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llvm-6502/lib/MC/MCExpr.cpp
Rafael Espindola 94ed5fca3f Change MCExpr::EvaluateAsRelocatableImpl of variables to return the original 
variable if recursing fails to simplify it.

Factor AliasedSymbol to be a method of MCSymbol.

Update MCAssembler::EvaluateFixup to match the change in
EvaluateAsRelocatableImpl.

Remove the WeakRefExpr hack, as the object writer now sees the weakref with
no extra effort needed.

Nothing else is using MCTargetExpr, but keep it for now.

Now that the ELF writer sees relocations with aliases, handle

    .weak    foo2
foo2:
    .weak    bar2
    .set    bar2,foo2
    .quad    bar2

the same way gas does and produce a relocation with bar2.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@119152 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-15 16:33:49 +00:00

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//===- MCExpr.cpp - Assembly Level Expression Implementation --------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "mcexpr"
#include "llvm/MC/MCExpr.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/MC/MCAsmLayout.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectFormat.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetAsmBackend.h"
using namespace llvm;
namespace {
namespace stats {
STATISTIC(MCExprEvaluate, "Number of MCExpr evaluations");
}
}
void MCExpr::print(raw_ostream &OS) const {
switch (getKind()) {
case MCExpr::Target:
return cast<MCTargetExpr>(this)->PrintImpl(OS);
case MCExpr::Constant:
OS << cast<MCConstantExpr>(*this).getValue();
return;
case MCExpr::SymbolRef: {
const MCSymbolRefExpr &SRE = cast<MCSymbolRefExpr>(*this);
const MCSymbol &Sym = SRE.getSymbol();
// Parenthesize names that start with $ so that they don't look like
// absolute names.
bool UseParens = Sym.getName()[0] == '$';
if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_HI16 ||
SRE.getKind() == MCSymbolRefExpr::VK_ARM_LO16)
OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
if (SRE.getKind() == MCSymbolRefExpr::VK_PPC_HA16 ||
SRE.getKind() == MCSymbolRefExpr::VK_PPC_LO16) {
OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
UseParens = true;
}
if (UseParens)
OS << '(' << Sym << ')';
else
OS << Sym;
if (SRE.getKind() == MCSymbolRefExpr::VK_ARM_PLT ||
SRE.getKind() == MCSymbolRefExpr::VK_ARM_TLSGD ||
SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOT ||
SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTOFF ||
SRE.getKind() == MCSymbolRefExpr::VK_ARM_TPOFF ||
SRE.getKind() == MCSymbolRefExpr::VK_ARM_GOTTPOFF)
OS << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
else if (SRE.getKind() != MCSymbolRefExpr::VK_None &&
SRE.getKind() != MCSymbolRefExpr::VK_ARM_HI16 &&
SRE.getKind() != MCSymbolRefExpr::VK_ARM_LO16 &&
SRE.getKind() != MCSymbolRefExpr::VK_PPC_HA16 &&
SRE.getKind() != MCSymbolRefExpr::VK_PPC_LO16)
OS << '@' << MCSymbolRefExpr::getVariantKindName(SRE.getKind());
return;
}
case MCExpr::Unary: {
const MCUnaryExpr &UE = cast<MCUnaryExpr>(*this);
switch (UE.getOpcode()) {
default: assert(0 && "Invalid opcode!");
case MCUnaryExpr::LNot: OS << '!'; break;
case MCUnaryExpr::Minus: OS << '-'; break;
case MCUnaryExpr::Not: OS << '~'; break;
case MCUnaryExpr::Plus: OS << '+'; break;
}
OS << *UE.getSubExpr();
return;
}
case MCExpr::Binary: {
const MCBinaryExpr &BE = cast<MCBinaryExpr>(*this);
// Only print parens around the LHS if it is non-trivial.
if (isa<MCConstantExpr>(BE.getLHS()) || isa<MCSymbolRefExpr>(BE.getLHS())) {
OS << *BE.getLHS();
} else {
OS << '(' << *BE.getLHS() << ')';
}
switch (BE.getOpcode()) {
default: assert(0 && "Invalid opcode!");
case MCBinaryExpr::Add:
// Print "X-42" instead of "X+-42".
if (const MCConstantExpr *RHSC = dyn_cast<MCConstantExpr>(BE.getRHS())) {
if (RHSC->getValue() < 0) {
OS << RHSC->getValue();
return;
}
}
OS << '+';
break;
case MCBinaryExpr::And: OS << '&'; break;
case MCBinaryExpr::Div: OS << '/'; break;
case MCBinaryExpr::EQ: OS << "=="; break;
case MCBinaryExpr::GT: OS << '>'; break;
case MCBinaryExpr::GTE: OS << ">="; break;
case MCBinaryExpr::LAnd: OS << "&&"; break;
case MCBinaryExpr::LOr: OS << "||"; break;
case MCBinaryExpr::LT: OS << '<'; break;
case MCBinaryExpr::LTE: OS << "<="; break;
case MCBinaryExpr::Mod: OS << '%'; break;
case MCBinaryExpr::Mul: OS << '*'; break;
case MCBinaryExpr::NE: OS << "!="; break;
case MCBinaryExpr::Or: OS << '|'; break;
case MCBinaryExpr::Shl: OS << "<<"; break;
case MCBinaryExpr::Shr: OS << ">>"; break;
case MCBinaryExpr::Sub: OS << '-'; break;
case MCBinaryExpr::Xor: OS << '^'; break;
}
// Only print parens around the LHS if it is non-trivial.
if (isa<MCConstantExpr>(BE.getRHS()) || isa<MCSymbolRefExpr>(BE.getRHS())) {
OS << *BE.getRHS();
} else {
OS << '(' << *BE.getRHS() << ')';
}
return;
}
}
assert(0 && "Invalid expression kind!");
}
void MCExpr::dump() const {
print(dbgs());
dbgs() << '\n';
}
/* *** */
const MCBinaryExpr *MCBinaryExpr::Create(Opcode Opc, const MCExpr *LHS,
const MCExpr *RHS, MCContext &Ctx) {
return new (Ctx) MCBinaryExpr(Opc, LHS, RHS);
}
const MCUnaryExpr *MCUnaryExpr::Create(Opcode Opc, const MCExpr *Expr,
MCContext &Ctx) {
return new (Ctx) MCUnaryExpr(Opc, Expr);
}
const MCConstantExpr *MCConstantExpr::Create(int64_t Value, MCContext &Ctx) {
return new (Ctx) MCConstantExpr(Value);
}
/* *** */
const MCSymbolRefExpr *MCSymbolRefExpr::Create(const MCSymbol *Sym,
VariantKind Kind,
MCContext &Ctx) {
return new (Ctx) MCSymbolRefExpr(Sym, Kind);
}
const MCSymbolRefExpr *MCSymbolRefExpr::Create(StringRef Name, VariantKind Kind,
MCContext &Ctx) {
return Create(Ctx.GetOrCreateSymbol(Name), Kind, Ctx);
}
StringRef MCSymbolRefExpr::getVariantKindName(VariantKind Kind) {
switch (Kind) {
default:
case VK_Invalid: return "<<invalid>>";
case VK_None: return "<<none>>";
case VK_GOT: return "GOT";
case VK_GOTOFF: return "GOTOFF";
case VK_GOTPCREL: return "GOTPCREL";
case VK_GOTTPOFF: return "GOTTPOFF";
case VK_INDNTPOFF: return "INDNTPOFF";
case VK_NTPOFF: return "NTPOFF";
case VK_GOTNTPOFF: return "GOTNTPOFF";
case VK_PLT: return "PLT";
case VK_TLSGD: return "TLSGD";
case VK_TLSLD: return "TLSLD";
case VK_TLSLDM: return "TLSLDM";
case VK_TPOFF: return "TPOFF";
case VK_DTPOFF: return "DTPOFF";
case VK_TLVP: return "TLVP";
case VK_ARM_HI16: return ":upper16:";
case VK_ARM_LO16: return ":lower16:";
case VK_ARM_PLT: return "(PLT)";
case VK_ARM_GOT: return "(GOT)";
case VK_ARM_GOTOFF: return "(GOTOFF)";
case VK_ARM_TPOFF: return "(tpoff)";
case VK_ARM_GOTTPOFF: return "(gottpoff)";
case VK_ARM_TLSGD: return "(tldgd)";
case VK_PPC_TOC: return "toc";
case VK_PPC_HA16: return "ha16";
case VK_PPC_LO16: return "lo16";
}
}
MCSymbolRefExpr::VariantKind
MCSymbolRefExpr::getVariantKindForName(StringRef Name) {
return StringSwitch<VariantKind>(Name)
.Case("GOT", VK_GOT)
.Case("GOTOFF", VK_GOTOFF)
.Case("GOTPCREL", VK_GOTPCREL)
.Case("GOTTPOFF", VK_GOTTPOFF)
.Case("INDNTPOFF", VK_INDNTPOFF)
.Case("NTPOFF", VK_NTPOFF)
.Case("GOTNTPOFF", VK_GOTNTPOFF)
.Case("PLT", VK_PLT)
.Case("TLSGD", VK_TLSGD)
.Case("TLSLD", VK_TLSLD)
.Case("TLSLDM", VK_TLSLDM)
.Case("TPOFF", VK_TPOFF)
.Case("DTPOFF", VK_DTPOFF)
.Case("TLVP", VK_TLVP)
.Default(VK_Invalid);
}
/* *** */
void MCTargetExpr::Anchor() {}
/* *** */
bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout *Layout) const {
MCValue Value;
// Fast path constants.
if (const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(this)) {
Res = CE->getValue();
return true;
}
if (!EvaluateAsRelocatable(Value, Layout) || !Value.isAbsolute()) {
// EvaluateAsAbsolute is defined to return the "current value" of
// the expression if we are given a Layout object, even in cases
// when the value is not fixed.
if (Layout) {
Res = Value.getConstant();
if (Value.getSymA()) {
Res += Layout->getSymbolAddress(
&Layout->getAssembler().getSymbolData(Value.getSymA()->getSymbol()));
}
if (Value.getSymB()) {
Res -= Layout->getSymbolAddress(
&Layout->getAssembler().getSymbolData(Value.getSymB()->getSymbol()));
}
}
return false;
}
Res = Value.getConstant();
return true;
}
static bool EvaluateSymbolicAdd(const MCAsmLayout *Layout, bool InSet,
const MCValue &LHS,const MCSymbolRefExpr *RHS_A,
const MCSymbolRefExpr *RHS_B, int64_t RHS_Cst,
MCValue &Res) {
// We can't add or subtract two symbols.
if ((LHS.getSymA() && RHS_A) ||
(LHS.getSymB() && RHS_B))
return false;
const MCSymbolRefExpr *A = LHS.getSymA() ? LHS.getSymA() : RHS_A;
const MCSymbolRefExpr *B = LHS.getSymB() ? LHS.getSymB() : RHS_B;
if (B) {
// If we have a negated symbol, then we must have also have a non-negated
// symbol in order to encode the expression. We can do this check later to
// permit expressions which eventually fold to a representable form -- such
// as (a + (0 - b)) -- if necessary.
if (!A)
return false;
}
// Absolutize symbol differences between defined symbols when we have a
// layout object and the target requests it.
if (Layout && A && B) {
const MCSymbol &SA = A->getSymbol();
const MCSymbol &SB = B->getSymbol();
const MCObjectFormat &F =
Layout->getAssembler().getBackend().getObjectFormat();
if (SA.isDefined() && SB.isDefined() && F.isAbsolute(InSet, SA, SB)) {
const MCAssembler &Asm = Layout->getAssembler();
MCSymbolData &AD = Asm.getSymbolData(A->getSymbol());
MCSymbolData &BD = Asm.getSymbolData(B->getSymbol());
Res = MCValue::get(+ Layout->getSymbolAddress(&AD)
- Layout->getSymbolAddress(&BD)
+ LHS.getConstant()
+ RHS_Cst);
return true;
}
}
Res = MCValue::get(A, B, LHS.getConstant() + RHS_Cst);
return true;
}
bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
const MCAsmLayout *Layout) const {
return EvaluateAsRelocatableImpl(Res, Layout, false);
}
bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
const MCAsmLayout *Layout,
bool InSet) const {
++stats::MCExprEvaluate;
switch (getKind()) {
case Target:
return cast<MCTargetExpr>(this)->EvaluateAsRelocatableImpl(Res, Layout);
case Constant:
Res = MCValue::get(cast<MCConstantExpr>(this)->getValue());
return true;
case SymbolRef: {
const MCSymbolRefExpr *SRE = cast<MCSymbolRefExpr>(this);
const MCSymbol &Sym = SRE->getSymbol();
// Evaluate recursively if this is a variable.
if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Layout,
true);
// If we failed to simplify this to a constant, let the target
// handle it.
if (Ret && !Res.getSymA() && !Res.getSymB())
return true;
}
Res = MCValue::get(SRE, 0, 0);
return true;
}
case Unary: {
const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
MCValue Value;
if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Layout, InSet))
return false;
switch (AUE->getOpcode()) {
case MCUnaryExpr::LNot:
if (!Value.isAbsolute())
return false;
Res = MCValue::get(!Value.getConstant());
break;
case MCUnaryExpr::Minus:
/// -(a - b + const) ==> (b - a - const)
if (Value.getSymA() && !Value.getSymB())
return false;
Res = MCValue::get(Value.getSymB(), Value.getSymA(),
-Value.getConstant());
break;
case MCUnaryExpr::Not:
if (!Value.isAbsolute())
return false;
Res = MCValue::get(~Value.getConstant());
break;
case MCUnaryExpr::Plus:
Res = Value;
break;
}
return true;
}
case Binary: {
const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
MCValue LHSValue, RHSValue;
if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Layout, InSet) ||
!ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Layout, InSet))
return false;
// We only support a few operations on non-constant expressions, handle
// those first.
if (!LHSValue.isAbsolute() || !RHSValue.isAbsolute()) {
switch (ABE->getOpcode()) {
default:
return false;
case MCBinaryExpr::Sub:
// Negate RHS and add.
return EvaluateSymbolicAdd(Layout, InSet, LHSValue,
RHSValue.getSymB(), RHSValue.getSymA(),
-RHSValue.getConstant(),
Res);
case MCBinaryExpr::Add:
return EvaluateSymbolicAdd(Layout, InSet, LHSValue,
RHSValue.getSymA(), RHSValue.getSymB(),
RHSValue.getConstant(),
Res);
}
}
// FIXME: We need target hooks for the evaluation. It may be limited in
// width, and gas defines the result of comparisons and right shifts
// differently from Apple as.
int64_t LHS = LHSValue.getConstant(), RHS = RHSValue.getConstant();
int64_t Result = 0;
switch (ABE->getOpcode()) {
case MCBinaryExpr::Add: Result = LHS + RHS; break;
case MCBinaryExpr::And: Result = LHS & RHS; break;
case MCBinaryExpr::Div: Result = LHS / RHS; break;
case MCBinaryExpr::EQ: Result = LHS == RHS; break;
case MCBinaryExpr::GT: Result = LHS > RHS; break;
case MCBinaryExpr::GTE: Result = LHS >= RHS; break;
case MCBinaryExpr::LAnd: Result = LHS && RHS; break;
case MCBinaryExpr::LOr: Result = LHS || RHS; break;
case MCBinaryExpr::LT: Result = LHS < RHS; break;
case MCBinaryExpr::LTE: Result = LHS <= RHS; break;
case MCBinaryExpr::Mod: Result = LHS % RHS; break;
case MCBinaryExpr::Mul: Result = LHS * RHS; break;
case MCBinaryExpr::NE: Result = LHS != RHS; break;
case MCBinaryExpr::Or: Result = LHS | RHS; break;
case MCBinaryExpr::Shl: Result = LHS << RHS; break;
case MCBinaryExpr::Shr: Result = LHS >> RHS; break;
case MCBinaryExpr::Sub: Result = LHS - RHS; break;
case MCBinaryExpr::Xor: Result = LHS ^ RHS; break;
}
Res = MCValue::get(Result);
return true;
}
}
assert(0 && "Invalid assembly expression kind!");
return false;
}
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