mirror of
https://github.com/RPCS3/llvm-mirror.git
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281e020b4e
Give up folding an expression if the fragment of one of the operands would require laying out a fragment already being laid out. This prevents hitting an infinite recursion when a fill size expression refers to a later fragment since computing the offset of that fragment would require laying out the fill fragment and thus computing its size expression. Reviewed By: echristo Differential Revision: https://reviews.llvm.org/D79570
481 lines
15 KiB
C++
481 lines
15 KiB
C++
//===- lib/MC/MCFragment.cpp - Assembler Fragment Implementation ----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/MC/MCFragment.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/MC/MCAsmLayout.h"
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#include "llvm/MC/MCAssembler.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/MCFixup.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/MC/MCValue.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/Compiler.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/raw_ostream.h"
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#include <cassert>
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#include <cstdint>
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#include <utility>
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using namespace llvm;
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MCAsmLayout::MCAsmLayout(MCAssembler &Asm) : Assembler(Asm) {
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// Compute the section layout order. Virtual sections must go last.
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for (MCSection &Sec : Asm)
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if (!Sec.isVirtualSection())
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SectionOrder.push_back(&Sec);
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for (MCSection &Sec : Asm)
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if (Sec.isVirtualSection())
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SectionOrder.push_back(&Sec);
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}
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bool MCAsmLayout::isFragmentValid(const MCFragment *F) const {
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const MCSection *Sec = F->getParent();
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const MCFragment *LastValid = LastValidFragment.lookup(Sec);
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if (!LastValid)
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return false;
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assert(LastValid->getParent() == Sec);
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return F->getLayoutOrder() <= LastValid->getLayoutOrder();
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}
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bool MCAsmLayout::canGetFragmentOffset(const MCFragment *F) const {
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MCSection *Sec = F->getParent();
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MCSection::iterator I;
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if (MCFragment *LastValid = LastValidFragment[Sec]) {
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// Fragment already valid, offset is available.
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if (F->getLayoutOrder() <= LastValid->getLayoutOrder())
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return true;
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I = ++MCSection::iterator(LastValid);
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} else
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I = Sec->begin();
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// A fragment ordered before F is currently being laid out.
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const MCFragment *FirstInvalidFragment = &*I;
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if (FirstInvalidFragment->IsBeingLaidOut)
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return false;
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return true;
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}
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void MCAsmLayout::invalidateFragmentsFrom(MCFragment *F) {
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// If this fragment wasn't already valid, we don't need to do anything.
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if (!isFragmentValid(F))
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return;
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// Otherwise, reset the last valid fragment to the previous fragment
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// (if this is the first fragment, it will be NULL).
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LastValidFragment[F->getParent()] = F->getPrevNode();
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}
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void MCAsmLayout::ensureValid(const MCFragment *F) const {
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MCSection *Sec = F->getParent();
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MCSection::iterator I;
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if (MCFragment *Cur = LastValidFragment[Sec])
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I = ++MCSection::iterator(Cur);
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else
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I = Sec->begin();
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// Advance the layout position until the fragment is valid.
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while (!isFragmentValid(F)) {
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assert(I != Sec->end() && "Layout bookkeeping error");
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const_cast<MCAsmLayout *>(this)->layoutFragment(&*I);
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++I;
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}
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}
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uint64_t MCAsmLayout::getFragmentOffset(const MCFragment *F) const {
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ensureValid(F);
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assert(F->Offset != ~UINT64_C(0) && "Address not set!");
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return F->Offset;
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}
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// Simple getSymbolOffset helper for the non-variable case.
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static bool getLabelOffset(const MCAsmLayout &Layout, const MCSymbol &S,
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bool ReportError, uint64_t &Val) {
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if (!S.getFragment()) {
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if (ReportError)
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report_fatal_error("unable to evaluate offset to undefined symbol '" +
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S.getName() + "'");
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return false;
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}
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Val = Layout.getFragmentOffset(S.getFragment()) + S.getOffset();
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return true;
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}
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static bool getSymbolOffsetImpl(const MCAsmLayout &Layout, const MCSymbol &S,
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bool ReportError, uint64_t &Val) {
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if (!S.isVariable())
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return getLabelOffset(Layout, S, ReportError, Val);
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// If SD is a variable, evaluate it.
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MCValue Target;
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if (!S.getVariableValue()->evaluateAsValue(Target, Layout))
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report_fatal_error("unable to evaluate offset for variable '" +
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S.getName() + "'");
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uint64_t Offset = Target.getConstant();
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const MCSymbolRefExpr *A = Target.getSymA();
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if (A) {
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uint64_t ValA;
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if (!getLabelOffset(Layout, A->getSymbol(), ReportError, ValA))
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return false;
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Offset += ValA;
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}
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const MCSymbolRefExpr *B = Target.getSymB();
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if (B) {
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uint64_t ValB;
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if (!getLabelOffset(Layout, B->getSymbol(), ReportError, ValB))
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return false;
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Offset -= ValB;
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}
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Val = Offset;
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return true;
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}
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bool MCAsmLayout::getSymbolOffset(const MCSymbol &S, uint64_t &Val) const {
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return getSymbolOffsetImpl(*this, S, false, Val);
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}
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uint64_t MCAsmLayout::getSymbolOffset(const MCSymbol &S) const {
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uint64_t Val;
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getSymbolOffsetImpl(*this, S, true, Val);
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return Val;
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}
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const MCSymbol *MCAsmLayout::getBaseSymbol(const MCSymbol &Symbol) const {
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if (!Symbol.isVariable())
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return &Symbol;
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const MCExpr *Expr = Symbol.getVariableValue();
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MCValue Value;
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if (!Expr->evaluateAsValue(Value, *this)) {
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Assembler.getContext().reportError(
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Expr->getLoc(), "expression could not be evaluated");
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return nullptr;
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}
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const MCSymbolRefExpr *RefB = Value.getSymB();
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if (RefB) {
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Assembler.getContext().reportError(
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Expr->getLoc(), Twine("symbol '") + RefB->getSymbol().getName() +
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"' could not be evaluated in a subtraction expression");
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return nullptr;
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}
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const MCSymbolRefExpr *A = Value.getSymA();
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if (!A)
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return nullptr;
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const MCSymbol &ASym = A->getSymbol();
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const MCAssembler &Asm = getAssembler();
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if (ASym.isCommon()) {
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Asm.getContext().reportError(Expr->getLoc(),
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"Common symbol '" + ASym.getName() +
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"' cannot be used in assignment expr");
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return nullptr;
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}
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return &ASym;
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}
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uint64_t MCAsmLayout::getSectionAddressSize(const MCSection *Sec) const {
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// The size is the last fragment's end offset.
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const MCFragment &F = Sec->getFragmentList().back();
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return getFragmentOffset(&F) + getAssembler().computeFragmentSize(*this, F);
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}
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uint64_t MCAsmLayout::getSectionFileSize(const MCSection *Sec) const {
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// Virtual sections have no file size.
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if (Sec->isVirtualSection())
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return 0;
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// Otherwise, the file size is the same as the address space size.
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return getSectionAddressSize(Sec);
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}
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uint64_t llvm::computeBundlePadding(const MCAssembler &Assembler,
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const MCEncodedFragment *F,
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uint64_t FOffset, uint64_t FSize) {
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uint64_t BundleSize = Assembler.getBundleAlignSize();
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assert(BundleSize > 0 &&
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"computeBundlePadding should only be called if bundling is enabled");
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uint64_t BundleMask = BundleSize - 1;
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uint64_t OffsetInBundle = FOffset & BundleMask;
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uint64_t EndOfFragment = OffsetInBundle + FSize;
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// There are two kinds of bundling restrictions:
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//
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// 1) For alignToBundleEnd(), add padding to ensure that the fragment will
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// *end* on a bundle boundary.
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// 2) Otherwise, check if the fragment would cross a bundle boundary. If it
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// would, add padding until the end of the bundle so that the fragment
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// will start in a new one.
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if (F->alignToBundleEnd()) {
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// Three possibilities here:
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//
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// A) The fragment just happens to end at a bundle boundary, so we're good.
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// B) The fragment ends before the current bundle boundary: pad it just
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// enough to reach the boundary.
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// C) The fragment ends after the current bundle boundary: pad it until it
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// reaches the end of the next bundle boundary.
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//
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// Note: this code could be made shorter with some modulo trickery, but it's
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// intentionally kept in its more explicit form for simplicity.
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if (EndOfFragment == BundleSize)
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return 0;
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else if (EndOfFragment < BundleSize)
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return BundleSize - EndOfFragment;
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else { // EndOfFragment > BundleSize
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return 2 * BundleSize - EndOfFragment;
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}
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} else if (OffsetInBundle > 0 && EndOfFragment > BundleSize)
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return BundleSize - OffsetInBundle;
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else
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return 0;
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}
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/* *** */
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void ilist_alloc_traits<MCFragment>::deleteNode(MCFragment *V) { V->destroy(); }
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MCFragment::MCFragment(FragmentType Kind, bool HasInstructions,
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MCSection *Parent)
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: Parent(Parent), Atom(nullptr), Offset(~UINT64_C(0)), LayoutOrder(0),
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Kind(Kind), IsBeingLaidOut(false), HasInstructions(HasInstructions) {
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if (Parent && !isa<MCDummyFragment>(*this))
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Parent->getFragmentList().push_back(this);
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}
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void MCFragment::destroy() {
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// First check if we are the sentinal.
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if (Kind == FragmentType(~0)) {
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delete this;
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return;
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}
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switch (Kind) {
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case FT_Align:
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delete cast<MCAlignFragment>(this);
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return;
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case FT_Data:
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delete cast<MCDataFragment>(this);
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return;
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case FT_CompactEncodedInst:
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delete cast<MCCompactEncodedInstFragment>(this);
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return;
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case FT_Fill:
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delete cast<MCFillFragment>(this);
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return;
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case FT_Relaxable:
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delete cast<MCRelaxableFragment>(this);
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return;
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case FT_Org:
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delete cast<MCOrgFragment>(this);
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return;
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case FT_Dwarf:
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delete cast<MCDwarfLineAddrFragment>(this);
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return;
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case FT_DwarfFrame:
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delete cast<MCDwarfCallFrameFragment>(this);
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return;
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case FT_LEB:
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delete cast<MCLEBFragment>(this);
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return;
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case FT_BoundaryAlign:
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delete cast<MCBoundaryAlignFragment>(this);
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return;
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case FT_SymbolId:
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delete cast<MCSymbolIdFragment>(this);
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return;
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case FT_CVInlineLines:
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delete cast<MCCVInlineLineTableFragment>(this);
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return;
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case FT_CVDefRange:
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delete cast<MCCVDefRangeFragment>(this);
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return;
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case FT_Dummy:
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delete cast<MCDummyFragment>(this);
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return;
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}
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}
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// Debugging methods
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namespace llvm {
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raw_ostream &operator<<(raw_ostream &OS, const MCFixup &AF) {
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OS << "<MCFixup" << " Offset:" << AF.getOffset()
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<< " Value:" << *AF.getValue()
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<< " Kind:" << AF.getKind() << ">";
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return OS;
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}
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} // end namespace llvm
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#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
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LLVM_DUMP_METHOD void MCFragment::dump() const {
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raw_ostream &OS = errs();
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OS << "<";
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switch (getKind()) {
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case MCFragment::FT_Align: OS << "MCAlignFragment"; break;
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case MCFragment::FT_Data: OS << "MCDataFragment"; break;
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case MCFragment::FT_CompactEncodedInst:
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OS << "MCCompactEncodedInstFragment"; break;
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case MCFragment::FT_Fill: OS << "MCFillFragment"; break;
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case MCFragment::FT_Relaxable: OS << "MCRelaxableFragment"; break;
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case MCFragment::FT_Org: OS << "MCOrgFragment"; break;
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case MCFragment::FT_Dwarf: OS << "MCDwarfFragment"; break;
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case MCFragment::FT_DwarfFrame: OS << "MCDwarfCallFrameFragment"; break;
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case MCFragment::FT_LEB: OS << "MCLEBFragment"; break;
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case MCFragment::FT_BoundaryAlign: OS<<"MCBoundaryAlignFragment"; break;
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case MCFragment::FT_SymbolId: OS << "MCSymbolIdFragment"; break;
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case MCFragment::FT_CVInlineLines: OS << "MCCVInlineLineTableFragment"; break;
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case MCFragment::FT_CVDefRange: OS << "MCCVDefRangeTableFragment"; break;
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case MCFragment::FT_Dummy: OS << "MCDummyFragment"; break;
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}
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OS << "<MCFragment " << (const void *)this << " LayoutOrder:" << LayoutOrder
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<< " Offset:" << Offset << " HasInstructions:" << hasInstructions();
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if (const auto *EF = dyn_cast<MCEncodedFragment>(this))
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OS << " BundlePadding:" << static_cast<unsigned>(EF->getBundlePadding());
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OS << ">";
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switch (getKind()) {
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case MCFragment::FT_Align: {
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const auto *AF = cast<MCAlignFragment>(this);
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if (AF->hasEmitNops())
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OS << " (emit nops)";
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OS << "\n ";
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OS << " Alignment:" << AF->getAlignment()
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<< " Value:" << AF->getValue() << " ValueSize:" << AF->getValueSize()
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<< " MaxBytesToEmit:" << AF->getMaxBytesToEmit() << ">";
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break;
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}
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case MCFragment::FT_Data: {
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const auto *DF = cast<MCDataFragment>(this);
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OS << "\n ";
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OS << " Contents:[";
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const SmallVectorImpl<char> &Contents = DF->getContents();
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for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
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if (i) OS << ",";
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OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
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}
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OS << "] (" << Contents.size() << " bytes)";
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if (DF->fixup_begin() != DF->fixup_end()) {
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OS << ",\n ";
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OS << " Fixups:[";
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for (MCDataFragment::const_fixup_iterator it = DF->fixup_begin(),
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ie = DF->fixup_end(); it != ie; ++it) {
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if (it != DF->fixup_begin()) OS << ",\n ";
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OS << *it;
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}
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OS << "]";
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}
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break;
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}
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case MCFragment::FT_CompactEncodedInst: {
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const auto *CEIF =
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cast<MCCompactEncodedInstFragment>(this);
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OS << "\n ";
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OS << " Contents:[";
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const SmallVectorImpl<char> &Contents = CEIF->getContents();
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for (unsigned i = 0, e = Contents.size(); i != e; ++i) {
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if (i) OS << ",";
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OS << hexdigit((Contents[i] >> 4) & 0xF) << hexdigit(Contents[i] & 0xF);
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}
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OS << "] (" << Contents.size() << " bytes)";
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break;
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}
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case MCFragment::FT_Fill: {
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const auto *FF = cast<MCFillFragment>(this);
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OS << " Value:" << static_cast<unsigned>(FF->getValue())
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<< " ValueSize:" << static_cast<unsigned>(FF->getValueSize())
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<< " NumValues:" << FF->getNumValues();
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break;
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}
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case MCFragment::FT_Relaxable: {
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const auto *F = cast<MCRelaxableFragment>(this);
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OS << "\n ";
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OS << " Inst:";
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F->getInst().dump_pretty(OS);
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OS << " (" << F->getContents().size() << " bytes)";
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break;
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}
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case MCFragment::FT_Org: {
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const auto *OF = cast<MCOrgFragment>(this);
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OS << "\n ";
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OS << " Offset:" << OF->getOffset()
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<< " Value:" << static_cast<unsigned>(OF->getValue());
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break;
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}
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case MCFragment::FT_Dwarf: {
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const auto *OF = cast<MCDwarfLineAddrFragment>(this);
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OS << "\n ";
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OS << " AddrDelta:" << OF->getAddrDelta()
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<< " LineDelta:" << OF->getLineDelta();
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break;
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}
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case MCFragment::FT_DwarfFrame: {
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const auto *CF = cast<MCDwarfCallFrameFragment>(this);
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OS << "\n ";
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OS << " AddrDelta:" << CF->getAddrDelta();
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break;
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}
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case MCFragment::FT_LEB: {
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const auto *LF = cast<MCLEBFragment>(this);
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OS << "\n ";
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OS << " Value:" << LF->getValue() << " Signed:" << LF->isSigned();
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break;
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}
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case MCFragment::FT_BoundaryAlign: {
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const auto *BF = cast<MCBoundaryAlignFragment>(this);
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OS << "\n ";
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OS << " BoundarySize:" << BF->getAlignment().value()
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<< " LastFragment:" << BF->getLastFragment()
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<< " Size:" << BF->getSize();
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break;
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}
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case MCFragment::FT_SymbolId: {
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const auto *F = cast<MCSymbolIdFragment>(this);
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OS << "\n ";
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OS << " Sym:" << F->getSymbol();
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break;
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}
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case MCFragment::FT_CVInlineLines: {
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const auto *F = cast<MCCVInlineLineTableFragment>(this);
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OS << "\n ";
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OS << " Sym:" << *F->getFnStartSym();
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break;
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}
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case MCFragment::FT_CVDefRange: {
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const auto *F = cast<MCCVDefRangeFragment>(this);
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OS << "\n ";
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for (std::pair<const MCSymbol *, const MCSymbol *> RangeStartEnd :
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F->getRanges()) {
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OS << " RangeStart:" << RangeStartEnd.first;
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OS << " RangeEnd:" << RangeStartEnd.second;
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}
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break;
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}
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case MCFragment::FT_Dummy:
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break;
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}
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OS << ">";
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}
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#endif
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