[OPENMP] Link libomp.lib on Windows

[ABataev]

Summary

Adds libomp.lib for -fopenmp=libomp and libiomp5md.lib for -fopenmp=libiomp5 on Windows

[ismail]

OpenMP/linking.c fails here with VS2015 (building with -DCLANG_DEFAULT_OPENMP_RUNTIME=libomp)

Command 21 Stderr:
C:\cygwin64\home\ismail\src\llvm\tools\clang\test\OpenMP\linking.c:75:24: error: expected string not found in input
// CHECK-MSVC-LINK-64: "link.exe"

^

<stdin>:1:1: note: scanning from here
clang version 3.8.0 (http://llvm.org/git/clang d7efa4b285d2464f1844b52b220381c64cd64bf6) (http://llvm.org/git/llvm bee32461e9d
466ed85439a026c62cb896b638653)
^
<stdin>:6:73: note: possible intended match here
"C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\BIN\\amd64\\link.exe" "-out:C:\\cygwin64\\home\\ismail\\src\\llvm
\\dist\\tools\\clang\\test\\OpenMP\\Output\\linking.c.tmp.o" "-defaultlib:libcmt" "-libpath:C:\\Program Files (x86)\\Microsoft
Visual Studio 14.0\\VC\\lib\\amd64" "-libpath:C:\\Program Files (x86)\\Windows Kits\\8.1\\Lib\\winv6.3\\um\\x64" "-nologo" "-
nodefaultlib:vcomp.lib" "-nodefaultlib:vcompd.lib" "-defaultlib:libomp.lib" "C:\\cygwin64\\tmp\\linking-19e90e.o"

^

[ABataev]

Test fix

[ismail]

Tests pass but, now when I tried to compile a file with -fopenmp I get:

LINK: fatal error LNK1104: cannot open file 'libomp.lib'

libomp.lib does exist in "C:\Program Files\LLVM\lib" but I guess we need to pass the library path down to linker.

[hfinkel]

In D11932#222515, @ismail wrote:

Tests pass but, now when I tried to compile a file with -fopenmp I get:

LINK: fatal error LNK1104: cannot open file 'libomp.lib'

libomp.lib does exist in "C:\Program Files\LLVM\lib" but I guess we need to pass the library path down to linker.

What library path should be passed (where did you build the OpenMP runtime library)?

[ismail]

In D11932#225158, @hfinkel wrote:

What library path should be passed (where did you build the OpenMP runtime library)?

This is a default installation so the lib path is $PATH_TO_CLANG_EXE/../lib which in my case is C:\Program Files\LLVM\lib

[ABataev]

Add path to libomp.lib.

[ismail]

Great work. Tested fine on Windows. Next step would be mapping /openmp flag to -fopenmp but I guess thats for another bug.

[rnk]

lgtm

lib/Driver/Tools.cpp

if (Args.hasArg(options::OPT__SLASH_MD, options::OPT__SLASH_MDd)) {
       };
       for (const auto &Component : CompilerRTComponents)
         CmdArgs.push_back(Args.MakeArgString(getCompilerRT(TC, Component)));
     }
   }
 
   Args.AddAllArgValues(CmdArgs, options::OPT__SLASH_link);
 
+  if (Args.hasFlag(options::OPT_fopenmp, options::OPT_fopenmp_EQ,
+                   options::OPT_fno_openmp, false)) {
+    CmdArgs.push_back("-nodefaultlib:vcomp.lib");
+    CmdArgs.push_back("-nodefaultlib:vcompd.lib");
+    switch (getOpenMPRuntime(getToolChain(), Args)) {
+    case OMPRT_OMP:
+      CmdArgs.push_back("-defaultlib:libomp.lib");
+      break;
+    case OMPRT_IOMP5:
+      CmdArgs.push_back("-defaultlib:libiomp5md.lib");
+      break;
+    case OMPRT_GOMP:
+      break;
+    case OMPRT_Unknown:
+      // Already diagnosed.
+      break;
+    }
+  }
+
   // Add filenames, libraries, and other linker inputs.
   for (const auto &Input : Inputs) {
     if (Input.isFilename()) {
       CmdArgs.push_back(Input.getFilename());
       continue;
     }
 
     const Arg &A = Input.getInputArg();

test/OpenMP/linking.c

 //
 // RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
 // RUN:     -fopenmp -fopenmp=libgomp -target x86_64-unknown-linux \
 // RUN:   | FileCheck --check-prefix=CHECK-LD-OVERRIDE-64 %s
 // CHECK-LD-OVERRIDE-64: "{{.*}}ld{{(.exe)?}}"
 // CHECK-LD-OVERRIDE-64: "-lgomp" "-lrt" "-lgcc"
 // CHECK-LD-OVERRIDE-64: "-lpthread" "-lc"
 //
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp=libomp -target x86_64-msvc-win32 \
+// RUN:   | FileCheck --check-prefix=CHECK-MSVC-LINK-64 %s
+// CHECK-MSVC-LINK-64: link.exe
+// CHECK-MSVC-LINK-64-SAME: -nodefaultlib:vcomp.lib
+// CHECK-MSVC-LINK-64-SAME: -nodefaultlib:vcompd.lib
+// CHECK-MSVC-LINK-64-SAME: -defaultlib:libomp.lib
+//
+// RUN: %clang -no-canonical-prefixes %s -### -o %t.o 2>&1 \
+// RUN:     -fopenmp=libiomp5 -target x86_64-msvc-win32 \
+// RUN:   | FileCheck --check-prefix=CHECK-MSVC-ILINK-64 %s
+// CHECK-MSVC-ILINK-64: link.exe
+// CHECK-MSVC-ILINK-64-SAME: -nodefaultlib:vcomp.lib
+// CHECK-MSVC-ILINK-64-SAME: -nodefaultlib:vcompd.lib
+// CHECK-MSVC-ILINK-64-SAME: -defaultlib:libiomp5md.lib
+//