Moved the "SmallExamples" out of the /projects directory and into a new

/examples directory. History was maintained. These programs do not need to
be configured but things in /projects must be.

llvm-svn: 16002

1 files changed, 109 insertions, 0 deletions

diff --git a/llvm/examples/HowToUseJIT/HowToUseJIT.cpp b/llvm/examples/HowToUseJIT/HowToUseJIT.cpp
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+//===--- HowToUseJIT.cpp - An example use of the JIT ----------------------===//
+// 
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Valery A. Khamenya and is distributed under the
+// University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+//  This small program provides an example of how to quickly build a small
+//  module with two functions and execute it with the JIT. 
+// 
+// Goal: 
+//  The goal of this snippet is to create in the memory
+//  the LLVM module consisting of two functions as follow:
+//
+// int add1(int x) {
+//   return x+1;
+// }
+// 
+// int foo() {
+//   return add1(10);
+// }
+// 
+// then compile the module via JIT, then execute the `foo' 
+// function and return result to a driver, i.e. to a "host program".
+// 
+// Some remarks and questions:
+// 
+// - could we invoke some code using noname functions too?
+//   e.g. evaluate "foo()+foo()" without fears to introduce 
+//   conflict of temporary function name with some real
+//   existing function name?
+// 
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Module.h"
+#include "llvm/Constants.h"
+#include "llvm/Type.h"
+#include "llvm/Instructions.h"
+#include "llvm/ModuleProvider.h"
+#include "llvm/ExecutionEngine/ExecutionEngine.h"
+#include "llvm/ExecutionEngine/GenericValue.h"
+#include <iostream>
+using namespace llvm;
+
+int main() {
+  // Create some module to put our function into it.
+  Module *M = new Module("test");
+
+  // Create the add1 function entry and insert this entry into module M.  The
+  // function will have a return type of "int" and take an argument of "int".
+  // The '0' terminates the list of argument types.
+  Function *Add1F = M->getOrInsertFunction("add1", Type::IntTy, Type::IntTy, 0);
+
+  // Add a basic block to the function. As before, it automatically inserts
+  // because of the last argument.
+  BasicBlock *BB = new BasicBlock("EntryBlock", Add1F);
+  
+  // Get pointers to the constant `1'.
+  Value *One = ConstantSInt::get(Type::IntTy, 1);
+
+  // Get pointers to the integer argument of the add1 function...
+  assert(Add1F->abegin() != Add1F->aend()); // Make sure there's an arg
+  Argument *ArgX = Add1F->abegin();  // Get the arg
+  ArgX->setName("AnArg");            // Give it a nice symbolic name for fun.
+
+  // Create the add instruction, inserting it into the end of BB.
+  Instruction *Add = BinaryOperator::createAdd(One, ArgX, "addresult", BB);
+  
+  // Create the return instruction and add it to the basic block
+  new ReturnInst(Add, BB);
+
+  // Now, function add1 is ready.
+
+
+  // Now we going to create function `foo', which returns an int and takes no
+  // arguments.
+  Function *FooF = M->getOrInsertFunction("foo", Type::IntTy, 0);
+
+  // Add a basic block to the FooF function.
+  BB = new BasicBlock("EntryBlock", FooF);
+
+  // Get pointers to the constant `10'.
+  Value *Ten = ConstantSInt::get(Type::IntTy, 10);
+
+  // Pass Ten to the call call:
+  std::vector<Value*> Params;
+  Params.push_back(Ten);
+  CallInst * Add1CallRes = new CallInst(Add1F, Params, "add1", BB);
+    
+  // Create the return instruction and add it to the basic block.
+  new ReturnInst(Add1CallRes, BB);
+
+  // Now we create the JIT.
+  ExistingModuleProvider* MP = new ExistingModuleProvider(M);
+  ExecutionEngine* EE = ExecutionEngine::create(MP, false);
+
+  std::cout << "We just constructed this LLVM module:\n\n" << *M;
+  std::cout << "\n\nRunning foo: " << std::flush;
+
+  // Call the `foo' function with no arguments:
+  std::vector<GenericValue> noargs;
+  GenericValue gv = EE->runFunction(FooF, noargs);
+
+  // Import result of execution:
+  std::cout << "Result: " << gv.IntVal << "\n";
+  return 0;
+}