Fix pr19645.

The fix itself is fairly simple: move getAccessVariant to MCValue so that we
replace the old weak expression evaluation with the far more general
EvaluateAsRelocatable.

This then requires that EvaluateAsRelocatable stop when it finds a non
trivial reference kind. And that in turn requires the ELF writer to look
harder for weak references.

Last but not least, this found a case where we were being bug by bug
compatible with gas and accepting an invalid input. I reported pr19647
to track it.

llvm-svn: 207920

1 files changed, 18 insertions, 0 deletions

diff --git a/llvm/lib/MC/MCValue.cpp b/llvm/lib/MC/MCValue.cpp
index 21d9e2102e2..9dfc56ef23d 100644
--- a/llvm/lib/MC/MCValue.cpp
+++ b/llvm/lib/MC/MCValue.cpp
@@ -10,6 +10,7 @@
 #include "llvm/MC/MCValue.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
@@ -41,3 +42,20 @@ void MCValue::dump() const {
   print(dbgs(), nullptr);
 }
 #endif
+
+MCSymbolRefExpr::VariantKind MCValue::getAccessVariant() const {
+  const MCSymbolRefExpr *B = getSymB();
+  if (B) {
+    if (B->getKind() != MCSymbolRefExpr::VK_None)
+      llvm_unreachable("unsupported");
+  }
+
+  const MCSymbolRefExpr *A = getSymA();
+  if (!A)
+    return MCSymbolRefExpr::VK_None;
+
+  MCSymbolRefExpr::VariantKind Kind = A->getKind();
+  if (Kind == MCSymbolRefExpr::VK_WEAKREF)
+    return MCSymbolRefExpr::VK_None;
+  return Kind;
+}