[Lldb-commits] [PATCH] D51319: Use a RAII guard to lock/unlock DisassemblerLLVMC [NFC]

[Raphael Isemann via Phabricator via lldb-commits]

teemperor created this revision.
teemperor added a reviewer: LLDB.
Herald added a subscriber: lldb-commits.

The manual lock/unlock calls make my LazyBool refactoring tricky (because now `return` potentially
cause deadlocks), so this patch just replaces them with a much safer lock guard that is using RAII.


Repository:
  rLLDB LLDB

https://reviews.llvm.org/D51319

Files:
  source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp
  source/Plugins/Disassembler/llvm/DisassemblerLLVMC.h


Index: source/Plugins/Disassembler/llvm/DisassemblerLLVMC.h
===================================================================
--- source/Plugins/Disassembler/llvm/DisassemblerLLVMC.h
+++ source/Plugins/Disassembler/llvm/DisassemblerLLVMC.h
@@ -77,6 +77,17 @@
                                           uint64_t ReferencePC,
                                           const char **ReferenceName);
 
+  struct Guard {
+    DisassemblerLLVMC *m_instance;
+    Guard(DisassemblerLLVMC *instance, InstructionLLVMC *inst,
+          const lldb_private::ExecutionContext *exe_ctx = nullptr)
+        : m_instance(instance) {
+      m_instance->Lock(inst, exe_ctx);
+    }
+
+    ~Guard() { m_instance->Unlock(); }
+  };
+
   void Lock(InstructionLLVMC *inst,
             const lldb_private::ExecutionContext *exe_ctx) {
     m_mutex.lock();
Index: source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp
===================================================================
--- source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp
+++ source/Plugins/Disassembler/llvm/DisassemblerLLVMC.cpp
@@ -100,7 +100,7 @@
     if (m_does_branch == eLazyBoolCalculate) {
       std::shared_ptr<DisassemblerLLVMC> disasm_sp(GetDisassembler());
       if (disasm_sp) {
-        disasm_sp->Lock(this, NULL);
+        DisassemblerLLVMC::Guard guard(disasm_sp.get(), this);
         DataExtractor data;
         if (m_opcode.GetData(data)) {
           bool is_alternate_isa;
@@ -125,7 +125,6 @@
               m_does_branch = eLazyBoolNo;
           }
         }
-        disasm_sp->Unlock();
       }
     }
     return m_does_branch == eLazyBoolYes;
@@ -135,7 +134,7 @@
     if (m_has_delay_slot == eLazyBoolCalculate) {
       std::shared_ptr<DisassemblerLLVMC> disasm_sp(GetDisassembler());
       if (disasm_sp) {
-        disasm_sp->Lock(this, NULL);
+        DisassemblerLLVMC::Guard guard(disasm_sp.get(), this);
         DataExtractor data;
         if (m_opcode.GetData(data)) {
           bool is_alternate_isa;
@@ -160,7 +159,6 @@
               m_has_delay_slot = eLazyBoolNo;
           }
         }
-        disasm_sp->Unlock();
       }
     }
     return m_has_delay_slot == eLazyBoolYes;
@@ -261,10 +259,13 @@
           const addr_t pc = m_address.GetFileAddress();
           llvm::MCInst inst;
 
-          disasm_sp->Lock(this, NULL);
-          const size_t inst_size =
-              mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len, pc, inst);
-          disasm_sp->Unlock();
+          size_t inst_size;
+          {
+            DisassemblerLLVMC::Guard guard(disasm_sp.get(), this);
+            inst_size = mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len,
+                                                 pc, inst);
+          }
+
           if (inst_size == 0)
             m_opcode.Clear();
           else {
@@ -878,7 +879,7 @@
     if (m_is_call == eLazyBoolCalculate) {
       std::shared_ptr<DisassemblerLLVMC> disasm_sp(GetDisassembler());
       if (disasm_sp) {
-        disasm_sp->Lock(this, NULL);
+        DisassemblerLLVMC::Guard guard(disasm_sp.get(), this);
         DataExtractor data;
         if (m_opcode.GetData(data)) {
           bool is_alternate_isa;
@@ -900,7 +901,6 @@
               m_is_call = eLazyBoolNo;
           }
         }
-        disasm_sp->Unlock();
       }
     }
     return m_is_call == eLazyBoolYes;


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