Add strncpy libcall creator. Use it when it should be used.

llvm-svn: 98219

Author: echristo

llvm/include/llvm/Transforms/Utils/BuildLibCalls.h

@@ -39,6 +39,11 @@ namespace llvm {
   Value *EmitStrCpy(Value *Dst, Value *Src, IRBuilder<> &B,
                     const TargetData *TD);
 
+  /// EmitStrNCpy - Emit a call to the strncpy function to the builder, for the
+  /// specified pointer arguments and length.
+  Value *EmitStrNCpy(Value *Dst, Value *Src, Value *Len, IRBuilder<> &B,
+                    const TargetData *TD);
+  
   /// EmitMemCpy - Emit a call to the memcpy function to the builder.  This
   /// always expects that the size has type 'intptr_t' and Dst/Src are pointers.
   Value *EmitMemCpy(Value *Dst, Value *Src, Value *Len,

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -850,7 +850,8 @@ Instruction *InstCombiner::tryOptimizeCall(CallInst *CI, const TargetData *TD) {
       return 0;
     if (SizeCI->isAllOnesValue() ||
         SizeCI->getZExtValue() <= SizeArg->getZExtValue()) {
-      Value *Ret = EmitStrCpy(CI->getOperand(1), CI->getOperand(2), B, TD);
+      Value *Ret = EmitStrNCpy(CI->getOperand(1), CI->getOperand(2),
+                               CI->getOperand(3), B, TD);
       return ReplaceInstUsesWith(*CI, Ret);
     }
     return 0; 

llvm/lib/Transforms/Utils/BuildLibCalls.cpp

@@ -87,6 +87,26 @@ Value *llvm::EmitStrCpy(Value *Dst, Value *Src, IRBuilder<> &B,
   return CI;
 }
 
+/// EmitStrNCpy - Emit a call to the strcpy function to the builder, for the
+/// specified pointer arguments.
+Value *llvm::EmitStrNCpy(Value *Dst, Value *Src, Value *Len,
+                         IRBuilder<> &B, const TargetData *TD) {
+  Module *M = B.GetInsertBlock()->getParent()->getParent();
+  AttributeWithIndex AWI[2];
+  AWI[0] = AttributeWithIndex::get(2, Attribute::NoCapture);
+  AWI[1] = AttributeWithIndex::get(~0u, Attribute::NoUnwind);
+  const Type *I8Ptr = B.getInt8PtrTy();
+  Value *StrNCpy = M->getOrInsertFunction("strncpy", AttrListPtr::get(AWI, 2),
+                                         I8Ptr, I8Ptr, I8Ptr,
+                                         Len->getType(), NULL);
+  CallInst *CI = B.CreateCall3(StrNCpy, CastToCStr(Dst, B), CastToCStr(Src, B),
+                               Len, "strncpy");
+  if (const Function *F = dyn_cast<Function>(StrNCpy->stripPointerCasts()))
+    CI->setCallingConv(F->getCallingConv());
+  return CI;
+}
+
+
 /// EmitMemCpy - Emit a call to the memcpy function to the builder.  This always
 /// expects that the size has type 'intptr_t' and Dst/Src are pointers.
 Value *llvm::EmitMemCpy(Value *Dst, Value *Src, Value *Len,