[OpenMP] Add JIT and IR tests

[jdoerfert]

Summary

The OpenMP target JIT needs testing, so does the IR we actually generate
for the device. This is the initial commit with variations of an "empty
OpenMP kernel" that should all result in a empty IR kernel.

[tianshilei1992]

openmp/libomptarget/test/jit/empty_kernel_target.c

5

cat doesn't look the right way. Wonder if FileCheck allows the input to be from a file.

[jdoerfert]

openmp/libomptarget/test/jit/empty_kernel_target.c

5

One of many:
llvm/test/Transforms/Util/strip-nonlinetable-debuginfo-loops.ll:; RUN: cat %t | FileCheck %s

[tianshilei1992]

openmp/libomptarget/test/jit/empty_kernel_target.c

5

Well, that's fair, but since FileCheck supports --input-file, I'd prefer to make it portable, though we only support Linux now.

[jdoerfert]

openmp/libomptarget/test/jit/empty_kernel_target.c

5

will change.

[jdoerfert]

update according to comments, more tests (consolidated)

[tianshilei1992]

LG

openmp/libomptarget/test/jit/empty_kernel.inc

+
+#ifndef DIRECTIVE
+#error DIRECTIVE should be defined
+#endif
+
+int main() {
+#pragma omp DIRECTIVE
+  {}
+}
+
+// Check for an empty kernel (IR level)
+// TARGET:  define weak_odr {{.*}} void @__omp_offloading_{{.*}}_main
+// TARGET-NEXT:   ret void

openmp/libomptarget/test/jit/empty_kernel_target.c

+// clang-format off
+// RUN: %libomptarget-compileopt-generic -DDIRECTIVE=target -fopenmp-target-jit
+// RUN: env LIBOMPTARGET_JIT_PRE_OPT_IR_MODULE=%T/pre.ll   \
+// RUN:     %libomptarget-run-generic
+// RUN: cat %T/pre.ll | %fcheck-plain-generic %S/empty_kernel.inc --check-prefix=TARGET
+// clang-format on
+
+// UNSUPPORTED: x86_64-pc-linux-gnu
+// UNSUPPORTED: x86_64-pc-linux-gnu-LTO
+
+#include "empty_kernel.inc"

openmp/libomptarget/test/jit/empty_kernel_target.cpp

+// clang-format off
+// RUN: %libomptarget-compileoptxx-generic -DDIRECTIVE=target -fopenmp-target-jit
+// RUN: env LIBOMPTARGET_JIT_PRE_OPT_IR_MODULE=%T/pre.ll   \
+// RUN:     %libomptarget-run-generic
+// RUN: cat %T/pre.ll | %fcheck-plain-generic %S/empty_kernel.inc --check-prefix=TARGET
+// clang-format on
+
+// UNSUPPORTED: x86_64-pc-linux-gnu
+// UNSUPPORTED: x86_64-pc-linux-gnu-LTO
+
+#include "empty_kernel.inc"

openmp/libomptarget/test/jit/empty_kernel_target_teams.c

+// clang-format off
+// RUN: %libomptarget-compileopt-generic -DDIRECTIVE="target teams" -fopenmp-target-jit
+// RUN: env LIBOMPTARGET_JIT_PRE_OPT_IR_MODULE=%T/pre.ll   \
+// RUN:     %libomptarget-run-generic
+// RUN: cat %T/pre.ll | %fcheck-plain-generic %S/empty_kernel.inc --check-prefix=TARGET
+// clang-format on
+
+// UNSUPPORTED: x86_64-pc-linux-gnu
+// UNSUPPORTED: x86_64-pc-linux-gnu-LTO
+
+#include "empty_kernel.inc"

openmp/libomptarget/test/jit/empty_kernel_target_teams.cpp

+// clang-format off
+// RUN: %libomptarget-compileoptxx-generic -DDIRECTIVE="target teams" -fopenmp-target-jit
+// RUN: env LIBOMPTARGET_JIT_PRE_OPT_IR_MODULE=%T/pre.ll   \
+// RUN:     %libomptarget-run-generic
+// RUN: cat %T/pre.ll | %fcheck-plain-generic %S/empty_kernel.inc --check-prefix=TARGET
+// clang-format on
+
+// UNSUPPORTED: x86_64-pc-linux-gnu
+// UNSUPPORTED: x86_64-pc-linux-gnu-LTO
+
+#include "empty_kernel.inc"

openmp/libomptarget/test/lit.cfg

             "%clang-" + libomptarget_target))
         config.substitutions.append(("%fcheck-generic",
             config.libomptarget_filecheck + " %s"))
+        config.substitutions.append(("%fcheck-plain-generic",
+            config.libomptarget_filecheck))
 
 
         config.substitutions.append(("%libomptarget-compilexx-run-and-check-" + \