added simple README.md providing build and run instructions

Author: tetzank

README.md

@@ -0,0 +1,50 @@
+SIGMOD Programming Contest 2018: Code Generation
+===
+
+This repository contains a prototype for the [SIGMOD Programming Contest 2018](http://sigmod18contest.db.in.tum.de/task.shtml).
+It is a showcase for code generation in databases and for [COAT](https://github.com/tetzank/coat), an EDSL for C++ which makes code generation easier.
+
+More details are explained in a [blog post](https://tetzank.github.io/posts/codegen-in-databases/).
+
+
+## Build Instructions
+
+Fetch the JIT engines LLVM and Asmjit, and build them (use more or less cores by changing `-j`, LLVM can take a while...):
+```
+$ ./buildDependencies.sh -j8
+```
+
+Then, build the prototype with cmake:
+```
+$ mkdir build
+$ cd build
+$ cmake ..
+$ make -j8
+```
+
+## Run Instructions
+
+Download and unpack the test workload from the contest:
+```
+$ cd workloads
+$ ./download.sh
+```
+
+Afterwards, run the test workload:
+```
+$ cd public
+$ ../../build/sig18 -t public.{init,work}
+```
+
+This runs the naive baseline with a tuple-at-a-time execution engine without code generation.
+
+For Asmjit, run:
+```
+$ ../../build/sig18 -a public.{init,work}
+```
+
+For LLVM, run:
+```
+$ ../../build/sig18 -l3 public.{init,work}
+```
+You can pick an optimization level from 0 to 3.