GCC: Compiling an OpenCL host on Windows - c

Question

I just wanted to try out using OpenCL under Windows.
Abstract: I got an "undefined reference to" error when I tried to compile (using the command gcc my.o -o my.exe -L "C:\Program Files (x86)\AMD APP\lib\x86_64" -l OpenCL).
My Code
#include <CL/cl.h>
#include <stdio.h>
int main(void) {
cl_platform_id platform;
int err;
err = clGetPlatformIDs(1, &platform, NULL);
if(err < 0) {
perror("There's No Platform!");
exit(1);
}
/* Some more code... */
system("PAUSE");
}
Makefile
all: addition
addition:
gcc -c -I "C:\Program Files (x86)\AMD APP\include" my.c -o my.o
gcc my.o -o my.exe -L "C:\Program Files (x86)\AMD APP\lib\x86_64" -l OpenCL
Used Programs
MinGW's gcc
Visual Studio's nmake
AMD's OpenCL™ APP SDK (that's where I took the OpenCL library and the CL.h file from)
The Structure of APP SDK's Folders
%>tree /F "C:\Program Files (x86)\AMD APP\lib\x86_64"
Auflistung der Ordnerpfade
Volumeseriennummer : D2DC-D765
C:\PROGRAM FILES (X86)\AMD APP\LIB\X86_64
libOpenCL.a
OpenCL.lib
OpenVideo64.lib
Es sind keine Unterordner vorhanden
%>tree /F "C:\Program Files (x86)\AMD APP\include"
Auflistung der Ordnerpfade
Volumeseriennummer : D2DC-D765
C:\PROGRAM FILES (X86)\AMD APP\INCLUDE
├───CAL
│ cal.h
│ calcl.h
│ cal_ext.h
│ cal_ext_counter.h
│ cal_ext_d3d10.h
│ cal_ext_d3d9.h
│
├───CL
│ cl.h
│ cl.hpp
│ cl_d3d10.h
│ cl_ext.h
│ cl_gl.h
│ cl_gl_ext.h
│ cl_platform.h
│ opencl.h
│
└───OpenVideo
OpenVideo.h
OVDecode.h
OVDecodeTypes.h
OVEncode.h
OVEncodeTypes.h
Error Message
gcc addition.o -o addition.exe -L "C:\Program Files (x86)\AMD APP\lib\x86_64" -l OpenCL
addition.o:addition.c:(.text+0x2d): undefined reference to `clGetPlatformIDs#12'
addition.o:addition.c:(.text+0x83): undefined reference to `clGetDeviceIDs#24'
addition.o:addition.c:(.text+0xc2): undefined reference to `clGetDeviceIDs#24'
collect2: ld returned 1 exit status
NMAKE : fatal error U1077: "C:\prog-x86\MinGW\bin\gcc.EXE": Rückgabe-Code "0x1"
Stop.
My Questions
My questions are simple:
Why doesn't my code compile how it is expected to?
What can I do to get rid of this problem?
Thanks.
UPDATE: The error message after dropping the spaces like described in #codaddict 's answer.
(Makefile)
all: addition
addition:
gcc -c -I "C:\prog-x86\AMD-APP\include" addition.c -o addition.o
gcc addition.o -o addition.exe -LC:\prog-x86\AMD-APP\lib\x86_64 -lOpenCL
(Shelldata)
%>nmake
Microsoft (R) Program Maintenance Utility, Version 11.00.50727.1
Copyright (C) Microsoft Corporation. Alle Rechte vorbehalten.
gcc -c -I "C:\Program Files (x86)\AMD APP\include" addition.c -o addition.o
addition.c: In function 'main':
addition.c:14:9: warning: incompatible implicit declaration of built-in function 'exit' [enabled by d
efault]
addition.c:23:9: warning: incompatible implicit declaration of built-in function 'exit' [enabled by d
efault]
gcc addition.o -o addition.exe -LC:\prog-x86\AMD-APP\lib\x86_64 -lOpenCL
addition.o:addition.c:(.text+0x2d): undefined reference to `clGetPlatformIDs#12'
addition.o:addition.c:(.text+0x83): undefined reference to `clGetDeviceIDs#24'
addition.o:addition.c:(.text+0xc2): undefined reference to `clGetDeviceIDs#24'
collect2: ld returned 1 exit status
NMAKE : fatal error U1077: "C:\prog-x86\MinGW\bin\gcc.EXE": Rückgabe-Code "0x1"
Stop.
%>

Answer 1

The default MinGW distribution only ships tools for building x86 applications. You cannot link against the x64 version of the OpenCL library. So you either have to use MinGW-w64 or use the x86 version (change the library path to the x86 subfolder of the APP SDK).

Answer 2

Try changing
-l OpenCL
to
-lOpenCL
in the compile line.
The -l option of gcc expects the name of the library (without the lib prefix) right next to it without any space. Remember using -lm in school to link to libm?

Answer 3

The 64 bit g++ compiler on windows 10 is also in the bin folder:
"C:\MinGW\bin\x86_64-w64-mingw32-g++.exe"
So this works for me:
C:\MinGW\bin>x86_64-w64-mingw32-g++ "C:\Users\...\main.cpp" -o
C:\Users\...\saxpy -L "C:\Program Files\...\x64" -lOpenCL -I
"C:\...\OpenCL\sdk\include"
Notes:
-o output name
-L folder contains OpenCL.lib
-I folder contains header file e.g. CL/cl.h