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b90e1b4a20
One is that AArch64 has additional restrictions on when local relocations can be used. We have to take those into consideration when deciding to put a L symbol in the symbol table or not. The other is that ld64 requires the relocations to cstring to use linker visible symbols on AArch64. Thanks to Michael Zolotukhin for testing this! Remove doesSectionRequireSymbols. In an assembly expression like bar: .long L0 + 1 the intended semantics is that bar will contain a pointer one byte past L0. In sections that are merged by content (strings, 4 byte constants, etc), a single position in the section doesn't give the linker enough information. For example, it would not be able to tell a relocation must point to the end of a string, since that would look just like the start of the next. The solution used in ELF to use relocation with symbols if there is a non-zero addend. In MachO before this patch we would just keep all symbols in some sections. This would miss some cases (only cstrings on x86_64 were implemented) and was inefficient since most relocations have an addend of 0 and can be represented without the symbol. This patch implements the non-zero addend logic for MachO too. llvm-svn: 225644
94 lines
2.9 KiB
C++
94 lines
2.9 KiB
C++
//===-- MCAsmInfoDarwin.cpp - Darwin asm properties -------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines target asm properties related what form asm statements
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// should take in general on Darwin-based targets
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/MC/MCAsmInfoDarwin.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCSectionMachO.h"
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#include "llvm/MC/MCStreamer.h"
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using namespace llvm;
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bool MCAsmInfoDarwin::isSectionAtomizableBySymbols(
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const MCSection &Section) const {
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const MCSectionMachO &SMO = static_cast<const MCSectionMachO &>(Section);
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// Sections holding 1 byte strings are atomized based on the data they
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// contain.
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// Sections holding 2 byte strings require symbols in order to be atomized.
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// There is no dedicated section for 4 byte strings.
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if (SMO.getType() == MachO::S_CSTRING_LITERALS)
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return false;
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if (SMO.getSegmentName() == "__DATA" && SMO.getSectionName() == "__cfstring")
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return false;
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switch (SMO.getType()) {
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default:
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return true;
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// These sections are atomized at the element boundaries without using
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// symbols.
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case MachO::S_4BYTE_LITERALS:
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case MachO::S_8BYTE_LITERALS:
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case MachO::S_16BYTE_LITERALS:
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case MachO::S_LITERAL_POINTERS:
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case MachO::S_NON_LAZY_SYMBOL_POINTERS:
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case MachO::S_LAZY_SYMBOL_POINTERS:
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case MachO::S_MOD_INIT_FUNC_POINTERS:
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case MachO::S_MOD_TERM_FUNC_POINTERS:
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case MachO::S_INTERPOSING:
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return false;
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}
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}
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MCAsmInfoDarwin::MCAsmInfoDarwin() {
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// Common settings for all Darwin targets.
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// Syntax:
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LinkerPrivateGlobalPrefix = "l";
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HasSingleParameterDotFile = false;
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HasSubsectionsViaSymbols = true;
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AlignmentIsInBytes = false;
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COMMDirectiveAlignmentIsInBytes = false;
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LCOMMDirectiveAlignmentType = LCOMM::Log2Alignment;
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InlineAsmStart = " InlineAsm Start";
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InlineAsmEnd = " InlineAsm End";
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// Directives:
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HasWeakDefDirective = true;
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HasWeakDefCanBeHiddenDirective = true;
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WeakRefDirective = "\t.weak_reference ";
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ZeroDirective = "\t.space\t"; // ".space N" emits N zeros.
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HasMachoZeroFillDirective = true; // Uses .zerofill
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HasMachoTBSSDirective = true; // Uses .tbss
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HasStaticCtorDtorReferenceInStaticMode = true;
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// FIXME: Change this once MC is the system assembler.
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HasAggressiveSymbolFolding = false;
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HiddenVisibilityAttr = MCSA_PrivateExtern;
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HiddenDeclarationVisibilityAttr = MCSA_Invalid;
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// Doesn't support protected visibility.
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ProtectedVisibilityAttr = MCSA_Invalid;
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HasDotTypeDotSizeDirective = false;
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HasNoDeadStrip = true;
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DwarfUsesRelocationsAcrossSections = false;
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UseIntegratedAssembler = true;
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SetDirectiveSuppressesReloc = true;
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}
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