PNaCl dynamic linking: Build an initial dynamically-linked newlib-based libc

tests/pnacl_dynamic_loading/nacl.scons

 # -*- python -*-
 # Copyright (c) 2014 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 Import('env')
 
 if not env.Bit('bitcode'):
   Return()
 # Translating the PSO to an ELF DSO doesn't work on x86-64 yet.  The
@@ skipping 34 matching lines @@
 
 def PsoFromLLVMAssembly(base_name):
   bitcode_file = env.Command(
       '%s.bc' % base_name, ['%s.ll' % base_name],
       [Action('${ASCOM}', '${ASCOMSTR}')])
   return MakeAndTranslatePso(base_name, [bitcode_file],
                              # Skip PNaCl passes because they add TLS functions.
                              llvm_passes='')
 
 
+LLVM_PASSES = (
+    # The following is a subset of "-pnacl-abi-simplify-preopt".  We don't
+    # want to run the full "-pnacl-abi-simplify-preopt" because it
+    # internalizes symbols that we want to export via "-convert-to-pso".
+    '-resolve-aliases '
+    '-nacl-global-cleanup '
+    '-expand-varargs '
+    '-rewrite-pnacl-library-calls '
+    '-rewrite-llvm-intrinsic-calls '
+    # Convert thread-local variables into non-thread-local global variables
+    # for now because ConvertToPSO doesn't support TLS yet.
+    '-minsfi-strip-tls '
+    '-convert-to-pso '
+    '-pnacl-abi-simplify-postopt')
+
+
 def MakeAndTranslatePll(dest, source_file):
   return MakeAndTranslatePso(
       dest, [env.ComponentObject(source_file)],
       # Skip the pre-opt passes because they add TLS functions.  However,
       # we still need to run the post-opt passes so that the LLVM IR passes
       # the PNaCl ABI checker.
-      llvm_passes='-convert-to-pso -pnacl-abi-simplify-postopt')
+      llvm_passes=LLVM_PASSES)
 
 
 # Under SFI NaCl, the loader currently depends on the allocate_code_data()
 # interface provided by the IRT.
 is_broken = not env.Bit('tests_use_irt') and not env.Bit('nonsfi_nacl')
 
 dso1 = MakeAndTranslatePso(
     'test_pso', [env.ComponentObject('test_pso.c')],
     llvm_passes='-pnacl-abi-simplify-preopt -pnacl-abi-simplify-postopt')
 dso2 = PsoFromLLVMAssembly('data_only_pso')
@@ skipping 38 matching lines @@
     'pll_loader_test', ['pll_loader_test.cc'],
     EXTRA_LIBS=['${NONIRT_LIBS}', 'pll_loader'])
 
 node = env.CommandSelLdrTestNacl(
     'pll_loader_test.out', pll_loader_test, [test_pll_a, test_pll_b],
     # Add '-a' to enable filesystem access for opening DSOs.
     sel_ldr_flags=['-a'])
 env.AddNodeToTestSuite(
     node, ['small_tests', 'toolchain_tests'],
     'run_pll_loader_test', is_broken=is_broken)
+
+
+libc_obj = env.Command(
+    'libc${OBJSUFFIX}',
+    # libnacl should come first so that it can override definitions in libc.
+    [env.File('${LIB_DIR}/libnacl.a'),
+     env.File('${NACL_SDK_LIB}/libc.a'),
+     env.ComponentObject('libc_entry.c')],
+    '${LD} -r --whole-archive ${SOURCES} -o ${TARGET}')
+
+translated_pll_libc = MakeAndTranslatePso(
+    'translated_pll_libc', libc_obj,
+    llvm_passes=LLVM_PASSES)
+translated_pll_hello_world = MakeAndTranslatePso(
+    'translated_pll_hello_world',
+    [env.ComponentObject('hello_world${OBJSUFFIX}',
+                         '../hello_world/hello_world.c')],
+    llvm_passes=LLVM_PASSES)
+
+# Ideally we would have this ComponentProgram() definition in
+# src/untrusted/pll_loader/nacl.scons instead; see the comment there for
+# why we don't.
+pll_loader = env.ComponentProgram(

[Sean Klein, 2016/02/29 18:18:07]

So pll_loader is a library (built in src/unstrusted/pll_loader/nacl.scons), but
pll_loader is also an executable (built here).

The "pll_loader" name is overloaded -- could this version of "pll_loader" be
renamed to "pll_loader_executable", or something like that, to break ambiguity?

[Mark Seaborn, 2016/02/29 20:08:43]

That overloading doesn't cause any technical problems because the two are in
different namespaces.  Do you mean you want a way to avoid ambiguity when
talking about these components?

I wouldn't want to call the executable "pll_loader_executable" because that's
rather verbose.

I could rename the library to "pll_loader_lib" if you want?  Or we could just
refer to it as "the PLL loader library"?

[Sean Klein, 2016/02/29 20:10:39]

I know it's not a technical problem, but I wanted to avoid any readability
issues.

I would prefer the "pll_loader_lib" solution.

[Mark Seaborn, 2016/02/29 22:26:11]

OK, done.

+    'pll_loader', [],
+    EXTRA_LIBS=['${NONIRT_LIBS}', 'pll_loader_main', 'pll_loader'])
+
+node = env.CommandSelLdrTestNacl(
+    'pll_hello_world_test.out', pll_loader,
+    [translated_pll_libc, translated_pll_hello_world],
+    # Add '-a' to enable filesystem access for opening DSOs.
+    sel_ldr_flags=['-a'],
+    stdout_golden=env.File('../hello_world/hello_world.stdout'))
+env.AddNodeToTestSuite(
+    node, ['small_tests', 'toolchain_tests'],
+    'run_pll_hello_world_test', is_broken=is_broken)