[llvm] r233595 - MC: For variable symbols, maintain MCSymbol::Section as a cache.
Peter Collingbourne
peter at pcc.me.uk
Mon Mar 30 13:41:22 PDT 2015
Author: pcc
Date: Mon Mar 30 15:41:21 2015
New Revision: 233595
URL: http://llvm.org/viewvc/llvm-project?rev=233595&view=rev
Log:
MC: For variable symbols, maintain MCSymbol::Section as a cache.
This fixes the visibility of symbols in certain edge cases involving aliases
with multiple levels of indirection.
Fixes PR19582.
Differential Revision: http://reviews.llvm.org/D8586
Added:
llvm/trunk/test/MC/ELF/alias-resolve.s
Modified:
llvm/trunk/include/llvm/MC/MCMachObjectWriter.h
llvm/trunk/include/llvm/MC/MCSymbol.h
llvm/trunk/lib/MC/MCExpr.cpp
llvm/trunk/lib/MC/MCSymbol.cpp
llvm/trunk/lib/MC/MachObjectWriter.cpp
llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp
llvm/trunk/test/MC/ELF/alias.s
llvm/trunk/test/MC/MachO/ARM/aliased-symbols.s
Modified: llvm/trunk/include/llvm/MC/MCMachObjectWriter.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCMachObjectWriter.h?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCMachObjectWriter.h (original)
+++ llvm/trunk/include/llvm/MC/MCMachObjectWriter.h Mon Mar 30 15:41:21 2015
@@ -257,8 +257,6 @@ public:
void computeSectionAddresses(const MCAssembler &Asm,
const MCAsmLayout &Layout);
- void markAbsoluteVariableSymbols(MCAssembler &Asm,
- const MCAsmLayout &Layout);
void ExecutePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) override;
Modified: llvm/trunk/include/llvm/MC/MCSymbol.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCSymbol.h?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/include/llvm/MC/MCSymbol.h (original)
+++ llvm/trunk/include/llvm/MC/MCSymbol.h Mon Mar 30 15:41:21 2015
@@ -15,6 +15,7 @@
#define LLVM_MC_MCSYMBOL_H
#include "llvm/ADT/StringRef.h"
+#include "llvm/MC/MCExpr.h"
#include "llvm/Support/Compiler.h"
namespace llvm {
@@ -42,8 +43,9 @@ namespace llvm {
/// Section - The section the symbol is defined in. This is null for
/// undefined symbols, and the special AbsolutePseudoSection value for
- /// absolute symbols.
- const MCSection *Section;
+ /// absolute symbols. If this is a variable symbol, this caches the
+ /// variable value's section.
+ mutable const MCSection *Section;
/// Value - If non-null, the value for a variable symbol.
const MCExpr *Value;
@@ -68,6 +70,12 @@ 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; }
@@ -103,7 +111,7 @@ namespace llvm {
///
/// Defined symbols are either absolute or in some section.
bool isDefined() const {
- return Section != nullptr;
+ return getSectionPtr() != nullptr;
}
/// isInSection - Check if this symbol is defined in some section (i.e., it
@@ -119,27 +127,27 @@ namespace llvm {
/// isAbsolute - Check if this is an absolute symbol.
bool isAbsolute() const {
- return Section == AbsolutePseudoSection;
+ return getSectionPtr() == AbsolutePseudoSection;
}
/// getSection - Get the section associated with a defined, non-absolute
/// symbol.
const MCSection &getSection() const {
assert(isInSection() && "Invalid accessor!");
- return *Section;
+ return *getSectionPtr();
}
/// setSection - Mark the symbol as defined in the section \p S.
- void setSection(const MCSection &S) { Section = &S; }
+ void setSection(const MCSection &S) {
+ assert(!isVariable() && "Cannot set section of variable");
+ 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
/// @{
Modified: llvm/trunk/lib/MC/MCExpr.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCExpr.cpp?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCExpr.cpp (original)
+++ llvm/trunk/lib/MC/MCExpr.cpp Mon Mar 30 15:41:21 2015
@@ -775,6 +775,9 @@ const MCSection *MCExpr::FindAssociatedS
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;
}
Modified: llvm/trunk/lib/MC/MCSymbol.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MCSymbol.cpp?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MCSymbol.cpp (original)
+++ llvm/trunk/lib/MC/MCSymbol.cpp Mon Mar 30 15:41:21 2015
@@ -55,13 +55,7 @@ void MCSymbol::setVariableValue(const MC
assert(!IsUsed && "Cannot set a variable that has already been used.");
assert(Value && "Invalid variable value!");
this->Value = Value;
-
- // Variables should always be marked as in the same "section" as the value.
- const MCSection *Section = Value->FindAssociatedSection();
- if (Section)
- setSection(*Section);
- else
- setUndefined();
+ this->Section = nullptr;
}
void MCSymbol::print(raw_ostream &OS) const {
Modified: llvm/trunk/lib/MC/MachObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MachObjectWriter.cpp?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/lib/MC/MachObjectWriter.cpp (original)
+++ llvm/trunk/lib/MC/MachObjectWriter.cpp Mon Mar 30 15:41:21 2015
@@ -649,33 +649,12 @@ void MachObjectWriter::computeSectionAdd
}
}
-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::
Modified: llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86AsmPrinter.cpp Mon Mar 30 15:41:21 2015
@@ -523,7 +523,6 @@ void X86AsmPrinter::EmitStartOfAsmFile(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()));
Added: llvm/trunk/test/MC/ELF/alias-resolve.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/alias-resolve.s?rev=233595&view=auto
==============================================================================
--- llvm/trunk/test/MC/ELF/alias-resolve.s (added)
+++ llvm/trunk/test/MC/ELF/alias-resolve.s Mon Mar 30 15:41:21 2015
@@ -0,0 +1,8 @@
+// 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
Modified: llvm/trunk/test/MC/ELF/alias.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/alias.s?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/test/MC/ELF/alias.s (original)
+++ llvm/trunk/test/MC/ELF/alias.s Mon Mar 30 15:41:21 2015
@@ -24,6 +24,15 @@ 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)
Modified: llvm/trunk/test/MC/MachO/ARM/aliased-symbols.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/MachO/ARM/aliased-symbols.s?rev=233595&r1=233594&r2=233595&view=diff
==============================================================================
--- llvm/trunk/test/MC/MachO/ARM/aliased-symbols.s (original)
+++ llvm/trunk/test/MC/MachO/ARM/aliased-symbols.s Mon Mar 30 15:41:21 2015
@@ -45,9 +45,9 @@ Ltmp0:
// CHECK-NEXT: Value: 0x[[DEFINED_EARLY]]
// 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)
@@ -56,9 +56,9 @@ Ltmp0:
// CHECK-NEXT: Value: 0x[[DEFINED_LATE:[0-9A-F]+]]
// 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)
@@ -72,7 +72,7 @@ Ltmp0:
// CHECK: Symbol {
// CHECK-NEXT: Name: alias_to_local (42)
// CHECK-NEXT: Type: Section (0xE)
-// CHECK-NEXT: Section: (0x0)
+// CHECK-NEXT: Section: __data (0x2)
// CHECK-NEXT: RefType: UndefinedNonLazy (0x0)
// CHECK-NEXT: Flags [ (0x0)
// CHECK-NEXT: ]
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