diff options
Diffstat (limited to 'lib/Target/X86/X86TargetObjectFile.cpp')
-rw-r--r-- | lib/Target/X86/X86TargetObjectFile.cpp | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/lib/Target/X86/X86TargetObjectFile.cpp b/lib/Target/X86/X86TargetObjectFile.cpp index 709fc97256..bc1064e17f 100644 --- a/lib/Target/X86/X86TargetObjectFile.cpp +++ b/lib/Target/X86/X86TargetObjectFile.cpp @@ -9,6 +9,7 @@ #include "X86TargetObjectFile.h" #include "llvm/IR/Mangler.h" +#include "llvm/IR/Operator.h" #include "llvm/MC/MCContext.h" #include "llvm/MC/MCExpr.h" #include "llvm/MC/MCSectionELF.h" @@ -53,3 +54,54 @@ X86LinuxTargetObjectFile::getDebugThreadLocalSymbol( const MCSymbol *Sym) const { return MCSymbolRefExpr::Create(Sym, MCSymbolRefExpr::VK_DTPOFF, getContext()); } + +const MCExpr * +X86WindowsTargetObjectFile::getExecutableRelativeSymbol(const ConstantExpr *CE, + Mangler *Mang) const { + // We are looking for the difference of two symbols, need a subtraction + // operation. + const SubOperator *Sub = dyn_cast<SubOperator>(CE); + if (!Sub) + return 0; + + // Symbols must first be numbers before we can subtract them, we need to see a + // ptrtoint on both subtraction operands. + const PtrToIntOperator *SubLHS = + dyn_cast<PtrToIntOperator>(Sub->getOperand(0)); + const PtrToIntOperator *SubRHS = + dyn_cast<PtrToIntOperator>(Sub->getOperand(1)); + if (!SubLHS || !SubRHS) + return 0; + + // Our symbols should exist in address space zero, cowardly no-op if + // otherwise. + if (SubLHS->getPointerAddressSpace() != 0 || + SubRHS->getPointerAddressSpace() != 0) + return 0; + + // Both ptrtoint instructions must wrap global variables: + // - Only global variables are eligible for image relative relocations. + // - The subtrahend refers to the special symbol __ImageBase, a global. + const GlobalVariable *GVLHS = + dyn_cast<GlobalVariable>(SubLHS->getPointerOperand()); + const GlobalVariable *GVRHS = + dyn_cast<GlobalVariable>(SubRHS->getPointerOperand()); + if (!GVLHS || !GVRHS) + return 0; + + // We expect __ImageBase to be a global variable without a section, externally + // defined. + // + // It should look something like this: @__ImageBase = external constant i8 + if (GVRHS->isThreadLocal() || GVRHS->getName() != "__ImageBase" || + !GVRHS->hasExternalLinkage() || GVRHS->hasInitializer() || + GVRHS->hasSection()) + return 0; + + // An image-relative, thread-local, symbol makes no sense. + if (GVLHS->isThreadLocal()) + return 0; + + return MCSymbolRefExpr::Create( + getSymbol(*Mang, GVLHS), MCSymbolRefExpr::VK_COFF_IMGREL32, getContext()); +} |