From 220a0448887e36265efcd590b372f41dec4c7359 Mon Sep 17 00:00:00 2001
From: Saleem Abdulrasool <compnerd@compnerd.org>
Date: Mon, 7 Jul 2014 05:18:30 +0000
Subject: [PATCH] ARM: correctly mangle dllimport symbols

Add support for tracking DLLImport storage class information on a per symbol
basis in the ARM instruction selection.  Use that information to correctly
mangle the symbol (dllimport symbols are referenced via *__imp_<name>).

llvm-svn: 212430
---
 llvm/lib/Target/ARM/ARMAsmPrinter.cpp          | 50 +++++++++++++++++---------
 llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h |  7 +++-
 2 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
index 33ad298..28d2610 100644
--- a/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
+++ b/llvm/lib/Target/ARM/ARMAsmPrinter.cpp
@@ -795,23 +795,41 @@ getModifierVariantKind(ARMCP::ARMCPModifier Modifier) {
 
 MCSymbol *ARMAsmPrinter::GetARMGVSymbol(const GlobalValue *GV,
                                         unsigned char TargetFlags) {
-  bool isIndirect = Subtarget->isTargetMachO() &&
-    (TargetFlags & ARMII::MO_NONLAZY) &&
-    Subtarget->GVIsIndirectSymbol(GV, TM.getRelocationModel());
-  if (!isIndirect)
-    return getSymbol(GV);
+  if (Subtarget->isTargetMachO()) {
+    bool IsIndirect = (TargetFlags & ARMII::MO_NONLAZY) &&
+      Subtarget->GVIsIndirectSymbol(GV, TM.getRelocationModel());
+
+    if (!IsIndirect)
+      return getSymbol(GV);
 
-  // FIXME: Remove this when Darwin transition to @GOT like syntax.
-  MCSymbol *MCSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
-  MachineModuleInfoMachO &MMIMachO =
-    MMI->getObjFileInfo<MachineModuleInfoMachO>();
-  MachineModuleInfoImpl::StubValueTy &StubSym =
-    GV->hasHiddenVisibility() ? MMIMachO.getHiddenGVStubEntry(MCSym) :
-    MMIMachO.getGVStubEntry(MCSym);
-  if (!StubSym.getPointer())
-    StubSym = MachineModuleInfoImpl::
-      StubValueTy(getSymbol(GV), !GV->hasInternalLinkage());
-  return MCSym;
+    // FIXME: Remove this when Darwin transition to @GOT like syntax.
+    MCSymbol *MCSym = getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");
+    MachineModuleInfoMachO &MMIMachO =
+      MMI->getObjFileInfo<MachineModuleInfoMachO>();
+    MachineModuleInfoImpl::StubValueTy &StubSym =
+      GV->hasHiddenVisibility() ? MMIMachO.getHiddenGVStubEntry(MCSym)
+                                : MMIMachO.getGVStubEntry(MCSym);
+    if (!StubSym.getPointer())
+      StubSym = MachineModuleInfoImpl::StubValueTy(getSymbol(GV),
+                                                   !GV->hasInternalLinkage());
+    return MCSym;
+  } else if (Subtarget->isTargetCOFF()) {
+    assert(Subtarget->isTargetWindows() &&
+           "Windows is the only supported COFF target");
+
+    bool IsIndirect = (TargetFlags & ARMII::MO_DLLIMPORT);
+    if (!IsIndirect)
+      return getSymbol(GV);
+
+    SmallString<128> Name;
+    Name = "__imp_";
+    getNameWithPrefix(Name, GV);
+
+    return OutContext.GetOrCreateSymbol(Name);
+  } else if (Subtarget->isTargetELF()) {
+    return getSymbol(GV);
+  }
+  llvm_unreachable("unexpected target");
 }
 
 void ARMAsmPrinter::
diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h b/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h
index 42a1cbb..1686d76 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h
@@ -295,7 +295,12 @@ namespace ARMII {
 
     /// MO_OPTION_MASK - Most flags are mutually exclusive; this mask selects
     /// just that part of the flag set.
-    MO_OPTION_MASK = 0x7f,
+    MO_OPTION_MASK = 0x3f,
+
+    /// MO_DLLIMPORT - On a symbol operand, this represents that the reference
+    /// to the symbol is for an import stub.  This is used for DLL import
+    /// storage class indication on Windows.
+    MO_DLLIMPORT = 0x40,
 
     /// MO_NONLAZY - This is an independent flag, on a symbol operand "FOO" it
     /// represents a symbol which, if indirect, will get special Darwin mangling
-- 
2.7.4