Modifying Your makefile

gcc makefile

# Use gcc compiler 
CC = gcc 
# Compile-time flags 
CFLAGS = -O2 -std=c99 
all: area_app 
area_app: area_main.o area_functions.o
    $(CC) area_main.o area_functions.o -o area 
area_main.o: area_main.c
    $(CC) -c $(CFLAGS) area_main.c 
area_functions.o: area_functions.c
    $(CC) -c -fno-asm $(CFLAGS) area_functions.c 
clean:
    rm -rf *o area

Modified makefile for Intel Compiler

# Use Intel C compiler 
CC = icc 
# Compile-time flags 
CFLAGS = -std=c99 
all: area-app 
area-app: area_main.o area_functions.o
    $(CC) area_main.o area_functions.o -o area 
area_main.o: area_main.c
    $(CC) -c $(CFLAGS) area_main.c 
area_functions.o: area_functions.c
    gcc -c -O2 -fno-asm $(CFLAGS) area_functions.c 
clean:
    rm -rf *o area

If your gcc code includes features that are not supported with the Intel® C++ compiler, such as compiler options, language extensions, macros, pragmas, etc., you can compile those sources separately with gcc if necessary.

In the above makefile, area_functions.c is an example of a source file that includes features unique to gcc. Since the Intel compiler uses the -O2 compiler option by default and gcc's default is -O0, we instruct gcc to compile with -O2. We also include the -fno-asm switch from the original makefile since this switch is not supported with the Intel compiler. With the modified makefile, the output of make is:

icc -c -std=c99 area_main.c
gcc -c -O2 -fno-asm -std=c99 area_functions.c
icc area_main.o area_functions.o -o area