+namespace {
+class CodeGenPrepareFortifiedLibCalls : public SimplifyFortifiedLibCalls {
+protected:
+ void replaceCall(Value *With) {
+ CI->replaceAllUsesWith(With);
+ CI->eraseFromParent();
+ }
+ bool isFoldable(unsigned SizeCIOp, unsigned, bool) const {
+ if (ConstantInt *SizeCI =
+ dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp)))
+ return SizeCI->isAllOnesValue();
+ return false;
+ }
+};
+} // end anonymous namespace
+
+bool CodeGenPrepare::OptimizeCallInst(CallInst *CI) {
+ // Lower all uses of llvm.objectsize.*
+ IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
+ if (II && II->getIntrinsicID() == Intrinsic::objectsize) {
+ bool Min = (cast<ConstantInt>(II->getArgOperand(1))->getZExtValue() == 1);
+ const Type *ReturnTy = CI->getType();
+ Constant *RetVal = ConstantInt::get(ReturnTy, Min ? 0 : -1ULL);
+ CI->replaceAllUsesWith(RetVal);
+ CI->eraseFromParent();
+ return true;
+ }
+
+ // From here on out we're working with named functions.
+ if (CI->getCalledFunction() == 0) return false;
+
+ // We'll need TargetData from here on out.
+ const TargetData *TD = TLI ? TLI->getTargetData() : 0;
+ if (!TD) return false;
+
+ // Lower all default uses of _chk calls. This is very similar
+ // to what InstCombineCalls does, but here we are only lowering calls
+ // that have the default "don't know" as the objectsize. Anything else
+ // should be left alone.
+ CodeGenPrepareFortifiedLibCalls Simplifier;
+ return Simplifier.fold(CI, TD);
+}