Update Kaleidoscope tutorial and improve Windows support

Many quoted code blocks were not in sync with the actual toy.cpp
files. Improve tutorial text slightly in several places.
Added some step descriptions crucial to avoid crashes (like
InitializeNativeTarget* calls).
Solve/workaround problems with Windows (JIT'ed method not found, using
custom and standard library functions from host process).

Patch by: Moritz Kroll <moritz.kroll@gmx.de>

Differential Revision: https://reviews.llvm.org/D29864

llvm-svn: 294870

1 files changed, 10 insertions, 4 deletions

diff --git a/llvm/examples/Kaleidoscope/Chapter5/toy.cpp b/llvm/examples/Kaleidoscope/Chapter5/toy.cpp
index 795f49c847e..6852973bae4 100644
--- a/llvm/examples/Kaleidoscope/Chapter5/toy.cpp
+++ b/llvm/examples/Kaleidoscope/Chapter5/toy.cpp
@@ -622,7 +622,7 @@ Value *IfExprAST::codegen() {
   if (!CondV)
     return nullptr;
 
-  // Convert condition to a bool by comparing equal to 0.0.
+  // Convert condition to a bool by comparing non-equal to 0.0.
   CondV = Builder.CreateFCmpONE(
       CondV, ConstantFP::get(TheContext, APFloat(0.0)), "ifcond");
 
@@ -736,7 +736,7 @@ Value *ForExprAST::codegen() {
   if (!EndCond)
     return nullptr;
 
-  // Convert condition to a bool by comparing equal to 0.0.
+  // Convert condition to a bool by comparing non-equal to 0.0.
   EndCond = Builder.CreateFCmpONE(
       EndCond, ConstantFP::get(TheContext, APFloat(0.0)), "loopcond");
 
@@ -924,14 +924,20 @@ static void MainLoop() {
 // "Library" functions that can be "extern'd" from user code.
 //===----------------------------------------------------------------------===//
 
+#ifdef LLVM_ON_WIN32
+#define DLLEXPORT __declspec(dllexport)
+#else
+#define DLLEXPORT
+#endif
+
 /// putchard - putchar that takes a double and returns 0.
-extern "C" double putchard(double X) {
+extern "C" DLLEXPORT double putchard(double X) {
   fputc((char)X, stderr);
   return 0;
 }
 
 /// printd - printf that takes a double prints it as "%f\n", returning 0.
-extern "C" double printd(double X) {
+extern "C" DLLEXPORT double printd(double X) {
   fprintf(stderr, "%f\n", X);
   return 0;
 }