/* *** */
-bool MCExpr::EvaluateAsAbsolute(int64_t &Res) const {
- return EvaluateAsAbsolute(Res, 0, 0, 0);
-}
-
-bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
- const MCAsmLayout &Layout) const {
- return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, 0);
-}
-
-bool MCExpr::EvaluateAsAbsolute(int64_t &Res,
- const MCAsmLayout &Layout,
- const SectionAddrMap &Addrs) const {
- return EvaluateAsAbsolute(Res, &Layout.getAssembler(), &Layout, &Addrs);
-}
-
-bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler &Asm) const {
- return EvaluateAsAbsolute(Res, &Asm, 0, 0);
-}
-
-bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
- const MCAsmLayout *Layout,
+bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAsmLayout *Layout,
const SectionAddrMap *Addrs) const {
MCValue Value;
return true;
}
- if (!EvaluateAsRelocatableImpl(Value, Asm, Layout, Addrs, Addrs) ||
+ // FIXME: This use of Addrs is wrong, right?
+ if (!EvaluateAsRelocatableImpl(Value, Layout, Addrs, /*InSet=*/Addrs) ||
!Value.isAbsolute()) {
// EvaluateAsAbsolute is defined to return the "current value" of
// the expression if we are given a Layout object, even in cases
return true;
}
-static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
- const MCAsmLayout *Layout,
+/// \brief Helper method for \see EvaluateSymbolAdd().
+static void AttemptToFoldSymbolOffsetDifference(const MCAsmLayout *Layout,
+ const MCSymbolRefExpr *&A,
+ const MCSymbolRefExpr *&B,
+ int64_t &Addend) {
+ const MCAssembler &Asm = Layout->getAssembler();
+
+ if (A && B &&
+ Asm.getWriter().IsSymbolRefDifferenceFullyResolved(Asm, A, B)) {
+ // Eagerly evaluate.
+ Addend += (Layout->getSymbolOffset(&Asm.getSymbolData(A->getSymbol())) -
+ Layout->getSymbolOffset(&Asm.getSymbolData(B->getSymbol())));
+
+ // Clear the symbol expr pointers to indicate we have folded these
+ // operands.
+ A = B = 0;
+ }
+}
+
+/// \brief Evaluate the result of an add between (conceptually) two MCValues.
+///
+/// This routine conceptually attempts to construct an MCValue:
+/// Result = (Result_A - Result_B + Result_Cst)
+/// from two MCValue's LHS and RHS where
+/// Result = LHS + RHS
+/// and
+/// Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
+///
+/// This routine attempts to aggresively fold the operands such that the result
+/// is representable in an MCValue, but may not always succeed.
+///
+/// \returns True on success, false if the result is not representable in an
+/// MCValue.
+static bool EvaluateSymbolicAdd(const MCAsmLayout *Layout,
const SectionAddrMap *Addrs,
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))
+ // FIXME: This routine (and other evaluation parts) are *incredibly* sloppy
+ // about dealing with modifiers. This will ultimately bite us, one day.
+ const MCSymbolRefExpr *LHS_A = LHS.getSymA();
+ const MCSymbolRefExpr *LHS_B = LHS.getSymB();
+ int64_t LHS_Cst = LHS.getConstant();
+
+ // Fold the result constant immediately.
+ int64_t Result_Cst = LHS_Cst + RHS_Cst;
+
+ // If we have a layout, we can fold resolved differences.
+ if (Layout) {
+ // First, fold out any differences which are fully resolved. By
+ // reassociating terms in
+ // Result = (LHS_A - LHS_B + LHS_Cst) + (RHS_A - RHS_B + RHS_Cst).
+ // we have the four possible differences:
+ // (LHS_A - LHS_B),
+ // (LHS_A - RHS_B),
+ // (RHS_A - LHS_B),
+ // (RHS_A - RHS_B).
+ // Since we are attempting to be as aggresive as possible about folding, we
+ // attempt to evaluate each possible alternative.
+ AttemptToFoldSymbolOffsetDifference(Layout, LHS_A, LHS_B, Result_Cst);
+ AttemptToFoldSymbolOffsetDifference(Layout, LHS_A, RHS_B, Result_Cst);
+ AttemptToFoldSymbolOffsetDifference(Layout, RHS_A, LHS_B, Result_Cst);
+ AttemptToFoldSymbolOffsetDifference(Layout, RHS_A, RHS_B, Result_Cst);
+ }
+
+ // We can't represent the addition or subtraction of two symbols.
+ if ((LHS_A && RHS_A) || (LHS_B && 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;
- }
+ // At this point, we have at most one additive symbol and one subtractive
+ // symbol -- find them.
+ const MCSymbolRefExpr *A = LHS_A ? LHS_A : RHS_A;
+ const MCSymbolRefExpr *B = LHS_B ? LHS_B : RHS_B;
+
+ // If we have a negated symbol, then we must have also have a non-negated
+ // symbol in order to encode the expression.
+ if (B && !A)
+ return false;
// Absolutize symbol differences between defined symbols when we have a
// layout object and the target requests it.
-
- assert(!(Layout && !Asm));
-
- if (Asm && A && B) {
+ if (Layout && A && B) {
+ const MCAssembler &Asm = Layout->getAssembler();
const MCSymbol &SA = A->getSymbol();
const MCSymbol &SB = B->getSymbol();
- const MCObjectFormat &F = Asm->getBackend().getObjectFormat();
+ const MCObjectFormat &F = Asm.getBackend().getObjectFormat();
if (SA.isDefined() && SB.isDefined() && F.isAbsolute(InSet, SA, SB)) {
- MCSymbolData &AD = Asm->getSymbolData(A->getSymbol());
- MCSymbolData &BD = Asm->getSymbolData(B->getSymbol());
+ MCSymbolData &AD = Asm.getSymbolData(A->getSymbol());
+ MCSymbolData &BD = Asm.getSymbolData(B->getSymbol());
if (AD.getFragment() == BD.getFragment()) {
Res = MCValue::get(+ AD.getOffset()
- BD.getOffset()
- + LHS.getConstant()
- + RHS_Cst);
+ + Result_Cst);
return true;
}
const MCSectionData &SecB = *BD.getFragment()->getParent();
int64_t Val = + Layout->getSymbolOffset(&AD)
- Layout->getSymbolOffset(&BD)
- + LHS.getConstant()
- + RHS_Cst;
+ + Result_Cst;
if (&SecA != &SecB) {
if (!Addrs)
return false;
}
}
- Res = MCValue::get(A, B, LHS.getConstant() + RHS_Cst);
+ Res = MCValue::get(A, B, Result_Cst);
return true;
}
-bool MCExpr::EvaluateAsRelocatable(MCValue &Res,
- const MCAsmLayout *Layout) const {
- if (Layout)
- return EvaluateAsRelocatableImpl(Res, &Layout->getAssembler(), Layout,
- 0, false);
- else
- return EvaluateAsRelocatableImpl(Res, 0, 0, 0, false);
-}
-
bool MCExpr::EvaluateAsRelocatableImpl(MCValue &Res,
- const MCAssembler *Asm,
const MCAsmLayout *Layout,
const SectionAddrMap *Addrs,
bool InSet) const {
// Evaluate recursively if this is a variable.
if (Sym.isVariable() && SRE->getKind() == MCSymbolRefExpr::VK_None) {
- bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Asm,
- Layout,
- Addrs,
- true);
+ bool Ret = Sym.getVariableValue()->EvaluateAsRelocatableImpl(Res, Layout,
+ Addrs, true);
// If we failed to simplify this to a constant, let the target
// handle it.
if (Ret && !Res.getSymA() && !Res.getSymB())
const MCUnaryExpr *AUE = cast<MCUnaryExpr>(this);
MCValue Value;
- if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Asm, Layout,
+ if (!AUE->getSubExpr()->EvaluateAsRelocatableImpl(Value, Layout,
Addrs, InSet))
return false;
const MCBinaryExpr *ABE = cast<MCBinaryExpr>(this);
MCValue LHSValue, RHSValue;
- if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Asm, Layout,
+ if (!ABE->getLHS()->EvaluateAsRelocatableImpl(LHSValue, Layout,
Addrs, InSet) ||
- !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Asm, Layout,
+ !ABE->getRHS()->EvaluateAsRelocatableImpl(RHSValue, Layout,
Addrs, InSet))
return false;
return false;
case MCBinaryExpr::Sub:
// Negate RHS and add.
- return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
+ return EvaluateSymbolicAdd(Layout, Addrs, InSet, LHSValue,
RHSValue.getSymB(), RHSValue.getSymA(),
-RHSValue.getConstant(),
Res);
case MCBinaryExpr::Add:
- return EvaluateSymbolicAdd(Asm, Layout, Addrs, InSet, LHSValue,
+ return EvaluateSymbolicAdd(Layout, Addrs, InSet, LHSValue,
RHSValue.getSymA(), RHSValue.getSymB(),
RHSValue.getConstant(),
Res);
projects / oota-llvm.git / blobdiff