Have CMake LLVM build share CFLAGS/CXXFLAGS with autoconf (e.g., libc++ flags).

toolchain_build/toolchain_build_pnacl.py

Index: toolchain_build/toolchain_build_pnacl.py
diff --git a/toolchain_build/toolchain_build_pnacl.py b/toolchain_build/toolchain_build_pnacl.py
index 32a6c798bb8524bdf8eb064c1a74f96cb7bc6300..8065ec528df4712b16850c1f7872d4a94d3fa900 100755
--- a/toolchain_build/toolchain_build_pnacl.py
+++ b/toolchain_build/toolchain_build_pnacl.py
@@ -139,8 +139,8 @@ def TripleIsX8664(t):
 def HostIsDebug(options):
   return options.host_flavor == 'debug'
 
-# Return a tuple (C compiler, C++ compiler) of the compilers to compile the host
-# toolchains
+# Return a tuple (C compiler, C++ compiler, ar, ranlib) of the compilers and
+# tools to compile the host toolchains.
 def CompilersForHost(host):
   compiler = {
       # For now we only do native builds for linux and mac
@@ -158,7 +158,6 @@ def CompilersForHost(host):
     nacl_sdk = os.environ.get('NACL_SDK_ROOT')
     assert nacl_sdk, 'NACL_SDK_ROOT not set'
     pnacl_bin_dir = os.path.join(nacl_sdk, 'toolchain/linux_pnacl/bin')
-    glibc_bin_dir = os.path.join(nacl_sdk, 'toolchain/linux_x86_glibc/bin')
     compiler.update({
         'le32-nacl': (os.path.join(pnacl_bin_dir, 'pnacl-clang'),
                       os.path.join(pnacl_bin_dir, 'pnacl-clang++'),
@@ -178,6 +177,41 @@ def FlavoredName(component_name, host, options):
     joined_name= joined_name + '_debug'
   return joined_name
 
+
+def HostArchToolFlags(host, extra_cflags, opts):
+  """Return the appropriate CFLAGS, CXXFLAGS, and LDFLAGS based on host
+  and opts. Does not attempt to determine flags that are attached
+  to CC and CXX directly.
+  """
+  extra_cc_flags = list(extra_cflags)
+  result = { 'LDFLAGS' : [],
+             'CFLAGS' : [],
+             'CXXFLAGS' : []}
+  if TripleIsWindows(host):
+    result['LDFLAGS'] += ['-L%(abs_libdl)s', '-ldl']
+    result['CFLAGS'] += ['-isystem','%(abs_libdl)s']
+    result['CXXFLAGS'] += ['-isystem', '%(abs_libdl)s']
+  else:
+    if TripleIsLinux(host) and not TripleIsX8664(host):
+      # Chrome clang defaults to 64-bit builds, even when run on 32-bit Linux.
+      extra_cc_flags += ['-m32']
+    elif TripleIsMac(host):
+      # This is required for building with recent libc++ against OSX 10.6
+      extra_cc_flags += ['-U__STRICT_ANSI__']
+    if opts.gcc or host == 'le32-nacl':
+      result['CFLAGS']  += extra_cc_flags
+      result['CXXFLAGS'] += extra_cc_flags
+    else:
+      result['CFLAGS'] += extra_cc_flags
+      result['LDFLAGS'] += ['-L%(' + FlavoredName('abs_libcxx',
+                                                  host, opts) + ')s/lib']
+      result['CXXFLAGS'] += ([
+        '-stdlib=libc++',
+        '-I%(' + FlavoredName('abs_libcxx', host, opts) + ')s/include/c++/v1'] +
+        extra_cc_flags)
+  return result
+
+
 def ConfigureHostArchFlags(host, extra_cflags, options, extra_configure=None):
   """ Return flags passed to LLVM and binutils configure for compilers and
   compile flags. """
@@ -201,9 +235,6 @@ def ConfigureHostArchFlags(host, extra_cflags, options, extra_configure=None):
       configure_args.append('--build=' + host)
     else:
       configure_args.append('--host=' + host)
-  if TripleIsLinux(host) and not TripleIsX8664(host):
-    # Chrome clang defaults to 64-bit builds, even when run on 32-bit Linux.
-    extra_cc_args += ['-m32']
 
   extra_cxx_args = list(extra_cc_args)
 
@@ -215,34 +246,20 @@ def ConfigureHostArchFlags(host, extra_cflags, options, extra_configure=None):
     configure_args.append('AR=' + ar)
     configure_args.append('RANLIB=' + ranlib)
 
+  tool_flags = HostArchToolFlags(host, extra_cflags, options)
+  configure_args.extend(
+       ['CFLAGS=' + ' '.join(tool_flags['CFLAGS']),
+        'CXXFLAGS=' + ' '.join(tool_flags['CXXFLAGS']),
+        'LDFLAGS=' + ' '.join(tool_flags['LDFLAGS']),
+       ])
   if TripleIsWindows(host):
     # The i18n support brings in runtime dependencies on MinGW DLLs
     # that we don't want to have to distribute alongside our binaries.
     # So just disable it, and compiler messages will always be in US English.
     configure_args.append('--disable-nls')
-    configure_args.extend(['LDFLAGS=-L%(abs_libdl)s -ldl',
-                           'CFLAGS=-isystem %(abs_libdl)s',
-                           'CXXFLAGS=-isystem %(abs_libdl)s'])
     if is_cross:
       # LLVM's linux->mingw cross build needs this
       configure_args.append('CC_FOR_BUILD=gcc')
-  else:
-    if TripleIsMac(host):
-      # This is required for building with recent libc++ against OSX 10.6
-      extra_cflags.append('-U__STRICT_ANSI__')
-    if options.gcc or host == 'le32-nacl':
-      configure_args.extend(['CFLAGS=' + ' '.join(extra_cflags),
-                             'CXXFLAGS=' + ' '.join(extra_cflags)])
-    else:
-      configure_args.extend(
-       ['CFLAGS=' + ' '.join(extra_cflags),
-        'LDFLAGS=-L%(' + FlavoredName('abs_libcxx',
-                                      host,
-                                      options) + ')s/lib',
-        'CXXFLAGS=-stdlib=libc++ -I%(' +
-            FlavoredName('abs_libcxx', host, options) +
-        ')s/include/c++/v1 ' + ' '.join(extra_cflags)])
-
   return configure_args
 
 
@@ -256,6 +273,7 @@ def LibCxxHostArchFlags(host):
                         '-DCMAKE_CXX_FLAGS=-m32'])
   return cmake_flags
 
+
 def CmakeHostArchFlags(host, options):
   """ Set flags passed to LLVM cmake for compilers and compile flags. """
   cmake_flags = []
@@ -268,13 +286,15 @@ def CmakeHostArchFlags(host, options):
   # msan-enabled compiler_rt, leaving references to __msan_allocated_memory
   # undefined.
   cmake_flags.append('-DHAVE_SANITIZER_MSAN_INTERFACE_H=FALSE')
-
+  tool_flags = HostArchToolFlags(host, [], options)
   if options.sanitize:
-    cmake_flags.extend(['-DCMAKE_%s_FLAGS=-fsanitize=%s' % (c, options.sanitize)
-                        for c in ('C', 'CXX')])
-    cmake_flags.append('-DCMAKE_EXE_LINKER_FLAGS=-fsanitize=%s' %
-                       options.sanitize)
-
+    for f in ['CFLAGS', 'CXXFLAGS', 'LDFLAGS']:
+      tool_flags[f] += '-fsanitize=%s' % options.sanitize
+  cmake_flags.extend(['-DCMAKE_C_FLAGS=' + ' '.join(tool_flags['CFLAGS'])])
+  cmake_flags.extend(['-DCMAKE_CXX_FLAGS=' + ' '.join(tool_flags['CXXFLAGS'])])
+  for linker_type in ['EXE', 'SHARED', 'MODULE']:

[Derek Schuff, 2015/03/10 00:01:37]

I seem to recall that there was some reason I made it just EXE and not all 3
before, but now I can't remember exactly what it was :(

[jvoung (off chromium), 2015/03/10 19:39:19]

Yeah, I'm not sure of the exact consequence. I started with EXE only, but then
added SHARED and MODULE and nothing was observably different. I looked at LLVM's
behavior w/ "-DLLVM_ENABLE_LIBCXX=OFF" switch to ON, and it would add
-stdlib=libc++ to EXE, SHARED, and MODULE, so I figured this might as well match
that.

[Derek Schuff, 2015/03/10 21:09:45]

actually now that I think about it, i'm not sure -stdlib=libc++ is what you want
when linking a shared object? anyway if it all works then this is fine with me.

+    cmake_flags.extend([('-DCMAKE_%s_LINKER_FLAGS=' % linker_type) +
+                        ' '.join(tool_flags['LDFLAGS'])])
   return cmake_flags
 
 
@@ -626,11 +646,16 @@ def HostTools(host, options):
                   '-DLLVM_ENABLE_ZLIB=OFF',
                   '-DLLVM_EXTERNAL_CLANG_SOURCE_DIR=%(clang_src)s',
                   '-DLLVM_TARGETS_TO_BUILD=X86;ARM;Mips',
-                  '%(llvm_src)s']),
-              command.Command(['ninja', '-v']),
-              command.Command(['ninja', 'install']),
-              ] +
-          CreateSymLinksToDirectToNaClTools(host)
+                  '%(llvm_src)s'],
+                  # Older CMake ignore CMAKE_*_LINKER_FLAGS during config step.
+                  # https://public.kitware.com/Bug/view.php?id=14066
+                  # The workaround is to set LDFLAGS in the environment.
+                  env={'LDFLAGS' : ' '.join(

[Derek Schuff, 2015/03/10 00:01:37]

I've been trying pretty hard to avoid having env override in Command, but I'm
out of ideas as to how to avoid it this time :( Maybe add to the comment here
that once we no longer care about older cmakes, we can remove that feature.

[jvoung (off chromium), 2015/03/10 19:39:19]

Added a comment about deprecating this after the cmake fix propagates for a
while.

Any issue with caching?

+                        HostArchToolFlags(host, [], options)['LDFLAGS'])})] +
+              CopyHostLibcxxForLLVMBuild(host, 'lib', options) +
+              [command.Command(['ninja', '-v']),
+               command.Command(['ninja', 'install'])] +
+              CreateSymLinksToDirectToNaClTools(host)
       },
   }
   cleanup_static_libs = []