[MinGW] [ARM] Add stubs for potential automatic dllimported variables

The runtime pseudo relocations can't handle the ARM format embedded
addresses in movw/movt pairs. By using stubs, the potentially
dllimported addresses can be touched up by the runtime pseudo relocation
framework.

Differential Revision: https://reviews.llvm.org/D51450

llvm-svn: 341176

4 files changed, 33 insertions, 6 deletions

diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index a19584c7d40..17dd7ee7b81 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -827,15 +827,31 @@ MCSymbol *ARMAsmPrinter::GetARMGVSymbol(const GlobalValue *GV,
     assert(Subtarget->isTargetWindows() &&
            "Windows is the only supported COFF target");
 
-    bool IsIndirect = (TargetFlags & ARMII::MO_DLLIMPORT);
+    bool IsIndirect =
+        (TargetFlags & (ARMII::MO_DLLIMPORT | ARMII::MO_COFFSTUB));
     if (!IsIndirect)
       return getSymbol(GV);
 
     SmallString<128> Name;
-    Name = "__imp_";
+    if (TargetFlags & ARMII::MO_DLLIMPORT)
+      Name = "__imp_";
+    else if (TargetFlags & ARMII::MO_COFFSTUB)
+      Name = ".refptr.";
     getNameWithPrefix(Name, GV);
 
-    return OutContext.getOrCreateSymbol(Name);
+    MCSymbol *MCSym = OutContext.getOrCreateSymbol(Name);
+
+    if (TargetFlags & ARMII::MO_COFFSTUB) {
+      MachineModuleInfoCOFF &MMICOFF =
+          MMI->getObjFileInfo<MachineModuleInfoCOFF>();
+      MachineModuleInfoImpl::StubValueTy &StubSym =
+          MMICOFF.getGVStubEntry(MCSym);
+
+      if (!StubSym.getPointer())
+        StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV), true);
+    }
+
+    return MCSym;
   } else if (Subtarget->isTargetELF()) {
     return getSymbol(GV);
   }
diff --git a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 1b626ff5580..9a4614c1686 100644
--- a/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -5081,6 +5081,7 @@ ARMBaseInstrInfo::getSerializableBitmaskMachineOperandTargetFlags() const {
   using namespace ARMII;
 
   static const std::pair<unsigned, const char *> TargetFlags[] = {
+      {MO_COFFSTUB, "arm-coffstub"},
       {MO_GOT, "arm-got"},
       {MO_SBREL, "arm-sbrel"},
       {MO_DLLIMPORT, "arm-dllimport"},
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index a6ce9615b8c..26f23c55698 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -3318,8 +3318,13 @@ SDValue ARMTargetLowering::LowerGlobalAddressWindows(SDValue Op,
          "ROPI/RWPI not currently supported for Windows");
 
   const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
-  const ARMII::TOF TargetFlags =
-    (GV->hasDLLImportStorageClass() ? ARMII::MO_DLLIMPORT : ARMII::MO_NO_FLAG);
+  ARMII::TOF TargetFlags = ARMII::MO_NO_FLAG;
+  if (GV->hasDLLImportStorageClass())
+    TargetFlags = ARMII::MO_DLLIMPORT;
+  else if (Subtarget->getTargetTriple().isWindowsGNUEnvironment() &&
+           !GV->isDSOLocal() && GV->isDeclarationForLinker() &&
+           isa<GlobalVariable>(GV))
+    TargetFlags = ARMII::MO_COFFSTUB;
   EVT PtrVT = getPointerTy(DAG.getDataLayout());
   SDValue Result;
   SDLoc DL(Op);
@@ -3331,7 +3336,7 @@ SDValue ARMTargetLowering::LowerGlobalAddressWindows(SDValue Op,
   Result = DAG.getNode(ARMISD::Wrapper, DL, PtrVT,
                        DAG.getTargetGlobalAddress(GV, DL, PtrVT, /*Offset=*/0,
                                                   TargetFlags));
-  if (GV->hasDLLImportStorageClass())
+  if (TargetFlags & (ARMII::MO_DLLIMPORT | ARMII::MO_COFFSTUB))
     Result = DAG.getLoad(PtrVT, DL, DAG.getEntryNode(), Result,
                          MachinePointerInfo::getGOT(DAG.getMachineFunction()));
   return Result;
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h
index b918006fe9e..cdadf198e90 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h
@@ -246,6 +246,11 @@ namespace ARMII {
     /// just that part of the flag set.
     MO_OPTION_MASK = 0x3,
 
+    /// MO_COFFSTUB - On a symbol operand "FOO", this indicates that the
+    /// reference is actually to the ".refptrp.FOO" symbol.  This is used for
+    /// stub symbols on windows.
+    MO_COFFSTUB = 0x4,
+
     /// MO_GOT - On a symbol operand, this represents a GOT relative relocation.
     MO_GOT = 0x8,