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llvm-project/llvm/lib/Target/TargetAsmInfo.cpp

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//===-- 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/GlobalVariable.h"
#include "llvm/Function.h"
#include "llvm/Module.h"
#include "llvm/Type.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/Dwarf.h"
#include <cctype>
#include <cstring>
using namespace llvm;
void TargetAsmInfo::fillDefaultValues() {
BSSSection = "\t.bss";
BSSSection_ = 0;
ReadOnlySection = 0;
SmallDataSection = 0;
SmallBSSSection = 0;
SmallRODataSection = 0;
TLSDataSection = 0;
TLSBSSSection = 0;
ZeroFillDirective = 0;
NonexecutableStackDirective = 0;
NeedsSet = false;
MaxInstLength = 4;
PCSymbol = "$";
SeparatorChar = ';';
CommentString = "#";
GlobalPrefix = "";
PrivateGlobalPrefix = ".";
LessPrivateGlobalPrefix = "";
JumpTableSpecialLabelPrefix = 0;
GlobalVarAddrPrefix = "";
GlobalVarAddrSuffix = "";
FunctionAddrPrefix = "";
FunctionAddrSuffix = "";
PersonalityPrefix = "";
PersonalitySuffix = "";
NeedsIndirectEncoding = false;
InlineAsmStart = "#APP";
InlineAsmEnd = "#NO_APP";
AssemblerDialect = 0;
StringConstantPrefix = ".str";
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;
GlobalEHDirective = 0;
SupportsWeakOmittedEHFrame = true;
DwarfSectionOffsetDirective = 0;
DwarfAbbrevSection = ".debug_abbrev";
DwarfInfoSection = ".debug_info";
DwarfLineSection = ".debug_line";
DwarfFrameSection = ".debug_frame";
DwarfPubNamesSection = ".debug_pubnames";
DwarfPubTypesSection = ".debug_pubtypes";
DwarfStrSection = ".debug_str";
DwarfLocSection = ".debug_loc";
DwarfARangesSection = ".debug_aranges";
DwarfRangesSection = ".debug_ranges";
DwarfMacInfoSection = ".debug_macinfo";
DwarfEHFrameSection = ".eh_frame";
DwarfExceptionSection = ".gcc_except_table";
AsmTransCBE = 0;
TextSection = getUnnamedSection("\t.text", SectionFlags::Code);
DataSection = getUnnamedSection("\t.data", SectionFlags::Writeable);
}
TargetAsmInfo::TargetAsmInfo(const TargetMachine &tm)
: TM(tm) {
fillDefaultValues();
}
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) {
if (!GV->hasInitializer())
return true;
// Leave constant zeros in readonly constant sections, so they can be shared
Constant *C = GV->getInitializer();
return (C->isNullValue() && !GV->isConstant() && !NoZerosInBSS);
}
SectionKind::Kind
TargetAsmInfo::SectionKindForGlobal(const GlobalValue *GV) const {
// Early exit - functions should be always in text sections.
if (isa<Function>(GV))
return SectionKind::Text;
const GlobalVariable* GVar = dyn_cast<GlobalVariable>(GV);
bool isThreadLocal = GVar->isThreadLocal();
assert(GVar && "Invalid global value for section selection");
if (isSuitableForBSS(GVar)) {
// Variable can be easily put to BSS section.
return (isThreadLocal ? SectionKind::ThreadBSS : SectionKind::BSS);
} else if (GVar->isConstant() && !isThreadLocal) {
// Now we know, that varible has initializer and it is constant. We need to
// check its initializer to decide, which section to output it into. Also
// note, there is no thread-local r/o section.
Constant *C = GVar->getInitializer();
if (C->ContainsRelocations())
return SectionKind::ROData;
else {
const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
// Check, if initializer is a null-terminated string
if (CVA && CVA->isCString())
return SectionKind::RODataMergeStr;
else
return SectionKind::RODataMergeConst;
}
}
// Variable is not constant or thread-local - emit to generic data section.
return (isThreadLocal ? SectionKind::ThreadData : SectionKind::Data);
}
unsigned
TargetAsmInfo::SectionFlagsForGlobal(const GlobalValue *GV,
const char* Name) const {
unsigned Flags = SectionFlags::None;
// Decode flags from global itself.
if (GV) {
SectionKind::Kind Kind = SectionKindForGlobal(GV);
switch (Kind) {
case SectionKind::Text:
Flags |= SectionFlags::Code;
break;
case SectionKind::ThreadData:
case SectionKind::ThreadBSS:
Flags |= SectionFlags::TLS;
// FALLS THROUGH
case SectionKind::Data:
case SectionKind::BSS:
Flags |= SectionFlags::Writeable;
break;
case SectionKind::ROData:
case SectionKind::RODataMergeStr:
case SectionKind::RODataMergeConst:
// No additional flags here
break;
case SectionKind::SmallData:
case SectionKind::SmallBSS:
Flags |= SectionFlags::Writeable;
// FALLS THROUGH
case SectionKind::SmallROData:
Flags |= SectionFlags::Small;
break;
default:
assert(0 && "Unexpected section kind!");
}
if (GV->mayBeOverridden())
Flags |= SectionFlags::Linkonce;
}
// Add flags from sections, if any.
if (Name && *Name) {
Flags |= SectionFlags::Named;
// Some lame default implementation based on some magic section names.
if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
Flags |= SectionFlags::BSS;
else if (strcmp(Name, ".tdata") == 0 ||
strncmp(Name, ".tdata.", 7) == 0 ||
strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
Flags |= SectionFlags::TLS;
else if (strcmp(Name, ".tbss") == 0 ||
strncmp(Name, ".tbss.", 6) == 0 ||
strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
Flags |= SectionFlags::BSS | SectionFlags::TLS;
}
return Flags;
}
const Section*
TargetAsmInfo::SectionForGlobal(const GlobalValue *GV) const {
const Section* S;
// Select section name
if (GV->hasSection()) {
// Honour section already set, if any
unsigned Flags = SectionFlagsForGlobal(GV,
GV->getSection().c_str());
S = getNamedSection(GV->getSection().c_str(), Flags);
} else {
// Use default section depending on the 'type' of global
S = SelectSectionForGlobal(GV);
}
return S;
}
// Lame default implementation. Calculate the section name for global.
const Section*
TargetAsmInfo::SelectSectionForGlobal(const GlobalValue *GV) const {
SectionKind::Kind Kind = SectionKindForGlobal(GV);
if (GV->mayBeOverridden()) {
std::string Name = UniqueSectionForGlobal(GV, Kind);
unsigned Flags = SectionFlagsForGlobal(GV, Name.c_str());
return getNamedSection(Name.c_str(), Flags);
} else {
if (Kind == SectionKind::Text)
return getTextSection();
else if (isBSS(Kind) && getBSSSection_())
return getBSSSection_();
else if (getReadOnlySection() && SectionKind::isReadOnly(Kind))
return getReadOnlySection();
}
return getDataSection();
}
// Lame default implementation. Calculate the section name for machine const.
const Section*
TargetAsmInfo::SelectSectionForMachineConst(const Type *Ty) const {
// FIXME: Support data.rel stuff someday
return getDataSection();
}
std::string
TargetAsmInfo::UniqueSectionForGlobal(const GlobalValue* GV,
SectionKind::Kind Kind) const {
switch (Kind) {
case SectionKind::Text:
return ".gnu.linkonce.t." + GV->getName();
case SectionKind::Data:
return ".gnu.linkonce.d." + GV->getName();
case SectionKind::SmallData:
return ".gnu.linkonce.s." + GV->getName();
case SectionKind::BSS:
return ".gnu.linkonce.b." + GV->getName();
case SectionKind::SmallBSS:
return ".gnu.linkonce.sb." + GV->getName();
case SectionKind::ROData:
case SectionKind::RODataMergeConst:
case SectionKind::RODataMergeStr:
return ".gnu.linkonce.r." + GV->getName();
case SectionKind::SmallROData:
return ".gnu.linkonce.s2." + GV->getName();
case SectionKind::ThreadData:
return ".gnu.linkonce.td." + GV->getName();
case SectionKind::ThreadBSS:
return ".gnu.linkonce.tb." + GV->getName();
default:
assert(0 && "Unknown section kind");
}
}
const Section*
TargetAsmInfo::getNamedSection(const char *Name, unsigned Flags,
bool Override) const {
Section& S = Sections[Name];
// This is newly-created section, set it up properly.
if (S.Flags == SectionFlags::Invalid || Override) {
S.Flags = Flags | SectionFlags::Named;
S.Name = Name;
}
return &S;
}
const Section*
TargetAsmInfo::getUnnamedSection(const char *Directive, unsigned Flags,
bool Override) const {
Section& S = Sections[Directive];
// This is newly-created section, set it up properly.
if (S.Flags == SectionFlags::Invalid || Override) {
S.Flags = Flags & ~SectionFlags::Named;
S.Name = Directive;
}
return &S;
}
const std::string&
TargetAsmInfo::getSectionFlags(unsigned Flags) const {
SectionFlags::FlagsStringsMapType::iterator I = FlagsStrings.find(Flags);
// We didn't print these flags yet, print and save them to map. This reduces
// amount of heap trashing due to std::string construction / concatenation.
if (I == FlagsStrings.end())
I = FlagsStrings.insert(std::make_pair(Flags,
printSectionFlags(Flags))).first;
return I->second;
}
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;
}
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