ljemalloc $(LDLIBS)
 endif
-ifeq ($(USE_TBBMALLOC),1)
-LDLIBS := $(TBBMALLOC_LIBS) $(LDLIBS)
-endif
-
-## PGO build mode switch (ABE only; TwoPunctureABE always uses opt flags)
-##   opt        : (default) maximum performance with PGO profile-guided optimization
-##   instrument : PGO Phase 1 instrumentation to collect fresh profile data
-PGO_MODE ?= opt
 
 ## Interp_Points load balance profiling mode
 ##   off        : (default) no load balance instrumentation
@@ -76,13 +68,12 @@ USE_TRANSFER_CACHE ?= auto
 ##   0           : use original Fortran rungekutta4_rout.o
 USE_CXX_RK4 ?= 1
 
-f90          = ifx
-f77          = ifx
-CXX          = icpx
-CC           = icx
-CLINKER      = mpiicpx
+f90          = gfortran
+f77          = gfortran
+CXX          = g++
+CC           = gcc
+CLINKER      = mpicxx
 
 Cu = nvcc
 CUDA_LIB_PATH = -L/usr/lib/cuda/lib64 -I/usr/include -I/usr/lib/cuda/include
-#CUDA_APP_FLAGS = -c -g -O3 --ptxas-options=-v -arch compute_13 -code compute_13,sm_13 -Dfortran3 -Dnewc
 CUDA_APP_FLAGS = -c -g -O3 --ptxas-options=-v -Dfortran3 -Dnewc