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
diff --git a/llvm/include/llvm/MC/MCAsmInfo.h b/llvm/include/llvm/MC/MCAsmInfo.h
index e2cef7a..c3c296e 100644
--- a/llvm/include/llvm/MC/MCAsmInfo.h
+++ b/llvm/include/llvm/MC/MCAsmInfo.h
@@ -177,6 +177,18 @@
const char *Data32bitsDirective; // Defaults to "\t.long\t"
const char *Data64bitsDirective; // Defaults to "\t.quad\t"
+ /// [Data|Code]Begin - These magic labels are used to marked a region as
+ /// data or code, and are used to provide additional information for
+ /// correct disassembly on targets that like to mix data and code within
+ /// a segment. These labels will be implicitly suffixed by the streamer
+ /// to give them unique names.
+ const char *DataBegin; // Defaults to "$d."
+ const char *CodeBegin; // Defaults to "$a."
+ const char *JT8Begin; // Defaults to "$a."
+ const char *JT16Begin; // Defaults to "$a."
+ const char *JT32Begin; // Defaults to "$a."
+ bool SupportsDataRegions;
+
/// GPRel32Directive - if non-null, a directive that is used to emit a word
/// which should be relocated as a 32-bit GP-relative offset, e.g. .gpword
/// on Mips or .gprel32 on Alpha.
@@ -371,6 +383,14 @@
}
const char *getGPRel32Directive() const { return GPRel32Directive; }
+ /// [Code|Data]Begin label name accessors.
+ const char *getCodeBeginLabelName() const { return CodeBegin; }
+ const char *getDataBeginLabelName() const { return DataBegin; }
+ const char *getJumpTable8BeginLabelName() const { return JT8Begin; }
+ const char *getJumpTable16BeginLabelName() const { return JT16Begin; }
+ const char *getJumpTable32BeginLabelName() const { return JT32Begin; }
+ bool getSupportsDataRegions() const { return SupportsDataRegions; }
+
/// getNonexecutableStackSection - Targets can implement this method to
/// specify a section to switch to if the translation unit doesn't have any
/// trampolines that require an executable stack.
diff --git a/llvm/include/llvm/MC/MCStreamer.h b/llvm/include/llvm/MC/MCStreamer.h
index 4279ef5..451efbf 100644
--- a/llvm/include/llvm/MC/MCStreamer.h
+++ b/llvm/include/llvm/MC/MCStreamer.h
@@ -71,7 +71,22 @@
SmallVector<std::pair<const MCSection *,
const MCSection *>, 4> SectionStack;
+ unsigned UniqueCodeBeginSuffix;
+ unsigned UniqueDataBeginSuffix;
+
protected:
+ /// Indicator of whether the previous data-or-code indicator was for
+ /// code or not. Used to determine when we need to emit a new indicator.
+ enum DataType {
+ Data,
+ Code,
+ JumpTable8,
+ JumpTable16,
+ JumpTable32
+ };
+ DataType RegionIndicator;
+
+
MCStreamer(MCContext &Ctx);
const MCExpr *BuildSymbolDiff(MCContext &Context, const MCSymbol *A,
@@ -224,6 +239,41 @@
/// used in an assignment.
virtual void EmitLabel(MCSymbol *Symbol);
+ /// EmitDataRegion - Emit a label that marks the beginning of a data
+ /// region.
+ /// On ELF targets, this corresponds to an assembler statement such as:
+ /// $d.1:
+ virtual void EmitDataRegion();
+
+ /// EmitJumpTable8Region - Emit a label that marks the beginning of a
+ /// jump table composed of 8-bit offsets.
+ /// On ELF targets, this corresponds to an assembler statement such as:
+ /// $d.1:
+ virtual void EmitJumpTable8Region();
+
+ /// EmitJumpTable16Region - Emit a label that marks the beginning of a
+ /// jump table composed of 16-bit offsets.
+ /// On ELF targets, this corresponds to an assembler statement such as:
+ /// $d.1:
+ virtual void EmitJumpTable16Region();
+
+ /// EmitJumpTable32Region - Emit a label that marks the beginning of a
+ /// jump table composed of 32-bit offsets.
+ /// On ELF targets, this corresponds to an assembler statement such as:
+ /// $d.1:
+ virtual void EmitJumpTable32Region();
+
+ /// EmitCodeRegion - Emit a label that marks the beginning of a code
+ /// region.
+ /// On ELF targets, this corresponds to an assembler statement such as:
+ /// $a.1:
+ virtual void EmitCodeRegion();
+
+ /// ForceCodeRegion - Forcibly sets the current region mode to code. Used
+ /// at function entry points.
+ void ForceCodeRegion() { RegionIndicator = Code; }
+
+
virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
MCSymbol *EHSymbol);
diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 8ac4fb6..1999f36 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -474,8 +474,10 @@
void AsmPrinter::EmitFunctionEntryLabel() {
// The function label could have already been emitted if two symbols end up
// conflicting due to asm renaming. Detect this and emit an error.
- if (CurrentFnSym->isUndefined())
+ if (CurrentFnSym->isUndefined()) {
+ OutStreamer.ForceCodeRegion();
return OutStreamer.EmitLabel(CurrentFnSym);
+ }
report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
"' label emitted multiple times to assembly file");
@@ -1058,6 +1060,15 @@
EmitAlignment(Log2_32(MJTI->getEntryAlignment(*TM.getTargetData())));
+ // If we know the form of the jump table, go ahead and tag it as such.
+ if (!JTInDiffSection) {
+ if (MJTI->getEntryKind() == MachineJumpTableInfo::EK_LabelDifference32) {
+ OutStreamer.EmitJumpTable32Region();
+ } else {
+ OutStreamer.EmitDataRegion();
+ }
+ }
+
for (unsigned JTI = 0, e = JT.size(); JTI != e; ++JTI) {
const std::vector<MachineBasicBlock*> &JTBBs = JT[JTI].MBBs;
diff --git a/llvm/lib/MC/MCAsmInfo.cpp b/llvm/lib/MC/MCAsmInfo.cpp
index 365df87..f34b313 100644
--- a/llvm/lib/MC/MCAsmInfo.cpp
+++ b/llvm/lib/MC/MCAsmInfo.cpp
@@ -57,6 +57,12 @@
Data16bitsDirective = "\t.short\t";
Data32bitsDirective = "\t.long\t";
Data64bitsDirective = "\t.quad\t";
+ DataBegin = "$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 365ddc4..434d910 100644
--- a/llvm/lib/MC/MCAsmInfoCOFF.cpp
+++ b/llvm/lib/MC/MCAsmInfoCOFF.cpp
@@ -35,4 +35,6 @@
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 61fbd29..b20e338 100644
--- a/llvm/lib/MC/MCAsmInfoDarwin.cpp
+++ b/llvm/lib/MC/MCAsmInfoDarwin.cpp
@@ -42,6 +42,13 @@
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 0fbf387..3afa22b 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 @@
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 @@
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 @@
}
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 81a36d1..ea3319f 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -290,6 +290,8 @@
}
void ARMAsmPrinter::EmitFunctionEntryLabel() {
+ OutStreamer.ForceCodeRegion();
+
if (AFI->isThumbFunction()) {
OutStreamer.EmitAssemblerFlag(MCAF_Code16);
OutStreamer.EmitThumbFunc(CurrentFnSym);
@@ -905,6 +907,9 @@
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 @@
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 @@
#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 @@
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 @@
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 1d603cf..50bc14d 100644
--- a/llvm/lib/Target/X86/X86MCInstLower.cpp
+++ b/llvm/lib/Target/X86/X86MCInstLower.cpp
@@ -592,6 +592,8 @@
}
void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
+ OutStreamer.EmitCodeRegion();
+
X86MCInstLower MCInstLowering(Mang, *MF, *this);
switch (MI->getOpcode()) {
case TargetOpcode::DBG_VALUE:
@@ -608,7 +610,7 @@
if (OutStreamer.hasRawTextSupport())
OutStreamer.EmitRawText(StringRef("\t#MEMBARRIER"));
return;
-
+
case X86::EH_RETURN:
case X86::EH_RETURN64: {
diff --git a/llvm/test/MC/ARM/elf-reloc-01.ll b/llvm/test/MC/ARM/elf-reloc-01.ll
index e6efe7e..148c361 100644
--- a/llvm/test/MC/ARM/elf-reloc-01.ll
+++ b/llvm/test/MC/ARM/elf-reloc-01.ll
@@ -62,9 +62,9 @@
;; OBJ: Relocation 1
;; OBJ-NEXT: 'r_offset',
-;; OBJ-NEXT: 'r_sym', 0x000002
+;; OBJ-NEXT: 'r_sym', 0x000003
;; OBJ-NEXT: 'r_type', 0x2b
-;; OBJ: Symbol 2
+;; OBJ: Symbol 3
;; OBJ-NEXT: '_MergedGlobals'
;; OBJ-NEXT: 'st_value', 0x00000010