[lldb][lldb-dap] Use the default disassembly flavour if none is provided. (llvm#141424)

This is the currently the default for
`SBTarget::ReadInstructions(SBAddress, uint32_t)`. But not for others,
to make it consistent used the user assigned instruction flavour.

Author: da-viper

lldb/source/API/SBTarget.cpp

@@ -1960,7 +1960,17 @@ lldb::SBInstructionList SBTarget::ReadInstructions(lldb::SBAddress base_addr,
       const size_t bytes_read =
           target_sp->ReadMemory(*addr_ptr, data.GetBytes(), data.GetByteSize(),
                                 error, force_live_memory, &load_addr);
+
       const bool data_from_file = load_addr == LLDB_INVALID_ADDRESS;
+      if (!flavor_string || flavor_string[0] == '\0') {
+        // FIXME - we don't have the mechanism in place to do per-architecture
+        // settings.  But since we know that for now we only support flavors on
+        // x86 & x86_64,
+        const llvm::Triple::ArchType arch =
+            target_sp->GetArchitecture().GetTriple().getArch();
+        if (arch == llvm::Triple::x86 || arch == llvm::Triple::x86_64)
+          flavor_string = target_sp->GetDisassemblyFlavor();
+      }
       sb_instructions.SetDisassembler(Disassembler::DisassembleBytes(
           target_sp->GetArchitecture(), nullptr, flavor_string,
           target_sp->GetDisassemblyCPU(), target_sp->GetDisassemblyFeatures(),
@@ -2017,7 +2027,16 @@ SBTarget::GetInstructionsWithFlavor(lldb::SBAddress base_addr,
     if (base_addr.get())
       addr = *base_addr.get();
 
-    const bool data_from_file = true;
+    constexpr bool data_from_file = true;
+    if (!flavor_string || flavor_string[0] == '\0') {
+      // FIXME - we don't have the mechanism in place to do per-architecture
+      // settings.  But since we know that for now we only support flavors on
+      // x86 & x86_64,
+      const llvm::Triple::ArchType arch =
+          target_sp->GetArchitecture().GetTriple().getArch();
+      if (arch == llvm::Triple::x86 || arch == llvm::Triple::x86_64)
+        flavor_string = target_sp->GetDisassemblyFlavor();
+    }
 
     sb_instructions.SetDisassembler(Disassembler::DisassembleBytes(
         target_sp->GetArchitecture(), nullptr, flavor_string,

lldb/source/Commands/CommandObjectDisassemble.cpp

@@ -190,7 +190,6 @@ void CommandObjectDisassemble::CommandOptions::OptionParsingStarting(
     // architecture.  For now GetDisassemblyFlavor is really only valid for x86
     // (and for the llvm assembler plugin, but I'm papering over that since that
     // is the only disassembler plugin we have...
-    // This logic is duplicated in `Handler/DisassembleRequestHandler`.
     if (target->GetArchitecture().GetTriple().getArch() == llvm::Triple::x86 ||
         target->GetArchitecture().GetTriple().getArch() ==
             llvm::Triple::x86_64) {

lldb/tools/lldb-dap/Handler/DisassembleRequestHandler.cpp

@@ -193,21 +193,6 @@ DisassembleRequestHandler::Run(const DisassembleArguments &args) const {
     return llvm::make_error<DAPError>(
         "Memory reference not found in the current binary.");
 
-  std::string flavor_string;
-  const auto target_triple = llvm::StringRef(dap.target.GetTriple());
-  // This handles both 32 and 64bit x86 architecture. The logic is duplicated in
-  // `CommandObjectDisassemble::CommandOptions::OptionParsingStarting`
-  if (target_triple.starts_with("x86")) {
-    const lldb::SBStructuredData flavor =
-        dap.debugger.GetSetting("target.x86-disassembly-flavor");
-
-    const size_t str_length = flavor.GetStringValue(nullptr, 0);
-    if (str_length != 0) {
-      flavor_string.resize(str_length + 1);
-      flavor.GetStringValue(flavor_string.data(), flavor_string.length());
-    }
-  }
-
   // Offset (in instructions) to be applied after the byte offset (if any)
   // before disassembling. Can be negative.
   int64_t instruction_offset = args.instructionOffset.value_or(0);
@@ -220,7 +205,7 @@ DisassembleRequestHandler::Run(const DisassembleArguments &args) const {
         "Unexpected error while disassembling instructions.");
 
   lldb::SBInstructionList insts = dap.target.ReadInstructions(
-      disassemble_start_addr, args.instructionCount, flavor_string.c_str());
+      disassemble_start_addr, args.instructionCount);
   if (!insts.IsValid())
     return llvm::make_error<DAPError>(
         "Unexpected error while disassembling instructions.");