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Fix pr19645. 

The fix itself is fairly simple: move getAccessVariant to MCValue so that we
replace the old weak expression evaluation with the far more general
EvaluateAsRelocatable.

This then requires that EvaluateAsRelocatable stop when it finds a non
trivial reference kind. And that in turn requires the ELF writer to look
harder for weak references.

Last but not least, this found a case where we were being bug by bug
compatible with gas and accepting an invalid input. I reported pr19647
to track it.

llvm-svn: 207920
This commit is contained in:
Rafael Espindola 2014-05-03 19:57:04 +00:00
parent 834652ade0
commit 3d082fa507
13 changed files with 55 additions and 58 deletions
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2
llvm/include/llvm/MC/MCFixup.h
View File

@ -88,8 +88,6 @@ public:
MCFixupKind getKind() const { return MCFixupKind(Kind); }
MCSymbolRefExpr::VariantKind getAccessVariant() const;
uint32_t getOffset() const { return Offset; }
void setOffset(uint32_t Value) { Offset = Value; }

5
llvm/include/llvm/MC/MCValue.h
View File

@ -14,14 +14,13 @@
#ifndef LLVM_MC_MCVALUE_H
#define LLVM_MC_MCVALUE_H
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Support/DataTypes.h"
#include <cassert>
namespace llvm {
class MCAsmInfo;
class MCSymbol;
class MCSymbolRefExpr;
class raw_ostream;
/// MCValue - This represents an "assembler immediate". In its most
@ -61,6 +60,8 @@ public:
/// dump - Print the value to stderr.
void dump() const;
MCSymbolRefExpr::VariantKind getAccessVariant() const;
static MCValue get(const MCSymbolRefExpr *SymA,
const MCSymbolRefExpr *SymB = nullptr,
int64_t Val = 0, uint32_t RefKind = 0) {

1
llvm/lib/MC/CMakeLists.txt
View File

@ -16,7 +16,6 @@ add_llvm_library(LLVMMC
MCELF.cpp
MCELFObjectTargetWriter.cpp
MCELFStreamer.cpp
MCFixup.cpp
MCFunction.cpp
MCExpr.cpp
MCExternalSymbolizer.cpp

23
llvm/lib/MC/ELFObjectWriter.cpp
View File

@ -787,6 +787,25 @@ bool ELFObjectWriter::shouldRelocateWithSymbol(const MCAssembler &Asm,
return false;
}
static const MCSymbol *getWeakRef(const MCSymbolRefExpr &Ref) {
const MCSymbol &Sym = Ref.getSymbol();
if (Ref.getKind() == MCSymbolRefExpr::VK_WEAKREF)
return &Sym;
if (!Sym.isVariable())
return nullptr;
const MCExpr *Expr = Sym.getVariableValue();
const auto *Inner = dyn_cast<MCSymbolRefExpr>(Expr);
if (!Inner)
return nullptr;
if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
return &Inner->getSymbol();
return nullptr;
}
void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
const MCAsmLayout &Layout,
const MCFragment *Fragment,
@ -872,8 +891,8 @@ void ELFObjectWriter::RecordRelocation(const MCAssembler &Asm,
if (const MCSymbol *R = Renames.lookup(SymA))
SymA = R;
if (RefA->getKind() == MCSymbolRefExpr::VK_WEAKREF)
WeakrefUsedInReloc.insert(SymA);
if (const MCSymbol *WeakRef = getWeakRef(*RefA))
WeakrefUsedInReloc.insert(WeakRef);
else
UsedInReloc.insert(SymA);
}

3
llvm/lib/MC/MCExpr.cpp
View File

@ -658,12 +658,11 @@ bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res, const MCAssembler *Asm,
case SymbolRef: {
const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
bool IsWeakRef = SRE->getKind() == MCSymbolRefExpr::VK_WEAKREF;
const MCSymbol &Sym = SRE->getSymbol();
const MCAsmInfo &MCAsmInfo = SRE->getMCAsmInfo();
// Evaluate recursively if this is a variable.
if (Sym.isVariable() && !IsWeakRef) {
if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
if (Sym.getVariableValue()->EvaluateAsRelocatableImpl(
Res, Asm, Layout, Addrs, true, ForceVarExpansion)) {
const MCSymbolRefExpr *A = Res.getSymA();

42
llvm/lib/MC/MCFixup.cpp
View File

@ -1,42 +0,0 @@
//===- MCFixup.cpp - Assembly Fixup Implementation ------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCFixup.h"
using namespace llvm;
static MCSymbolRefExpr::VariantKind getAccessVariant(const MCExpr *Expr) {
switch (Expr->getKind()) {
case MCExpr::Unary: {
assert(getAccessVariant(cast<MCUnaryExpr>(Expr)->getSubExpr()) ==
MCSymbolRefExpr::VK_None);
return MCSymbolRefExpr::VK_None;
}
case MCExpr::Target:
llvm_unreachable("unsupported");
case MCExpr::Constant:
return MCSymbolRefExpr::VK_None;
case MCExpr::SymbolRef: {
const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(Expr);
return SRE->getKind();
}
case MCExpr::Binary: {
const MCBinaryExpr *ABE = cast<MCBinaryExpr>(Expr);
assert(getAccessVariant(ABE->getRHS()) == MCSymbolRefExpr::VK_None);
return getAccessVariant(ABE->getLHS());
}
}
llvm_unreachable("unknown MCExpr kind");
}
MCSymbolRefExpr::VariantKind MCFixup::getAccessVariant() const {
return ::getAccessVariant(getValue());
}

18
llvm/lib/MC/MCValue.cpp
View File

@ -10,6 +10,7 @@
#include "llvm/MC/MCValue.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
@ -41,3 +42,20 @@ void MCValue::dump() const {
print(dbgs(), nullptr);
}
#endif
MCSymbolRefExpr::VariantKind MCValue::getAccessVariant() const {
const MCSymbolRefExpr *B = getSymB();
if (B) {
if (B->getKind() != MCSymbolRefExpr::VK_None)
llvm_unreachable("unsupported");
}
const MCSymbolRefExpr *A = getSymA();
if (!A)
return MCSymbolRefExpr::VK_None;
MCSymbolRefExpr::VariantKind Kind = A->getKind();
if (Kind == MCSymbolRefExpr::VK_WEAKREF)
return MCSymbolRefExpr::VK_None;
return Kind;
}

2
llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
View File

@ -74,7 +74,7 @@ unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const {
MCSymbolRefExpr::VariantKind Modifier = Fixup.getAccessVariant();
MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
unsigned Type = 0;
if (IsPCRel) {

7
llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
View File

@ -41,11 +41,12 @@ PPCELFObjectWriter::PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI)
PPCELFObjectWriter::~PPCELFObjectWriter() {
}
static MCSymbolRefExpr::VariantKind getAccessVariant(const MCFixup &Fixup) {
static MCSymbolRefExpr::VariantKind getAccessVariant(const MCValue &Target,
const MCFixup &Fixup) {
const MCExpr *Expr = Fixup.getValue();
if (Expr->getKind() != MCExpr::Target)
return Fixup.getAccessVariant();
return Target.getAccessVariant();
switch (cast<PPCMCExpr>(Expr)->getKind()) {
case PPCMCExpr::VK_PPC_None:
@ -72,7 +73,7 @@ unsigned PPCELFObjectWriter::getRelocTypeInner(const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const
{
MCSymbolRefExpr::VariantKind Modifier = getAccessVariant(Fixup);
MCSymbolRefExpr::VariantKind Modifier = getAccessVariant(Target, Fixup);
// determine the type of the relocation
unsigned Type;

2
llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCObjectWriter.cpp
View File

@ -82,7 +82,7 @@ static unsigned getPLTReloc(unsigned Kind) {
unsigned SystemZObjectWriter::GetRelocType(const MCValue &Target,
const MCFixup &Fixup,
bool IsPCRel) const {
MCSymbolRefExpr::VariantKind Modifier = Fixup.getAccessVariant();
MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
unsigned Kind = Fixup.getKind();
switch (Modifier) {
case MCSymbolRefExpr::VK_None:

2
llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp
View File

@ -43,7 +43,7 @@ unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
bool IsPCRel) const {
// determine the type of the relocation
MCSymbolRefExpr::VariantKind Modifier = Fixup.getAccessVariant();
MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
unsigned Type;
if (getEMachine() == ELF::EM_X86_64) {
if (IsPCRel) {

3
llvm/test/MC/ELF/relocation-386.s
View File

@ -62,6 +62,7 @@
// CHECK-NEXT: 0x9E R_386_PC16 und_symbol 0x0
// Relocation 28 (und_symbol-bar2) is of type R_386_PC8
// CHECK-NEXT: 0xA0 R_386_PC8 und_symbol 0x0
// CHECK-NEXT: 0xA3 R_386_GOTOFF und_symbol 0x0
// CHECK-NEXT: }
// CHECK-NEXT: ]
@ -127,6 +128,8 @@ bar2:
.word und_symbol-bar2
.byte und_symbol-bar2
leal 1 + und_symbol@GOTOFF, %edi
.section zedsec,"awT",@progbits
zed:
.long 0

3
llvm/test/MC/ELF/relocation.s
View File

@ -25,6 +25,7 @@ bar:
.word foo-bar
.byte foo-bar
# this should probably be an error...
zed = foo +2
call zed@PLT
@ -57,7 +58,7 @@ bar:
// CHECK-NEXT: 0x85 R_X86_64_TPOFF64 baz 0x0
// CHECK-NEXT: 0x8D R_X86_64_PC16 foo 0x8D
// CHECK-NEXT: 0x8F R_X86_64_PC8 foo 0x8F
// CHECK-NEXT: 0x91 R_X86_64_PLT32 foo 0xFFFFFFFFFFFFFFFE
// CHECK-NEXT: 0x91 R_X86_64_PLT32 zed 0xFFFFFFFFFFFFFFFC
// CHECK-NEXT: 0x98 R_X86_64_PC32 foo 0xFFFFFFFFFFFFFFFB
// CHECK-NEXT: 0x9D R_X86_64_GOTPC32 _GLOBAL_OFFSET_TABLE_ 0x1
// CHECK-NEXT: 0xA3 R_X86_64_GOTPC64 _GLOBAL_OFFSET_TABLE_ 0x2