Assembly fragment fails to compile with clang -O3

[bredelings]

Hi Marc,

I have found that the inline assembly fragment in BeagleCPUSSEPlugin.cpp fails to compile on linux with clang.

#else // HAVE_CPUID.H
	// Determine if cpuid supported:
    unsigned int res;
    __asm__("mov %%ecx, %%eax;"
            "xor $200000, %%eax;"
            "xor %%ecx, %%eax;"
            "je no;"
            "mov $1, %%eax;"
            "jmp end;"
            "no: mov $0, %%eax;"
            "end:;"
            : "=a" (res)
            :
            : "cc");

The compilation error looks like this:

$ clang++-16 -DBEAGLE_ACTION -DPACKAGE_BUGREPORT=\"beagle-dev@googlegroups.com\" -DPACKAGE_NAME=\"libhmsbeagle\" -DPACKAGE_STRING="\"libhmsbeagle 4.0.1\"" -DPACKAGE_TARNAME=\"libhmsbeagle\" -DPACKAGE_URL=\"\" -DPACKAGE_VERSION=\"4.0.1\" -DPLUGIN_VERSION=\"40\" -Dhmsbeagle_cpu_sse_EXPORTS -I/home/bredelings/Devel/beagle/git -I/include -I/usr/lib/jvm/default-java/include -I/usr/lib/jvm/default-java/include/linux -O3 -g -pthread -march=native -std=gnu++17 -fPIC -MD -MT libhmsbeagle/CPU/CMakeFiles/hmsbeagle-cpu-sse.dir/BeagleCPUSSEPlugin.cpp.o -MF libhmsbeagle/CPU/CMakeFiles/hmsbeagle-cpu-sse.dir/BeagleCPUSSEPlugin.cpp.o.d -o libhmsbeagle/CPU/CMakeFiles/hmsbeagle-cpu-sse.dir/BeagleCPUSSEPlugin.cpp.o -c /home/bredelings/Devel/beagle/git/libhmsbeagle/CPU/BeagleCPUSSEPlugin.cpp
/home/bredelings/Devel/beagle/git/libhmsbeagle/CPU/BeagleCPUSSEPlugin.cpp:122:13: error: symbol 'no' is already defined
    __asm__("mov %%ecx, %%eax;"
            ^
<inline asm>:1:77: note: instantiated into assembly here
        mov %ecx, %eax;xor $200000, %eax;xor %ecx, %eax;je no;mov $1, %eax;jmp end;no: mov $0, %eax;end:;
                                                                                   ^
/home/bredelings/Devel/beagle/git/libhmsbeagle/CPU/BeagleCPUSSEPlugin.cpp:122:13: error: symbol 'end' is already defined
    __asm__("mov %%ecx, %%eax;"
            ^
<inline asm>:1:94: note: instantiated into assembly here
        mov %ecx, %eax;xor $200000, %eax;xor %ecx, %eax;je no;mov $1, %eax;jmp end;no: mov $0, %eax;end:;
                                                                                                    ^
2 errors generated.

It looks like the code is being inlined into multiple places when optimization is enabled, yielding multiple instances of each assembly label.

However, it also seems like resorting to inline assembly is not needed here. The code only tries to use inline assembly when HAVE_CPUID_H is not defined. Now, we actually do have <cpuid.h>, and if I add -DHAVE_CPUID_H, then the code does compile.

It looks like HAVE_CPUID_H used to be defined, but then became undefined with config.h was removed.

The thing that occurs to me is to make cmake look for <cpuid.h> and then define HAVE_CPUID_H if we fine it. Do you have any thoughts on this?

[bredelings]

Also, this isn't really specific to the action branch. Should I propose a PR with a change to master, or just lump this into the action branch changes?