This guide is modified from section (d) of the worksheet inside Module 10 of Phys 6810 Computational Physics (Spring 2023).

NOTE: gprof does not work on macOS. Please use a linux machine (such as OSC)

To use gprof, compile and link the relevant codes with the -pg option:
Take a look at the Makefile make_hello_world and modify both the CFLAGS and LDFLAGS lines to include -pg

Compile and link the script by typing
    make -f make_hello_world

Execute the program
    ./hello_world.x

With the -pg flags, the execution will generate a file called gmon.out that is used by gprof.
The program has to exit normally (e.g. we can't stop with a ctrl-C).
Warning: Any existing gmon.out file will be overwritten.

Run gprof and save the output to a file (e.g., gprof.out) by
    gprof hello_world.x > gprof.out

We should at this point see a text file called gprof.out which contains the profile of hello_world.cpp
    vim gprof.out

#include <iostream>
#include <thread>
#include <chrono>
#include <cmath>


using namespace std;

void nap(){
  // usleep(3000);
  // this_thread::sleep_for(30000ms);

  for (int i=0;i<1000000000;i++){
    double j = sqrt(i^2);
  }
}

int main(){

  cout << "taking a nap" << endl;

  nap();

  cout << "hello world" << endl;

}

SHELL=/bin/sh

# Note: Comments start with #.  $(FOOBAR) means: evaluate the variable 
#        defined by FOOBAR= (something).

# This file contains a set of rules used by the "make" command.
#   This makefile $(MAKEFILE) tells "make" how the executable $(COMMAND) 
#   should be create from the source files $(SRCS) and the header files 
#   $(HDRS) via the object files $(OBJS); type the command:
#        "make -f make_program"
#   where make_program should be replaced by the name of the makefile.
# 
# Programmer:  Dick Furnstahl (furnstahl.1@osu.edu)
# Latest revision: 12-Jan-2016 
# 
# Notes:
#  * If you are ok with the default options for compiling and linking, you
#     only need to change the entries in section 1.
#
#  * Defining BASE determines the name for the makefile (prepend "make_"), 
#     executable (append ".x"), zip archive (append ".zip") and gzipped 
#     tar file (append ".tar.gz"). 
#
#  * To remove the executable and object files, type the command:
#          "make -f $(MAKEFILE) clean"
#
#  * To create a zip archive with name $(BASE).zip containing this 
#     makefile and the SRCS and HDRS files, type the command:
#        "make -f $(MAKEFILE) zip"
#
#  * To create a gzipped tar file with name $(BASE).tar.gz containing this 
#     makefile and the source and header files, type the command:
#          "make -f $(MAKEFILE) tarz"
#
#  * Continuation lines are indicated by \ with no space after it.  
#     If you get a "missing separator" error, it is probably because there
#     is a space after a \ somewhere.
#

###########################################################################
# 1. Specify base name, source files, header files, input files
########################################################################### 

# The base for the names of the makefile, executable command, etc.
BASE= hello_world

# Put all C++ (or other) source files here.  NO SPACES after continuation \'s.
SRCS= \
hello_world.cpp

# Put all header files here.  NO SPACES after continuation \'s.
HDRS= \

# Put any input files you want to be saved in tarballs (e.g., sample files).
INPFILE= \

###########################################################################
# 2. Generate names for object files, makefile, command to execute, tar file
########################################################################### 

# *** YOU should not edit these lines unless to change naming conventions ***

OBJS= $(addsuffix .o, $(basename $(SRCS)))
MAKEFILE= make_$(BASE)
COMMAND=  $(BASE).x
TARFILE= $(BASE).tar.gz
ZIPFILE= $(BASE).zip

###########################################################################
# 3. Commands and options for different compilers
########################################################################### 

#
# Compiler parameters
#
# CXX           Name of the C++ compiler to use
# CFLAGS        Flags to the C++ compiler
# CWARNS        Warning options for C++ compiler
# F90           Name of the fortran compiler to use (if relevant) 
# FFLAGS        Flags to the fortran compiler 
# LDFLAGS       Flags to the loader
# LIBS          A list of libraries 
#

CXX= g++
CFLAGS=  -g
CWARNS= -Wall -W -Wshadow -fno-common 
MOREFLAGS= -Wpedantic -Wpointer-arith -Wcast-qual -Wcast-align \
           -Wwrite-strings -fshort-enums 

# add relevant libraries and link options
LIBS=           
# LDFLAGS= -lgsl -lgslcblas 
LDFLAGS=

###########################################################################
# 4. Instructions to compile and link, with dependencies
########################################################################### 
all:    $(COMMAND) 

.SUFFIXES:
.SUFFIXES: .o .mod .f90 .f .cpp

#%.o:   %.mod 

# This is the command to link all of the object files together. 
#  For fortran, replace CXX by F90.
$(COMMAND): $(OBJS) $(MAKEFILE) 
	$(CXX) -o $(COMMAND) $(OBJS) $(LDFLAGS) $(LIBS)

# Command to make object (.o) files from C++ source files (assumed to be .cpp).
#  Add $(MOREFLAGS) if you want additional warning options.
%.o: %.cpp $(HDRS) $(MAKEFILE)
	$(CXX) -c $(CFLAGS) $(CWARNS) -o $@ $<

# Commands to make object (.o) files from Fortran-90 (or beyond) and
#  Fortran-77 source files (.f90 and .f, respectively).
.f90.mod:
	$(F90) -c $(F90FLAGS) -o $@ $< 
 
.f90.o: 
	$(F90) -c $(F90FLAGS) -o $@ $<
 
.f.o:   
	$(F90) -c $(FFLAGS) -o $@ $<
      
##########################################################################
# 5. Additional tasks      
##########################################################################
      
# Delete the program and the object files (and any module files)
clean:
	/bin/rm -f $(COMMAND) $(OBJS)
	/bin/rm -f $(MODIR)/*.mod
 
# Pack up the code in a compressed gnu tar file 
tarz:
	tar cfvz $(TARFILE) $(MAKEFILE) $(SRCS) $(HDRS) $(MODIR) $(INPFILE) 

# Pack up the code in a zip archive
zip:
	zip -r $(ZIPFILE) $(MAKEFILE) $(SRCS) $(HDRS) $(MODIR) $(INPFILE) 

##########################################################################
# That's all, folks!     
##########################################################################