llvm-6502/lib/Target/TargetAsmInfo.cpp
2009-07-27 17:39:40 +00:00

405 lines
14 KiB
C++

//===-- TargetAsmInfo.cpp - Asm Info ---------------------------------------==//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines target asm properties related what form asm statements
// should take.
//
//===----------------------------------------------------------------------===//
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/GlobalVariable.h"
#include "llvm/Function.h"
#include "llvm/Module.h"
#include "llvm/Type.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
#include <cctype>
#include <cstring>
using namespace llvm;
TargetAsmInfo::TargetAsmInfo(const TargetMachine &tm) : TM(tm) {
BSSSection = "\t.bss";
BSSSection_ = 0;
ReadOnlySection = 0;
TLSDataSection = 0;
TLSBSSSection = 0;
ZeroFillDirective = 0;
NonexecutableStackDirective = 0;
NeedsSet = false;
MaxInstLength = 4;
PCSymbol = "$";
SeparatorChar = ';';
CommentColumn = 60;
CommentString = "#";
FirstOperandColumn = 0;
MaxOperandLength = 0;
GlobalPrefix = "";
PrivateGlobalPrefix = ".";
LinkerPrivateGlobalPrefix = "";
JumpTableSpecialLabelPrefix = 0;
GlobalVarAddrPrefix = "";
GlobalVarAddrSuffix = "";
FunctionAddrPrefix = "";
FunctionAddrSuffix = "";
PersonalityPrefix = "";
PersonalitySuffix = "";
NeedsIndirectEncoding = false;
InlineAsmStart = "#APP";
InlineAsmEnd = "#NO_APP";
AssemblerDialect = 0;
AllowQuotesInName = false;
ZeroDirective = "\t.zero\t";
ZeroDirectiveSuffix = 0;
AsciiDirective = "\t.ascii\t";
AscizDirective = "\t.asciz\t";
Data8bitsDirective = "\t.byte\t";
Data16bitsDirective = "\t.short\t";
Data32bitsDirective = "\t.long\t";
Data64bitsDirective = "\t.quad\t";
AlignDirective = "\t.align\t";
AlignmentIsInBytes = true;
TextAlignFillValue = 0;
SwitchToSectionDirective = "\t.section\t";
TextSectionStartSuffix = "";
DataSectionStartSuffix = "";
SectionEndDirectiveSuffix = 0;
ConstantPoolSection = "\t.section .rodata";
JumpTableDataSection = "\t.section .rodata";
JumpTableDirective = 0;
CStringSection = 0;
CStringSection_ = 0;
// FIXME: Flags are ELFish - replace with normal section stuff.
StaticCtorsSection = "\t.section .ctors,\"aw\",@progbits";
StaticDtorsSection = "\t.section .dtors,\"aw\",@progbits";
GlobalDirective = "\t.globl\t";
SetDirective = 0;
LCOMMDirective = 0;
COMMDirective = "\t.comm\t";
COMMDirectiveTakesAlignment = true;
HasDotTypeDotSizeDirective = true;
HasSingleParameterDotFile = true;
UsedDirective = 0;
WeakRefDirective = 0;
WeakDefDirective = 0;
// FIXME: These are ELFish - move to ELFTAI.
HiddenDirective = "\t.hidden\t";
ProtectedDirective = "\t.protected\t";
AbsoluteDebugSectionOffsets = false;
AbsoluteEHSectionOffsets = false;
HasLEB128 = false;
HasDotLocAndDotFile = false;
SupportsDebugInformation = false;
SupportsExceptionHandling = false;
DwarfRequiresFrameSection = true;
DwarfUsesInlineInfoSection = false;
Is_EHSymbolPrivate = true;
GlobalEHDirective = 0;
SupportsWeakOmittedEHFrame = true;
DwarfSectionOffsetDirective = 0;
DwarfAbbrevSection = ".debug_abbrev";
DwarfInfoSection = ".debug_info";
DwarfLineSection = ".debug_line";
DwarfFrameSection = ".debug_frame";
DwarfPubNamesSection = ".debug_pubnames";
DwarfPubTypesSection = ".debug_pubtypes";
DwarfDebugInlineSection = ".debug_inlined";
DwarfStrSection = ".debug_str";
DwarfLocSection = ".debug_loc";
DwarfARangesSection = ".debug_aranges";
DwarfRangesSection = ".debug_ranges";
DwarfMacroInfoSection = ".debug_macinfo";
DwarfEHFrameSection = ".eh_frame";
DwarfExceptionSection = ".gcc_except_table";
AsmTransCBE = 0;
}
TargetAsmInfo::~TargetAsmInfo() {
}
/// Measure the specified inline asm to determine an approximation of its
/// length.
/// Comments (which run till the next SeparatorChar or newline) do not
/// count as an instruction.
/// Any other non-whitespace text is considered an instruction, with
/// multiple instructions separated by SeparatorChar or newlines.
/// Variable-length instructions are not handled here; this function
/// may be overloaded in the target code to do that.
unsigned TargetAsmInfo::getInlineAsmLength(const char *Str) const {
// Count the number of instructions in the asm.
bool atInsnStart = true;
unsigned Length = 0;
for (; *Str; ++Str) {
if (*Str == '\n' || *Str == SeparatorChar)
atInsnStart = true;
if (atInsnStart && !isspace(*Str)) {
Length += MaxInstLength;
atInsnStart = false;
}
if (atInsnStart && strncmp(Str, CommentString, strlen(CommentString))==0)
atInsnStart = false;
}
return Length;
}
unsigned TargetAsmInfo::PreferredEHDataFormat(DwarfEncoding::Target Reason,
bool Global) const {
return dwarf::DW_EH_PE_absptr;
}
static bool isSuitableForBSS(const GlobalVariable *GV) {
Constant *C = GV->getInitializer();
// Must have zero initializer.
if (!C->isNullValue())
return false;
// Leave constant zeros in readonly constant sections, so they can be shared.
if (GV->isConstant())
return false;
// If the global has an explicit section specified, don't put it in BSS.
if (!GV->getSection().empty())
return false;
// If -nozero-initialized-in-bss is specified, don't ever use BSS.
if (NoZerosInBSS)
return false;
// Otherwise, put it in BSS!
return true;
}
static bool isConstantString(const Constant *C) {
// First check: is we have constant array of i8 terminated with zero
const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
// Check, if initializer is a null-terminated string
if (CVA && CVA->isCString())
return true;
// Another possibility: [1 x i8] zeroinitializer
if (isa<ConstantAggregateZero>(C))
if (const ArrayType *Ty = dyn_cast<ArrayType>(C->getType()))
return (Ty->getElementType() == Type::Int8Ty &&
Ty->getNumElements() == 1);
return false;
}
static SectionKind::Kind SectionKindForGlobal(const GlobalValue *GV,
const TargetMachine &TM) {
Reloc::Model ReloModel = TM.getRelocationModel();
// Early exit - functions should be always in text sections.
const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
if (GVar == 0)
return SectionKind::Text;
// Handle thread-local data first.
if (GVar->isThreadLocal()) {
if (isSuitableForBSS(GVar))
return SectionKind::ThreadBSS;
return SectionKind::ThreadData;
}
// Variable can be easily put to BSS section.
if (isSuitableForBSS(GVar))
return SectionKind::BSS;
Constant *C = GVar->getInitializer();
// If the global is marked constant, we can put it into a mergable section,
// a mergable string section, or general .data if it contains relocations.
if (GVar->isConstant()) {
// If the initializer for the global contains something that requires a
// relocation, then we may have to drop this into a wriable data section
// even though it is marked const.
switch (C->getRelocationInfo()) {
default: llvm_unreachable("unknown relocation info kind");
case Constant::NoRelocation:
// If initializer is a null-terminated string, put it in a "cstring"
// section if the target has it.
if (isConstantString(C))
return SectionKind::MergeableCString;
// Otherwise, just drop it into a mergable constant section. If we have
// a section for this size, use it, otherwise use the arbitrary sized
// mergable section.
switch (TM.getTargetData()->getTypeAllocSize(C->getType())) {
case 4: return SectionKind::MergeableConst4;
case 8: return SectionKind::MergeableConst8;
case 16: return SectionKind::MergeableConst16;
default: return SectionKind::MergeableConst;
}
case Constant::LocalRelocation:
// In static relocation model, the linker will resolve all addresses, so
// the relocation entries will actually be constants by the time the app
// starts up. However, we can't put this into a mergable section, because
// the linker doesn't take relocations into consideration when it tries to
// merge entries in the section.
if (ReloModel == Reloc::Static)
return SectionKind::ReadOnly;
// Otherwise, the dynamic linker needs to fix it up, put it in the
// writable data.rel.local section.
return SectionKind::ReadOnlyWithRelLocal;
case Constant::GlobalRelocations:
// In static relocation model, the linker will resolve all addresses, so
// the relocation entries will actually be constants by the time the app
// starts up. However, we can't put this into a mergable section, because
// the linker doesn't take relocations into consideration when it tries to
// merge entries in the section.
if (ReloModel == Reloc::Static)
return SectionKind::ReadOnly;
// Otherwise, the dynamic linker needs to fix it up, put it in the
// writable data.rel section.
return SectionKind::ReadOnlyWithRel;
}
}
// Okay, this isn't a constant. If the initializer for the global is going
// to require a runtime relocation by the dynamic linker, put it into a more
// specific section to improve startup time of the app. This coalesces these
// globals together onto fewer pages, improving the locality of the dynamic
// linker.
if (ReloModel == Reloc::Static)
return SectionKind::DataNoRel;
switch (C->getRelocationInfo()) {
default: llvm_unreachable("unknown relocation info kind");
case Constant::NoRelocation:
return SectionKind::DataNoRel;
case Constant::LocalRelocation:
return SectionKind::DataRelLocal;
case Constant::GlobalRelocations:
return SectionKind::DataRel;
}
}
/// SectionForGlobal - This method computes the appropriate section to emit
/// the specified global variable or function definition. This should not
/// be passed external (or available externally) globals.
const Section *TargetAsmInfo::SectionForGlobal(const GlobalValue *GV) const {
assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
"Can only be used for global definitions");
SectionKind::Kind GVKind = SectionKindForGlobal(GV, TM);
SectionKind Kind = SectionKind::get(GVKind, GV->isWeakForLinker(),
GV->hasSection());
// Select section name.
if (GV->hasSection()) {
// If the target has special section hacks for specifically named globals,
// return them now.
if (const Section *TS = getSpecialCasedSectionGlobals(GV, Kind))
return TS;
// If the target has magic semantics for certain section names, make sure to
// pick up the flags. This allows the user to write things with attribute
// section and still get the appropriate section flags printed.
GVKind = getKindForNamedSection(GV->getSection().c_str(), GVKind);
return getOrCreateSection(GV->getSection().c_str(), false, GVKind);
}
// If this global is linkonce/weak and the target handles this by emitting it
// into a 'uniqued' section name, create and return the section now.
if (Kind.isWeak()) {
if (const char *Prefix = getSectionPrefixForUniqueGlobal(Kind)) {
// FIXME: Use mangler interface (PR4584).
std::string Name = Prefix+GV->getNameStr();
return getOrCreateSection(Name.c_str(), false, GVKind);
}
}
// Use default section depending on the 'type' of global
return SelectSectionForGlobal(GV, Kind);
}
// Lame default implementation. Calculate the section name for global.
const Section*
TargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV,
SectionKind Kind) const {
assert(!Kind.isThreadLocal() && "Doesn't support TLS");
if (Kind.isText())
return getTextSection();
if (Kind.isBSS())
if (const Section *S = getBSSSection_())
return S;
if (Kind.isReadOnly())
if (const Section *S = getReadOnlySection())
return S;
return getDataSection();
}
/// getSectionForMergableConstant - Given a mergable constant with the
/// specified size and relocation information, return a section that it
/// should be placed in.
const Section *
TargetAsmInfo::getSectionForMergeableConstant(SectionKind Kind) const {
if (Kind.isReadOnly())
if (const Section *S = getReadOnlySection())
return S;
return getDataSection();
}
const Section *TargetAsmInfo::getOrCreateSection(const char *Name,
bool isDirective,
SectionKind::Kind Kind) const {
Section &S = Sections[Name];
// This is newly-created section, set it up properly.
if (S.Name.empty()) {
S.Kind = SectionKind::get(Kind, false /*weak*/, !isDirective);
S.Name = Name;
}
return &S;
}
unsigned TargetAsmInfo::getULEB128Size(unsigned Value) {
unsigned Size = 0;
do {
Value >>= 7;
Size += sizeof(int8_t);
} while (Value);
return Size;
}
unsigned TargetAsmInfo::getSLEB128Size(int Value) {
unsigned Size = 0;
int Sign = Value >> (8 * sizeof(Value) - 1);
bool IsMore;
do {
unsigned Byte = Value & 0x7f;
Value >>= 7;
IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
Size += sizeof(int8_t);
} while (IsMore);
return Size;
}