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

4 files changed, 7 insertions, 6 deletions

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
index a6f7258e651..1c842633f43 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMELFObjectWriter.cpp
@@ -74,7 +74,7 @@ unsigned ARMELFObjectWriter::GetRelocType(const MCValue &Target,
 unsigned ARMELFObjectWriter::GetRelocTypeInner(const MCValue &Target,
                                                const MCFixup &Fixup,
                                                bool IsPCRel) const  {
-  MCSymbolRefExpr::VariantKind Modifier = Fixup.getAccessVariant();
+  MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
 
   unsigned Type = 0;
   if (IsPCRel) {
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
index d19f6a0214d..cd3b4f45359 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
@@ -41,11 +41,12 @@ PPCELFObjectWriter::PPCELFObjectWriter(bool Is64Bit, uint8_t OSABI)
 PPCELFObjectWriter::~PPCELFObjectWriter() {
 }
 
-static MCSymbolRefExpr::VariantKind getAccessVariant(const MCFixup &Fixup) {
+static MCSymbolRefExpr::VariantKind getAccessVariant(const MCValue &Target,
+                                                     const MCFixup &Fixup) {
   const MCExpr *Expr = Fixup.getValue();
 
   if (Expr->getKind() != MCExpr::Target)
-    return Fixup.getAccessVariant();
+    return Target.getAccessVariant();
 
   switch (cast<PPCMCExpr>(Expr)->getKind()) {
   case PPCMCExpr::VK_PPC_None:
@@ -72,7 +73,7 @@ unsigned PPCELFObjectWriter::getRelocTypeInner(const MCValue &Target,
                                                const MCFixup &Fixup,
                                                bool IsPCRel) const
 {
-  MCSymbolRefExpr::VariantKind Modifier = getAccessVariant(Fixup);
+  MCSymbolRefExpr::VariantKind Modifier = getAccessVariant(Target, Fixup);
 
   // determine the type of the relocation
   unsigned Type;
diff --git a/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCObjectWriter.cpp b/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCObjectWriter.cpp
index 54c6987ca2f..c6a18165889 100644
--- a/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCObjectWriter.cpp
+++ b/llvm/lib/Target/SystemZ/MCTargetDesc/SystemZMCObjectWriter.cpp
@@ -82,7 +82,7 @@ static unsigned getPLTReloc(unsigned Kind) {
 unsigned SystemZObjectWriter::GetRelocType(const MCValue &Target,
                                            const MCFixup &Fixup,
                                            bool IsPCRel) const {
-  MCSymbolRefExpr::VariantKind Modifier = Fixup.getAccessVariant();
+  MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
   unsigned Kind = Fixup.getKind();
   switch (Modifier) {
   case MCSymbolRefExpr::VK_None:
diff --git a/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp b/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp
index c4a1af86157..3fdec874cba 100644
--- a/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp
+++ b/llvm/lib/Target/X86/MCTargetDesc/X86ELFObjectWriter.cpp
@@ -43,7 +43,7 @@ unsigned X86ELFObjectWriter::GetRelocType(const MCValue &Target,
                                           bool IsPCRel) const {
   // determine the type of the relocation
 
-  MCSymbolRefExpr::VariantKind Modifier = Fixup.getAccessVariant();
+  MCSymbolRefExpr::VariantKind Modifier = Target.getAccessVariant();
   unsigned Type;
   if (getEMachine() == ELF::EM_X86_64) {
     if (IsPCRel) {