[lit][tests]Add feature libcxx-used and use it in llvm-*-fuzzer tests

[xingxue]

Summary

When a LLVM binary such as llvm-*-fuzzer is built with libc++, it has dependency on libc++. The path to find shared libraries specified in llvm-*-fuzzer is relative. As a result, these binaries cannot be copied to an arbitrary directory and launched from there. Changes in this patch add a LIT feature to indicate that libc++ is used to build and, based on the feature exclude test cases that test by copying llvm-*-fuzzer binaries to a directory.

The changes in this patch use macro LLVM_LIBCXX_USED introduced in patch https://reviews.llvm.org/D61016. D61016 should be committed before this patch.

[hubert.reinterpretcast]

The limitation seems unfortunate, but makes sense.

[amyk]

LGTM.

[hubert.reinterpretcast]

LGTM.

llvm/trunk/test/lit.cfg.py

for line in readobj_out.splitlines():
             needed_libs = False
         if needed_libs and regex.search(line.lower()):
             return True
     return False
 
 if have_cxx_shared_library():
     config.available_features.add('cxx-shared-library')
 
+if config.libcxx_used:
+    config.available_features.add('libcxx-used')
+
 # Direct object generation
 if not 'hexagon' in config.target_triple:
     config.available_features.add('object-emission')
 
 # LLVM can be configured with an empty default triple
 # Some tests are "generic" and require a valid default triple
 if config.target_triple:
     config.available_features.add('default_triple')

llvm/trunk/test/lit.site.cfg.py.in

 config.build_examples = @LLVM_BUILD_EXAMPLES@
 config.enable_threads = @LLVM_ENABLE_THREADS@
 config.build_shared_libs = @BUILD_SHARED_LIBS@
 config.link_llvm_dylib = @LLVM_LINK_LLVM_DYLIB@
 config.llvm_libxml2_enabled = @LLVM_LIBXML2_ENABLED@
 config.llvm_host_triple = '@LLVM_HOST_TRIPLE@'
 config.host_arch = "@HOST_ARCH@"
 config.have_opt_viewer_modules = @LLVM_HAVE_OPT_VIEWER_MODULES@
+config.libcxx_used = @LLVM_LIBCXX_USED@
 
 # Support substitution of the tools_dir with user parameters. This is
 # used when we can't determine the tool dir at configuration time.
 try:
     config.llvm_tools_dir = config.llvm_tools_dir % lit_config.params
     config.llvm_shlib_dir = config.llvm_shlib_dir % lit_config.params
 except KeyError:
     e = sys.exc_info()[1]
     key, = e.args
     lit_config.fatal("unable to find %r parameter, use '--param=%s=VALUE'" % (key,key))
 
 import lit.llvm
 lit.llvm.initialize(lit_config, config)
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@LLVM_SOURCE_DIR@/test/lit.cfg.py")

llvm/trunk/test/tools/llvm-isel-fuzzer/aarch64-execname-options.ll

 ; If the binary looks up libraries using an rpath, we can't test this
 ; without copying the whole lib dir or polluting the build dir.
 ; REQUIRES: static-libs
 ; REQUIRES: aarch64-registered-target
 
+; The above also applies if the binary is built with libc++.
+; UNSUPPORTED: libcxx-used
+
 ; RUN: echo > %t.input
 
 ; RUN: cp llvm-isel-fuzzer %t.bin--aarch64
 ; RUN: %t.bin--aarch64 %t.input 2>&1 | FileCheck -check-prefix=AARCH64 %s
 ; AARCH64: Injected args: -mtriple=aarch64
 
 ; RUN: cp llvm-isel-fuzzer %t.bin--aarch64-O1
 ; RUN: %t.bin--aarch64-O1 %t.input 2>&1 | FileCheck -check-prefix=OPT-AFTER %s
 ; OPT-AFTER: Injected args: -mtriple=aarch64 -O1
 
 ; RUN: cp llvm-isel-fuzzer %t.bin--O3-aarch64
 ; RUN: %t.bin--O3-aarch64 %t.input 2>&1 | FileCheck -check-prefix=OPT-BEFORE %s
 ; OPT-BEFORE: Injected args: -O3 -mtriple=aarch64

llvm/trunk/test/tools/llvm-isel-fuzzer/execname-options.ll

 ; If the binary looks up libraries using an rpath, we can't test this
 ; without copying the whole lib dir or polluting the build dir.
 ; REQUIRES: static-libs
 
+; The above also applies if the binary is built with libc++.
+; UNSUPPORTED: libcxx-used
+
 ; RUN: echo > %t.input
 
 ; RUN: cp llvm-isel-fuzzer %t.bin--gisel
 ; RUN: not %t.bin--gisel %t.input 2>&1 | FileCheck -check-prefix=GISEL %s
 ; GISEL: Injected args: -global-isel -O0
 ; GISEL: -mtriple must be specified
 
 ; RUN: cp llvm-isel-fuzzer %t.bin--gisel-O2
 ; RUN: not %t.bin--gisel-O2 %t.input 2>&1 | FileCheck -check-prefix=GISEL-O2 %s
 ; GISEL-O2: Injected args: -global-isel -O0 -O2
 ; GISEL-O2: -mtriple must be specified
 
 ; RUN: cp llvm-isel-fuzzer %t.bin--unexist
 ; RUN: not %t.bin--unexist %t.input 2>&1 | FileCheck -check-prefix=NO-OPT %s
 ; NO-OPT: Unknown option:

llvm/trunk/test/tools/llvm-opt-fuzzer/exec-options.ll

 ; If the binary looks up libraries using an rpath, we can't test this
 ; without copying the whole lib dir or polluting the build dir.
 ; REQUIRES: static-libs
 ; REQUIRES: x86-registered-target
 
+; The above also applies if the binary is built with libc++.
+; UNSUPPORTED: libcxx-used
+
 ; This test is really flaky on Windows. On Windows, executables and DLLs cannot
 ; be deleted or written while they are loaded. The OS unlocks the file some
 ; time after the process terminates, so if 'rm' runs too quickly, it will fail
 ; with "access denied".
 ; UNSUPPORTED: system-windows
 
 ; Temporary bitcode file
 ; RUN: opt -o %t.input %s