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-rw-r--r--lib/MC/MCAssembler.cpp386
1 files changed, 298 insertions, 88 deletions
diff --git a/lib/MC/MCAssembler.cpp b/lib/MC/MCAssembler.cpp
index bdc886b..96227db 100644
--- a/lib/MC/MCAssembler.cpp
+++ b/lib/MC/MCAssembler.cpp
@@ -16,11 +16,17 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MachO.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Debug.h"
+
+// FIXME: Gross.
+#include "../Target/X86/X86FixupKinds.h"
+
#include <vector>
using namespace llvm;
@@ -36,6 +42,8 @@ STATISTIC(EmittedFragments, "Number of emitted assembler fragments");
static void WriteFileData(raw_ostream &OS, const MCSectionData &SD,
MachObjectWriter &MOW);
+static uint64_t WriteNopData(uint64_t Count, MachObjectWriter &MOW);
+
/// isVirtualSection - Check if this is a section which does not actually exist
/// in the object file.
static bool isVirtualSection(const MCSection &Section) {
@@ -45,6 +53,30 @@ static bool isVirtualSection(const MCSection &Section) {
return (Type == MCSectionMachO::S_ZEROFILL);
}
+static unsigned getFixupKindLog2Size(unsigned Kind) {
+ switch (Kind) {
+ default: llvm_unreachable("invalid fixup kind!");
+ case X86::reloc_pcrel_1byte:
+ case FK_Data_1: return 0;
+ case FK_Data_2: return 1;
+ case X86::reloc_pcrel_4byte:
+ case X86::reloc_riprel_4byte:
+ case FK_Data_4: return 2;
+ case FK_Data_8: return 3;
+ }
+}
+
+static bool isFixupKindPCRel(unsigned Kind) {
+ switch (Kind) {
+ default:
+ return false;
+ case X86::reloc_pcrel_1byte:
+ case X86::reloc_pcrel_4byte:
+ case X86::reloc_riprel_4byte:
+ return true;
+ }
+}
+
class MachObjectWriter {
// See <mach-o/loader.h>.
enum {
@@ -402,13 +434,14 @@ public:
uint32_t Word0;
uint32_t Word1;
};
- void ComputeScatteredRelocationInfo(MCAssembler &Asm,
- MCSectionData::Fixup &Fixup,
+ void ComputeScatteredRelocationInfo(MCAssembler &Asm, MCFragment &Fragment,
+ MCAsmFixup &Fixup,
const MCValue &Target,
DenseMap<const MCSymbol*,MCSymbolData*> &SymbolMap,
std::vector<MachRelocationEntry> &Relocs) {
- uint32_t Address = Fixup.Fragment->getOffset() + Fixup.Offset;
+ uint32_t Address = Fragment.getOffset() + Fixup.Offset;
unsigned IsPCRel = 0;
+ unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind);
unsigned Type = RIT_Vanilla;
// See <reloc.h>.
@@ -424,11 +457,12 @@ public:
Value2 = SD->getFragment()->getAddress() + SD->getOffset();
}
- unsigned Log2Size = Log2_32(Fixup.Size);
- assert((1U << Log2Size) == Fixup.Size && "Invalid fixup size!");
-
// The value which goes in the fixup is current value of the expression.
Fixup.FixedValue = Value - Value2 + Target.getConstant();
+ if (isFixupKindPCRel(Fixup.Kind)) {
+ Fixup.FixedValue -= Address;
+ IsPCRel = 1;
+ }
MachRelocationEntry MRE;
MRE.Word0 = ((Address << 0) |
@@ -453,8 +487,8 @@ public:
}
}
- void ComputeRelocationInfo(MCAssembler &Asm,
- MCSectionData::Fixup &Fixup,
+ void ComputeRelocationInfo(MCAssembler &Asm, MCDataFragment &Fragment,
+ MCAsmFixup &Fixup,
DenseMap<const MCSymbol*,MCSymbolData*> &SymbolMap,
std::vector<MachRelocationEntry> &Relocs) {
MCValue Target;
@@ -466,19 +500,22 @@ public:
if (Target.getSymB() ||
(Target.getSymA() && !Target.getSymA()->isUndefined() &&
Target.getConstant()))
- return ComputeScatteredRelocationInfo(Asm, Fixup, Target,
+ return ComputeScatteredRelocationInfo(Asm, Fragment, Fixup, Target,
SymbolMap, Relocs);
// See <reloc.h>.
- uint32_t Address = Fixup.Fragment->getOffset() + Fixup.Offset;
+ uint32_t Address = Fragment.getOffset() + Fixup.Offset;
uint32_t Value = 0;
unsigned Index = 0;
unsigned IsPCRel = 0;
+ unsigned Log2Size = getFixupKindLog2Size(Fixup.Kind);
unsigned IsExtern = 0;
unsigned Type = 0;
if (Target.isAbsolute()) { // constant
// SymbolNum of 0 indicates the absolute section.
+ //
+ // FIXME: When is this generated?
Type = RIT_Vanilla;
Value = 0;
llvm_unreachable("FIXME: Not yet implemented!");
@@ -495,10 +532,11 @@ public:
//
// FIXME: O(N)
Index = 1;
- for (MCAssembler::iterator it = Asm.begin(),
- ie = Asm.end(); it != ie; ++it, ++Index)
+ MCAssembler::iterator it = Asm.begin(), ie = Asm.end();
+ for (; it != ie; ++it, ++Index)
if (&*it == SD->getFragment()->getParent())
break;
+ assert(it != ie && "Unable to find section index!");
Value = SD->getFragment()->getAddress() + SD->getOffset();
}
@@ -508,8 +546,10 @@ public:
// The value which goes in the fixup is current value of the expression.
Fixup.FixedValue = Value + Target.getConstant();
- unsigned Log2Size = Log2_32(Fixup.Size);
- assert((1U << Log2Size) == Fixup.Size && "Invalid fixup size!");
+ if (isFixupKindPCRel(Fixup.Kind)) {
+ Fixup.FixedValue -= Address;
+ IsPCRel = 1;
+ }
// struct relocation_info (8 bytes)
MachRelocationEntry MRE;
@@ -766,17 +806,20 @@ public:
// is written.
std::vector<MachRelocationEntry> RelocInfos;
uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
- for (MCAssembler::iterator it = Asm.begin(), ie = Asm.end(); it != ie;
- ++it) {
+ for (MCAssembler::iterator it = Asm.begin(),
+ ie = Asm.end(); it != ie; ++it) {
MCSectionData &SD = *it;
// The assembler writes relocations in the reverse order they were seen.
//
// FIXME: It is probably more complicated than this.
unsigned NumRelocsStart = RelocInfos.size();
- for (unsigned i = 0, e = SD.fixup_size(); i != e; ++i)
- ComputeRelocationInfo(Asm, SD.getFixups()[e - i - 1], SymbolMap,
- RelocInfos);
+ for (MCSectionData::reverse_iterator it2 = SD.rbegin(),
+ ie2 = SD.rend(); it2 != ie2; ++it2)
+ if (MCDataFragment *DF = dyn_cast<MCDataFragment>(&*it2))
+ for (unsigned i = 0, e = DF->fixup_size(); i != e; ++i)
+ ComputeRelocationInfo(Asm, *DF, DF->getFixups()[e - i - 1],
+ SymbolMap, RelocInfos);
unsigned NumRelocs = RelocInfos.size() - NumRelocsStart;
uint64_t SectionStart = SectionDataStart + SD.getAddress();
@@ -871,6 +914,16 @@ public:
OS << StringTable.str();
}
}
+
+ void ApplyFixup(const MCAsmFixup &Fixup, MCDataFragment &DF) {
+ unsigned Size = 1 << getFixupKindLog2Size(Fixup.Kind);
+
+ // FIXME: Endianness assumption.
+ assert(Fixup.Offset + Size <= DF.getContents().size() &&
+ "Invalid fixup offset!");
+ for (unsigned i = 0; i != Size; ++i)
+ DF.getContents()[Fixup.Offset + i] = uint8_t(Fixup.FixedValue >> (i * 8));
+ }
};
/* *** */
@@ -905,35 +958,12 @@ MCSectionData::MCSectionData(const MCSection &_Section, MCAssembler *A)
Address(~UINT64_C(0)),
Size(~UINT64_C(0)),
FileSize(~UINT64_C(0)),
- LastFixupLookup(~0),
HasInstructions(false)
{
if (A)
A->getSectionList().push_back(this);
}
-const MCSectionData::Fixup *
-MCSectionData::LookupFixup(const MCFragment *Fragment, uint64_t Offset) const {
- // Use a one level cache to turn the common case of accessing the fixups in
- // order into O(1) instead of O(N).
- unsigned i = LastFixupLookup, Count = Fixups.size(), End = Fixups.size();
- if (i >= End)
- i = 0;
- while (Count--) {
- const Fixup &F = Fixups[i];
- if (F.Fragment == Fragment && F.Offset == Offset) {
- LastFixupLookup = i;
- return &F;
- }
-
- ++i;
- if (i == End)
- i = 0;
- }
-
- return 0;
-}
-
/* *** */
MCSymbolData::MCSymbolData() : Symbol(0) {}
@@ -980,31 +1010,10 @@ void MCAssembler::LayoutSection(MCSectionData &SD) {
}
case MCFragment::FT_Data:
+ case MCFragment::FT_Fill:
F.setFileSize(F.getMaxFileSize());
break;
- case MCFragment::FT_Fill: {
- MCFillFragment &FF = cast<MCFillFragment>(F);
-
- F.setFileSize(F.getMaxFileSize());
-
- MCValue Target;
- if (!FF.getValue().EvaluateAsRelocatable(Target))
- llvm_report_error("expected relocatable expression");
-
- // If the fill value is constant, thats it.
- if (Target.isAbsolute())
- break;
-
- // Otherwise, add fixups for the values.
- for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
- MCSectionData::Fixup Fix(F, i * FF.getValueSize(),
- FF.getValue(),FF.getValueSize());
- SD.getFixups().push_back(Fix);
- }
- break;
- }
-
case MCFragment::FT_Org: {
MCOrgFragment &OF = cast<MCOrgFragment>(F);
@@ -1051,6 +1060,64 @@ void MCAssembler::LayoutSection(MCSectionData &SD) {
SD.setFileSize(Address - SD.getAddress());
}
+/// WriteNopData - Write optimal nops to the output file for the \arg Count
+/// bytes. This returns the number of bytes written. It may return 0 if
+/// the \arg Count is more than the maximum optimal nops.
+///
+/// FIXME this is X86 32-bit specific and should move to a better place.
+static uint64_t WriteNopData(uint64_t Count, MachObjectWriter &MOW) {
+ static const uint8_t Nops[16][16] = {
+ // nop
+ {0x90},
+ // xchg %ax,%ax
+ {0x66, 0x90},
+ // nopl (%[re]ax)
+ {0x0f, 0x1f, 0x00},
+ // nopl 0(%[re]ax)
+ {0x0f, 0x1f, 0x40, 0x00},
+ // nopl 0(%[re]ax,%[re]ax,1)
+ {0x0f, 0x1f, 0x44, 0x00, 0x00},
+ // nopw 0(%[re]ax,%[re]ax,1)
+ {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
+ // nopl 0L(%[re]ax)
+ {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
+ // nopl 0L(%[re]ax,%[re]ax,1)
+ {0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
+ // nopw 0L(%[re]ax,%[re]ax,1)
+ {0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
+ // nopw %cs:0L(%[re]ax,%[re]ax,1)
+ {0x66, 0x2e, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},
+ // nopl 0(%[re]ax,%[re]ax,1)
+ // nopw 0(%[re]ax,%[re]ax,1)
+ {0x0f, 0x1f, 0x44, 0x00, 0x00,
+ 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
+ // nopw 0(%[re]ax,%[re]ax,1)
+ // nopw 0(%[re]ax,%[re]ax,1)
+ {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00,
+ 0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},
+ // nopw 0(%[re]ax,%[re]ax,1)
+ // nopl 0L(%[re]ax) */
+ {0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00,
+ 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
+ // nopl 0L(%[re]ax)
+ // nopl 0L(%[re]ax)
+ {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00,
+ 0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},
+ // nopl 0L(%[re]ax)
+ // nopl 0L(%[re]ax,%[re]ax,1)
+ {0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00,
+ 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}
+ };
+
+ if (Count > 15)
+ return 0;
+
+ for (uint64_t i = 0; i < Count; i++)
+ MOW.Write8 (uint8_t(Nops[Count - 1][i]));
+
+ return Count;
+}
+
/// WriteFileData - Write the \arg F data to the output file.
static void WriteFileData(raw_ostream &OS, const MCFragment &F,
MachObjectWriter &MOW) {
@@ -1074,6 +1141,14 @@ static void WriteFileData(raw_ostream &OS, const MCFragment &F,
"' is not a divisor of padding size '" +
Twine(AF.getFileSize()) + "'");
+ // See if we are aligning with nops, and if so do that first to try to fill
+ // the Count bytes. Then if that did not fill any bytes or there are any
+ // bytes left to fill use the the Value and ValueSize to fill the rest.
+ if (AF.getEmitNops()) {
+ uint64_t NopByteCount = WriteNopData(Count, MOW);
+ Count -= NopByteCount;
+ }
+
for (uint64_t i = 0; i != Count; ++i) {
switch (AF.getValueSize()) {
default:
@@ -1087,39 +1162,30 @@ static void WriteFileData(raw_ostream &OS, const MCFragment &F,
break;
}
- case MCFragment::FT_Data:
+ case MCFragment::FT_Data: {
+ MCDataFragment &DF = cast<MCDataFragment>(F);
+
+ // Apply the fixups.
+ //
+ // FIXME: Move elsewhere.
+ for (MCDataFragment::const_fixup_iterator it = DF.fixup_begin(),
+ ie = DF.fixup_end(); it != ie; ++it)
+ MOW.ApplyFixup(*it, DF);
+
OS << cast<MCDataFragment>(F).getContents().str();
break;
+ }
case MCFragment::FT_Fill: {
MCFillFragment &FF = cast<MCFillFragment>(F);
-
- int64_t Value = 0;
-
- MCValue Target;
- if (!FF.getValue().EvaluateAsRelocatable(Target))
- llvm_report_error("expected relocatable expression");
-
- if (Target.isAbsolute())
- Value = Target.getConstant();
for (uint64_t i = 0, e = FF.getCount(); i != e; ++i) {
- if (!Target.isAbsolute()) {
- // Find the fixup.
- //
- // FIXME: Find a better way to write in the fixes.
- const MCSectionData::Fixup *Fixup =
- F.getParent()->LookupFixup(&F, i * FF.getValueSize());
- assert(Fixup && "Missing fixup for fill value!");
- Value = Fixup->FixedValue;
- }
-
switch (FF.getValueSize()) {
default:
assert(0 && "Invalid size!");
- case 1: MOW.Write8 (uint8_t (Value)); break;
- case 2: MOW.Write16(uint16_t(Value)); break;
- case 4: MOW.Write32(uint32_t(Value)); break;
- case 8: MOW.Write64(uint64_t(Value)); break;
+ case 1: MOW.Write8 (uint8_t (FF.getValue())); break;
+ case 2: MOW.Write16(uint16_t(FF.getValue())); break;
+ case 4: MOW.Write32(uint32_t(FF.getValue())); break;
+ case 8: MOW.Write64(uint64_t(FF.getValue())); break;
}
}
break;
@@ -1167,6 +1233,10 @@ static void WriteFileData(raw_ostream &OS, const MCSectionData &SD,
}
void MCAssembler::Finish() {
+ DEBUG_WITH_TYPE("mc-dump", {
+ llvm::errs() << "assembler backend - pre-layout\n--\n";
+ dump(); });
+
// Layout the concrete sections and fragments.
uint64_t Address = 0;
MCSectionData *Prev = 0;
@@ -1205,9 +1275,149 @@ void MCAssembler::Finish() {
Address += SD.getSize();
}
+ DEBUG_WITH_TYPE("mc-dump", {
+ llvm::errs() << "assembler backend - post-layout\n--\n";
+ dump(); });
+
// Write the object file.
MachObjectWriter MOW(OS);
MOW.WriteObject(*this);
OS.flush();
}
+
+
+// Debugging methods
+
+namespace llvm {
+
+raw_ostream &operator<<(raw_ostream &OS, const MCAsmFixup &AF) {
+ OS << "<MCAsmFixup" << " Offset:" << AF.Offset << " Value:" << *AF.Value
+ << " Kind:" << AF.Kind << ">";
+ return OS;
+}
+
+}
+
+void MCFragment::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCFragment " << (void*) this << " Offset:" << Offset
+ << " FileSize:" << FileSize;
+
+ OS << ">";
+}
+
+void MCAlignFragment::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCAlignFragment ";
+ this->MCFragment::dump();
+ OS << "\n ";
+ OS << " Alignment:" << getAlignment()
+ << " Value:" << getValue() << " ValueSize:" << getValueSize()
+ << " MaxBytesToEmit:" << getMaxBytesToEmit() << ">";
+}
+
+void MCDataFragment::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCDataFragment ";
+ this->MCFragment::dump();
+ OS << "\n ";
+ OS << " Contents:[";
+ for (unsigned i = 0, e = getContents().size(); i != e; ++i) {
+ if (i) OS << ",";
+ OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
+ }
+ OS << "] (" << getContents().size() << " bytes)";
+
+ if (!getFixups().empty()) {
+ OS << ",\n ";
+ OS << " Fixups:[";
+ for (fixup_iterator it = fixup_begin(), ie = fixup_end(); it != ie; ++it) {
+ if (it != fixup_begin()) OS << ",\n ";
+ OS << *it;
+ }
+ OS << "]";
+ }
+
+ OS << ">";
+}
+
+void MCFillFragment::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCFillFragment ";
+ this->MCFragment::dump();
+ OS << "\n ";
+ OS << " Value:" << getValue() << " ValueSize:" << getValueSize()
+ << " Count:" << getCount() << ">";
+}
+
+void MCOrgFragment::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCOrgFragment ";
+ this->MCFragment::dump();
+ OS << "\n ";
+ OS << " Offset:" << getOffset() << " Value:" << getValue() << ">";
+}
+
+void MCZeroFillFragment::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCZeroFillFragment ";
+ this->MCFragment::dump();
+ OS << "\n ";
+ OS << " Size:" << getSize() << " Alignment:" << getAlignment() << ">";
+}
+
+void MCSectionData::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCSectionData";
+ OS << " Alignment:" << getAlignment() << " Address:" << Address
+ << " Size:" << Size << " FileSize:" << FileSize
+ << " Fragments:[";
+ for (iterator it = begin(), ie = end(); it != ie; ++it) {
+ if (it != begin()) OS << ",\n ";
+ it->dump();
+ }
+ OS << "]>";
+}
+
+void MCSymbolData::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCSymbolData Symbol:" << getSymbol()
+ << " Fragment:" << getFragment() << " Offset:" << getOffset()
+ << " Flags:" << getFlags() << " Index:" << getIndex();
+ if (isCommon())
+ OS << " (common, size:" << getCommonSize()
+ << " align: " << getCommonAlignment() << ")";
+ if (isExternal())
+ OS << " (external)";
+ if (isPrivateExtern())
+ OS << " (private extern)";
+ OS << ">";
+}
+
+void MCAssembler::dump() {
+ raw_ostream &OS = llvm::errs();
+
+ OS << "<MCAssembler\n";
+ OS << " Sections:[";
+ for (iterator it = begin(), ie = end(); it != ie; ++it) {
+ if (it != begin()) OS << ",\n ";
+ it->dump();
+ }
+ OS << "],\n";
+ OS << " Symbols:[";
+
+ for (symbol_iterator it = symbol_begin(), ie = symbol_end(); it != ie; ++it) {
+ if (it != symbol_begin()) OS << ",\n ";
+ it->dump();
+ }
+ OS << "]>\n";
+}
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