Adding dllimport, dllexport and external weak linkage types.

DLL* linkages got full (I hope) codegeneration support in C & both x86
assembler backends.
External weak linkage added for future use, we don't provide any
codegeneration, etc. support for it.

llvm-svn: 30374

2 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 8324b432e89..609bd94aa1a 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1245,7 +1245,7 @@ static Constant *getVal(std::map<Value*, Constant*> &ComputedValues,
 static bool isSimpleEnoughPointerToCommit(Constant *C) {
   if (GlobalVariable *GV = dyn_cast<GlobalVariable>(C)) {
     if (!GV->hasExternalLinkage() && !GV->hasInternalLinkage())
-      return false;  // do not allow weak/linkonce linkage.
+      return false;  // do not allow weak/linkonce/dllimport/dllexport linkage.
     return !GV->isExternal();  // reject external globals.
   }
   if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C))
@@ -1254,7 +1254,7 @@ static bool isSimpleEnoughPointerToCommit(Constant *C) {
         isa<GlobalVariable>(CE->getOperand(0))) {
       GlobalVariable *GV = cast<GlobalVariable>(CE->getOperand(0));
       if (!GV->hasExternalLinkage() && !GV->hasInternalLinkage())
-        return false;  // do not allow weak/linkonce linkage.
+        return false;  // do not allow weak/linkonce/dllimport/dllexport linkage.
       return GV->hasInitializer() &&
              ConstantFoldLoadThroughGEPConstantExpr(GV->getInitializer(), CE);
     }
diff --git a/llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp b/llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp
index 79cdf28e0a4..9f9c52788bc 100644
--- a/llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/IPO/SimplifyLibCalls.cpp
@@ -178,8 +178,10 @@ public:
         // All the "well-known" functions are external and have external linkage
         // because they live in a runtime library somewhere and were (probably)
         // not compiled by LLVM.  So, we only act on external functions that
-        // have external linkage and non-empty uses.
-        if (!FI->isExternal() || !FI->hasExternalLinkage() || FI->use_empty())
+        // have external or dllimport linkage and non-empty uses.
+        if (!FI->isExternal() ||
+            !(FI->hasExternalLinkage() || FI->hasDLLImportLinkage()) ||
+            FI->use_empty())
           continue;
 
         // Get the optimization class that pertains to this function