[lldb] Load embedded type summary section (#7859) (#8040) #113743

adrian-prantl · 2024-10-25T23:25:30Z

Add support for type summaries embedded into the binary.

These embedded summaries will typically be generated by Swift macros, but can also be generated by any other means.

rdar://115184658

This upstreams the embedded type summary feature from the swiftlang branch of LLDB, since it shares a lot of the same goals and design points with #113398

…#8040) Add support for type summaries embedded into the binary. These embedded summaries will typically be generated by Swift macros, but can also be generated by any other means. rdar://115184658

llvmbot · 2024-10-25T23:26:00Z

@llvm/pr-subscribers-lldb

Author: Adrian Prantl (adrian-prantl)

Changes

Add support for type summaries embedded into the binary.

These embedded summaries will typically be generated by Swift macros, but can also be generated by any other means.

rdar://115184658

This upstreams the embedded type summary feature from the swiftlang branch of LLDB, since it shares a lot of the same goals and design points with #113398

Full diff: https://github.com/llvm/llvm-project/pull/113743.diff

10 Files Affected:

(modified) lldb/include/lldb/lldb-enumerations.h (+1)
(modified) lldb/source/Core/Section.cpp (+3)
(modified) lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp (+1)
(modified) lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp (+4)
(modified) lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp (+1)
(modified) lldb/source/Symbol/ObjectFile.cpp (+1)
(modified) lldb/source/Target/Target.cpp (+72)
(added) lldb/test/API/functionalities/data-formatter/embedded-summary/Makefile (+2)
(added) lldb/test/API/functionalities/data-formatter/embedded-summary/TestEmbeddedTypeSummary.py (+12)
(added) lldb/test/API/functionalities/data-formatter/embedded-summary/main.c (+22)

diff --git a/lldb/include/lldb/lldb-enumerations.h b/lldb/include/lldb/lldb-enumerations.h
index 938f6e3abe8f2a..1ca4aa62218c09 100644
--- a/lldb/include/lldb/lldb-enumerations.h
+++ b/lldb/include/lldb/lldb-enumerations.h
@@ -761,6 +761,7 @@ enum SectionType {
   eSectionTypeDWARFDebugLocListsDwo,
   eSectionTypeDWARFDebugTuIndex,
   eSectionTypeCTF,
+  eSectionTypeLLDBTypeSummaries,
   eSectionTypeSwiftModules,
 };
 
diff --git a/lldb/source/Core/Section.cpp b/lldb/source/Core/Section.cpp
index 0763e88d4608f4..ee01b4ce06ca1e 100644
--- a/lldb/source/Core/Section.cpp
+++ b/lldb/source/Core/Section.cpp
@@ -147,6 +147,8 @@ const char *Section::GetTypeAsCString() const {
     return "dwarf-gnu-debugaltlink";
   case eSectionTypeCTF:
     return "ctf";
+  case eSectionTypeLLDBTypeSummaries:
+    return "lldb-type-summaries";
   case eSectionTypeOther:
     return "regular";
   case eSectionTypeSwiftModules:
@@ -457,6 +459,7 @@ bool Section::ContainsOnlyDebugInfo() const {
   case eSectionTypeDWARFAppleObjC:
   case eSectionTypeDWARFGNUDebugAltLink:
   case eSectionTypeCTF:
+  case eSectionTypeLLDBTypeSummaries:
   case eSectionTypeSwiftModules:
     return true;
   }
diff --git a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
index 10d09662c0a47a..ad4a84ef02bf72 100644
--- a/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
+++ b/lldb/source/Plugins/ObjectFile/ELF/ObjectFileELF.cpp
@@ -1678,6 +1678,7 @@ static SectionType GetSectionTypeFromName(llvm::StringRef Name) {
       .Case(".gnu_debugaltlink", eSectionTypeDWARFGNUDebugAltLink)
       .Case(".gosymtab", eSectionTypeGoSymtab)
       .Case(".text", eSectionTypeCode)
+      .Case(".lldbsummaries", lldb::eSectionTypeLLDBTypeSummaries)
       .Case(".swift_ast", eSectionTypeSwiftModules)
       .Default(eSectionTypeOther);
 }
diff --git a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
index b542e237f023d4..d6bec5d84aea19 100644
--- a/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
+++ b/lldb/source/Plugins/ObjectFile/Mach-O/ObjectFileMachO.cpp
@@ -1209,6 +1209,7 @@ AddressClass ObjectFileMachO::GetAddressClass(lldb::addr_t file_addr) {
         case eSectionTypeDWARFAppleObjC:
         case eSectionTypeDWARFGNUDebugAltLink:
         case eSectionTypeCTF:
+        case eSectionTypeLLDBTypeSummaries:
         case eSectionTypeSwiftModules:
           return AddressClass::eDebug;
 
@@ -1484,6 +1485,7 @@ static lldb::SectionType GetSectionType(uint32_t flags,
   static ConstString g_sect_name_data("__data");
   static ConstString g_sect_name_go_symtab("__gosymtab");
   static ConstString g_sect_name_ctf("__ctf");
+  static ConstString g_sect_name_lldb_summaries("__lldbsummaries");
   static ConstString g_sect_name_swift_ast("__swift_ast");
 
   if (section_name == g_sect_name_dwarf_debug_abbrev)
@@ -1564,6 +1566,8 @@ static lldb::SectionType GetSectionType(uint32_t flags,
     return eSectionTypeGoSymtab;
   if (section_name == g_sect_name_ctf)
     return eSectionTypeCTF;
+  if (section_name == g_sect_name_lldb_summaries)
+    return lldb::eSectionTypeLLDBTypeSummaries;
   if (section_name == g_sect_name_swift_ast)
     return eSectionTypeSwiftModules;
   if (section_name == g_sect_name_objc_data ||
diff --git a/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp b/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
index 8d9c919bc9b101..bb712da7f6d67d 100644
--- a/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
+++ b/lldb/source/Plugins/ObjectFile/PECOFF/ObjectFilePECOFF.cpp
@@ -1010,6 +1010,7 @@ SectionType ObjectFilePECOFF::GetSectionType(llvm::StringRef sect_name,
           // .eh_frame can be truncated to 8 chars.
           .Cases(".eh_frame", ".eh_fram", eSectionTypeEHFrame)
           .Case(".gosymtab", eSectionTypeGoSymtab)
+          .Case(".lldbsummaries", lldb::eSectionTypeLLDBTypeSummaries)
           .Case("swiftast", eSectionTypeSwiftModules)
           .Default(eSectionTypeInvalid);
   if (section_type != eSectionTypeInvalid)
diff --git a/lldb/source/Symbol/ObjectFile.cpp b/lldb/source/Symbol/ObjectFile.cpp
index 35317d209de1f9..3100e6b813b631 100644
--- a/lldb/source/Symbol/ObjectFile.cpp
+++ b/lldb/source/Symbol/ObjectFile.cpp
@@ -366,6 +366,7 @@ AddressClass ObjectFile::GetAddressClass(addr_t file_addr) {
           case eSectionTypeDWARFAppleObjC:
           case eSectionTypeDWARFGNUDebugAltLink:
           case eSectionTypeCTF:
+          case eSectionTypeLLDBTypeSummaries:
           case eSectionTypeSwiftModules:
             return AddressClass::eDebug;
           case eSectionTypeEHFrame:
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index 04395e37f0425d..37670b108d9631 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -26,6 +26,7 @@
 #include "lldb/Core/StructuredDataImpl.h"
 #include "lldb/Core/ValueObject.h"
 #include "lldb/Core/ValueObjectConstResult.h"
+#include "lldb/DataFormatters/DataVisualization.h"
 #include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/ExpressionVariable.h"
 #include "lldb/Expression/REPL.h"
@@ -1537,6 +1538,76 @@ static void LoadScriptingResourceForModule(const ModuleSP &module_sp,
                                                   feedback_stream.GetData());
 }
 
+// Load type summaries embedded in the binary. These are type summaries provided
+// by the authors of the code.
+static void LoadTypeSummariesForModule(ModuleSP module_sp) {
+  auto *sections = module_sp->GetSectionList();
+  if (!sections)
+    return;
+
+  auto summaries_sp =
+      sections->FindSectionByType(eSectionTypeLLDBTypeSummaries, true);
+  if (!summaries_sp)
+    return;
+
+  Log *log = GetLog(LLDBLog::DataFormatters);
+  const char *module_name = module_sp->GetObjectName().GetCString();
+
+  TypeCategoryImplSP category;
+  DataVisualization::Categories::GetCategory(ConstString("default"), category);
+
+  // The type summary record is serialized as follows.
+  //
+  // Each record contains, in order:
+  //   * Version number of the record format
+  //   * The remaining size of the record
+  //   * The size of the type identifier
+  //   * The type identifier, either a type name, or a regex
+  //   * The size of the summary string
+  //   * The summary string
+  //
+  // Integers are encoded using ULEB.
+  //
+  // Strings are encoded with first a length (ULEB), then the string contents,
+  // and lastly a null terminator. The length includes the null.
+
+  DataExtractor extractor;
+  auto section_size = summaries_sp->GetSectionData(extractor);
+  lldb::offset_t offset = 0;
+  while (offset < section_size) {
+    uint64_t version = extractor.GetULEB128(&offset);
+    uint64_t record_size = extractor.GetULEB128(&offset);
+    if (version == 1) {
+      uint64_t type_size = extractor.GetULEB128(&offset);
+      llvm::StringRef type_name = extractor.GetCStr(&offset, type_size);
+      uint64_t summary_size = extractor.GetULEB128(&offset);
+      llvm::StringRef summary_string = extractor.GetCStr(&offset, summary_size);
+      if (!type_name.empty() && !summary_string.empty()) {
+        TypeSummaryImpl::Flags flags;
+        auto summary_sp =
+            std::make_shared<StringSummaryFormat>(flags, summary_string.data());
+        FormatterMatchType match_type = eFormatterMatchExact;
+        if (summary_string.front() == '^' && summary_string.back() == '$')
+          match_type = eFormatterMatchRegex;
+        category->AddTypeSummary(type_name, match_type, summary_sp);
+        LLDB_LOGF(log, "Loaded embedded type summary for '%s' from %s.",
+                  type_name.data(), module_name);
+      } else {
+        if (type_name.empty())
+          LLDB_LOGF(log, "Missing string(s) in embedded type summary in %s.",
+                    module_name);
+      }
+    } else {
+      // Skip unsupported record.
+      offset += record_size;
+      LLDB_LOGF(
+          log,
+          "Skipping unsupported embedded type summary of version %llu in %s.",
+          version, module_name);
+    }
+  }
+}
+
 void Target::ClearModules(bool delete_locations) {
   ModulesDidUnload(m_images, delete_locations);
   m_section_load_history.Clear();
@@ -1775,6 +1846,7 @@ void Target::ModulesDidLoad(ModuleList &module_list) {
     for (size_t idx = 0; idx < num_images; ++idx) {
       ModuleSP module_sp(module_list.GetModuleAtIndex(idx));
       LoadScriptingResourceForModule(module_sp, this);
+      LoadTypeSummariesForModule(module_sp);
     }
     m_breakpoint_list.UpdateBreakpoints(module_list, true, false);
     m_internal_breakpoint_list.UpdateBreakpoints(module_list, true, false);
diff --git a/lldb/test/API/functionalities/data-formatter/embedded-summary/Makefile b/lldb/test/API/functionalities/data-formatter/embedded-summary/Makefile
new file mode 100644
index 00000000000000..c9319d6e6888a4
--- /dev/null
+++ b/lldb/test/API/functionalities/data-formatter/embedded-summary/Makefile
@@ -0,0 +1,2 @@
+C_SOURCES := main.c
+include Makefile.rules
diff --git a/lldb/test/API/functionalities/data-formatter/embedded-summary/TestEmbeddedTypeSummary.py b/lldb/test/API/functionalities/data-formatter/embedded-summary/TestEmbeddedTypeSummary.py
new file mode 100644
index 00000000000000..b8ce7d9f76eb9e
--- /dev/null
+++ b/lldb/test/API/functionalities/data-formatter/embedded-summary/TestEmbeddedTypeSummary.py
@@ -0,0 +1,12 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestCase(TestBase):
+    @skipUnlessDarwin
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "break here", lldb.SBFileSpec("main.c"))
+        self.expect("v player", substrs=['"Dirk" (41)'])
diff --git a/lldb/test/API/functionalities/data-formatter/embedded-summary/main.c b/lldb/test/API/functionalities/data-formatter/embedded-summary/main.c
new file mode 100644
index 00000000000000..9ddd64246f726c
--- /dev/null
+++ b/lldb/test/API/functionalities/data-formatter/embedded-summary/main.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+
+struct Player {
+  char *name;
+  int number;
+};
+
+__attribute__((used, section("__DATA_CONST,__lldbsummaries"))) unsigned char
+    _Player_type_summary[] = "\x01"     // version
+                             "\x25"     // record size
+                             "\x07"     // type name size
+                             "Player\0" // type name
+                             "\x1c"     // summary string size
+                             "${var.name} (${var.number})"; // summary string
+
+int main() {
+  struct Player player;
+  player.name = "Dirk";
+  player.number = 41;
+  puts("break here");
+  return 0;
+}

DavidSpickett · 2024-10-28T13:47:36Z

This upstreams the embedded type summary feature from the swiftlang branch of LLDB, since it shares a lot of the same goals and design points with #113398

Just want to be extra clear here, this shares some of the same goals but is not part of that thing.

This is simply upstreaming a thing that already exists in the Swift fork, correct?

Because I was about to bikeshed the section name but if it's already in use then it's fine. You suggested a new one for the bytecode approach anyway.

DavidSpickett · 2024-10-28T13:51:15Z

lldb/test/API/functionalities/data-formatter/embedded-summary/main.c

+  struct Player player;
+  player.name = "Dirk";
+  player.number = 41;
+  puts("break here");


Does this actually show up in the logs? If so return 0 // break here would be a bit more tidy.

DavidSpickett · 2024-10-28T13:55:01Z

lldb/source/Target/Target.cpp

+          LLDB_LOGF(log, "Missing string(s) in embedded type summary in %s.",
+                    module_name);
+      }
+    } else {


Could if version != 1: continue instead of putting this at the end of the loop.

Also you could if (type_name.empty() || summary_string.empty()): log(whatever); continue; to again exit this iteration early.

DavidSpickett · 2024-10-28T13:56:30Z

lldb/source/Target/Target.cpp

+        LLDB_LOGF(log, "Loaded embedded type summary for '%s' from %s.",
+                  type_name.data(), module_name);
+      } else {
+        if (type_name.empty())


Should this log message always be printed? It looks like you have to have both strings so if you get to the else, one of them is empty. This will only log if one of them is empty but not the other one.

Might as well put in what strings they are too. "Missing type or summary string in....".

DavidSpickett · 2024-10-28T13:58:28Z

lldb/source/Target/Target.cpp

+      offset += record_size;
+      LLDB_LOGF(
+          log,
+          "Skipping unsupported embedded type summary of version %llu in %s.",


Use the PRIu64 and other generic 64 bit printf options so that I don't have to fix a warning on Arm 32 bit later :)

adrian-prantl · 2024-12-10T17:50:06Z

Superseded by #114333

adrian-prantl · 2024-12-10T17:55:38Z

I believe I also addressed all outstanding review feedback.

[lldb] Load embedded type summary section (swiftlang#7859) (swiftlang…

c9a4d24

…#8040) Add support for type summaries embedded into the binary. These embedded summaries will typically be generated by Swift macros, but can also be generated by any other means. rdar://115184658

adrian-prantl requested a review from JDevlieghere as a code owner October 25, 2024 23:25

llvmbot added the lldb label Oct 25, 2024

adrian-prantl requested a review from kastiglione October 25, 2024 23:25

DavidSpickett reviewed Oct 28, 2024

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SingleAccretion mentioned this pull request Nov 30, 2024

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