CodeGen: Use PLT relocations for relative references to unnamed_addr functions.
The relative vtable ABI (PR26723) needs PLT relocations to refer to virtual
functions defined in other DSOs. The unnamed_addr attribute means that the
function's address is not significant, so we're allowed to substitute it
with the address of a PLT entry.
Also includes a bonus feature: addends for COFF image-relative references.
Differential Revision: http://reviews.llvm.org/D17938
llvm-svn: 267211
diff --git a/llvm/lib/Target/X86/X86TargetObjectFile.cpp b/llvm/lib/Target/X86/X86TargetObjectFile.cpp
index e72f3a7..d664cff 100644
--- a/llvm/lib/Target/X86/X86TargetObjectFile.cpp
+++ b/llvm/lib/Target/X86/X86TargetObjectFile.cpp
@@ -73,53 +73,30 @@
InitializeELF(TM.Options.UseInitArray);
}
-const MCExpr *X86WindowsTargetObjectFile::getExecutableRelativeSymbol(
- const ConstantExpr *CE, Mangler &Mang, const TargetMachine &TM) const {
- // We are looking for the difference of two symbols, need a subtraction
- // operation.
- const SubOperator *Sub = dyn_cast<SubOperator>(CE);
- if (!Sub)
- return nullptr;
-
- // 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 nullptr;
-
+const MCExpr *X86WindowsTargetObjectFile::lowerRelativeReference(
+ const GlobalValue *LHS, const GlobalValue *RHS, Mangler &Mang,
+ const TargetMachine &TM) const {
// Our symbols should exist in address space zero, cowardly no-op if
// otherwise.
- if (SubLHS->getPointerAddressSpace() != 0 ||
- SubRHS->getPointerAddressSpace() != 0)
+ if (LHS->getType()->getPointerAddressSpace() != 0 ||
+ RHS->getType()->getPointerAddressSpace() != 0)
return nullptr;
// Both ptrtoint instructions must wrap global objects:
// - Only global variables are eligible for image relative relocations.
// - The subtrahend refers to the special symbol __ImageBase, a GlobalVariable.
- const auto *GOLHS = dyn_cast<GlobalObject>(SubLHS->getPointerOperand());
- const auto *GVRHS = dyn_cast<GlobalVariable>(SubRHS->getPointerOperand());
- if (!GOLHS || !GVRHS)
- return nullptr;
-
// 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())
+ if (!isa<GlobalObject>(LHS) || !isa<GlobalVariable>(RHS) ||
+ LHS->isThreadLocal() || RHS->isThreadLocal() ||
+ RHS->getName() != "__ImageBase" || !RHS->hasExternalLinkage() ||
+ cast<GlobalVariable>(RHS)->hasInitializer() || RHS->hasSection())
return nullptr;
- // An image-relative, thread-local, symbol makes no sense.
- if (GOLHS->isThreadLocal())
- return nullptr;
-
- return MCSymbolRefExpr::create(TM.getSymbol(GOLHS, Mang),
- MCSymbolRefExpr::VK_COFF_IMGREL32,
- getContext());
+ return MCSymbolRefExpr::create(
+ TM.getSymbol(LHS, Mang), MCSymbolRefExpr::VK_COFF_IMGREL32, getContext());
}
static std::string APIntToHexString(const APInt &AI) {