Revert r233595, "MC: For variable symbols, maintain MCSymbol::Section as a cache."

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233898 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne 2015-04-02 07:02:51 +00:00
parent 2eb21d0245
commit a8432640e8
9 changed files with 45 additions and 43 deletions

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@ -257,6 +257,8 @@ public:
void computeSectionAddresses(const MCAssembler &Asm,
const MCAsmLayout &Layout);
void markAbsoluteVariableSymbols(MCAssembler &Asm,
const MCAsmLayout &Layout);
void ExecutePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) override;

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@ -15,7 +15,6 @@
#define LLVM_MC_MCSYMBOL_H
#include "llvm/ADT/StringRef.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/Support/Compiler.h"
namespace llvm {
@ -43,9 +42,8 @@ namespace llvm {
/// Section - The section the symbol is defined in. This is null for
/// undefined symbols, and the special AbsolutePseudoSection value for
/// absolute symbols. If this is a variable symbol, this caches the
/// variable value's section.
mutable const MCSection *Section;
/// absolute symbols.
const MCSection *Section;
/// Value - If non-null, the value for a variable symbol.
const MCExpr *Value;
@ -70,12 +68,6 @@ namespace llvm {
MCSymbol(const MCSymbol&) = delete;
void operator=(const MCSymbol&) = delete;
const MCSection *getSectionPtr() const {
if (Section || !Value)
return Section;
return Section = Value->FindAssociatedSection();
}
public:
/// getName - Get the symbol name.
StringRef getName() const { return Name; }
@ -111,7 +103,7 @@ namespace llvm {
///
/// Defined symbols are either absolute or in some section.
bool isDefined() const {
return getSectionPtr() != nullptr;
return Section != nullptr;
}
/// isInSection - Check if this symbol is defined in some section (i.e., it
@ -127,27 +119,27 @@ namespace llvm {
/// isAbsolute - Check if this is an absolute symbol.
bool isAbsolute() const {
return getSectionPtr() == AbsolutePseudoSection;
return Section == AbsolutePseudoSection;
}
/// getSection - Get the section associated with a defined, non-absolute
/// symbol.
const MCSection &getSection() const {
assert(isInSection() && "Invalid accessor!");
return *getSectionPtr();
return *Section;
}
/// setSection - Mark the symbol as defined in the section \p S.
void setSection(const MCSection &S) {
assert(!isVariable() && "Cannot set section of variable");
Section = &S;
}
void setSection(const MCSection &S) { Section = &S; }
/// setUndefined - Mark the symbol as undefined.
void setUndefined() {
Section = nullptr;
}
/// setAbsolute - Mark the symbol as absolute.
void setAbsolute() { Section = AbsolutePseudoSection; }
/// @}
/// @name Variable Symbols
/// @{

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@ -775,9 +775,6 @@ const MCSection *MCExpr::FindAssociatedSection() const {
if (RHS_S == MCSymbol::AbsolutePseudoSection)
return LHS_S;
if (BE->getOpcode() == MCBinaryExpr::Sub)
return MCSymbol::AbsolutePseudoSection;
// Otherwise, return the first non-null section.
return LHS_S ? LHS_S : RHS_S;
}

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@ -55,7 +55,13 @@ void MCSymbol::setVariableValue(const MCExpr *Value) {
assert(!IsUsed && "Cannot set a variable that has already been used.");
assert(Value && "Invalid variable value!");
this->Value = Value;
this->Section = nullptr;
// Variables should always be marked as in the same "section" as the value.
const MCSection *Section = Value->FindAssociatedSection();
if (Section)
setSection(*Section);
else
setUndefined();
}
void MCSymbol::print(raw_ostream &OS) const {

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@ -649,12 +649,33 @@ void MachObjectWriter::computeSectionAddresses(const MCAssembler &Asm,
}
}
void MachObjectWriter::markAbsoluteVariableSymbols(MCAssembler &Asm,
const MCAsmLayout &Layout) {
for (MCSymbolData &SD : Asm.symbols()) {
if (!SD.getSymbol().isVariable())
continue;
// Is the variable is a symbol difference (SA - SB + C) expression,
// and neither symbol is external, mark the variable as absolute.
const MCExpr *Expr = SD.getSymbol().getVariableValue();
MCValue Value;
if (Expr->EvaluateAsRelocatable(Value, &Layout, nullptr)) {
if (Value.getSymA() && Value.getSymB())
const_cast<MCSymbol*>(&SD.getSymbol())->setAbsolute();
}
}
}
void MachObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) {
computeSectionAddresses(Asm, Layout);
// Create symbol data for any indirect symbols.
BindIndirectSymbols(Asm);
// Mark symbol difference expressions in variables (from .set or = directives)
// as absolute.
markAbsoluteVariableSymbols(Asm, Layout);
}
bool MachObjectWriter::

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@ -523,6 +523,7 @@ void X86AsmPrinter::EmitStartOfAsmFile(Module &M) {
// must be registered in .sxdata. Use of any unregistered handlers will
// cause the process to terminate immediately. LLVM does not know how to
// register any SEH handlers, so its object files should be safe.
S->setAbsolute();
OutStreamer.EmitSymbolAttribute(S, MCSA_Global);
OutStreamer.EmitAssignment(
S, MCConstantExpr::Create(int64_t(1), MMI->getContext()));

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@ -1,8 +0,0 @@
// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -r | FileCheck %s
a:
.section foo
c = b
b:
// CHECK: 0x0 R_X86_64_PC32 .text 0x0
.long a - c

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@ -24,15 +24,6 @@ bar5 = bar4
bar6 = bar5
bar6:
// Test that indirect local aliases do not appear as symbols.
.data
.Llocal:
.text
leaq .Llocal1(%rip), %rdi
.Llocal1 = .Llocal2
.Llocal2 = .Llocal
// CHECK: Symbols [
// CHECK-NEXT: Symbol {
// CHECK-NEXT: Name: (0)

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@ -45,9 +45,9 @@ Ltmp0:
// CHECK-NEXT: Value: 0x[[DEFINED_EARLY]]
// CHECK-NEXT: }
// alias_to_late was an alias to defined_late. But we can resolve it.
// defined_late was defined. Just after defined_early.
// CHECK: Symbol {
// CHECK-NEXT: Name: alias_to_late
// CHECK-NEXT: Name: defined_late
// CHECK-NEXT: Type: Section (0xE)
// CHECK-NEXT: Section: __data (0x2)
// CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
@ -56,9 +56,9 @@ Ltmp0:
// CHECK-NEXT: Value: 0x[[DEFINED_LATE:[0-9A-F]+]]
// CHECK-NEXT: }
// defined_late was defined. Just after defined_early.
// alias_to_late was an alias to defined_late. But we can resolve it.
// CHECK: Symbol {
// CHECK-NEXT: Name: defined_late
// CHECK-NEXT: Name: alias_to_late
// CHECK-NEXT: Type: Section (0xE)
// CHECK-NEXT: Section: __data (0x2)
// CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
@ -72,7 +72,7 @@ Ltmp0:
// CHECK: Symbol {
// CHECK-NEXT: Name: alias_to_local (42)
// CHECK-NEXT: Type: Section (0xE)
// CHECK-NEXT: Section: __data (0x2)
// CHECK-NEXT: Section: (0x0)
// CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
// CHECK-NEXT: Flags [ (0x0)
// CHECK-NEXT: ]