1 files changed, 278 insertions, 0 deletions
diff --git a/contrib/llvm-project/llvm/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp b/contrib/llvm-project/llvm/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp
new file mode 100644
index 000000000000..f9bf3f85d30f
--- /dev/null
+++ b/contrib/llvm-project/llvm/lib/Target/WebAssembly/Disassembler/WebAssemblyDisassembler.cpp
@@ -0,0 +1,278 @@
+//==- WebAssemblyDisassembler.cpp - Disassembler for WebAssembly -*- C++ -*-==//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file is part of the WebAssembly Disassembler.
+///
+/// It contains code to translate the data produced by the decoder into
+/// MCInsts.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyInstPrinter.h"
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "TargetInfo/WebAssemblyTargetInfo.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCDisassembler/MCDisassembler.h"
+#include "llvm/MC/MCFixedLenDisassembler.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/LEB128.h"
+#include "llvm/Support/TargetRegistry.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "wasm-disassembler"
+
+using DecodeStatus = MCDisassembler::DecodeStatus;
+
+#include "WebAssemblyGenDisassemblerTables.inc"
+
+namespace {
+static constexpr int WebAssemblyInstructionTableSize = 256;
+
+class WebAssemblyDisassembler final : public MCDisassembler {
+  std::unique_ptr<const MCInstrInfo> MCII;
+
+  DecodeStatus getInstruction(MCInst &Instr, uint64_t &Size,
+                              ArrayRef<uint8_t> Bytes, uint64_t Address,
+                              raw_ostream &VStream,
+                              raw_ostream &CStream) const override;
+  DecodeStatus onSymbolStart(StringRef Name, uint64_t &Size,
+                             ArrayRef<uint8_t> Bytes, uint64_t Address,
+                             raw_ostream &VStream,
+                             raw_ostream &CStream) const override;
+
+public:
+  WebAssemblyDisassembler(const MCSubtargetInfo &STI, MCContext &Ctx,
+                          std::unique_ptr<const MCInstrInfo> MCII)
+      : MCDisassembler(STI, Ctx), MCII(std::move(MCII)) {}
+};
+} // end anonymous namespace
+
+static MCDisassembler *createWebAssemblyDisassembler(const Target &T,
+                                                     const MCSubtargetInfo &STI,
+                                                     MCContext &Ctx) {
+  std::unique_ptr<const MCInstrInfo> MCII(T.createMCInstrInfo());
+  return new WebAssemblyDisassembler(STI, Ctx, std::move(MCII));
+}
+
+extern "C" void LLVMInitializeWebAssemblyDisassembler() {
+  // Register the disassembler for each target.
+  TargetRegistry::RegisterMCDisassembler(getTheWebAssemblyTarget32(),
+                                         createWebAssemblyDisassembler);
+  TargetRegistry::RegisterMCDisassembler(getTheWebAssemblyTarget64(),
+                                         createWebAssemblyDisassembler);
+}
+
+static int nextByte(ArrayRef<uint8_t> Bytes, uint64_t &Size) {
+  if (Size >= Bytes.size())
+    return -1;
+  auto V = Bytes[Size];
+  Size++;
+  return V;
+}
+
+static bool nextLEB(int64_t &Val, ArrayRef<uint8_t> Bytes, uint64_t &Size,
+                    bool Signed) {
+  unsigned N = 0;
+  const char *Error = nullptr;
+  Val = Signed ? decodeSLEB128(Bytes.data() + Size, &N,
+                               Bytes.data() + Bytes.size(), &Error)
+               : static_cast<int64_t>(decodeULEB128(Bytes.data() + Size, &N,
+                                                    Bytes.data() + Bytes.size(),
+                                                    &Error));
+  if (Error)
+    return false;
+  Size += N;
+  return true;
+}
+
+static bool parseLEBImmediate(MCInst &MI, uint64_t &Size,
+                              ArrayRef<uint8_t> Bytes, bool Signed) {
+  int64_t Val;
+  if (!nextLEB(Val, Bytes, Size, Signed))
+    return false;
+  MI.addOperand(MCOperand::createImm(Val));
+  return true;
+}
+
+template <typename T>
+bool parseImmediate(MCInst &MI, uint64_t &Size, ArrayRef<uint8_t> Bytes) {
+  if (Size + sizeof(T) > Bytes.size())
+    return false;
+  T Val = support::endian::read<T, support::endianness::little, 1>(
+      Bytes.data() + Size);
+  Size += sizeof(T);
+  if (std::is_floating_point<T>::value) {
+    MI.addOperand(MCOperand::createFPImm(static_cast<double>(Val)));
+  } else {
+    MI.addOperand(MCOperand::createImm(static_cast<int64_t>(Val)));
+  }
+  return true;
+}
+
+MCDisassembler::DecodeStatus WebAssemblyDisassembler::onSymbolStart(
+    StringRef Name, uint64_t &Size, ArrayRef<uint8_t> Bytes, uint64_t Address,
+    raw_ostream &VStream, raw_ostream &CStream) const {
+  Size = 0;
+  if (Address == 0) {
+    // Start of a code section: we're parsing only the function count.
+    int64_t FunctionCount;
+    if (!nextLEB(FunctionCount, Bytes, Size, false))
+      return MCDisassembler::Fail;
+    outs() << "        # " << FunctionCount << " functions in section.";
+  } else {
+    // Parse the start of a single function.
+    int64_t BodySize, LocalEntryCount;
+    if (!nextLEB(BodySize, Bytes, Size, false) ||
+        !nextLEB(LocalEntryCount, Bytes, Size, false))
+      return MCDisassembler::Fail;
+    if (LocalEntryCount) {
+      outs() << "        .local ";
+      for (int64_t I = 0; I < LocalEntryCount; I++) {
+        int64_t Count, Type;
+        if (!nextLEB(Count, Bytes, Size, false) ||
+            !nextLEB(Type, Bytes, Size, false))
+          return MCDisassembler::Fail;
+        for (int64_t J = 0; J < Count; J++) {
+          if (I || J)
+            outs() << ", ";
+          outs() << WebAssembly::anyTypeToString(Type);
+        }
+      }
+    }
+  }
+  outs() << "\n";
+  return MCDisassembler::Success;
+}
+
+MCDisassembler::DecodeStatus WebAssemblyDisassembler::getInstruction(
+    MCInst &MI, uint64_t &Size, ArrayRef<uint8_t> Bytes, uint64_t /*Address*/,
+    raw_ostream & /*OS*/, raw_ostream &CS) const {
+  CommentStream = &CS;
+  Size = 0;
+  int Opc = nextByte(Bytes, Size);
+  if (Opc < 0)
+    return MCDisassembler::Fail;
+  const auto *WasmInst = &InstructionTable0[Opc];
+  // If this is a prefix byte, indirect to another table.
+  if (WasmInst->ET == ET_Prefix) {
+    WasmInst = nullptr;
+    // Linear search, so far only 2 entries.
+    for (auto PT = PrefixTable; PT->Table; PT++) {
+      if (PT->Prefix == Opc) {
+        WasmInst = PT->Table;
+        break;
+      }
+    }
+    if (!WasmInst)
+      return MCDisassembler::Fail;
+    int64_t PrefixedOpc;
+    if (!nextLEB(PrefixedOpc, Bytes, Size, false))
+      return MCDisassembler::Fail;
+    if (PrefixedOpc < 0 || PrefixedOpc >= WebAssemblyInstructionTableSize)
+      return MCDisassembler::Fail;
+    WasmInst += PrefixedOpc;
+  }
+  if (WasmInst->ET == ET_Unused)
+    return MCDisassembler::Fail;
+  // At this point we must have a valid instruction to decode.
+  assert(WasmInst->ET == ET_Instruction);
+  MI.setOpcode(WasmInst->Opcode);
+  // Parse any operands.
+  for (uint8_t OPI = 0; OPI < WasmInst->NumOperands; OPI++) {
+    auto OT = OperandTable[WasmInst->OperandStart + OPI];
+    switch (OT) {
+    // ULEB operands:
+    case WebAssembly::OPERAND_BASIC_BLOCK:
+    case WebAssembly::OPERAND_LOCAL:
+    case WebAssembly::OPERAND_GLOBAL:
+    case WebAssembly::OPERAND_FUNCTION32:
+    case WebAssembly::OPERAND_OFFSET32:
+    case WebAssembly::OPERAND_P2ALIGN:
+    case WebAssembly::OPERAND_TYPEINDEX:
+    case WebAssembly::OPERAND_EVENT:
+    case MCOI::OPERAND_IMMEDIATE: {
+      if (!parseLEBImmediate(MI, Size, Bytes, false))
+        return MCDisassembler::Fail;
+      break;
+    }
+    // SLEB operands:
+    case WebAssembly::OPERAND_I32IMM:
+    case WebAssembly::OPERAND_I64IMM: {
+      if (!parseLEBImmediate(MI, Size, Bytes, true))
+        return MCDisassembler::Fail;
+      break;
+    }
+    // block_type operands (uint8_t).
+    case WebAssembly::OPERAND_SIGNATURE: {
+      if (!parseImmediate<uint8_t>(MI, Size, Bytes))
+        return MCDisassembler::Fail;
+      break;
+    }
+    // FP operands.
+    case WebAssembly::OPERAND_F32IMM: {
+      if (!parseImmediate<float>(MI, Size, Bytes))
+        return MCDisassembler::Fail;
+      break;
+    }
+    case WebAssembly::OPERAND_F64IMM: {
+      if (!parseImmediate<double>(MI, Size, Bytes))
+        return MCDisassembler::Fail;
+      break;
+    }
+    // Vector lane operands (not LEB encoded).
+    case WebAssembly::OPERAND_VEC_I8IMM: {
+      if (!parseImmediate<uint8_t>(MI, Size, Bytes))
+        return MCDisassembler::Fail;
+      break;
+    }
+    case WebAssembly::OPERAND_VEC_I16IMM: {
+      if (!parseImmediate<uint16_t>(MI, Size, Bytes))
+        return MCDisassembler::Fail;
+      break;
+    }
+    case WebAssembly::OPERAND_VEC_I32IMM: {
+      if (!parseImmediate<uint32_t>(MI, Size, Bytes))
+        return MCDisassembler::Fail;
+      break;
+    }
+    case WebAssembly::OPERAND_VEC_I64IMM: {
+      if (!parseImmediate<uint64_t>(MI, Size, Bytes))
+        return MCDisassembler::Fail;
+      break;
+    }
+    case WebAssembly::OPERAND_BRLIST: {
+      int64_t TargetTableLen;
+      if (!nextLEB(TargetTableLen, Bytes, Size, false))
+        return MCDisassembler::Fail;
+      for (int64_t I = 0; I < TargetTableLen; I++) {
+        if (!parseLEBImmediate(MI, Size, Bytes, false))
+          return MCDisassembler::Fail;
+      }
+      // Default case.
+      if (!parseLEBImmediate(MI, Size, Bytes, false))
+        return MCDisassembler::Fail;
+      break;
+    }
+    case MCOI::OPERAND_REGISTER:
+      // The tablegen header currently does not have any register operands since
+      // we use only the stack (_S) instructions.
+      // If you hit this that probably means a bad instruction definition in
+      // tablegen.
+      llvm_unreachable("Register operand in WebAssemblyDisassembler");
+    default:
+      llvm_unreachable("Unknown operand type in WebAssemblyDisassembler");
+    }
+  }
+  return MCDisassembler::Success;
+}