Added a small optimization example

README.md

@@ -7,6 +7,7 @@ purpose of practicing OCaml LLVM bindings and seeing how well LLVM optimizes
 arrays. Brainfuck commands are transformed to LLVM IR, which is generated in
 such a way that it is easy to optimize for LLVM's `opt` utility.
 
+
 Building and usage
 ==================
 
@@ -15,7 +16,7 @@ Building the `bf` compiler (Debian dependencies):
     $ sudo apt-get install ocaml llvm-3.4 libllvm-3.4-ocaml-dev
     $ make
 
-Building a brainfuck program (plain and optimized):
+Building a Brainfuck program (plain and optimized):
 
     $ make hello hello-opt  # compile file "hello.b" to binaries
     $ ./hello
@@ -35,3 +36,58 @@ Examining generated LLVM:
     ...
     $ echo ++++++++++++. | ./bf | opt -O3 -S
     ...
+
+
+Optimization example
+--------------------
+
+The `text.py` utility genrates single-cell Brainfuck code for a given text:
+
+    $ ./text.py Hello World!
+    ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++.
+    +++++++++++++++++++++++++++++.
+    +++++++.
+    .
+    +++.
+    -------------------------------------------------------------------------------.
+    +++++++++++++++++++++++++++++++++++++++++++++++++++++++.
+    ++++++++++++++++++++++++.
+    +++.
+    ------.
+    --------.
+    -------------------------------------------------------------------.
+    -----------------------.
+
+The LLVM optimization engine is able to completely optimize away array accesses
+(in the absence of loops):
+
+    $ ./text.py Hello World! | ./bf | opt -O3 -S
+    ; ModuleID = '<stdin>'
+    target datalayout = "e"
+
+    ; Function Attrs: nounwind
+    declare i32 @putchar(i8) #0
+
+    declare void @exit(i32)
+
+    define void @_start() {
+    entry:
+        %0 = tail call i32 @putchar(i8 72)
+        %1 = tail call i32 @putchar(i8 101)
+        %2 = tail call i32 @putchar(i8 108)
+        %3 = tail call i32 @putchar(i8 108)
+        %4 = tail call i32 @putchar(i8 111)
+        %5 = tail call i32 @putchar(i8 32)
+        %6 = tail call i32 @putchar(i8 87)
+        %7 = tail call i32 @putchar(i8 111)
+        %8 = tail call i32 @putchar(i8 114)
+        %9 = tail call i32 @putchar(i8 108)
+        %10 = tail call i32 @putchar(i8 100)
+        %11 = tail call i32 @putchar(i8 33)
+        %12 = tail call i32 @putchar(i8 10)
+        tail call void @exit(i32 0)
+        ret void
+    }
+
+    attributes #0 = { nounwind }
+