[lldb] Change synthetic symbol names to have file address (#138416)

* Changes the default synthetic symbol names to contain their file
address

This is a new PR after the first PR (#137512) was reverted because it
didn't update the way unnamed symbols were searched in the symbol table,
which relied on the index being in the name.

This time also added extra test to make sure the symbol is found as
expected

Author: eronnen

lldb/include/lldb/Symbol/Symbol.h

@@ -258,7 +258,7 @@ class Symbol : public SymbolContextScope {
   bool ContainsFileAddress(lldb::addr_t file_addr) const;
 
   static llvm::StringRef GetSyntheticSymbolPrefix() {
-    return "___lldb_unnamed_symbol";
+    return "___lldb_unnamed_symbol_";
   }
 
   /// Decode a serialized version of this object from data.

lldb/source/Symbol/Symbol.cpp

@@ -639,7 +639,9 @@ void Symbol::SynthesizeNameIfNeeded() const {
     // breakpoints on them.
     llvm::SmallString<256> name;
     llvm::raw_svector_ostream os(name);
-    os << GetSyntheticSymbolPrefix() << GetID();
+    os << GetSyntheticSymbolPrefix()
+       << llvm::format_hex_no_prefix(
+              m_addr_range.GetBaseAddress().GetFileAddress(), 0);
     m_mangled.SetDemangledName(ConstString(os.str()));
   }
 }

lldb/source/Symbol/Symtab.cpp

@@ -654,20 +654,21 @@ uint32_t Symtab::GetNameIndexes(ConstString symbol_name,
   if (count)
     return count;
   // Synthetic symbol names are not added to the name indexes, but they start
-  // with a prefix and end with a the symbol UserID. This allows users to find
-  // these symbols without having to add them to the name indexes. These
+  // with a prefix and end with the symbol file address. This allows users to
+  // find these symbols without having to add them to the name indexes. These
   // queries will not happen very often since the names don't mean anything, so
   // performance is not paramount in this case.
   llvm::StringRef name = symbol_name.GetStringRef();
   // String the synthetic prefix if the name starts with it.
   if (!name.consume_front(Symbol::GetSyntheticSymbolPrefix()))
     return 0; // Not a synthetic symbol name
 
-  // Extract the user ID from the symbol name
-  unsigned long long uid = 0;
-  if (getAsUnsignedInteger(name, /*Radix=*/10, uid))
+  // Extract the file address from the symbol name
+  unsigned long long file_address = 0;
+  if (getAsUnsignedInteger(name, /*Radix=*/16, file_address))
     return 0; // Failed to extract the user ID as an integer
-  Symbol *symbol = FindSymbolByID(uid);
+
+  Symbol *symbol = FindSymbolAtFileAddress(static_cast<addr_t>(file_address));
   if (symbol == nullptr)
     return 0;
   const uint32_t symbol_idx = GetIndexForSymbol(symbol);

lldb/test/API/python_api/unnamed_symbol_lookup/Makefile

@@ -0,0 +1,23 @@
+C_SOURCES := main.c
+
+include Makefile.rules
+
+all: a.out.stripped
+
+ifeq "$(OS)" "Darwin"
+STRIP_COMMAND = $(STRIP) -s keep_symbols.txt
+else
+STRIP_COMMAND = $(STRIP) --keep-symbol=main
+endif
+
+a.out.stripped: a.out
+ifeq "$(OS)" "Darwin"
+	echo "_main" > keep_symbols.txt
+	$(STRIP) -s keep_symbols.txt -o a.out.stripped a.out
+else
+	$(STRIP) --keep-symbol=main -o a.out.stripped a.out
+endif
+
+ifneq "$(CODESIGN)" ""
+	$(CODESIGN) -fs - a.out.stripped
+endif

lldb/test/API/python_api/unnamed_symbol_lookup/TestUnnamedSymbolLookup.py

@@ -0,0 +1,40 @@
+"""
+Test lookup unnamed symbols.
+"""
+
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestUnnamedSymbolLookup(TestBase):
+    def test_unnamed_symbol_lookup(self):
+        """Test looking up unnamed symbol synthetic name"""
+        self.build()
+        (target, process, thread, bkpt) = lldbutil.run_to_name_breakpoint(
+            self, "main", exe_name="a.out.stripped"
+        )
+
+        main_frame = thread.GetFrameAtIndex(0)
+
+        # Step until reaching the unnamed symbol called from main
+        for _ in range(100):
+            thread.StepInto()
+            if thread.GetFrameAtIndex(0) != main_frame:
+                break
+
+            thread.StepInto()
+
+        self.assertEqual(
+            main_frame, thread.GetFrameAtIndex(1), "Expected to be called from main"
+        )
+        symbol = thread.GetFrameAtIndex(0).GetSymbol()
+        self.assertIsNotNone(symbol, "unnamed symbol called from main not reached")
+        self.assertTrue(symbol.name.startswith("___lldb_unnamed_symbol"))
+
+        exe_module = symbol.GetStartAddress().GetModule()
+        found_symbols = exe_module.FindSymbols(symbol.name)
+        self.assertIsNotNone(found_symbols)
+        self.assertEqual(found_symbols.GetSize(), 1)

lldb/test/API/python_api/unnamed_symbol_lookup/main.c

@@ -0,0 +1,6 @@
+__attribute__((nodebug)) int stripped_function(int val) { return val * val; }
+
+int main(void) {
+  stripped_function(10);
+  return 0;
+}

lldb/test/Shell/ObjectFile/ELF/eh_frame-symbols.yaml

@@ -3,8 +3,8 @@
 
 # CHECK: Index   UserID DSX Type            File Address/Value Load Address       Size               Flags      Name
 # CHECK: [    0]      1     SourceFile      0x0000000000000000                    0x0000000000000000 0x00000004 -
-# CHECK: [    1]      2  SX Code            0x0000000000201180                    0x0000000000000010 0x00000000 ___lldb_unnamed_symbol{{[0-9]*}}
-# CHECK: [    2]      3  SX Code            0x0000000000201190                    0x0000000000000006 0x00000000 ___lldb_unnamed_symbol{{[0-9]*}}
+# CHECK: [    1]      2  SX Code            0x0000000000201180                    0x0000000000000010 0x00000000 ___lldb_unnamed_symbol_{{[0-9a-f]*}}
+# CHECK: [    2]      3  SX Code            0x0000000000201190                    0x0000000000000006 0x00000000 ___lldb_unnamed_symbol_{{[0-9a-f]*}}
 
 --- !ELF
 FileHeader:

lldb/test/Shell/SymbolFile/Breakpad/symtab-sorted-by-size.test

@@ -3,7 +3,7 @@
 # RUN:   -s %s | FileCheck %s
 
 # CHECK: num_symbols = 4 (sorted by size):
-# CHECK: [    0]      0  SX Code            0x0000000000400000                    0x00000000000000b0 0x00000000 ___lldb_unnamed_symbol0
+# CHECK: [    0]      0  SX Code            0x0000000000400000                    0x00000000000000b0 0x00000000 ___lldb_unnamed_symbol_400000
 # CHECK: [    1]      0   X Code            0x00000000004000d0                    0x0000000000000022 0x00000000 _start
 # CHECK: [    2]      0   X Code            0x00000000004000b0                    0x0000000000000010 0x00000000 f1
 # CHECK: [    3]      0   X Code            0x00000000004000c0                    0x0000000000000010 0x00000000 f2

lldb/test/Shell/SymbolFile/Breakpad/symtab.test

@@ -5,7 +5,7 @@
 # CHECK-LABEL: (lldb) image dump symtab symtab.out
 # CHECK: Symtab, file = {{.*}}symtab.out, num_symbols = 4:
 # CHECK: Index   UserID DSX Type            File Address/Value Load Address       Size               Flags      Name
-# CHECK: [    0]      0  SX Code            0x0000000000400000                    0x00000000000000b0 0x00000000 ___lldb_unnamed_symbol{{[0-9]*}}
+# CHECK: [    0]      0  SX Code            0x0000000000400000                    0x00000000000000b0 0x00000000 ___lldb_unnamed_symbol_{{[0-9a-f]*}}
 # CHECK: [    1]      0   X Code            0x00000000004000b0                    0x0000000000000010 0x00000000 f1
 # CHECK: [    2]      0   X Code            0x00000000004000c0                    0x0000000000000010 0x00000000 f2
 # CHECK: [    3]      0   X Code            0x00000000004000d0                    0x0000000000000022 0x00000000 _start