Teach the MC to output code/data region marker labels in MachO and ELF modes. These are used by disassemblers to provide better disassembly, particularly on targets like ARM Thumb that like to intermingle data in the TEXT segment.

llvm-svn: 141135

7 files changed, 136 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 8ac4fb6361c..1999f360878 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -474,8 +474,10 @@ void AsmPrinter::EmitFunctionHeader() {
 void AsmPrinter::EmitFunctionEntryLabel() {
   // The function label could have already been emitted if two symbols end up
   // conflicting due to asm renaming.  Detect this and emit an error.
-  if (CurrentFnSym->isUndefined())
+  if (CurrentFnSym->isUndefined()) {
+    OutStreamer.ForceCodeRegion();
     return OutStreamer.EmitLabel(CurrentFnSym);
+  }
 
   report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
                      "' label emitted multiple times to assembly file");
@@ -1058,6 +1060,15 @@ void AsmPrinter::EmitJumpTableInfo() {
 
   EmitAlignment(Log2_32(MJTI->getEntryAlignment(*TM.getTargetData())));
 
+  // If we know the form of the jump table, go ahead and tag it as such.
+  if (!JTInDiffSection) {
+    if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32) {
+      OutStreamer.EmitJumpTable32Region();
+    } else {
+      OutStreamer.EmitDataRegion();
+    }
+  }
+
   for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
     const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
 
diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp
index 365df87d8db..f34b313ebd0 100644
--- a/llvm/lib/MC/MCAsmInfo.cpp
+++ b/llvm/lib/MC/MCAsmInfo.cpp
@@ -57,6 +57,12 @@ MCAsmInfo::MCAsmInfo() {
   Data16bitsDirective = "\t.short\t";
   Data32bitsDirective = "\t.long\t";
   Data64bitsDirective = "\t.quad\t";
+  DataBegin = "$d.";
+  CodeBegin = "$a.";
+  JT8Begin = "$d.";
+  JT16Begin = "$d.";
+  JT32Begin = "$d.";
+  SupportsDataRegions = true;
   SunStyleELFSectionSwitchSyntax = false;
   UsesELFSectionDirectiveForBSS = false;
   AlignDirective = "\t.align\t";
diff --git a/llvm/lib/MC/MCAsmInfoCOFF.cpp b/llvm/lib/MC/MCAsmInfoCOFF.cpp
index 365ddc49c69..434d9103a71 100644
--- a/llvm/lib/MC/MCAsmInfoCOFF.cpp
+++ b/llvm/lib/MC/MCAsmInfoCOFF.cpp
@@ -35,4 +35,6 @@ MCAsmInfoCOFF::MCAsmInfoCOFF() {
   SupportsDebugInformation = true;
   DwarfSectionOffsetDirective = "\t.secrel32\t";
   HasMicrosoftFastStdCallMangling = true;
+
+  SupportsDataRegions = false;
 }
diff --git a/llvm/lib/MC/MCAsmInfoDarwin.cpp b/llvm/lib/MC/MCAsmInfoDarwin.cpp
index 61fbd29a285..b20e338f790 100644
--- a/llvm/lib/MC/MCAsmInfoDarwin.cpp
+++ b/llvm/lib/MC/MCAsmInfoDarwin.cpp
@@ -42,6 +42,13 @@ MCAsmInfoDarwin::MCAsmInfoDarwin() {
   StructorOutputOrder = Structors::PriorityOrder;
   HasStaticCtorDtorReferenceInStaticMode = true;
 
+  CodeBegin = "L$start$code$";
+  DataBegin = "L$start$data$";
+  JT8Begin  = "L$start$jt8$";
+  JT16Begin = "L$start$jt16$";
+  JT32Begin = "L$start$jt32$";
+  SupportsDataRegions = true;
+
   // FIXME: Darwin 10 and newer don't need this.
   LinkerRequiresNonEmptyDwarfLines = true;
 
diff --git a/llvm/lib/MC/MCStreamer.cpp b/llvm/lib/MC/MCStreamer.cpp
index 0fbf3875f1a..3afa22b0d0b 100644
--- a/llvm/lib/MC/MCStreamer.cpp
+++ b/llvm/lib/MC/MCStreamer.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/Twine.h"
 #include <cstdlib>
 using namespace llvm;
@@ -23,7 +24,9 @@ using namespace llvm;
 MCStreamer::MCStreamer(MCContext &Ctx) : Context(Ctx), EmitEHFrame(true),
                                          EmitDebugFrame(false),
                                          CurrentW64UnwindInfo(0),
-                                         LastSymbol(0) {
+                                         LastSymbol(0),
+                                         UniqueCodeBeginSuffix(0),
+                                         UniqueDataBeginSuffix(0) {
   const MCSection *section = NULL;
   SectionStack.push_back(std::make_pair(section, section));
 }
@@ -175,6 +178,87 @@ void MCStreamer::EmitLabel(MCSymbol *Symbol) {
   LastSymbol = Symbol;
 }
 
+void MCStreamer::EmitDataRegion() {
+  if (RegionIndicator == Data) return;
+
+  MCContext &Context = getContext();
+  const MCAsmInfo &MAI = Context.getAsmInfo();
+  if (!MAI.getSupportsDataRegions()) return;
+
+  // Generate a unique symbol name.
+  MCSymbol *NewSym = Context.GetOrCreateSymbol(
+      Twine(MAI.getDataBeginLabelName()) +
+        utostr(UniqueDataBeginSuffix++));
+  EmitLabel(NewSym);
+
+  RegionIndicator = Data;
+}
+
+void MCStreamer::EmitCodeRegion() {
+  if (RegionIndicator == Code) return;
+
+  MCContext &Context = getContext();
+  const MCAsmInfo &MAI = Context.getAsmInfo();
+  if (!MAI.getSupportsDataRegions()) return;
+
+  // Generate a unique symbol name.
+  MCSymbol *NewSym = Context.GetOrCreateSymbol(
+      Twine(MAI.getCodeBeginLabelName()) +
+        utostr(UniqueCodeBeginSuffix++));
+  EmitLabel(NewSym);
+
+  RegionIndicator = Code;
+}
+
+void MCStreamer::EmitJumpTable8Region() {
+  if (RegionIndicator == JumpTable8) return;
+
+  MCContext &Context = getContext();
+  const MCAsmInfo &MAI = Context.getAsmInfo();
+  if (!MAI.getSupportsDataRegions()) return;
+
+  // Generate a unique symbol name.
+  MCSymbol *NewSym = Context.GetOrCreateSymbol(
+      Twine(MAI.getJumpTable8BeginLabelName()) +
+        utostr(UniqueDataBeginSuffix++));
+  EmitLabel(NewSym);
+
+  RegionIndicator = JumpTable8;
+}
+
+void MCStreamer::EmitJumpTable16Region() {
+  if (RegionIndicator == JumpTable16) return;
+
+  MCContext &Context = getContext();
+  const MCAsmInfo &MAI = Context.getAsmInfo();
+  if (!MAI.getSupportsDataRegions()) return;
+
+  // Generate a unique symbol name.
+  MCSymbol *NewSym = Context.GetOrCreateSymbol(
+      Twine(MAI.getJumpTable16BeginLabelName()) +
+        utostr(UniqueDataBeginSuffix++));
+  EmitLabel(NewSym);
+
+  RegionIndicator = JumpTable16;
+}
+
+
+void MCStreamer::EmitJumpTable32Region() {
+  if (RegionIndicator == JumpTable32) return;
+
+  MCContext &Context = getContext();
+  const MCAsmInfo &MAI = Context.getAsmInfo();
+  if (!MAI.getSupportsDataRegions()) return;
+
+  // Generate a unique symbol name.
+  MCSymbol *NewSym = Context.GetOrCreateSymbol(
+      Twine(MAI.getJumpTable32BeginLabelName()) +
+        utostr(UniqueDataBeginSuffix++));
+  EmitLabel(NewSym);
+
+  RegionIndicator = JumpTable32;
+}
+
 void MCStreamer::EmitCompactUnwindEncoding(uint32_t CompactUnwindEncoding) {
   EnsureValidFrame();
   MCDwarfFrameInfo *CurFrame = getCurrentFrameInfo();
@@ -206,6 +290,7 @@ void MCStreamer::EmitCFIStartProc() {
   }
 
   FrameInfos.push_back(Frame);
+  RegionIndicator = Code;
 }
 
 void MCStreamer::EmitCFIEndProc() {
diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index 81a36d16d77..ea3319fb0e0 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -290,6 +290,8 @@ void ARMAsmPrinter::EmitDwarfRegOp(const MachineLocation &MLoc) const {
 }
 
 void ARMAsmPrinter::EmitFunctionEntryLabel() {
+  OutStreamer.ForceCodeRegion();
+
   if (AFI->isThumbFunction()) {
     OutStreamer.EmitAssemblerFlag(MCAF_Code16);
     OutStreamer.EmitThumbFunc(CurrentFnSym);
@@ -905,6 +907,9 @@ void ARMAsmPrinter::EmitJumpTable(const MachineInstr *MI) {
   const MachineOperand &MO2 = MI->getOperand(OpNum+1); // Unique Id
   unsigned JTI = MO1.getIndex();
 
+  // Tag the jump table appropriately for precise disassembly.
+  OutStreamer.EmitJumpTable32Region();
+
   // Emit a label for the jump table.
   MCSymbol *JTISymbol = GetARMJTIPICJumpTableLabel2(JTI, MO2.getImm());
   OutStreamer.EmitLabel(JTISymbol);
@@ -947,6 +952,14 @@ void ARMAsmPrinter::EmitJump2Table(const MachineInstr *MI) {
   unsigned JTI = MO1.getIndex();
 
   // Emit a label for the jump table.
+  if (MI->getOpcode() == ARM::t2TBB_JT) {
+    OutStreamer.EmitJumpTable8Region();
+  } else if (MI->getOpcode() == ARM::t2TBH_JT) {
+    OutStreamer.EmitJumpTable16Region();
+  } else {
+    OutStreamer.EmitJumpTable32Region();
+  }
+
   MCSymbol *JTISymbol = GetARMJTIPICJumpTableLabel2(JTI, MO2.getImm());
   OutStreamer.EmitLabel(JTISymbol);
 
@@ -1165,6 +1178,9 @@ extern cl::opt<bool> EnableARMEHABI;
 #include "ARMGenMCPseudoLowering.inc"
 
 void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
+  if (MI->getOpcode() != ARM::CONSTPOOL_ENTRY)
+    OutStreamer.EmitCodeRegion();
+
   // Emit unwinding stuff for frame-related instructions
   if (EnableARMEHABI && MI->getFlag(MachineInstr::FrameSetup))
     EmitUnwindingInstruction(MI);
@@ -1470,6 +1486,10 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
     unsigned CPIdx   = (unsigned)MI->getOperand(1).getIndex();
 
     EmitAlignment(2);
+
+    // Mark the constant pool entry as data if we're not already in a data
+    // region.
+    OutStreamer.EmitDataRegion();
     OutStreamer.EmitLabel(GetCPISymbol(LabelId));
 
     const MachineConstantPoolEntry &MCPE = MCP->getConstants()[CPIdx];
@@ -1477,7 +1497,6 @@ void ARMAsmPrinter::EmitInstruction(const MachineInstr *MI) {
       EmitMachineConstantPoolValue(MCPE.Val.MachineCPVal);
     else
       EmitGlobalConstant(MCPE.Val.ConstVal);
-
     return;
   }
   case ARM::t2BR_JT: {
diff --git a/llvm/lib/Target/X86/X86MCInstLower.cpp b/llvm/lib/Target/X86/X86MCInstLower.cpp
index 1d603cf6e1b..50bc14d357f 100644
--- a/llvm/lib/Target/X86/X86MCInstLower.cpp
+++ b/llvm/lib/Target/X86/X86MCInstLower.cpp
@@ -592,6 +592,8 @@ static void LowerTlsAddr(MCStreamer &OutStreamer,
 }
 
 void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
+  OutStreamer.EmitCodeRegion();
+
   X86MCInstLower MCInstLowering(Mang, *MF, *this);
   switch (MI->getOpcode()) {
   case TargetOpcode::DBG_VALUE:
@@ -608,7 +610,7 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
     if (OutStreamer.hasRawTextSupport())
       OutStreamer.EmitRawText(StringRef("\t#MEMBARRIER"));
     return;
-        
+
 
   case X86::EH_RETURN:
   case X86::EH_RETURN64: {