Automerge: Revert branch island experiments (#139192)

This test is failing because when we step to what is the branch island
address and ask for its symbol, we can't resolve the symbol, and just
call it the last padding symbol plus a bajillion.

That has nothing to do with the changes in this patch, but I'll revert
this and keep trying to figure out why symbol reading on this bot is
wrong.

Author: jimingham

lldb/source/Plugins/DynamicLoader/MacOSX-DYLD/DynamicLoaderDarwin.cpp

@@ -26,7 +26,6 @@
 #include "lldb/Target/Thread.h"
 #include "lldb/Target/ThreadPlanCallFunction.h"
 #include "lldb/Target/ThreadPlanRunToAddress.h"
-#include "lldb/Target/ThreadPlanStepInstruction.h"
 #include "lldb/Utility/DataBuffer.h"
 #include "lldb/Utility/DataBufferHeap.h"
 #include "lldb/Utility/LLDBLog.h"
@@ -924,15 +923,15 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread &thread,
   if (current_symbol != nullptr) {
     std::vector<Address> addresses;
 
-    ConstString current_name =
-        current_symbol->GetMangled().GetName(Mangled::ePreferMangled);
     if (current_symbol->IsTrampoline()) {
+      ConstString trampoline_name =
+          current_symbol->GetMangled().GetName(Mangled::ePreferMangled);
 
-      if (current_name) {
+      if (trampoline_name) {
         const ModuleList &images = target_sp->GetImages();
 
         SymbolContextList code_symbols;
-        images.FindSymbolsWithNameAndType(current_name, eSymbolTypeCode,
+        images.FindSymbolsWithNameAndType(trampoline_name, eSymbolTypeCode,
                                           code_symbols);
         for (const SymbolContext &context : code_symbols) {
           Address addr = context.GetFunctionOrSymbolAddress();
@@ -946,8 +945,8 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread &thread,
         }
 
         SymbolContextList reexported_symbols;
-        images.FindSymbolsWithNameAndType(current_name, eSymbolTypeReExported,
-                                          reexported_symbols);
+        images.FindSymbolsWithNameAndType(
+            trampoline_name, eSymbolTypeReExported, reexported_symbols);
         for (const SymbolContext &context : reexported_symbols) {
           if (context.symbol) {
             Symbol *actual_symbol =
@@ -969,7 +968,7 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread &thread,
         }
 
         SymbolContextList indirect_symbols;
-        images.FindSymbolsWithNameAndType(current_name, eSymbolTypeResolver,
+        images.FindSymbolsWithNameAndType(trampoline_name, eSymbolTypeResolver,
                                           indirect_symbols);
 
         for (const SymbolContext &context : indirect_symbols) {
@@ -1029,32 +1028,6 @@ DynamicLoaderDarwin::GetStepThroughTrampolinePlan(Thread &thread,
       thread_plan_sp = std::make_shared<ThreadPlanRunToAddress>(
           thread, load_addrs, stop_others);
     }
-    // One more case we have to consider is "branch islands".  These are regular
-    // TEXT symbols but their names end in .island plus maybe a .digit suffix.
-    // They are to allow arm64 code to branch further than the size of the
-    // address slot allows.  We just need to single-instruction step in that
-    // case.
-    static const char *g_branch_island_pattern = "\\.island\\.?[0-9]*$";
-    static RegularExpression g_branch_island_regex(g_branch_island_pattern);
-
-    bool is_branch_island = g_branch_island_regex.Execute(current_name);
-    // FIXME: this is extra logging so I can figure out why this test is failing
-    // on the bot but not locally with all the same tools, etc...
-    if (thread_plan_sp && is_branch_island) {
-      if (log) {
-        StreamString s;
-        thread_plan_sp->GetDescription(&s, eDescriptionLevelVerbose);
-        LLDB_LOGF(log, "Am at a branch island, but already had plan: \n\t%s", s.GetData());
-      }
-    }
-    if (!thread_plan_sp && is_branch_island) {
-      thread_plan_sp = std::make_shared<ThreadPlanStepInstruction>(
-          thread,
-          /* step_over= */ false, /* stop_others */ false, eVoteNoOpinion,
-          eVoteNoOpinion);
-      LLDB_LOG(log, "Stepping one instruction over branch island: '{0}'.",
-               current_name);
-    }
   } else {
     LLDB_LOGF(log, "Could not find symbol for step through.");
   }