Imported Upstream version 5.18.0.246

Former-commit-id: 0c7ce5b1a7851e13f22acfd379b7f9fb304e4833

external/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp

@@ -0,0 +1,206 @@
+//===-- WebAssemblyAsmBackend.cpp - WebAssembly Assembler Backend ---------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief This file implements the WebAssemblyAsmBackend class.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyFixupKinds.h"
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCDirectives.h"
+#include "llvm/MC/MCELFObjectWriter.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCFixupKindInfo.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/MC/MCWasmObjectWriter.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+namespace {
+class WebAssemblyAsmBackendELF final : public MCAsmBackend {
+  bool Is64Bit;
+
+public:
+  explicit WebAssemblyAsmBackendELF(bool Is64Bit)
+      : MCAsmBackend(), Is64Bit(Is64Bit) {}
+  ~WebAssemblyAsmBackendELF() override {}
+
+  void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
+                  const MCValue &Target, MutableArrayRef<char> Data,
+                  uint64_t Value, bool IsPCRel) const override;
+
+  std::unique_ptr<MCObjectWriter>
+  createObjectWriter(raw_pwrite_stream &OS) const override;
+
+  // No instruction requires relaxation
+  bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
+                            const MCRelaxableFragment *DF,
+                            const MCAsmLayout &Layout) const override {
+    return false;
+  }
+
+  unsigned getNumFixupKinds() const override {
+    // We currently just use the generic fixups in MCFixup.h and don't have any
+    // target-specific fixups.
+    return 0;
+  }
+
+  bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
+
+  void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
+                        MCInst &Res) const override {}
+
+  bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
+};
+
+class WebAssemblyAsmBackend final : public MCAsmBackend {
+  bool Is64Bit;
+
+public:
+  explicit WebAssemblyAsmBackend(bool Is64Bit)
+      : MCAsmBackend(), Is64Bit(Is64Bit) {}
+  ~WebAssemblyAsmBackend() override {}
+
+  unsigned getNumFixupKinds() const override {
+    return WebAssembly::NumTargetFixupKinds;
+  }
+
+  const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override;
+
+  void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
+                  const MCValue &Target, MutableArrayRef<char> Data,
+                  uint64_t Value, bool IsPCRel) const override;
+
+  std::unique_ptr<MCObjectWriter>
+  createObjectWriter(raw_pwrite_stream &OS) const override;
+
+  // No instruction requires relaxation
+  bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
+                            const MCRelaxableFragment *DF,
+                            const MCAsmLayout &Layout) const override {
+    return false;
+  }
+
+  bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
+
+  void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
+                        MCInst &Res) const override {}
+
+  bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
+};
+
+bool WebAssemblyAsmBackendELF::writeNopData(uint64_t Count,
+                                            MCObjectWriter *OW) const {
+  for (uint64_t i = 0; i < Count; ++i)
+    OW->write8(WebAssembly::Nop);
+
+  return true;
+}
+
+void WebAssemblyAsmBackendELF::applyFixup(const MCAssembler &Asm,
+                                          const MCFixup &Fixup,
+                                          const MCValue &Target,
+                                          MutableArrayRef<char> Data,
+                                          uint64_t Value, bool IsPCRel) const {
+  const MCFixupKindInfo &Info = getFixupKindInfo(Fixup.getKind());
+  assert(Info.Flags == 0 && "WebAssembly does not use MCFixupKindInfo flags");
+
+  unsigned NumBytes = alignTo(Info.TargetSize, 8) / 8;
+  if (Value == 0)
+    return; // Doesn't change encoding.
+
+  // Shift the value into position.
+  Value <<= Info.TargetOffset;
+
+  unsigned Offset = Fixup.getOffset();
+  assert(Offset + NumBytes <= Data.size() && "Invalid fixup offset!");
+
+  // For each byte of the fragment that the fixup touches, mask in the
+  // bits from the fixup value.
+  for (unsigned i = 0; i != NumBytes; ++i)
+    Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff);
+}
+
+std::unique_ptr<MCObjectWriter>
+WebAssemblyAsmBackendELF::createObjectWriter(raw_pwrite_stream &OS) const {
+  return createWebAssemblyELFObjectWriter(OS, Is64Bit, 0);
+}
+
+const MCFixupKindInfo &
+WebAssemblyAsmBackend::getFixupKindInfo(MCFixupKind Kind) const {
+  const static MCFixupKindInfo Infos[WebAssembly::NumTargetFixupKinds] = {
+    // This table *must* be in the order that the fixup_* kinds are defined in
+    // WebAssemblyFixupKinds.h.
+    //
+    // Name                     Offset (bits) Size (bits)     Flags
+    { "fixup_code_sleb128_i32", 0,            5*8,            0 },
+    { "fixup_code_sleb128_i64", 0,            10*8,           0 },
+    { "fixup_code_uleb128_i32", 0,            5*8,            0 },
+  };
+
+  if (Kind < FirstTargetFixupKind)
+    return MCAsmBackend::getFixupKindInfo(Kind);
+
+  assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
+         "Invalid kind!");
+  return Infos[Kind - FirstTargetFixupKind];
+}
+
+bool WebAssemblyAsmBackend::writeNopData(uint64_t Count,
+                                         MCObjectWriter *OW) const {
+  if (Count == 0)
+    return true;
+
+  for (uint64_t i = 0; i < Count; ++i)
+    OW->write8(WebAssembly::Nop);
+
+  return true;
+}
+
+void WebAssemblyAsmBackend::applyFixup(const MCAssembler &Asm,
+                                       const MCFixup &Fixup,
+                                       const MCValue &Target,
+                                       MutableArrayRef<char> Data,
+                                       uint64_t Value, bool IsPCRel) const {
+  const MCFixupKindInfo &Info = getFixupKindInfo(Fixup.getKind());
+  assert(Info.Flags == 0 && "WebAssembly does not use MCFixupKindInfo flags");
+
+  unsigned NumBytes = alignTo(Info.TargetSize, 8) / 8;
+  if (Value == 0)
+    return; // Doesn't change encoding.
+
+  // Shift the value into position.
+  Value <<= Info.TargetOffset;
+
+  unsigned Offset = Fixup.getOffset();
+  assert(Offset + NumBytes <= Data.size() && "Invalid fixup offset!");
+
+  // For each byte of the fragment that the fixup touches, mask in the
+  // bits from the fixup value.
+  for (unsigned i = 0; i != NumBytes; ++i)
+    Data[Offset + i] |= uint8_t((Value >> (i * 8)) & 0xff);
+}
+
+std::unique_ptr<MCObjectWriter>
+WebAssemblyAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
+  return createWebAssemblyWasmObjectWriter(OS, Is64Bit);
+}
+} // end anonymous namespace
+
+MCAsmBackend *llvm::createWebAssemblyAsmBackend(const Triple &TT) {
+  if (TT.isOSBinFormatELF())
+    return new WebAssemblyAsmBackendELF(TT.isArch64Bit());
+  return new WebAssemblyAsmBackend(TT.isArch64Bit());
+}