Dropped non-supoorted "--no-as-needed" flag from OMPT tests for macOS

[simoatze]

Summary

The flag "--no-as-needed" is not recognized by the linker on macOS making the following tests fail:

• ompt/loadtool/tool_available/tool_available.c
• ompt/loadtool/tool_not_available/tool_not_available.c

This patch removes this flag for macOS and adds it only for Linux and Windows.
I tested it on Ubuntu 16.04 and macOS HighSierra, with Clang/LLVM 6.0.1 and OpenMP trunk.

This solution was also discussed in the OpenMP-dev mailing list.

[protze.joachim]

As discussed on the mailing list, the flag should only be dropped on Mac OS. My pragmatic solution would be:

if config.operating_system == 'Darwin':
    config.substitutions.append(("--Wl,--no-as-needed", ""))

Not sure what @Hahnfeld thinks about this solution :)

The cleaner solution would probably be to define a %no-as-needed-flag substitution.

[Hahnfeld]

In D48888#1151198, @protze.joachim wrote:

As discussed on the mailing list, the flag should only be dropped on Mac OS. My pragmatic solution would be:

if config.operating_system == 'Darwin':
    config.substitutions.append(("--Wl,--no-as-needed", ""))

Not sure what @Hahnfeld thinks about this solution :)

The cleaner solution would probably be to define a %no-as-needed-flag substitution.

I'd prefer the second solution :D bonus points for a CMake check to see if the linker actually supports the flag. However, I'm not sure there is an OS except Darwin where the linker doesn't have that flag, so ...

[simoatze]

I updated the patch and the description.
I have no way at this moment to test it on Windows, is the "--no-as-needed" flag supported?

[protze.joachim]

LGTM

[Hahnfeld]

@simoatze you might want to add a bot building the OpenMP runtime upon each commit to make sure there are no regressions like this...

openmp/trunk/runtime/test/lit.cfg

 config.substitutions.append(("%flags", config.test_flags))
 
 if config.has_ompt:
     config.substitutions.append(("FileCheck", config.test_filecheck))
     config.substitutions.append(("%sort-threads", "sort --numeric-sort --stable"))
     if config.operating_system == 'Windows':
         # No such environment variable on Windows.
         config.substitutions.append(("%preload-tool", "true ||"))
+        config.substitutions.append(("%no-as-needed-flag", "-Wl,--no-as-needed"))
     elif config.operating_system == 'Darwin':
         config.substitutions.append(("%preload-tool", "env DYLD_INSERT_LIBRARIES=%T/tool.so"))
+        # No such linker flag on Darwin.
+        config.substitutions.append(("%no-as-needed-flag", ""))
     else:
         config.substitutions.append(("%preload-tool", "env LD_PRELOAD=%T/tool.so"))
+        config.substitutions.append(("%no-as-needed-flag", "-Wl,--no-as-needed"))

openmp/trunk/runtime/test/ompt/loadtool/tool_available/tool_available.c

 // The OpenMP standard defines 3 ways of providing ompt_start_tool:
 // 1. "statically-linking the tool’s definition of ompt_start_tool into an OpenMP application"
 // RUN: %libomp-compile -DCODE -DTOOL && %libomp-run | FileCheck %s
 
 // Note: We should compile the tool without -fopenmp as other tools developer
 //       would do. Otherwise this test may pass for the wrong reasons on Darwin.
 // RUN: %clang %flags -DTOOL -shared -fPIC %s -o %T/tool.so
 // 2. "introducing a dynamically-linked library that includes the tool’s definition of ompt_start_tool into the application’s address space"
 // 2.1 Link with tool during compilation
-// RUN: %libomp-compile -DCODE -Wl,--no-as-needed %T/tool.so && %libomp-run | FileCheck %s
+// RUN: %libomp-compile -DCODE %no-as-needed-flag %T/tool.so && %libomp-run | FileCheck %s
 // 2.2 Link with tool during compilation, but AFTER the runtime
-// RUN: %libomp-compile -DCODE -lomp -Wl,--no-as-needed %T/tool.so && %libomp-run | FileCheck %s
+// RUN: %libomp-compile -DCODE -lomp %no-as-needed-flag %T/tool.so && %libomp-run | FileCheck %s
 // 2.3 Inject tool via the dynamic loader
 // RUN: %libomp-compile -DCODE && %preload-tool %libomp-run | FileCheck %s
 
 // 3. "providing the name of a dynamically-linked library appropriate for the architecture and operating system used by the application in the tool-libraries-var ICV"
 // RUN: %libomp-compile -DCODE && env OMP_TOOL_LIBRARIES=%T/tool.so %libomp-run | FileCheck %s
 
 // REQUIRES: ompt
 

openmp/trunk/runtime/test/ompt/loadtool/tool_not_available/tool_not_available.c

 // The OpenMP standard defines 3 ways of providing ompt_start_tool:
 // 1. "statically-linking the tool’s definition of ompt_start_tool into an OpenMP application"
 // RUN: %libomp-compile -DCODE -DTOOL && %libomp-run | FileCheck %s
 
 // Note: We should compile the tool without -fopenmp as other tools developer
 //       would do. Otherwise this test may pass for the wrong reasons on Darwin.
 // RUN: %clang %flags -DTOOL -shared -fPIC %s -o %T/tool.so
 // 2. "introducing a dynamically-linked library that includes the tool’s definition of ompt_start_tool into the application’s address space"
 // 2.1 Link with tool during compilation
-// RUN: %libomp-compile -DCODE -Wl,--no-as-needed %T/tool.so && %libomp-run | FileCheck %s
+// RUN: %libomp-compile -DCODE %no-as-needed-flag %T/tool.so && %libomp-run | FileCheck %s
 // 2.2 Link with tool during compilation, but AFTER the runtime
-// RUN: %libomp-compile -DCODE -lomp -Wl,--no-as-needed %T/tool.so && %libomp-run | FileCheck %s
+// RUN: %libomp-compile -DCODE -lomp %no-as-needed-flag %T/tool.so && %libomp-run | FileCheck %s
 // 2.3 Inject tool via the dynamic loader
 // RUN: %libomp-compile -DCODE && %preload-tool %libomp-run | FileCheck %s
 
 // 3. "providing the name of a dynamically-linked library appropriate for the architecture and operating system used by the application in the tool-libraries-var ICV"
 // RUN: %libomp-compile -DCODE && env OMP_TOOL_LIBRARIES=%T/tool.so %libomp-run | FileCheck %s
 
 // REQUIRES: ompt