[llvm-commits] [llvm] r163853 - in /llvm/trunk: include/llvm/MC/MCMachObjectWriter.h lib/MC/MachObjectWriter.cpp

[Rafael Espíndola]

Can you add a test?

On 13 September 2012 19:11, Jim Grosbach <grosbach at apple.com> wrote:
> Author: grosbach
> Date: Thu Sep 13 18:11:25 2012
> New Revision: 163853
>
> URL: http://llvm.org/viewvc/llvm-project?rev=163853&view=rev
> Log:
> MachO: Correctly mark symbol-difference variables as N_ABS.
>
> .set a, b - c + CONSTANT
> d = b - c + CONSTANT
>
> Both 'a' and 'd' should be marked as absolute symbols (N_ABS).
>
> rdar://12219394
>
> Modified:
>     llvm/trunk/include/llvm/MC/MCMachObjectWriter.h
>     llvm/trunk/lib/MC/MachObjectWriter.cpp
>
> Modified: llvm/trunk/include/llvm/MC/MCMachObjectWriter.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/MC/MCMachObjectWriter.h?rev=163853&r1=163852&r2=163853&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/MC/MCMachObjectWriter.h (original)
> +++ llvm/trunk/include/llvm/MC/MCMachObjectWriter.h Thu Sep 13 18:11:25 2012
> @@ -233,6 +233,8 @@
>    void computeSectionAddresses(const MCAssembler &Asm,
>                                 const MCAsmLayout &Layout);
>
> +  void markAbsoluteVariableSymbols(MCAssembler &Asm,
> +                                   const MCAsmLayout &Layout);
>    void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout);
>
>    virtual bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
>
> Modified: llvm/trunk/lib/MC/MachObjectWriter.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/MachObjectWriter.cpp?rev=163853&r1=163852&r2=163853&view=diff
> ==============================================================================
> --- llvm/trunk/lib/MC/MachObjectWriter.cpp (original)
> +++ llvm/trunk/lib/MC/MachObjectWriter.cpp Thu Sep 13 18:11:25 2012
> @@ -68,6 +68,11 @@
>
>    // If this is a variable, then recursively evaluate now.
>    if (S.isVariable()) {
> +    if (const MCConstantExpr *C =
> +          dyn_cast<const MCConstantExpr>(S.getVariableValue()))
> +      return C->getValue();
> +
> +
>      MCValue Target;
>      if (!S.getVariableValue()->EvaluateAsRelocatable(Target, Layout))
>        report_fatal_error("unable to evaluate offset for variable '" +
> @@ -315,11 +320,7 @@
>
>    // Compute the symbol address.
>    if (Symbol.isDefined()) {
> -    if (Symbol.isAbsolute()) {
> -      Address = cast<MCConstantExpr>(Symbol.getVariableValue())->getValue();
> -    } else {
> -      Address = getSymbolAddress(&Data, Layout);
> -    }
> +    Address = getSymbolAddress(&Data, Layout);
>    } else if (Data.isCommon()) {
>      // Common symbols are encoded with the size in the address
>      // field, and their alignment in the flags.
> @@ -557,6 +558,26 @@
>    }
>  }
>
> +void MachObjectWriter::markAbsoluteVariableSymbols(MCAssembler &Asm,
> +                                                   const MCAsmLayout &Layout) {
> +  for (MCAssembler::symbol_iterator i = Asm.symbol_begin(),
> +                                    e = Asm.symbol_end();
> +      i != e; ++i) {
> +    MCSymbolData &SD = *i;
> +    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)) {
> +      if (Value.getSymA() && Value.getSymB())
> +        const_cast<MCSymbol*>(&SD.getSymbol())->setAbsolute();
> +    }
> +  }
> +}
> +
>  void MachObjectWriter::ExecutePostLayoutBinding(MCAssembler &Asm,
>                                                  const MCAsmLayout &Layout) {
>    computeSectionAddresses(Asm, Layout);
> @@ -564,6 +585,10 @@
>    // Create symbol data for any indirect symbols.
>    BindIndirectSymbols(Asm);
>
> +  // Mark symbol difference expressions in variables (from .set or = directives)
> +  // as absolute.
> +  markAbsoluteVariableSymbols(Asm, Layout);
> +
>    // Compute symbol table information and bind symbol indices.
>    ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData,
>                       UndefinedSymbolData);
>
>
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