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Given bar = foo + 4 .long bar MC would eat the 4. GNU as includes it in the relocation. The rule seems to be that a variable that defines a symbol is used in the relocation and one that does not define a symbol is evaluated and the result included in the relocation. Fixing this unfortunately required some other changes: * Since the variable is now evaluated, it would prevent the ELF writer from noticing the weakref marker the elf streamer uses. This patch then replaces that with a VariantKind in MCSymbolRefExpr. * Using VariantKind then requires us to look past other VariantKind to see .weakref bar,foo call bar@PLT doing this also fixes zed = foo +2 call zed@PLT so that is a good thing. * Looking past VariantKind means that the relocation selection has to use the fixup instead of the target. This is a reboot of the previous fixes for MC. I will watch the sanitizer buildbot and wait for a build before adding back the previous fixes. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204294 91177308-0d34-0410-b5e6-96231b3b80d8
37 lines
1.1 KiB
C++
37 lines
1.1 KiB
C++
//===- MCFixup.cpp - Assembly Fixup Implementation ------------------------===//
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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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#include "llvm/MC/MCFixup.h"
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using namespace llvm;
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static MCSymbolRefExpr::VariantKind getAccessVariant(const MCExpr *Expr) {
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switch (Expr->getKind()) {
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case MCExpr::Unary:
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case MCExpr::Target:
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llvm_unreachable("unsupported");
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case MCExpr::Constant:
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return MCSymbolRefExpr::VK_None;
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case MCExpr::SymbolRef: {
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const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(Expr);
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return SRE->getKind();
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}
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case MCExpr::Binary: {
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const MCBinaryExpr *ABE = cast<MCBinaryExpr>(Expr);
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assert(getAccessVariant(ABE->getRHS()) == MCSymbolRefExpr::VK_None);
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return getAccessVariant(ABE->getLHS());
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}
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}
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}
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MCSymbolRefExpr::VariantKind MCFixup::getAccessVariant() const {
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return ::getAccessVariant(getValue());
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}
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