[lldb] Display MachO seg,sec of memory region

[kastiglione]

Summary

memory region displays the top-level section name, which for MachO is the segment name. The segment name alone is not much use, it's very coarse grained. This changes memory region to display the segment and section names for MachO images. For example, display __DATA,__const instead of only __DATA.

[kastiglione]

I see now this isn't valid as written. The address range and rwx permissions printed by memory region are for the segment not the section. I think it would be helpful to print the section too, but as this change is written now, it could appear that all the info is for the section, when it's really for the segment. Maybe a better change would be to print a second line with an address range for the section, and the section's name.

[aprantl]

lldb/test/API/functionalities/memory-region/TestMemoryRegion.py

76

Doesn't lldbutil.run_break_set_by_symbol() do the "file" and "run" already and this run command runs it a second time?

[aprantl]

lldb/source/Commands/CommandObjectMemory.cpp

1695

Why did section_sp->GetName(); return the Segment name in the original code? Is that a bug?

[kastiglione]

lldb/source/Commands/CommandObjectMemory.cpp

1695

The original code is traversing the parent chain of sections, which for mach-o ends up on the segment. Now that I have learned the address range printed is for the segment, then it makes sense why the segment name alone is printed.

lldb/test/API/functionalities/memory-region/TestMemoryRegion.py

76

I will learn more to find out.

lldb/source/Commands/CommandObjectMemory.cpp

 //===-- CommandObjectMemory.cpp -------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 

 #include "lldb/Target/Process.h"
 #include "lldb/Target/StackFrame.h"
 #include "lldb/Target/Target.h"
 #include "lldb/Target/Thread.h"
 #include "lldb/Utility/Args.h"
 #include "lldb/Utility/DataBufferHeap.h"
 #include "lldb/Utility/DataBufferLLVM.h"
 #include "lldb/Utility/StreamString.h"
+#include "llvm/Support/FormatVariadic.h"
 #include "llvm/Support/MathExtras.h"
 #include <cinttypes>
 #include <memory>
 
 using namespace lldb;
 using namespace lldb_private;
 
 #define LLDB_OPTIONS_memory_read
bool DoExecute(Args &command, CommandReturnObject &result) override {
     }
 
     lldb_private::MemoryRegionInfo range_info;
     error = process_sp->GetMemoryRegionInfo(load_addr, range_info);
     if (error.Success()) {
       lldb_private::Address addr;
       ConstString name = range_info.GetName();
       ConstString section_name;
-      if (process_sp->GetTarget().ResolveLoadAddress(load_addr, addr)) {
+      auto &target = process_sp->GetTarget();
+      if (target.ResolveLoadAddress(load_addr, addr)) {
         SectionSP section_sp(addr.GetSection());
         if (section_sp) {
+          if (target.GetArchitecture().GetTriple().isOSBinFormatMachO()) {
+            // Display the conventional Mach-O format: __SEG,__SECT
+            if (auto segment_sp = section_sp->GetParent()) {
+              auto segment_name = segment_sp->GetName();
+              auto section_name_ = section_sp->GetName();
+              section_name = ConstString(
+                  llvm::formatv("{0},{1}", segment_name, section_name_).str());
+            }
+          }
+
+          if (section_name.IsEmpty()) {
             // Got the top most section, not the deepest section
             while (section_sp->GetParent())
               section_sp = section_sp->GetParent();
             section_name = section_sp->GetName();
           }
         }
+      }
 
       result.AppendMessageWithFormatv(
           "[{0:x16}-{1:x16}) {2:r}{3:w}{4:x}{5}{6}{7}{8}",
           range_info.GetRange().GetRangeBase(),
           range_info.GetRange().GetRangeEnd(), range_info.GetReadable(),
           range_info.GetWritable(), range_info.GetExecutable(), name ? " " : "",
           name, section_name ? " " : "", section_name);
       MemoryRegionInfo::OptionalBool memory_tagged =

lldb/test/API/functionalities/memory-region/TestMemoryRegion.py

def test(self):
             interp.HandleCommand("memory region", result)
             if not result.Succeeded():
                 break
 
         # Now that we reached the end, 'memory region' should again print the usage.
         interp.HandleCommand("memory region", result)
         self.assertFalse(result.Succeeded())
         self.assertRegexpMatches(result.GetError(), "Usage: memory region ADDR")
+
+    @skipUnlessDarwin
+    def test_macho(self):
+        self.build()
+
+        # Set breakpoint in main and run
+        self.runCmd("file " + self.getBuildArtifact("a.out"), CURRENT_EXECUTABLE_SET)
+        lldbutil.run_break_set_by_symbol(
+            self, "main", sym_exact=True, num_expected_locations=1
+        )
+
+        self.runCmd("run", RUN_SUCCEEDED)
+
+        interp = self.dbg.GetCommandInterpreter()
+        result = lldb.SBCommandReturnObject()
+
+        interp.HandleCommand("memory region $pc", result)
+        self.assertRegexpMatches(result.GetOutput(), r"\b__TEXT,__text\b")