From f35332cf8985266d99392c077de74bd2cec5c8ff Mon Sep 17 00:00:00 2001
From: Stefano Sanfilippo <a.little.coder@gmail.com>
Date: Mon, 9 Mar 2015 22:48:10 +0100
Subject: [PATCH] Enable simple optimizations.

---
 BitcodeEmitter.cpp | 19 +++++++++++++++++++
 README.md          |  5 +++--
 2 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/BitcodeEmitter.cpp b/BitcodeEmitter.cpp
index d8f548d..0d1c5a1 100644
--- a/BitcodeEmitter.cpp
+++ b/BitcodeEmitter.cpp
@@ -27,6 +27,9 @@
 #include <llvm/IR/IRBuilder.h>
 #include <llvm/IR/LLVMContext.h>
 #include <llvm/IR/Module.h>
+#include <llvm/IR/LegacyPassManager.h>
+#include <llvm/Transforms/Scalar.h>
+#include <llvm/Analysis/Passes.h>
 
 #include <cassert>
 #include <string>
@@ -54,6 +57,7 @@ struct BitcodeEmitter::Private {
 
     llvm::IRBuilder<> builder = llvm::IRBuilder<>(getGlobalContext());
     Scope<std::string, llvm::AllocaInst*> scope;
+    Pointer<llvm::legacy::FunctionPassManager> optimizer;
 };
 
 static
@@ -234,6 +238,17 @@ BitcodeEmitter::BitcodeEmitter() {
         new llvm::Module("monicelli", getGlobalContext())
     );
     d = new Private;
+
+    d->optimizer = Pointer<llvm::legacy::FunctionPassManager>(
+        new llvm::legacy::FunctionPassManager(module.get())
+    );
+
+    d->optimizer->add(llvm::createBasicAliasAnalysisPass());
+    d->optimizer->add(llvm::createInstructionCombiningPass());
+    d->optimizer->add(llvm::createReassociatePass());
+    d->optimizer->add(llvm::createGVNPass());
+    d->optimizer->add(llvm::createCFGSimplificationPass());
+    d->optimizer->doInitialization();
 }
 
 BitcodeEmitter::~BitcodeEmitter() {
@@ -599,6 +614,8 @@ bool BitcodeEmitter::emit(Function const& node) {
 
     verifyFunction(*func);
 
+    d->optimizer->run(*func);
+
     return true;
 }
 
@@ -624,6 +641,8 @@ bool BitcodeEmitter::emit(Program const& program) {
         GUARDED(program.getMain()->emit(this));
     }
 
+    verifyModule(*module);
+
     return true;
 }
 
diff --git a/README.md b/README.md
index dcdee92..9a5efd5 100644
--- a/README.md
+++ b/README.md
@@ -76,13 +76,14 @@ Usually, the relevant package goes under the name `llvm`.
 A C compiler is used to simplify the assembling and linking step, but it could
 be skipped altogether with a small effort. If you want to try ;)
 
-`mcc` does not optimize the emitted bytecode to ensure readibility when
+`mcc` only performs minimal optimizations in order to ensure readibility when
 disassembling with `llvm-dis`. However, you might want to optimize the code
 using `opt` LLVM utility:
 
     $ opt example.bc | llc -o example.s
 
-in place of the simple `llc` compilation step.
+in place of the simple `llc` compilation step. See `opt` documentation for a 
+comprehensive list of optimizations available.
 
 ###C++ transpiler
 `mcc` can be configured as a source to source compiler, which reads Monicelli