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Fixed version of 122160 (the previous one would fold undefined symbols).

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122167 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2010-12-19 04:18:56 +00:00
parent af0e6ce80f
commit c5b0e44aca
1 changed files with 52 additions and 50 deletions
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102
lib/MC/MCExpr.cpp
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@ -293,22 +293,55 @@ bool MCExpr::EvaluateAsAbsolute(int64_t &Res, const MCAssembler *Asm,
}
/// \brief Helper method for \see EvaluateSymbolAdd().
static void AttemptToFoldSymbolOffsetDifference(const MCAsmLayout *Layout,
static void AttemptToFoldSymbolOffsetDifference(const MCAssembler *Asm,
const MCAsmLayout *Layout,
const SectionAddrMap *Addrs,
bool InSet,
const MCSymbolRefExpr *&A,
const MCSymbolRefExpr *&B,
int64_t &Addend) {
const MCAssembler &Asm = Layout->getAssembler();
if (!A || !B)
return;
if (A && B &&
Asm.getWriter().IsSymbolRefDifferenceFullyResolved(Asm, A, B, false)) {
// Eagerly evaluate.
Addend += (Layout->getSymbolOffset(&Asm.getSymbolData(A->getSymbol())) -
Layout->getSymbolOffset(&Asm.getSymbolData(B->getSymbol())));
const MCSymbol &SA = A->getSymbol();
const MCSymbol &SB = B->getSymbol();
if (SA.isUndefined() || SB.isUndefined())
return;
if (!Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B, InSet))
return;
MCSymbolData &AD = Asm->getSymbolData(SA);
MCSymbolData &BD = Asm->getSymbolData(SB);
if (AD.getFragment() == BD.getFragment()) {
Addend += (AD.getOffset() - BD.getOffset());
// Clear the symbol expr pointers to indicate we have folded these
// operands.
A = B = 0;
return;
}
if (!Layout)
return;
const MCSectionData &SecA = *AD.getFragment()->getParent();
const MCSectionData &SecB = *BD.getFragment()->getParent();
if ((&SecA != &SecB) && !Addrs)
return;
// Eagerly evaluate.
Addend += (Layout->getSymbolOffset(&Asm->getSymbolData(A->getSymbol())) -
Layout->getSymbolOffset(&Asm->getSymbolData(B->getSymbol())));
if (Addrs && (&SecA != &SecB))
Addend += (Addrs->lookup(&SecA) - Addrs->lookup(&SecB));
// 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.
@ -346,8 +379,11 @@ static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
// Fold the result constant immediately.
int64_t Result_Cst = LHS_Cst + RHS_Cst;
assert((!Layout || Asm) &&
"Must have an assembler object if layout is given!");
// If we have a layout, we can fold resolved differences.
if (Layout) {
if (Asm) {
// 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).
@ -358,10 +394,14 @@ static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
// (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);
AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, LHS_B,
Result_Cst);
AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, LHS_A, RHS_B,
Result_Cst);
AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, LHS_B,
Result_Cst);
AttemptToFoldSymbolOffsetDifference(Asm, Layout, Addrs, InSet, RHS_A, RHS_B,
Result_Cst);
}
// We can't represent the addition or subtraction of two symbols.
@ -378,44 +418,6 @@ static bool EvaluateSymbolicAdd(const MCAssembler *Asm,
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) &&
"Must have an assembler object if layout is given!");
if (Asm && A && B) {
if (A->getSymbol().isDefined() && B->getSymbol().isDefined() &&
Asm->getWriter().IsSymbolRefDifferenceFullyResolved(*Asm, A, B,
InSet)) {
MCSymbolData &AD = Asm->getSymbolData(A->getSymbol());
MCSymbolData &BD = Asm->getSymbolData(B->getSymbol());
if (AD.getFragment() == BD.getFragment()) {
Res = MCValue::get(+ AD.getOffset()
- BD.getOffset()
+ Result_Cst);
return true;
}
if (Layout) {
const MCSectionData &SecA = *AD.getFragment()->getParent();
const MCSectionData &SecB = *BD.getFragment()->getParent();
int64_t Val = + Layout->getSymbolOffset(&AD)
- Layout->getSymbolOffset(&BD)
+ Result_Cst;
if (&SecA != &SecB) {
if (!Addrs)
return false;
Val += Addrs->lookup(&SecA);
Val -= Addrs->lookup(&SecB);
}
Res = MCValue::get(Val);
return true;
}
}
}
Res = MCValue::get(A, B, Result_Cst);
return true;
}