Revert "Move dllimport name mangling to IR mangler."

This reverts commit r239437.

This broke clang-cl self-hosts. We'd end up calling the __imp_ symbol
directly instead of using it to do an indirect function call.

llvm-svn: 239502

llvm/lib/IR/Mangler.cpp

@@ -112,10 +112,6 @@ void Mangler::getNameWithPrefix(raw_ostream &OS, const GlobalValue *GV,
     return;
   }
 
-  // dllimported symbols have a __imp_ prefix.
-  if (GV->hasDLLImportStorageClass())
-    OS << "__imp_";
-
   StringRef Name = GV->getName();
   char Prefix = DL->getGlobalPrefix();
 

llvm/lib/Target/ARM/ARMAsmPrinter.cpp

@@ -851,7 +851,16 @@ MCSymbol *ARMAsmPrinter::GetARMGVSymbol(const GlobalValue *GV,
   } else if (Subtarget->isTargetCOFF()) {
     assert(Subtarget->isTargetWindows() &&
            "Windows is the only supported COFF target");
-    return getSymbol(GV);
+
+    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/lib/Target/ARM/ARMISelLowering.cpp

@@ -1751,8 +1751,11 @@ ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
     } else if (Subtarget->isTargetCOFF()) {
       assert(Subtarget->isTargetWindows() &&
              "Windows is the only supported COFF target");
+      unsigned TargetFlags = GV->hasDLLImportStorageClass()
+                                 ? ARMII::MO_DLLIMPORT
+                                 : ARMII::MO_NO_FLAG;
       Callee = DAG.getTargetGlobalAddress(GV, dl, getPointerTy(), /*Offset=*/0,
-                                          ARMII::MO_NO_FLAG);
+                                          TargetFlags);
       if (GV->hasDLLImportStorageClass())
         Callee = DAG.getLoad(getPointerTy(), dl, DAG.getEntryNode(),
                              DAG.getNode(ARMISD::Wrapper, dl, getPointerTy(),
@@ -2643,6 +2646,8 @@ SDValue ARMTargetLowering::LowerGlobalAddressWindows(SDValue Op,
          "Windows on ARM expects to use movw/movt");
 
   const GlobalValue *GV = cast<GlobalAddressSDNode>(Op)->getGlobal();
+  const ARMII::TOF TargetFlags =
+    (GV->hasDLLImportStorageClass() ? ARMII::MO_DLLIMPORT : ARMII::MO_NO_FLAG);
   EVT PtrVT = getPointerTy();
   SDValue Result;
   SDLoc DL(Op);
@@ -2653,7 +2658,7 @@ SDValue ARMTargetLowering::LowerGlobalAddressWindows(SDValue Op,
   // operands, expand this into two nodes.
   Result = DAG.getNode(ARMISD::Wrapper, DL, PtrVT,
                        DAG.getTargetGlobalAddress(GV, DL, PtrVT, /*Offset=*/0,
-                                                  ARMII::MO_NO_FLAG));
+                                                  TargetFlags));
   if (GV->hasDLLImportStorageClass())
     Result = DAG.getLoad(PtrVT, DL, DAG.getEntryNode(), Result,
                          MachinePointerInfo::getGOT(), false, false, false, 0);

llvm/lib/Target/ARM/MCTargetDesc/ARMBaseInfo.h

@@ -297,12 +297,17 @@ namespace ARMII {
     /// just that part of the flag set.
     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
     /// as a non-lazy-ptr indirect symbol (i.e. "L_FOO$non_lazy_ptr"). Can be
     /// combined with MO_LO16, MO_HI16 or MO_NO_FLAG (in a constant-pool, for
     /// example).
-    MO_NONLAZY = 0x40,
+    MO_NONLAZY = 0x80,
 
     // It's undefined behaviour if an enum overflows the range between its
     // smallest and largest values, but since these are |ed together, it can

llvm/lib/Target/X86/X86AsmPrinter.cpp

@@ -94,6 +94,11 @@ static void printSymbolOperand(X86AsmPrinter &P, const MachineOperand &MO,
     else
       GVSym = P.getSymbol(GV);
 
+    // Handle dllimport linkage.
+    if (MO.getTargetFlags() == X86II::MO_DLLIMPORT)
+      GVSym =
+          P.OutContext.getOrCreateSymbol(Twine("__imp_") + GVSym->getName());
+
     if (MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY ||
         MO.getTargetFlags() == X86II::MO_DARWIN_NONLAZY_PIC_BASE) {
       MCSymbol *Sym = P.getSymbolWithGlobalValueBase(GV, "$non_lazy_ptr");

llvm/lib/Target/X86/X86MCInstLower.cpp

@@ -133,6 +133,10 @@ GetSymbolFromOperand(const MachineOperand &MO) const {
   StringRef Suffix;
 
   switch (MO.getTargetFlags()) {
+  case X86II::MO_DLLIMPORT:
+    // Handle dllimport linkage.
+    Name += "__imp_";
+    break;
   case X86II::MO_DARWIN_STUB:
     Suffix = "$stub";
     break;

llvm/test/Object/dllimport.ll

@@ -1,17 +0,0 @@
-; RUN: llvm-as %s -o - | llvm-nm - | FileCheck %s
-
-target datalayout = "e-m:w-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-windows-msvc"
-
-; CHECK: U __imp_f
-; CHECK: U __imp_v
-; CHECK: T g
-
-declare dllimport void @f()
-@v = external dllimport global i32
-
-define void @g() {
-  call void @f()
-  store i32 42, i32* @v
-  ret void
-}