[Orc] Add a Kaleidoscope/Orc tutorial demonstrating lazy-irgen.

This tutorial builds on the lazy_codegen kaleidoscope/orc tutorial by making
a small set of changes (~75 lines diff) to defer ir-generation for function
definitions until functions are actually referenced.

llvm-svn: 228466

examples/Kaleidoscope/Orc/lazy_irgen/Makefile

@@ -0,0 +1,9 @@
+.PHONY: all
+all: toy
+
+toy: toy.cpp
+	clang++ -std=c++11 toy.cpp -g -O0 -rdynamic -fno-rtti `llvm-config --cppflags --ldflags --system-libs --libs core orcjit native` -o toy
+
+.PHONY: clean
+clean:
+	rm -f toy

examples/Kaleidoscope/Orc/lazy_irgen/README.txt

@@ -0,0 +1,16 @@
+//===----------------------------------------------------------------------===/
+//                 Kaleidoscope with Orc - Lazy IRGen Version
+//===----------------------------------------------------------------------===//
+
+This version of Kaleidoscope with Orc demonstrates lazy IR-generation.
+Building on the lazy-codegen version of the tutorial, this version reduces the
+amount of up-front work that must be done by lazily IRgen'ing ASTs. When a
+function definition is entered, its AST is added to a map of available
+definitions. No IRGen is performed at this point and nothing is added to the JIT.
+When attempting to resolve symbol addresses, the lambda in
+KaleidoscopeJIT::getSymbolAddress will scan the AST map and generate IR on the
+fly.
+
+This directory contains a Makefile that allows the code to be built in a
+standalone manner, independent of the larger LLVM build infrastructure. To build
+the program you will need to have 'clang++' and 'llvm-config' in your path.