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[Kaleidoscope] Update Chapter 3 of the "Implementing a Language" tutorial to

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take into account modernizations in r246002 and r270381.

Patch based on http://reviews.llvm.org/D20954 by Miroslav Hrncir.
Thanks Miroslav!

llvm-svn: 271985
This commit is contained in:
Lang Hames 2016-06-07 05:40:08 +00:00
parent e2db98503c
commit 90a9836da7
1 changed files with 14 additions and 8 deletions
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20
docs/tutorial/LangImpl3.rst
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@ -73,8 +73,9 @@ parser, which will be used to report errors found during code generation
.. code-block:: c++
static std::unique_ptr<Module> *TheModule;
static IRBuilder<> Builder(LLVMContext);
static LLVMContext TheContext;
static IRBuilder<> Builder(TheContext);
static std::unique_ptr<Module> TheModule;
static std::map<std::string, Value *> NamedValues;
Value *LogErrorV(const char *Str) {
@ -82,11 +83,10 @@ parser, which will be used to report errors found during code generation
return nullptr;
}
The static variables will be used during code generation. ``TheModule``
is an LLVM construct that contains functions and global variables. In many
ways, it is the top-level structure that the LLVM IR uses to contain code.
It will own the memory for all of the IR that we generate, which is why
the codegen() method returns a raw Value\*, rather than a unique_ptr<Value>.
The static variables will be used during code generation. ``TheContext``
is an opaque object that owns a lot of core LLVM data structures, such as
the type and constant value tables. We don't need to understand it in
detail, we just need a single instance to pass into APIs that require it.
The ``Builder`` object is a helper object that makes it easy to generate
LLVM instructions. Instances of the
@ -94,6 +94,12 @@ LLVM instructions. Instances of the
class template keep track of the current place to insert instructions
and has methods to create new instructions.
``TheModule`` is an LLVM construct that contains functions and global
variables. In many ways, it is the top-level structure that the LLVM IR
uses to contain code. It will own the memory for all of the IR that we
generate, which is why the codegen() method returns a raw Value\*,
rather than a unique_ptr<Value>.
The ``NamedValues`` map keeps track of which values are defined in the
current scope and what their LLVM representation is. (In other words, it
is a symbol table for the code). In this form of Kaleidoscope, the only