[Bug libgomp/56357] New: [4.8 Regression] missing symbol references for libgomp when using -flto -fopenmp on mingw32

[daniel.f.starke at freenet dot de]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56357



             Bug #: 56357

           Summary: [4.8 Regression] missing symbol references for libgomp

                    when using -flto -fopenmp on mingw32

    Classification: Unclassified

           Product: gcc

           Version: 4.8.0

            Status: UNCONFIRMED

          Severity: normal

          Priority: P3

         Component: libgomp

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: daniel.f.sta...@freenet.de

                CC: ja...@gcc.gnu.org





The combination of -flto and -fopenmp is broken for mingw32 in r196092.



#define ARRAY_SIZE 10



int main() {

    int i;

    volatile int a[ARRAY_SIZE];

    #pragma omp parallel for private(a)

    for (i = 0; i < ARRAY_SIZE; i++) {

        a[i] += i;

    }



    return 0;

}



This code works fine with "gcc -fopenmp gcc-lto-gomp.c" but results in errors

for "gcc -fopenmp -flto gcc-lto-gomp.c". Adding -lgomp does not solves this.



Error output:

C:\Users\Me\AppData\Local\Temp\cccobKR8.ltrans0.ltrans.o:cccobKR8.ltrans0.o:(.text+0x6):

undefined reference to `omp_get_num_threads'

C:\Users\Me\AppData\Local\Temp\cccobKR8.ltrans0.ltrans.o:cccobKR8.ltrans0.o:(.text+0xd):

undefined reference to `omp_get_thread_num'

C:\Users\Me\AppData\Local\Temp\cccobKR8.ltrans0.ltrans.o:cccobKR8.ltrans0.o:(.text.startup+0x26):

undefined reference to `GOMP_parallel_start'

C:\Users\Me\AppData\Local\Temp\cccobKR8.ltrans0.ltrans.o:cccobKR8.ltrans0.o:(.text.startup+0x37):

undefined reference to `GOMP_parallel_end'

could not unlink output filecollect2.exe: error: ld returned 1 exit status



This all works fine in gcc 4.7.2 with the same build configuration.



Using built-in specs.

COLLECT_GCC=D:\Programme\msys\gcc\bin\gcc.exe

COLLECT_LTO_WRAPPER=d:/programme/msys/gcc/bin/../libexec/gcc/mingw32/4.8.0/lto-wrapper.exe

Target: mingw32

Configured with: ../gcc-4.8.0-r196092/configure

--enable-languages=c,ada,c++,fortran,objc,obj-c++ --disable-sjlj-exceptions

--disable-nls --disable-shared --enable-static --enable-fully-dynamic-string

--enable-libgomp --enable-lto --with-dwarf2 --disable-win32-registry

--enable-version-specific-runtime-libs --enable-bootstrap --build=mingw32

--enable-abi=32 --enable-checking=release --prefix=/mingw

Thread model: win32

gcc version 4.8.0 20130215 (experimental) (GCC)