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13ff8033c2
The issues was 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. Original message: 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: 225048
98 lines
3.1 KiB
C++
98 lines
3.1 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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// no_dead_strip sections are not atomized in practice.
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if (SMO.hasAttribute(MachO::S_ATTR_NO_DEAD_STRIP))
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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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