[libc++] Support -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=on in CI

[MaskRay]

Summary

This fixes -isystem/-L/-Wl,-rpath paths when -DLLVM_ENABLE_PER_TARGET_RUNTIME_DIR=on
is used (https://reviews.llvm.org/D107799#2969650).

• -isystem path/to/build/generic-cxx17/include/c++/v1. build/generic-cxx17/include/x86_64-unknown-linux-gnu/c++/v1 (__config_site) is missing.
• -L path/to/build/generic-cxx17/lib. Should be build/generic-cxx17/lib/x86_64-unknown-linux-gnu instead

[MaskRay]

drop unrelated libcxx/utils/ci/run-buildbot change

[phosek]

LGTM

[ldionne]

I'm somewhat concerned that we need to include two directories to properly handle libc++ here. I would prefer if we only needed to add build/generic-cxx17/include/x86_64-unknown-linux-gnu/c++/v1, i.e. the target-specific directory. Adding two directories is a change from how we've always done things in libc++. @phosek Was it intended that folks wouldn't be able to use libc++ without providing two include paths going forward?

Apart from that concern, the patch LGTM. Marking as "request changes" until we've resolved that.

[MaskRay]

In D108836#2972688, @ldionne wrote:

I'm somewhat concerned that we need to include two directories to properly handle libc++ here. I would prefer if we only needed to add build/generic-cxx17/include/x86_64-unknown-linux-gnu/c++/v1, i.e. the target-specific directory. Adding two directories is a change from how we've always done things in libc++. @phosek Was it intended that folks wouldn't be able to use libc++ without providing two include paths going forward?

Apart from that concern, the patch LGTM. Marking as "request changes" until we've resolved that.

I am not the designer, but I think two trees make sense to me.

Most headers are generic and sharable by all targets, therefore they are under include/c++/v1.
__config_site is target dependent and therefore under include/x86_64-unknown-linux-gnu/c++/v1.

Say we want to support -m32 in the same build (multiarch), we can use: include/i386-unknown-linux-gnu/c++/v1

FWIW this hierarchy also resembles libstdc++, though it places x86_64-glibc-linux-gnu in the last path component:

#include <...> search starts here:
 /tmp/glibc-many/install/compilers/x86_64-linux-gnu/lib/gcc/x86_64-glibc-linux-gnu/10.2.1/../../../../x86_64-glibc-linux-gnu/include/c++/10.2.1
 /tmp/glibc-many/install/compilers/x86_64-linux-gnu/lib/gcc/x86_64-glibc-linux-gnu/10.2.1/../../../../x86_64-glibc-linux-gnu/include/c++/10.2.1/x86_64-glibc-linux-gnu
 /tmp/glibc-many/install/compilers/x86_64-linux-gnu/lib/gcc/x86_64-glibc-linux-gnu/10.2.1/../../../../x86_64-glibc-linux-gnu/include/c++/10.2.1/backward

[phosek]

@ldionne having to use two directories is not great from the usability perspective, but it is the most efficient solution because you can separate target-independent and target-specific headers and avoid any duplication. In practice, this should be handled by the compiler driver and so most developers shouldn't notice any difference, it's only the scripts and build systems that manage headers manually which should be uncommon.

libcxx/test/configs/libcxx-trunk-shared.cfg.in

 @AUTO_GEN_COMMENT@
 
 @SERIALIZED_LIT_PARAMS@
 
 LIBCXX_ROOT = "@LIBCXX_SOURCE_DIR@"
 INSTALL_ROOT = "@CMAKE_BINARY_DIR@"
 COMPILER = "@CMAKE_CXX_COMPILER@"
 EXEC_ROOT = "@LIBCXX_BINARY_DIR@"
 CMAKE_OSX_SYSROOT = "@CMAKE_OSX_SYSROOT@"
+INCLUDE_DIR = "@LIBCXX_INSTALL_INCLUDE_DIR@"
+INCLUDE_TARGET_DIR = "@LIBCXX_INSTALL_INCLUDE_TARGET_DIR@"
+LIBRARY_DIR = "@LIBCXX_INSTALL_LIBRARY_DIR@"
 
 import os
 import pipes
 import site
 import sys
 site.addsitedir(os.path.join(LIBCXX_ROOT, 'utils'))
 import libcxx.test.features
 import libcxx.test.format

 
 # Configure basic substitutions
 runPy = os.path.join(LIBCXX_ROOT, 'utils', 'run.py')
 config.substitutions.append(('%{cxx}', COMPILER))
 config.substitutions.append(('%{flags}',
     '-isysroot {}'.format(CMAKE_OSX_SYSROOT) if CMAKE_OSX_SYSROOT else ''
 ))
 config.substitutions.append(('%{compile_flags}',
-    '-nostdinc++ -isystem {} -I {}'.format(
-        os.path.join(INSTALL_ROOT, 'include', 'c++', 'v1'),
+    '-nostdinc++ -isystem {} -isystem {} -I {}'.format(
+        os.path.join(INSTALL_ROOT, INCLUDE_DIR),
+        os.path.join(INSTALL_ROOT, INCLUDE_TARGET_DIR),
         os.path.join(LIBCXX_ROOT, 'test', 'support'))
 ))
 config.substitutions.append(('%{link_flags}',
     '-nostdlib++ -L {0} -lc++ -Wl,-rpath,{0} -pthread'.format(
-        os.path.join(INSTALL_ROOT, 'lib'))
+        os.path.join(INSTALL_ROOT, LIBRARY_DIR))
 ))
 config.substitutions.append(('%{exec}',
     '{} {} --execdir %T -- '.format(
         pipes.quote(sys.executable),
         pipes.quote(runPy))
 ))
 
 # Add parameters and features to the config
 libcxx.test.newconfig.configure(
     libcxx.test.params.DEFAULT_PARAMETERS,
     libcxx.test.features.DEFAULT_FEATURES,
     config,
     lit_config
 )

libcxx/test/configs/libcxx-trunk-static.cfg.in

 @AUTO_GEN_COMMENT@
 
 @SERIALIZED_LIT_PARAMS@
 
 LIBCXX_ROOT = "@LIBCXX_SOURCE_DIR@"
 INSTALL_ROOT = "@CMAKE_BINARY_DIR@"
 COMPILER = "@CMAKE_CXX_COMPILER@"
 EXEC_ROOT = "@LIBCXX_BINARY_DIR@"
 CMAKE_OSX_SYSROOT = "@CMAKE_OSX_SYSROOT@"
+INCLUDE_DIR = "@LIBCXX_INSTALL_INCLUDE_DIR@"
+INCLUDE_TARGET_DIR = "@LIBCXX_INSTALL_INCLUDE_TARGET_DIR@"
+LIBRARY_DIR = "@LIBCXX_INSTALL_LIBRARY_DIR@"
 
 import os
 import pipes
 import site
 import sys
 site.addsitedir(os.path.join(LIBCXX_ROOT, 'utils'))
 import libcxx.test.features
 import libcxx.test.format

 
 # Configure basic substitutions
 runPy = os.path.join(LIBCXX_ROOT, 'utils', 'run.py')
 config.substitutions.append(('%{cxx}', COMPILER))
 config.substitutions.append(('%{flags}',
     '-isysroot {}'.format(CMAKE_OSX_SYSROOT) if CMAKE_OSX_SYSROOT else ''
 ))
 config.substitutions.append(('%{compile_flags}',
-    '-nostdinc++ -isystem {} -I {}'.format(
-        os.path.join(INSTALL_ROOT, 'include', 'c++', 'v1'),
+    '-nostdinc++ -isystem {} -isystem {} -I {}'.format(
+        os.path.join(INSTALL_ROOT, INCLUDE_DIR),
+        os.path.join(INSTALL_ROOT, INCLUDE_TARGET_DIR),
         os.path.join(LIBCXX_ROOT, 'test', 'support'))
 ))
 config.substitutions.append(('%{link_flags}',
     '-nostdlib++ -L {} -lc++ -lc++abi -pthread'.format(
-        os.path.join(INSTALL_ROOT, 'lib'))
+        os.path.join(INSTALL_ROOT, LIBRARY_DIR))
 ))
 config.substitutions.append(('%{exec}',
     '{} {} --execdir %T -- '.format(
         pipes.quote(sys.executable),
         pipes.quote(runPy))
 ))
 
 # Add parameters and features to the config
 libcxx.test.newconfig.configure(
     libcxx.test.params.DEFAULT_PARAMETERS,
     libcxx.test.features.DEFAULT_FEATURES,
     config,
     lit_config
 )