[PATCH] D17938: CodeGen: Use PLT relocations for relative references to unnamed_addr functions.

[Peter Collingbourne via llvm-commits]

pcc added inline comments.

================
Comment at: lib/Target/X86/X86TargetObjectFile.cpp:78-91
@@ -77,16 @@
-    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;
-
----------------
majnemer wrote:
> Removing this logic seems problematic, no?
> 
> Won't this fire on `x * __ImageBase` ?
This part of the logic has been moved to `AsmPrinter::lowerConstant`, which will only call `lowerRelativeReference` if the expression is a substraction.

================
Comment at: lib/Target/X86/X86TargetObjectFile.h:44-45
@@ +43,4 @@
+  public:
+    X86ELFTargetObjectFile() {
+      PLTRelativeVariantKind = MCSymbolRefExpr::VK_PLT;
+    }
----------------
majnemer wrote:
> Should this be:
>   X86ELFTargetObjectFile() : PLTRelativeVariantKind(MCSymbolRefExpr::VK_PLT) {}
> 
> ?
No, because `PLTRelativeVariantKind` is a field of a base, so we can't initialize it that way.


http://reviews.llvm.org/D17938