Fix support for distinguishing archive members by timestamp on Darwin.

[jyknight]

Summary

On Darwin, the binary's symbol table points to debug info in object
files -- potentially object files within a static library. Such a
library may have multiple entries with the same name, distinguished
only by timestamp.

The code was already _attempting_ to handle this case (see the code in
ObjectContainerBSDArchive::Archive::FindObject which disambiguates via
timestamp). But, unfortunately, while the timestamp was taken into
account on the _first_ lookup, the result was then cached in a map
keyed only off of the path.

Added the timestamp to the cache, and added a test case.

[aprantl]

Very nice! Thanks.

lldb/packages/Python/lldbsuite/test/macosx/duplicate-archive-members/Makefile

4

dsymutil also implements the same mechanism, so as an end-to-end test it wouldn't hurt to also allow the dSYM variant of this test to be run.

Does MAKE_DSYM=NO disable the dsym category for this test or does it just prevent the dwarf variant from also producing a dSYM?

[jyknight]

lldb/packages/Python/lldbsuite/test/macosx/duplicate-archive-members/Makefile

4

Yeah, I'm not sure why that's there -- deleted.

I think I just copied it from another test's Makefile without thinking too hard. :)
AFAICT it doesn't even do anything -- the test infrastructure overrides MAKE_DSYM to NO or YES explicitly anyways, so this gets ignored. I suspect that it should be removed from all the other Makefiles too.

lldb/packages/Python/lldbsuite/test/macosx/duplicate-archive-members/Makefile

+LEVEL = ../../make
+
+C_SOURCES := main.c
+MAKE_DSYM := NO
+
+# Make an archive that has two object files with the same name, but
+# different timestamps. Do it all in one rule so that the timestamps
+# can be controlled without confusing Make.
+libfoo.a: a.c sub1/a.c
+  $(CC) $(CFLAGS) -c $(<D)/a.c -o a.o
+  mkdir -p sub1
+  $(CC) $(CFLAGS) -c $(<D)/sub1/a.c -o sub1/a.o
+  touch -t '198001010000.00' a.o
+  touch -t '198001010000.01' sub1/a.o
+  $(AR) $(ARFLAGS) $@ a.o sub1/a.o
+  rm a.o sub1/a.o
+
+include $(LEVEL)/Makefile.rules
+
+# Needs to come after include
+OBJECTS += libfoo.a
+$(EXE) : libfoo.a
+.DEFAULT_GOAL := $(EXE)

lldb/packages/Python/lldbsuite/test/macosx/duplicate-archive-members/TestDuplicateMembers.py

+"""Test breaking inside functions defined within a BSD archive file libfoo.a."""
+
+from __future__ import print_function
+
+
+import os
+import time
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class BSDArchivesTestCase(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def setUp(self):
+        # Call super's setUp().
+        TestBase.setUp(self)
+        # Find the line number in a(int) to break at.
+        self.line = line_number(
+            'a.c', '// Set file and line breakpoint inside a().')
+
+    @expectedFailureAll(
+        oslist=["windows"],
+        bugnumber="llvm.org/pr24527.  Makefile.rules doesn't know how to build static libs on Windows")
+    def test(self):
+        """Break inside a() and b() defined within libfoo.a."""
+        self.build()
+
+        exe = self.getBuildArtifact("a.out")
+        self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
+
+        # Break on a() and b() symbols
+        lldbutil.run_break_set_by_symbol(
+            self, "a", sym_exact=True)
+        lldbutil.run_break_set_by_symbol(
+            self, "b", sym_exact=True)
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        # The stop reason of the thread should be breakpoint.
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+                    substrs=['stopped',
+                             'stop reason = breakpoint'])
+
+        # Break at a(int) first.
+        self.expect("frame variable", VARIABLES_DISPLAYED_CORRECTLY,
+                    substrs=['(int) arg = 1'])
+        self.expect("frame variable __a_global", VARIABLES_DISPLAYED_CORRECTLY,
+                    substrs=['(int) __a_global = 1'])
+
+        # Continue the program, we should break at b(int) next.
+        self.runCmd("continue")
+        self.expect("thread list", STOPPED_DUE_TO_BREAKPOINT,
+                    substrs=['stopped',
+                             'stop reason = breakpoint'])
+        self.expect("frame variable", VARIABLES_DISPLAYED_CORRECTLY,
+                    substrs=['(int) arg = 2'])
+        self.expect("frame variable __b_global", VARIABLES_DISPLAYED_CORRECTLY,
+                    substrs=['(int) __b_global = 2'])

lldb/packages/Python/lldbsuite/test/macosx/duplicate-archive-members/a.c

+//===-- a.c -----------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+int __a_global = 1;
+
+int a(int arg) {
+    int result = arg + __a_global;
+    return result;
+}

lldb/packages/Python/lldbsuite/test/macosx/duplicate-archive-members/main.c

+//===-- main.c --------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#include <stdio.h>
+
+extern int a(int);
+extern int b(int);
+int main (int argc, char const *argv[])
+{
+    printf ("a(1) returns %d\n", a(1));
+    printf ("b(2) returns %d\n", b(2));
+}

lldb/packages/Python/lldbsuite/test/macosx/duplicate-archive-members/sub1/a.c

+//===-- a.c -----------------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+static int __b_global = 2;
+
+int b(int arg) {
+    int result = arg + __b_global;
+    return result;
+}

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h

protected:
 
   //------------------------------------------------------------------
   // Member Variables
   //------------------------------------------------------------------
   std::bitset<kNumFlags> m_flags;
   std::vector<CompileUnitInfo> m_compile_unit_infos;
   std::vector<uint32_t> m_func_indexes; // Sorted by address
   std::vector<uint32_t> m_glob_indexes;
-  std::map<lldb_private::ConstString, OSOInfoSP> m_oso_map;
+  std::map<std::pair<lldb_private::ConstString, llvm::sys::TimePoint<>>, OSOInfoSP> m_oso_map;
   UniqueDWARFASTTypeMap m_unique_ast_type_map;
   lldb_private::LazyBool m_supports_DW_AT_APPLE_objc_complete_type;
   DebugMap m_debug_map;
 
   //------------------------------------------------------------------
   // When an object file from the debug map gets parsed in
   // SymbolFileDWARF, it needs to tell the debug map about the object
   // files addresses by calling this function once for each N_FUN,

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp

Module *SymbolFileDWARFDebugMap::GetModuleByOSOIndex(uint32_t oso_idx) {
   if (oso_idx < cu_count)
     return GetModuleByCompUnitInfo(&m_compile_unit_infos[oso_idx]);
   return NULL;
 }
 
 Module *SymbolFileDWARFDebugMap::GetModuleByCompUnitInfo(
     CompileUnitInfo *comp_unit_info) {
   if (!comp_unit_info->oso_sp) {
-    auto pos = m_oso_map.find(comp_unit_info->oso_path);
+    auto pos = m_oso_map.find({comp_unit_info->oso_path, comp_unit_info->oso_mod_time});
     if (pos != m_oso_map.end()) {
       comp_unit_info->oso_sp = pos->second;
     } else {
       ObjectFile *obj_file = GetObjectFile();
       comp_unit_info->oso_sp.reset(new OSOInfo());
-      m_oso_map[comp_unit_info->oso_path] = comp_unit_info->oso_sp;
+      m_oso_map[{comp_unit_info->oso_path, comp_unit_info->oso_mod_time}] = comp_unit_info->oso_sp;
       const char *oso_path = comp_unit_info->oso_path.GetCString();
       FileSpec oso_file(oso_path, false);
       ConstString oso_object;
       if (oso_file.Exists()) {
         auto oso_mod_time = FileSystem::GetModificationTime(oso_file);
         if (oso_mod_time != comp_unit_info->oso_mod_time) {
           obj_file->GetModule()->ReportError(
               "debug map object file '%s' has changed (actual time is "