Move architecture-specific address adjustment to architecture plugins

Differential Revision: https://reviews.llvm.org/D48623

llvm-svn: 342762

1 files changed, 240 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Architecture/Mips/ArchitectureMips.cpp b/lldb/source/Plugins/Architecture/Mips/ArchitectureMips.cpp
new file mode 100644
index 00000000000..58230a59b49
--- /dev/null
+++ b/lldb/source/Plugins/Architecture/Mips/ArchitectureMips.cpp
@@ -0,0 +1,240 @@
+//===-- ArchitectureMips.cpp -------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Plugins/Architecture/Mips/ArchitectureMips.h"
+#include "lldb/Core/Address.h"
+#include "lldb/Core/Disassembler.h"
+#include "lldb/Core/Module.h"
+#include "lldb/Core/PluginManager.h"
+#include "lldb/Symbol/Function.h"
+#include "lldb/Symbol/SymbolContext.h"
+#include "lldb/Target/SectionLoadList.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Utility/ArchSpec.h"
+#include "lldb/Utility/Log.h"
+
+using namespace lldb_private;
+using namespace lldb;
+
+ConstString ArchitectureMips::GetPluginNameStatic() {
+  return ConstString("mips");
+}
+
+void ArchitectureMips::Initialize() {
+  PluginManager::RegisterPlugin(GetPluginNameStatic(),
+                                "Mips-specific algorithms",
+                                &ArchitectureMips::Create);
+}
+
+void ArchitectureMips::Terminate() {
+  PluginManager::UnregisterPlugin(&ArchitectureMips::Create);
+}
+
+std::unique_ptr<Architecture> ArchitectureMips::Create(const ArchSpec &arch) {
+  return arch.IsMIPS() ?
+      std::unique_ptr<Architecture>(new ArchitectureMips(arch)) : nullptr;
+}
+
+ConstString ArchitectureMips::GetPluginName() { return GetPluginNameStatic(); }
+uint32_t ArchitectureMips::GetPluginVersion() { return 1; }
+
+addr_t ArchitectureMips::GetCallableLoadAddress(addr_t code_addr,
+                                                AddressClass addr_class) const {
+  bool is_alternate_isa = false;
+
+  switch (addr_class) {
+  case AddressClass::eData:
+  case AddressClass::eDebug:
+    return LLDB_INVALID_ADDRESS;
+  case AddressClass::eCodeAlternateISA:
+    is_alternate_isa = true;
+    break;
+  default: break;
+  }
+
+  if ((code_addr & 2ull) || is_alternate_isa)
+    return code_addr | 1u;
+  return code_addr;
+}
+
+addr_t ArchitectureMips::GetOpcodeLoadAddress(addr_t opcode_addr,
+                                              AddressClass addr_class) const {
+  switch (addr_class) {
+  case AddressClass::eData:
+  case AddressClass::eDebug:
+    return LLDB_INVALID_ADDRESS;
+  default: break;
+  }
+  return opcode_addr & ~(1ull);
+}
+
+lldb::addr_t ArchitectureMips::GetBreakableLoadAddress(lldb::addr_t addr,
+                                                       Target &target) const {
+
+  Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_BREAKPOINTS));
+
+  Address resolved_addr;
+
+  SectionLoadList &section_load_list = target.GetSectionLoadList();
+  if (section_load_list.IsEmpty())
+    // No sections are loaded, so we must assume we are not running yet and
+    // need to operate only on file address.
+    target.ResolveFileAddress(addr, resolved_addr);
+  else
+    target.ResolveLoadAddress(addr, resolved_addr);
+
+  addr_t current_offset = 0;
+
+  // Get the function boundaries to make sure we don't scan back before the
+  // beginning of the current function.
+  ModuleSP temp_addr_module_sp(resolved_addr.GetModule());
+  if (temp_addr_module_sp) {
+    SymbolContext sc;
+    uint32_t resolve_scope = eSymbolContextFunction | eSymbolContextSymbol;
+    temp_addr_module_sp->ResolveSymbolContextForAddress(resolved_addr,
+      resolve_scope, sc);
+    Address sym_addr;
+    if (sc.function)
+      sym_addr = sc.function->GetAddressRange().GetBaseAddress();
+    else if (sc.symbol)
+      sym_addr = sc.symbol->GetAddress();
+
+    addr_t function_start = sym_addr.GetLoadAddress(&target);
+    if (function_start == LLDB_INVALID_ADDRESS)
+      function_start = sym_addr.GetFileAddress();
+
+    if (function_start)
+      current_offset = addr - function_start;
+  }
+
+  // If breakpoint address is start of function then we dont have to do
+  // anything.
+  if (current_offset == 0)
+    return addr;
+
+  ExecutionContext ctx;
+  target.CalculateExecutionContext(ctx);
+  auto insn = GetInstructionAtAddress(ctx, current_offset, addr);
+
+  if (nullptr == insn || !insn->HasDelaySlot())
+    return addr;
+
+  // Adjust the breakable address
+  auto breakable_addr = addr - insn->GetOpcode().GetByteSize();
+  if (log)
+    log->Printf("Target::%s Breakpoint at 0x%8.8" PRIx64
+      " is adjusted to 0x%8.8" PRIx64 " due to delay slot\n",
+      __FUNCTION__, addr, breakable_addr);
+
+  return breakable_addr;
+}
+
+Instruction *ArchitectureMips::GetInstructionAtAddress(
+    const ExecutionContext &exe_ctx, const Address &resolved_addr,
+    addr_t symbol_offset) const {
+
+  auto loop_count = symbol_offset / 2;
+
+  uint32_t arch_flags = m_arch.GetFlags();
+  bool IsMips16 = arch_flags & ArchSpec::eMIPSAse_mips16;
+  bool IsMicromips = arch_flags & ArchSpec::eMIPSAse_micromips;
+
+  if (loop_count > 3) {
+    // Scan previous 6 bytes
+    if (IsMips16 | IsMicromips)
+      loop_count = 3;
+    // For mips-only, instructions are always 4 bytes, so scan previous 4
+    // bytes only.
+    else
+      loop_count = 2;
+  }
+
+  // Create Disassembler Instance
+  lldb::DisassemblerSP disasm_sp(
+    Disassembler::FindPlugin(m_arch, nullptr, nullptr));
+
+  InstructionList instruction_list;
+  InstructionSP prev_insn;
+  bool prefer_file_cache = true; // Read from file
+  uint32_t inst_to_choose = 0;
+
+  Address addr = resolved_addr;
+
+  for (uint32_t i = 1; i <= loop_count; i++) {
+    // Adjust the address to read from.
+    addr.Slide(-2);
+    AddressRange range(addr, i * 2);
+    uint32_t insn_size = 0;
+
+    disasm_sp->ParseInstructions(&exe_ctx, range, nullptr, prefer_file_cache);
+
+    uint32_t num_insns = disasm_sp->GetInstructionList().GetSize();
+    if (num_insns) {
+      prev_insn = disasm_sp->GetInstructionList().GetInstructionAtIndex(0);
+      insn_size = prev_insn->GetOpcode().GetByteSize();
+      if (i == 1 && insn_size == 2) {
+        // This looks like a valid 2-byte instruction (but it could be a part
+        // of upper 4 byte instruction).
+        instruction_list.Append(prev_insn);
+        inst_to_choose = 1;
+      }
+      else if (i == 2) {
+        // Here we may get one 4-byte instruction or two 2-byte instructions.
+        if (num_insns == 2) {
+          // Looks like there are two 2-byte instructions above our
+          // breakpoint target address. Now the upper 2-byte instruction is
+          // either a valid 2-byte instruction or could be a part of it's
+          // upper 4-byte instruction. In both cases we don't care because in
+          // this case lower 2-byte instruction is definitely a valid
+          // instruction and whatever i=1 iteration has found out is true.
+          inst_to_choose = 1;
+          break;
+        }
+        else if (insn_size == 4) {
+          // This instruction claims its a valid 4-byte instruction. But it
+          // could be a part of it's upper 4-byte instruction. Lets try
+          // scanning upper 2 bytes to verify this.
+          instruction_list.Append(prev_insn);
+          inst_to_choose = 2;
+        }
+      }
+      else if (i == 3) {
+        if (insn_size == 4)
+          // FIXME: We reached here that means instruction at [target - 4] has
+          // already claimed to be a 4-byte instruction, and now instruction
+          // at [target - 6] is also claiming that it's a 4-byte instruction.
+          // This can not be true. In this case we can not decide the valid
+          // previous instruction so we let lldb set the breakpoint at the
+          // address given by user.
+          inst_to_choose = 0;
+        else
+          // This is straight-forward
+          inst_to_choose = 2;
+        break;
+      }
+    }
+    else {
+      // Decode failed, bytes do not form a valid instruction. So whatever
+      // previous iteration has found out is true.
+      if (i > 1) {
+        inst_to_choose = i - 1;
+        break;
+      }
+    }
+  }
+
+  // Check if we are able to find any valid instruction.
+  if (inst_to_choose) {
+    if (inst_to_choose > instruction_list.GetSize())
+      inst_to_choose--;
+    return instruction_list.GetInstructionAtIndex(inst_to_choose - 1).get();
+  }
+
+  return nullptr;
+}