Intel® oneAPI DPC++/C++ Compiler Developer Guide and Reference

Development Reference Guides

Contents

Modify Your makefile

If you use makefiles to build your GCC* application, you need to change the value for the GCC compiler variable to use the
Intel® oneAPI
DPC++/C++
 Compiler
. You may also want to review the options specified by
CFLAGS
. For example, a sample 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 the
Intel® oneAPI
DPC++/C++
 Compiler

In this example, the name of the compiler is changed to use
icpx
# Use Intel C/C++/DPC++ Compiler
  CC = icpx

# 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
    $(CC) -c -fno-asm $(CFLAGS) area_functions.c 

clean: rm -rf *o area
If your GCC code includes features that are not supported with the
Intel® oneAPI
DPC++/C++
 Compiler
 (compiler options, language extensions, macros, pragmas, and so on), 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. Because the
Intel® oneAPI
DPC++/C++
 Compiler
 uses the
O2
 option by default and GCC uses option
O0
 as the default, we instruct GCC to compile at option
O2
. We also include the
-fno-asm
 switch from the original makefile because this switch is not supported with the
Intel® oneAPI
DPC++/C++
 Compiler
. The following sample makefile is modified for using the
Intel® oneAPI
DPC++/C++
 Compiler
 and GCC together: 
# Use Intel C/C++/DPC++ Compiler
  CC = icpx
# Use gcc for files that cannot be compiled by icpx
  GCC = gcc
# 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
Output of
make
 using a modified makefile: 

icpx -c -std=c99 area_main.c
gcc -c -O2 -fno-asm -std=c99 area_functions.c
icpx area_main.o area_functions.o -o area
Use IPO in Makefiles
By default, IPO generates "dummy" object files containing Interprocedural information used by the compiler. To link or create static libraries with these object files requires special Intel-provided tools. To use them in your makefile, simply replace references to "ld" with "xild" and references to "ar" with "xiar", or use
icx
 or
icpx
 (for C++) or
dpcpp
 (for SYCL*)
 to link as shown in the example: 
# Use Intel C/C++/DPC++ Compiler 
  CC = icpx
# Compile-time flags 
  CFLAGS = -std=c99 -ipo
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 $(CFLAGS) area_functions.c 

clean: rm -rf *o area

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.