Introduce FuzzMutate library

This introduces the FuzzMutate library, which provides structured
fuzzing for LLVM IR, as described in my [EuroLLVM 2017 talk][1]. Most
of the basic mutators to inject and delete IR are provided, with
support for most basic operations.

I will follow up with the instruction selection fuzzer, which is
implemented in terms of this library.

[1]: http://llvm.org/devmtg/2017-03//2017/02/20/accepted-sessions.html#2

llvm-svn: 311356

1 files changed, 38 insertions, 0 deletions

diff --git a/llvm/lib/FuzzMutate/OpDescriptor.cpp b/llvm/lib/FuzzMutate/OpDescriptor.cpp
new file mode 100644
index 00000000000..1c5d8f606ae
--- /dev/null
+++ b/llvm/lib/FuzzMutate/OpDescriptor.cpp
@@ -0,0 +1,38 @@
+//===-- OpDescriptor.cpp --------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/FuzzMutate/OpDescriptor.h"
+#include "llvm/IR/Constants.h"
+
+using namespace llvm;
+using namespace fuzzerop;
+
+void fuzzerop::makeConstantsWithType(Type *T, std::vector<Constant *> &Cs) {
+  if (auto *IntTy = dyn_cast<IntegerType>(T)) {
+    uint64_t W = IntTy->getBitWidth();
+    Cs.push_back(ConstantInt::get(IntTy, APInt::getMaxValue(W)));
+    Cs.push_back(ConstantInt::get(IntTy, APInt::getMinValue(W)));
+    Cs.push_back(ConstantInt::get(IntTy, APInt::getSignedMaxValue(W)));
+    Cs.push_back(ConstantInt::get(IntTy, APInt::getSignedMinValue(W)));
+    Cs.push_back(ConstantInt::get(IntTy, APInt::getOneBitSet(W, W / 2)));
+  } else if (T->isFloatingPointTy()) {
+    auto &Ctx = T->getContext();
+    auto &Sem = T->getFltSemantics();
+    Cs.push_back(ConstantFP::get(Ctx, APFloat::getZero(Sem)));
+    Cs.push_back(ConstantFP::get(Ctx, APFloat::getLargest(Sem)));
+    Cs.push_back(ConstantFP::get(Ctx, APFloat::getSmallest(Sem)));
+  } else
+    Cs.push_back(UndefValue::get(T));
+}
+
+std::vector<Constant *> fuzzerop::makeConstantsWithType(Type *T) {
+  std::vector<Constant *> Result;
+  makeConstantsWithType(T, Result);
+  return Result;
+}