[llvm] r255869 - [WebAssembly] Experimental ELF writer support

Dan Gohman via llvm-commits llvm-commits at lists.llvm.org
Wed Dec 16 17:39:01 PST 2015


Author: djg
Date: Wed Dec 16 19:39:00 2015
New Revision: 255869

URL: http://llvm.org/viewvc/llvm-project?rev=255869&view=rev
Log:
[WebAssembly] Experimental ELF writer support

This creates the initial infrastructure for writing ELF output files. It
doesn't yet have any implementation for encoding instructions.

Differential Revision: http://reviews.llvm.org/D15555

Added:
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyELFObjectWriter.cpp
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
Modified:
    llvm/trunk/lib/Support/Triple.cpp
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/CMakeLists.txt
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
    llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
    llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
    llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

Modified: llvm/trunk/lib/Support/Triple.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Triple.cpp?rev=255869&r1=255868&r2=255869&view=diff
==============================================================================
--- llvm/trunk/lib/Support/Triple.cpp (original)
+++ llvm/trunk/lib/Support/Triple.cpp Wed Dec 16 19:39:00 2015
@@ -550,6 +550,8 @@ static Triple::ObjectFormatType getDefau
   case Triple::sparc:
   case Triple::sparcv9:
   case Triple::systemz:
+  case Triple::wasm32:
+  case Triple::wasm64:
   case Triple::xcore:
   case Triple::ppc64le:
     return Triple::ELF;
@@ -559,11 +561,6 @@ static Triple::ObjectFormatType getDefau
     if (T.isOSDarwin())
       return Triple::MachO;
     return Triple::ELF;
-
-  case Triple::wasm32:
-  case Triple::wasm64:
-    // Unknown for now, until an object format is specified.
-    return Triple::UnknownObjectFormat;
   }
 
   if (T.isOSDarwin())

Modified: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/CMakeLists.txt?rev=255869&r1=255868&r2=255869&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/CMakeLists.txt (original)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/CMakeLists.txt Wed Dec 16 19:39:00 2015
@@ -1,4 +1,7 @@
 add_llvm_library(LLVMWebAssemblyDesc
+  WebAssemblyAsmBackend.cpp
+  WebAssemblyELFObjectWriter.cpp
   WebAssemblyMCAsmInfo.cpp
+  WebAssemblyMCCodeEmitter.cpp
   WebAssemblyMCTargetDesc.cpp
 )

Added: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp?rev=255869&view=auto
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp (added)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyAsmBackend.cpp Wed Dec 16 19:39:00 2015
@@ -0,0 +1,103 @@
+//===-- 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/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/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+namespace {
+class WebAssemblyAsmBackend final : public MCAsmBackend {
+  bool Is64Bit;
+
+public:
+  explicit WebAssemblyAsmBackend(bool Is64Bit)
+      : MCAsmBackend(), Is64Bit(Is64Bit) {}
+  ~WebAssemblyAsmBackend() override {}
+
+  void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
+                  uint64_t Value, bool IsPCRel) const override;
+
+  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, MCInst &Res) const override {}
+
+  bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
+};
+
+bool WebAssemblyAsmBackend::writeNopData(uint64_t Count,
+                                         MCObjectWriter *OW) const {
+  if (Count == 0)
+    return true;
+
+  // FIXME: Do something.
+  return false;
+}
+
+void WebAssemblyAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
+                                       unsigned DataSize, uint64_t Value,
+                                       bool IsPCRel) const {
+  const MCFixupKindInfo &Info = getFixupKindInfo(Fixup.getKind());
+  unsigned NumBytes = RoundUpToAlignment(Info.TargetSize, 8);
+  if (!Value)
+    return; // Doesn't change encoding.
+
+  // Shift the value into position.
+  Value <<= Info.TargetOffset;
+
+  unsigned Offset = Fixup.getOffset();
+  assert(Offset + NumBytes <= DataSize && "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);
+}
+
+MCObjectWriter *
+WebAssemblyAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
+  return createWebAssemblyELFObjectWriter(OS, Is64Bit, 0);
+}
+} // end anonymous namespace
+
+MCAsmBackend *llvm::createWebAssemblyAsmBackend(const Target &T,
+                                                const MCRegisterInfo &MRI,
+                                                const Triple &TT,
+                                                StringRef CPU) {
+  return new WebAssemblyAsmBackend(TT.isArch64Bit());
+}

Added: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyELFObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyELFObjectWriter.cpp?rev=255869&view=auto
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyELFObjectWriter.cpp (added)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyELFObjectWriter.cpp Wed Dec 16 19:39:00 2015
@@ -0,0 +1,58 @@
+//===-- WebAssemblyELFObjectWriter.cpp - WebAssembly ELF Writer -----------===//
+//
+//                     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 handles ELF-specific object emission, converting LLVM's
+/// internal fixups into the appropriate relocations.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "llvm/MC/MCELFObjectWriter.h"
+#include "llvm/MC/MCFixup.h"
+#include "llvm/Support/ErrorHandling.h"
+using namespace llvm;
+
+namespace {
+class WebAssemblyELFObjectWriter final : public MCELFObjectTargetWriter {
+public:
+  WebAssemblyELFObjectWriter(bool Is64Bit, uint8_t OSABI);
+
+  ~WebAssemblyELFObjectWriter() override;
+
+protected:
+  unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
+                        bool IsPCRel) const override;
+};
+} // end anonymous namespace
+
+// FIXME: Use EM_NONE as a temporary hack. Should we decide to pursue ELF
+// writing seriously, we should email generic-abi at googlegroups.com and ask
+// for our own ELF code.
+WebAssemblyELFObjectWriter::WebAssemblyELFObjectWriter(bool Is64Bit,
+                                                       uint8_t OSABI)
+    : MCELFObjectTargetWriter(Is64Bit, OSABI, ELF::EM_NONE,
+                              /*HasRelocationAddend=*/true) {}
+
+WebAssemblyELFObjectWriter::~WebAssemblyELFObjectWriter() {}
+
+unsigned WebAssemblyELFObjectWriter::GetRelocType(const MCValue &Target,
+                                                  const MCFixup &Fixup,
+                                                  bool IsPCRel) const {
+  // FIXME: Do we need our own relocs?
+  return Fixup.getKind();
+}
+
+MCObjectWriter *llvm::createWebAssemblyELFObjectWriter(raw_pwrite_stream &OS,
+                                                       bool Is64Bit,
+                                                       uint8_t OSABI) {
+  MCELFObjectTargetWriter *MOTW =
+      new WebAssemblyELFObjectWriter(Is64Bit, OSABI);
+  return createELFObjectWriter(MOTW, OS, /*IsLittleEndian=*/true);
+}

Added: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp?rev=255869&view=auto
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp (added)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCCodeEmitter.cpp Wed Dec 16 19:39:00 2015
@@ -0,0 +1,104 @@
+//=- WebAssemblyMCCodeEmitter.cpp - Convert WebAssembly code to machine code -//
+//
+//                     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 WebAssemblyMCCodeEmitter class.
+///
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/MC/MCCodeEmitter.h"
+#include "llvm/MC/MCFixup.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "mccodeemitter"
+
+namespace {
+class WebAssemblyMCCodeEmitter final : public MCCodeEmitter {
+  const MCInstrInfo &MCII;
+  const MCRegisterInfo &MRI;
+  const MCContext &Ctx;
+
+public:
+  WebAssemblyMCCodeEmitter(const MCInstrInfo &mcii, const MCRegisterInfo &mri,
+                           MCContext &ctx)
+      : MCII(mcii), MRI(mri), Ctx(ctx) {}
+
+  ~WebAssemblyMCCodeEmitter() override {}
+
+  /// TableGen'erated function for getting the binary encoding for an
+  /// instruction.
+  uint64_t getBinaryCodeForInstr(const MCInst &MI,
+                                 SmallVectorImpl<MCFixup> &Fixups,
+                                 const MCSubtargetInfo &STI) const;
+
+  /// Return binary encoding of operand. If the machine operand requires
+  /// relocation, record the relocation and return zero.
+  unsigned getMachineOpValue(const MCInst &MI, const MCOperand &MO,
+                             SmallVectorImpl<MCFixup> &Fixups,
+                             const MCSubtargetInfo &STI) const;
+
+  uint64_t getMemoryOpValue(const MCInst &MI, unsigned Op,
+                            SmallVectorImpl<MCFixup> &Fixups,
+                            const MCSubtargetInfo &STI) const;
+
+  void encodeInstruction(const MCInst &MI, raw_ostream &OS,
+                         SmallVectorImpl<MCFixup> &Fixups,
+                         const MCSubtargetInfo &STI) const override;
+};
+} // end anonymous namespace
+
+MCCodeEmitter *llvm::createWebAssemblyMCCodeEmitter(const MCInstrInfo &MCII,
+                                                    const MCRegisterInfo &MRI,
+                                                    MCContext &Ctx) {
+  return new WebAssemblyMCCodeEmitter(MCII, MRI, Ctx);
+}
+
+unsigned WebAssemblyMCCodeEmitter::getMachineOpValue(
+    const MCInst &MI, const MCOperand &MO, SmallVectorImpl<MCFixup> &Fixups,
+    const MCSubtargetInfo &STI) const {
+  if (MO.isReg())
+    return MRI.getEncodingValue(MO.getReg());
+  if (MO.isImm())
+    return static_cast<unsigned>(MO.getImm());
+
+  assert(MO.isExpr());
+
+  const MCExpr *Expr = MO.getExpr();
+
+  assert(Expr->getKind() == MCExpr::SymbolRef);
+
+  assert(false && "FIXME: not implemented yet");
+
+  return 0;
+}
+
+void WebAssemblyMCCodeEmitter::encodeInstruction(
+    const MCInst &MI, raw_ostream &OS, SmallVectorImpl<MCFixup> &Fixups,
+    const MCSubtargetInfo &STI) const {
+  assert(false && "FIXME: not implemented yet");
+}
+
+// Encode WebAssembly Memory Operand
+uint64_t
+WebAssemblyMCCodeEmitter::getMemoryOpValue(const MCInst &MI, unsigned Op,
+                                           SmallVectorImpl<MCFixup> &Fixups,
+                                           const MCSubtargetInfo &STI) const {
+  assert(false && "FIXME: not implemented yet");
+  return 0;
+}
+
+#include "WebAssemblyGenMCCodeEmitter.inc"

Modified: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp?rev=255869&r1=255868&r2=255869&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.cpp Wed Dec 16 19:39:00 2015
@@ -46,6 +46,14 @@ static MCInstrInfo *createWebAssemblyMCI
   return X;
 }
 
+static MCStreamer *createWebAssemblyMCStreamer(const Triple &T, MCContext &Ctx,
+                                               MCAsmBackend &MAB,
+                                               raw_pwrite_stream &OS,
+                                               MCCodeEmitter *Emitter,
+                                               bool RelaxAll) {
+  return createELFStreamer(Ctx, MAB, OS, Emitter, RelaxAll);
+}
+
 static MCInstPrinter *
 createWebAssemblyMCInstPrinter(const Triple & /*T*/, unsigned SyntaxVariant,
                                const MCAsmInfo &MAI, const MCInstrInfo &MII,
@@ -63,7 +71,16 @@ extern "C" void LLVMInitializeWebAssembl
     // Register the MC instruction info.
     TargetRegistry::RegisterMCInstrInfo(*T, createWebAssemblyMCInstrInfo);
 
+    // Register the object streamer
+    TargetRegistry::RegisterELFStreamer(*T, createWebAssemblyMCStreamer);
+
     // Register the MCInstPrinter.
     TargetRegistry::RegisterMCInstPrinter(*T, createWebAssemblyMCInstPrinter);
+
+    // Register the MC code emitter
+    TargetRegistry::RegisterMCCodeEmitter(*T, createWebAssemblyMCCodeEmitter);
+
+    // Register the ASM Backend
+    TargetRegistry::RegisterMCAsmBackend(*T, createWebAssemblyAsmBackend);
   }
 }

Modified: llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h?rev=255869&r1=255868&r2=255869&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h (original)
+++ llvm/trunk/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyMCTargetDesc.h Wed Dec 16 19:39:00 2015
@@ -46,6 +46,9 @@ MCAsmBackend *createWebAssemblyAsmBacken
                                           const MCRegisterInfo &MRI,
                                           const Triple &TT, StringRef CPU);
 
+MCObjectWriter *createWebAssemblyELFObjectWriter(raw_pwrite_stream &OS,
+                                                 bool Is64Bit, uint8_t OSABI);
+
 } // end namespace llvm
 
 // Defines symbolic names for WebAssembly registers. This defines a mapping from

Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp?rev=255869&r1=255868&r2=255869&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp Wed Dec 16 19:39:00 2015
@@ -17,7 +17,6 @@
 #include "WebAssemblyMachineFunctionInfo.h"
 #include "WebAssemblySubtarget.h"
 #include "WebAssemblyTargetMachine.h"
-#include "WebAssemblyTargetObjectFile.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/CallingConvLower.h"
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
@@ -650,10 +649,3 @@ SDValue WebAssemblyTargetLowering::Lower
 //===----------------------------------------------------------------------===//
 //                          WebAssembly Optimization Hooks
 //===----------------------------------------------------------------------===//
-
-MCSection *WebAssemblyTargetObjectFile::SelectSectionForGlobal(
-    const GlobalValue *GV, SectionKind /*Kind*/, Mangler & /*Mang*/,
-    const TargetMachine & /*TM*/) const {
-  // TODO: Be more sophisticated than this.
-  return isa<Function>(GV) ? getTextSection() : getDataSection();
-}

Modified: llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp?rev=255869&r1=255868&r2=255869&view=diff
==============================================================================
--- llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp (original)
+++ llvm/trunk/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp Wed Dec 16 19:39:00 2015
@@ -15,7 +15,6 @@
 #include "WebAssembly.h"
 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
 #include "WebAssemblyTargetMachine.h"
-#include "WebAssemblyTargetObjectFile.h"
 #include "WebAssemblyTargetTransformInfo.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
 #include "llvm/CodeGen/Passes.h"
@@ -49,7 +48,7 @@ WebAssemblyTargetMachine::WebAssemblyTar
     : LLVMTargetMachine(T, TT.isArch64Bit() ? "e-p:64:64-i64:64-n32:64-S128"
                                             : "e-p:32:32-i64:64-n32:64-S128",
                         TT, CPU, FS, Options, RM, CM, OL),
-      TLOF(make_unique<WebAssemblyTargetObjectFile>()) {
+      TLOF(make_unique<TargetLoweringObjectFileELF>()) {
   // WebAssembly type-checks expressions, but a noreturn function with a return
   // type that doesn't match the context will cause a check failure. So we lower
   // LLVM 'unreachable' to ISD::TRAP and then lower that to WebAssembly's
@@ -171,7 +170,7 @@ void WebAssemblyPassConfig::addPreRegAll
   addPass(createWebAssemblyRegStackify());
   // The register coalescing pass has a bad interaction with COPY MIs which have
   // EXPR_STACK as an extra operand
-  //disablePass(&RegisterCoalescerID);
+  // disablePass(&RegisterCoalescerID);
 }
 
 void WebAssemblyPassConfig::addPostRegAlloc() {
@@ -198,7 +197,7 @@ void WebAssemblyPassConfig::addPostRegAl
 
 void WebAssemblyPassConfig::addPreEmitPass() {
   TargetPassConfig::addPreEmitPass();
-    
+
   // Put the CFG in structured form; insert BLOCK and LOOP markers.
   addPass(createWebAssemblyCFGStackify());
 




More information about the llvm-commits mailing list