[lldb][NFC] Rename forward_branch_offset to branch_offset in UnwindAssemblyInstEmulation (#169631)

This will reduce the diff in subsequent patches

Part of a sequence of PRs:
[lldb][NFCI] Rewrite UnwindAssemblyInstEmulation in terms of a CFG visit
#169630
[lldb][NFC] Rename forward_branch_offset to branch_offset in
UnwindAssemblyInstEmulation #169631
[lldb] Add DisassemblerLLVMC::IsBarrier API #169632
[lldb] Handle backwards branches in UnwindAssemblyInstEmulation #169633
commit-id:5e758a22

Author: felipepiovezan

lldb/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.cpp

@@ -166,7 +166,7 @@ bool UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly(
     DumpInstToLog(log, inst, inst_list);
 
     m_curr_row_modified = false;
-    m_forward_branch_offset = 0;
+    m_branch_offset = 0;
 
     lldb::addr_t current_offset =
         inst.GetAddress().GetFileAddress() - base_addr;
@@ -211,13 +211,13 @@ bool UnwindAssemblyInstEmulation::GetNonCallSiteUnwindPlanFromAssembly(
     // If the current instruction is a branch forward then save the current
     // CFI information for the offset where we are branching.
     Address branch_address = inst.GetAddress();
-    branch_address.Slide(m_forward_branch_offset);
-    if (m_forward_branch_offset != 0 &&
+    branch_address.Slide(m_branch_offset);
+    if (m_branch_offset != 0 &&
         range.ContainsFileAddress(branch_address.GetFileAddress())) {
       if (auto [it, inserted] = saved_unwind_states.emplace(
-              current_offset + m_forward_branch_offset, m_state);
+              current_offset + m_branch_offset, m_state);
           inserted) {
-        it->second.row.SetOffset(current_offset + m_forward_branch_offset);
+        it->second.row.SetOffset(current_offset + m_branch_offset);
         if (std::size_t dest_instr_index =
                 inst_list.GetIndexOfInstructionAtAddress(branch_address);
             dest_instr_index < inst_list.GetSize()) {
@@ -531,20 +531,19 @@ bool UnwindAssemblyInstEmulation::WriteRegister(
   case EmulateInstruction::eContextRelativeBranchImmediate: {
     if (context.GetInfoType() == EmulateInstruction::eInfoTypeISAAndImmediate &&
         context.info.ISAAndImmediate.unsigned_data32 > 0) {
-      m_forward_branch_offset = context.info.ISAAndImmediate.unsigned_data32;
+      m_branch_offset = context.info.ISAAndImmediate.unsigned_data32;
     } else if (context.GetInfoType() ==
                    EmulateInstruction::eInfoTypeISAAndImmediateSigned &&
                context.info.ISAAndImmediateSigned.signed_data32 > 0) {
-      m_forward_branch_offset =
-          context.info.ISAAndImmediateSigned.signed_data32;
+      m_branch_offset = context.info.ISAAndImmediateSigned.signed_data32;
     } else if (context.GetInfoType() ==
                    EmulateInstruction::eInfoTypeImmediate &&
                context.info.unsigned_immediate > 0) {
-      m_forward_branch_offset = context.info.unsigned_immediate;
+      m_branch_offset = context.info.unsigned_immediate;
     } else if (context.GetInfoType() ==
                    EmulateInstruction::eInfoTypeImmediateSigned &&
                context.info.signed_immediate > 0) {
-      m_forward_branch_offset = context.info.signed_immediate;
+      m_branch_offset = context.info.signed_immediate;
     }
   } break;
 

lldb/source/Plugins/UnwindAssembly/InstEmulation/UnwindAssemblyInstEmulation.h

@@ -64,7 +64,7 @@ class UnwindAssemblyInstEmulation : public lldb_private::UnwindAssembly {
                               lldb_private::EmulateInstruction *inst_emulator)
       : UnwindAssembly(arch), m_inst_emulator_up(inst_emulator),
         m_range_ptr(nullptr), m_unwind_plan_ptr(nullptr),
-        m_curr_row_modified(false), m_forward_branch_offset(0) {
+        m_curr_row_modified(false) {
     if (m_inst_emulator_up) {
       m_inst_emulator_up->SetBaton(this);
       m_inst_emulator_up->SetCallbacks(ReadMemory, WriteMemory, ReadRegister,
@@ -152,7 +152,7 @@ class UnwindAssemblyInstEmulation : public lldb_private::UnwindAssembly {
   bool m_curr_row_modified;
   // The instruction is branching forward with the given offset. 0 value means
   // no branching.
-  uint32_t m_forward_branch_offset;
+  uint32_t m_branch_offset = 0;
 };
 
 #endif // LLDB_SOURCE_PLUGINS_UNWINDASSEMBLY_INSTEMULATION_UNWINDASSEMBLYINSTEMULATION_H