llvm-3.7 release and OpenMP

[Jack Howarth]

   You really will want to rewrite the llvm37 Portfile to use a cmake
build. The openmp 3.7 can be built in-tree using cmake (with the
sources placed at projects/openmp. Also the default for -fopenmp is
still left as -fopenmp=libgomp in 3.7.0 but this can be changed
with...

--- cfe-3.7.0.src/CMakeLists.txt.orig 2015-09-02 12:21:32.000000000 -0400
+++ cfe-3.7.0.src/CMakeLists.txt 2015-09-02 12:21:51.000000000 -0400
@@ -182,7 +182,7 @@
 set(DEFAULT_SYSROOT "" CACHE PATH
   "Default <path> to all compiler invocations for --sysroot=<path>." )

-set(CLANG_DEFAULT_OPENMP_RUNTIME "libgomp" CACHE STRING
+set(CLANG_DEFAULT_OPENMP_RUNTIME "libomp" CACHE STRING
   "Default OpenMP runtime used by -fopenmp.")

 set(CLANG_VENDOR "" CACHE STRING

In fink, we set the explicit location of the buried libomp.dylib with...

--- cfe-3.7.0.src/lib/Driver/Tools.cpp.orig     2015-07-02
09:10:45.000000000 -0400
+++ cfe-3.7.0.src/lib/Driver/Tools.cpp  2015-07-03 21:43:42.000000000 -0400
@@ -6368,12 +6368,18 @@
                    options::OPT_fno_openmp, false)) {
     switch (getOpenMPRuntime(getToolChain(), Args)) {
     case OMPRT_OMP:
+      // Help clang find libomp.dylib
+      CmdArgs.push_back("-L at FINK_PREFIX@/opt/llvm- at BRV@/lib");
       CmdArgs.push_back("-lomp");
       break;
     case OMPRT_GOMP:
+      // Help clang find libgomp.dylib
+      CmdArgs.push_back("-L at FINK_PREFIX@/opt/llvm- at BRV@/lib");
       CmdArgs.push_back("-lgomp");
       break;
     case OMPRT_IOMP5:
+      // Help clang find libiomp5.dylib
+      CmdArgs.push_back("-L at FINK_PREFIX@/opt/llvm- at BRV@/lib");
       CmdArgs.push_back("-liomp5");
       break;
     case OMPRT_Unknown:
@@ -8079,9 +8085,13 @@
         // Also link the particular OpenMP runtimes.
         switch (getOpenMPRuntime(ToolChain, Args)) {
         case OMPRT_OMP:
+         // Help clang find libomp.dylib
+         CmdArgs.push_back("-L at FINK_PREFIX@/opt/llvm- at BRV@/lib");
           CmdArgs.push_back("-lomp");
           break;
         case OMPRT_GOMP:
+          // Help clang find libgomp.dylib
+          CmdArgs.push_back("-L at FINK_PREFIX@/opt/llvm- at BRV@/lib");
           CmdArgs.push_back("-lgomp");

           // FIXME: Exclude this for platforms with libgomp that don't require
@@ -8089,6 +8099,8 @@
           CmdArgs.push_back("-lrt");
           break;
         case OMPRT_IOMP5:
+         // Help clang find libiomp5.dylib
+         CmdArgs.push_back("-L at FINK_PREFIX@/opt/llvm- at BRV@/lib");
           CmdArgs.push_back("-liomp5");
           break;
         case OMPRT_Unknown:

to produce -L/sw/opt/llvm-3.7/lib on the linkage. Lastly, to build the
fat binary of libomp,
you need to pass cmake the flag -DLIBOMP_OSX_ARCHITECTURES="x86_64;i386".
               Jack
ps Note that the perl-based Makefile build is no longer functional in
3.7.0 and is in the process of being completely removed for the 3.8.0
release.

On Wed, Sep 2, 2015 at 9:59 PM, Jeremy Huddleston Sequoia
<jeremyhu at macports.org> wrote:
> Looks good to me.  Could you go ahead and push this to svn and also do similar changes to the llvm-3.8 port for your openmp variant?
>
> Thanks,
> Jeremy
>
>> On Sep 2, 2015, at 15:34, Eric A. Borisch <eborisch at macports.org> wrote:
>>
>> Would have done a ticket, but with trac down....
>>
>> Attached is a patch to update to the released llvm/clang-3.7 (this comments out the svn fetch code, removes the default +assertions, and adds checksums)
>>
>> As OpenMP is one of the much discussed items that llvm-3.7 brings to the table, I've added a +openmp variant to clang-3.7. This variants pulls in port:libomp and sets up clang such that "-fopenmp" will use it by default. This makes it much more likely for tools like autoconf to detect OpenMP support. (Without the variant, openmp support is still there, but it requires -fopenmp=libomp, which isn't in the set of standard "can we do OpenMP" flags.) If people are supportive of it, I would suggest making it a default variant.
>>
>> Note that -I/opt/local/include and -L/opt/local/lib (assuming standard MacPorts install location) are required with -fopenmp for things to work and not complain about missing omp.h or -lomp.
>>
>> If there is someone more familiar with clang/llvm building (of the tools themselves), it might be interesting to consider baking in those -I/-L flags (or move the libomp include/lib install directories so they only have omp.h and the libomp*.dylib files and using those) so -fopenmp would "just work." (Without the extra -I and -L)... Let me know if there is interest and I can rework the libomp port to support this.
>>
>> Thanks,
>>   - Eric
>> <llvm-3.7.patch>
>
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