Add WoA object file emission support

Introduce support for WoA PE/COFF object file emission from LLVM.  Add the new
target specific PE/COFF Streamer (ARMWinCOFFStreamer) that handles the ARM
specific behaviour of PE/COFF object emission.  ARM exception information is not
yet emitted and is a TODO item.

The ARM specific object writer (ARMWinCOFFObjectWriter) handles the ARM specific
relocation handling in conjunction with the WinCOFFObjectWriter in the MC layer.
The MC layer needs to be updated to deal with the relocation adjustments.
Branch relocations are adjusted by 4 bytes (unlikely their ELF counterparts).

Minor tweaks to switch multiple conditional checks into equivalent switch
statements.  The ObjectFileInfo is updated to relax the object file setup for
Windows COFF.  Move the architecture checks into an assertion.  Windows COFF is
currently only supported on x86, x86_64, and ARM (thumb).  Rather than
defaulting to ELF, we will refuse to generate an object file.  This is better
though as you do not get an (arbitrary) object file which is different from the
request.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207345 91177308-0d34-0410-b5e6-96231b3b80d8

lib/MC/MCObjectFileInfo.cpp

@@ -780,8 +780,10 @@ void MCObjectFileInfo::InitMCObjectFileInfo(StringRef TT, Reloc::Model relocm,
       (T.isOSDarwin() || T.isOSBinFormatMachO())) {
     Env = IsMachO;
     InitMachOMCObjectFileInfo(T);
-  } else if ((Arch == Triple::x86 || Arch == Triple::x86_64) &&
-             T.getObjectFormat() != Triple::ELF && T.isOSWindows()) {
+  } else if (T.isOSWindows() && T.getObjectFormat() == Triple::COFF) {
+    assert((Arch == Triple::x86 || Arch == Triple::x86_64 ||
+            Arch == Triple::arm || Arch == Triple::thumb) &&
+           "unsupported Windows COFF architecture");
     Env = IsCOFF;
     InitCOFFMCObjectFileInfo(T);
   } else {

lib/MC/WinCOFFObjectWriter.cpp

@@ -761,6 +761,44 @@ void WinCOFFObjectWriter::RecordRelocation(const MCAssembler &Asm,
        Reloc.Data.Type == COFF::IMAGE_REL_I386_REL32))
     FixedValue += 4;
 
+  if (Header.Machine == COFF::IMAGE_FILE_MACHINE_ARMNT) {
+    switch (Reloc.Data.Type) {
+    case COFF::IMAGE_REL_ARM_ABSOLUTE:
+    case COFF::IMAGE_REL_ARM_ADDR32:
+    case COFF::IMAGE_REL_ARM_ADDR32NB:
+    case COFF::IMAGE_REL_ARM_TOKEN:
+    case COFF::IMAGE_REL_ARM_SECTION:
+    case COFF::IMAGE_REL_ARM_SECREL:
+      break;
+    case COFF::IMAGE_REL_ARM_BRANCH11:
+    case COFF::IMAGE_REL_ARM_BLX11:
+      // IMAGE_REL_ARM_BRANCH11 and IMAGE_REL_ARM_BLX11 are only used for
+      // pre-ARMv7, which implicitly rules it out of ARMNT (it would be valid
+      // for Windows CE).
+    case COFF::IMAGE_REL_ARM_BRANCH24:
+    case COFF::IMAGE_REL_ARM_BLX24:
+    case COFF::IMAGE_REL_ARM_MOV32A:
+      // IMAGE_REL_ARM_BRANCH24, IMAGE_REL_ARM_BLX24, IMAGE_REL_ARM_MOV32A are
+      // only used for ARM mode code, which is documented as being unsupported
+      // by Windows on ARM.  Emperical proof indicates that masm is able to
+      // generate the relocations however the rest of the MSVC toolchain is
+      // unable to handle it.
+      llvm_unreachable("unsupported relocation");
+      break;
+    case COFF::IMAGE_REL_ARM_MOV32T:
+      break;
+    case COFF::IMAGE_REL_ARM_BRANCH20T:
+    case COFF::IMAGE_REL_ARM_BRANCH24T:
+    case COFF::IMAGE_REL_ARM_BLX23T:
+      // IMAGE_REL_BRANCH20T, IMAGE_REL_ARM_BRANCH24T, IMAGE_REL_ARM_BLX23T all
+      // perform a 4 byte adjustment to the relocation.  Relative branches are
+      // offset by 4 on ARM, however, because there is no RELA relocations, all
+      // branches are offset by 4.
+      FixedValue = FixedValue + 4;
+      break;
+    }
+  }
+
   coff_section->Relocations.push_back(Reloc);
 }
 

lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp

@@ -737,6 +737,15 @@ void ARMAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
 }
 
 namespace {
+// FIXME: This should be in a separate file.
+class ARMWinCOFFAsmBackend : public ARMAsmBackend {
+public:
+  ARMWinCOFFAsmBackend(const Target &T, const StringRef &Triple)
+    : ARMAsmBackend(T, Triple, true) { }
+  MCObjectWriter *createObjectWriter(raw_ostream &OS) const override {
+    return createARMWinCOFFObjectWriter(OS, /*Is64Bit=*/false);
+  }
+};
 
 // FIXME: This should be in a separate file.
 // ELF is an ELF of course...
@@ -777,7 +786,9 @@ MCAsmBackend *llvm::createARMAsmBackend(const Target &T,
                                         bool isLittle) {
   Triple TheTriple(TT);
 
-  if (TheTriple.isOSBinFormatMachO()) {
+  switch (TheTriple.getObjectFormat()) {
+  default: llvm_unreachable("unsupported object format");
+  case Triple::MachO: {
     MachO::CPUSubTypeARM CS =
       StringSwitch<MachO::CPUSubTypeARM>(TheTriple.getArchName())
       .Cases("armv4t", "thumbv4t", MachO::CPU_SUBTYPE_ARM_V4T)
@@ -792,16 +803,15 @@ MCAsmBackend *llvm::createARMAsmBackend(const Target &T,
 
     return new DarwinARMAsmBackend(T, TT, CS);
   }
-
-#if 0
-  // FIXME: Introduce yet another checker but assert(0).
-  if (TheTriple.isOSBinFormatCOFF())
-    assert(0 && "Windows not supported on ARM");
-#endif
-
+  case Triple::COFF:
+    assert(TheTriple.isOSWindows() && "non-Windows ARM COFF is not supported");
+    return new ARMWinCOFFAsmBackend(T, TT);
+  case Triple::ELF:
+    assert(TheTriple.isOSBinFormatELF() && "using ELF for non-ELF target");
     uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(Triple(TT).getOS());
     return new ELFARMAsmBackend(T, TT, OSABI, isLittle);
   }
+}
 
 MCAsmBackend *llvm::createARMLEAsmBackend(const Target &T,
                                           const MCRegisterInfo &MRI,

lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp

@@ -1029,6 +1029,9 @@ ARMMCCodeEmitter::getHiLo16ImmOpValue(const MCInst &MI, unsigned OpIdx,
     switch (ARM16Expr->getKind()) {
     default: llvm_unreachable("Unsupported ARMFixup");
     case ARMMCExpr::VK_ARM_HI16:
+      if (Triple(STI.getTargetTriple()).isOSWindows())
+        return 0;
+
       Kind = MCFixupKind(isThumb2(STI) ? ARM::fixup_t2_movt_hi16
                                        : ARM::fixup_arm_movt_hi16);
       break;
@@ -1037,6 +1040,7 @@ ARMMCCodeEmitter::getHiLo16ImmOpValue(const MCInst &MI, unsigned OpIdx,
                                        : ARM::fixup_arm_movw_lo16);
       break;
     }
+
     Fixups.push_back(MCFixup::Create(0, E, Kind, MI.getLoc()));
     return 0;
   }

lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.cpp

@@ -21,6 +21,7 @@
 #include "llvm/MC/MCInstrAnalysis.h"
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSubtargetInfo.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/TargetRegistry.h"
@@ -275,19 +276,21 @@ static MCStreamer *createMCStreamer(const Target &T, StringRef TT,
                                     bool NoExecStack) {
   Triple TheTriple(TT);
 
-  if (TheTriple.isOSBinFormatMachO()) {
+  switch (TheTriple.getObjectFormat()) {
+  default: llvm_unreachable("unsupported object format");
+  case Triple::MachO: {
     MCStreamer *S = createMachOStreamer(Ctx, MAB, OS, Emitter, false);
     new ARMTargetStreamer(*S);
     return S;
   }
-
-  if (TheTriple.isOSWindows()) {
-    llvm_unreachable("ARM does not support Windows COFF format");
-  }
-
+  case Triple::COFF:
+    assert(TheTriple.isOSWindows() && "non-Windows ARM COFF is not supported");
+    return createARMWinCOFFStreamer(Ctx, MAB, *Emitter, OS);
+  case Triple::ELF:
     return createARMELFStreamer(Ctx, MAB, OS, Emitter, false, NoExecStack,
                                 TheTriple.getArch() == Triple::thumb);
   }
+}
 
 static MCInstPrinter *createARMMCInstPrinter(const Target &T,
                                              unsigned SyntaxVariant,

lib/Target/ARM/MCTargetDesc/ARMMCTargetDesc.h

@@ -78,6 +78,11 @@ MCAsmBackend *createThumbLEAsmBackend(const Target &T, const MCRegisterInfo &MRI
 MCAsmBackend *createThumbBEAsmBackend(const Target &T, const MCRegisterInfo &MRI,
                                       StringRef TT, StringRef CPU);
 
+/// createARMWinCOFFStreamer - Construct a PE/COFF machine code streamer which
+/// will generate a PE/COFF object file.
+MCStreamer *createARMWinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB,
+                                     MCCodeEmitter &Emitter, raw_ostream &OS);
+
 /// createARMELFObjectWriter - Construct an ELF Mach-O object writer.
 MCObjectWriter *createARMELFObjectWriter(raw_ostream &OS,
                                          uint8_t OSABI,
@@ -89,6 +94,8 @@ MCObjectWriter *createARMMachObjectWriter(raw_ostream &OS,
                                           uint32_t CPUType,
                                           uint32_t CPUSubtype);
 
+/// createARMWinCOFFObjectWriter - Construct an ARM PE/COFF object writer.
+MCObjectWriter *createARMWinCOFFObjectWriter(raw_ostream &OS, bool Is64Bit);
 
 /// createARMMachORelocationInfo - Construct ARM Mach-O relocation info.
 MCRelocationInfo *createARMMachORelocationInfo(MCContext &Ctx);

lib/Target/ARM/MCTargetDesc/ARMWinCOFFObjectWriter.cpp

@@ -0,0 +1,74 @@
+//===-- ARMWinCOFFObjectWriter.cpp - ARM Windows COFF Object Writer -- C++ -==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MCTargetDesc/ARMFixupKinds.h"
+#include "llvm/MC/MCFixup.h"
+#include "llvm/MC/MCValue.h"
+#include "llvm/MC/MCWinCOFFObjectWriter.h"
+#include "llvm/Support/COFF.h"
+#include "llvm/Support/Debug.h"
+
+using namespace llvm;
+
+namespace {
+class ARMWinCOFFObjectWriter : public MCWinCOFFObjectTargetWriter {
+public:
+  ARMWinCOFFObjectWriter(bool Is64Bit)
+    : MCWinCOFFObjectTargetWriter(COFF::IMAGE_FILE_MACHINE_ARMNT) {
+    assert(!Is64Bit && "AArch64 support not yet implemented");
+  }
+  virtual ~ARMWinCOFFObjectWriter() = default;
+
+  unsigned getRelocType(const MCValue &Target, const MCFixup &Fixup,
+                        bool IsCrossSection) const override;
+};
+
+unsigned ARMWinCOFFObjectWriter::getRelocType(const MCValue &Target,
+                                              const MCFixup &Fixup,
+                                              bool IsCrossSection) const {
+  assert(getMachine() == COFF::IMAGE_FILE_MACHINE_ARMNT &&
+         "AArch64 support not yet implemented");
+
+  MCSymbolRefExpr::VariantKind Modifier =
+    Target.isAbsolute() ? MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
+
+  switch (static_cast<unsigned>(Fixup.getKind())) {
+  default: llvm_unreachable("unsupported relocation type");
+  case FK_Data_4:
+    switch (Modifier) {
+    case MCSymbolRefExpr::VK_COFF_IMGREL32:
+      return COFF::IMAGE_REL_ARM_ADDR32NB;
+    case MCSymbolRefExpr::VK_SECREL:
+      return COFF::IMAGE_REL_ARM_SECREL;
+    default:
+      return COFF::IMAGE_REL_ARM_ADDR32;
+    }
+  case ARM::fixup_t2_condbranch:
+    return COFF::IMAGE_REL_ARM_BRANCH20T;
+  case ARM::fixup_t2_uncondbranch:
+    return COFF::IMAGE_REL_ARM_BRANCH24T;
+  case ARM::fixup_arm_thumb_bl:
+  case ARM::fixup_arm_thumb_blx:
+    return COFF::IMAGE_REL_ARM_BLX23T;
+  case ARM::fixup_t2_movw_lo16:
+    return COFF::IMAGE_REL_ARM_MOV32T;
+  case ARM::fixup_t2_movt_hi16:
+    llvm_unreachable("High-word for pair-wise relocations are contiguously "
+                     "addressed as an IMAGE_REL_ARM_MOV32T relocation");
+  }
+}
+}
+
+namespace llvm {
+MCObjectWriter *createARMWinCOFFObjectWriter(raw_ostream &OS, bool Is64Bit) {
+  MCWinCOFFObjectTargetWriter *MOTW = new ARMWinCOFFObjectWriter(Is64Bit);
+  return createWinCOFFObjectWriter(MOTW, OS);
+}
+}
+

lib/Target/ARM/MCTargetDesc/ARMWinCOFFStreamer.cpp

@@ -0,0 +1,46 @@
+//===-- ARMWinCOFFStreamer.cpp - ARM Target WinCOFF Streamer ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ARMMCTargetDesc.h"
+#include "llvm/MC/MCWinCOFFStreamer.h"
+
+using namespace llvm;
+
+namespace {
+class ARMWinCOFFStreamer : public MCWinCOFFStreamer {
+public:
+  ARMWinCOFFStreamer(MCContext &C, MCAsmBackend &AB, MCCodeEmitter &CE,
+                     raw_ostream &OS)
+    : MCWinCOFFStreamer(C, AB, CE, OS) { }
+
+  void EmitAssemblerFlag(MCAssemblerFlag Flag) override;
+  void EmitThumbFunc(MCSymbol *Symbol) override;
+};
+
+void ARMWinCOFFStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
+  switch (Flag) {
+  default: llvm_unreachable("not implemented");
+  case MCAF_SyntaxUnified:
+  case MCAF_Code16:
+    break;
+  }
+}
+
+void ARMWinCOFFStreamer::EmitThumbFunc(MCSymbol *Symbol) {
+  getAssembler().setIsThumbFunc(Symbol);
+}
+}
+
+namespace llvm {
+MCStreamer *createARMWinCOFFStreamer(MCContext &Context, MCAsmBackend &MAB,
+                                     MCCodeEmitter &Emitter, raw_ostream &OS) {
+  return new ARMWinCOFFStreamer(Context, MAB, Emitter, OS);
+}
+}
+

lib/Target/ARM/MCTargetDesc/CMakeLists.txt

@@ -11,4 +11,6 @@ add_llvm_library(LLVMARMDesc
   ARMMCTargetDesc.cpp
   ARMTargetStreamer.cpp
   ARMUnwindOpAsm.cpp
+  ARMWinCOFFObjectWriter.cpp
+  ARMWinCOFFStreamer.cpp
   )

test/MC/COFF/arm-relocations.s

@@ -0,0 +1,101 @@
+@ RUN: llvm-mc -triple thumbv7-windows-itanium -filetype obj -o - %s \
+@ RUN:   | llvm-readobj -r - | FileCheck %s -check-prefix CHECK-RELOCATION
+
+@ RUN: llvm-mc -triple thumbv7-windows-itanium -filetype obj -o - %s \
+@ RUN:   | llvm-objdump -d - | FileCheck %s -check-prefix CHECK-ENCODING
+
+	.syntax unified
+	.text
+	.thumb
+
+	.global target
+
+	.thumb_func
+branch24t:
+	b target
+
+@ CHECK-ENCODING-LABEL: branch24t
+@ CHECK-ENCODING-NEXT: b.w #0
+
+	.thumb_func
+branch20t:
+	bcc target
+
+@ CHECK-ENCODING-LABEL: branch20t
+@ CHECK-ENCODING-NEXT: blo.w #0
+
+	.thumb_func
+blx23t:
+	bl target
+
+@ CHECK-ENCODING-LABEL: blx23t
+@ CHECK-ENCODING-NEXT: bl #0
+
+	.thumb_func
+mov32t:
+	movw r0, :lower16:target
+	movt r0, :upper16:target
+	blx r0
+
+@ CHECK-ENCODING-LABEL: mov32t
+@ CHECK-ENCODING-NEXT: movw r0, #0
+@ CHECK-ENCODING-NEXT: movt r0, #0
+@ CHECK-ENCODING-NEXT: blx r0
+
+	.thumb_func
+addr32:
+	ldr r0, .Laddr32
+	bx r0
+	trap
+.Laddr32:
+	.long target
+
+@ CHECK-ENCODING-LABEL: addr32
+@ CHECK-ENCODING-NEXT: ldr r0, [pc, #4]
+@ CHECK-ENCODING-NEXT: bx r0
+@ CHECK-ENCODING-NEXT: trap
+@ CHECK-ENCODING-NEXT: movs r0, r0
+@ CHECK-ENCODING-NEXT: movs r0, r0
+
+	.thumb_func
+addr32nb:
+	ldr r0, .Laddr32nb
+	bx r0
+	trap
+.Laddr32nb:
+	.long target(imgrel)
+
+@ CHECK-ENCODING-LABEL: addr32nb
+@ CHECK-ENCODING-NEXT: ldr.w r0, [pc, #4]
+@ CHECK-ENCODING-NEXT: bx r0
+@ CHECK-ENCODING-NEXT: trap
+@ CHECK-ENCODING-NEXT: movs r0, r0
+@ CHECK-ENCODING-NEXT: movs r0, r0
+
+       .thumb_func
+secrel:
+	ldr r0, .Lsecrel
+	bx r0
+	trap
+.Lsecrel:
+	.long target(secrel32)
+
+@ CHECK-ENCODING-LABEL: secrel
+@ CHECK-ENCODING-NEXT: ldr.w r0, [pc, #4]
+@ CHECK-ENCODING-NEXT: bx r0
+@ CHECK-ENCODING-NEXT: trap
+@ CHECK-ENCODING-NEXT: movs r0, r0
+@ CHECK-ENCODING-NEXT: movs r0, r0
+
+@ CHECK-RELOCATION: Relocations [
+@ CHECK-RELOCATION:   Section (1) .text {
+@ CHCEK-RELOCATION:     0x0 IMAGE_REL_ARM_BRANCH24T
+@ CHECK-RELOCATION:     0x4 IMAGE_REL_ARM_BRANCH20T
+@ CHECK-RELOCATION:     0x8 IMAGE_REL_ARM_BLX23T
+@ CHECK-RELOCATION:     0xC IMAGE_REL_ARM_MOV32T
+@ CHECK-RELOCATION:     0x1C IMAGE_REL_ARM_ADDR32
+@ CHECK-RELOCATION:     0x28 IMAGE_REL_ARM_ADDR32NB
+@ CHECK-RELOCATION:     0x34 IMAGE_REL_ARM_SECREL
+@ CHECK-RELOCATION:   }
+@ CHECK-RELOCATION: ]
+