[llvm] r210354 - Mention the IRBuilder in Programmer's Manual with a few small examples.
Dan Liew
dan at su-root.co.uk
Fri Jun 6 10:25:47 PDT 2014
Author: delcypher
Date: Fri Jun 6 12:25:47 2014
New Revision: 210354
URL: http://llvm.org/viewvc/llvm-project?rev=210354&view=rev
Log:
Mention the IRBuilder in Programmer's Manual with a few small examples.
Modified:
llvm/trunk/docs/ProgrammersManual.rst
Modified: llvm/trunk/docs/ProgrammersManual.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/ProgrammersManual.rst?rev=210354&r1=210353&r2=210354&view=diff
==============================================================================
--- llvm/trunk/docs/ProgrammersManual.rst (original)
+++ llvm/trunk/docs/ProgrammersManual.rst Fri Jun 6 12:25:47 2014
@@ -1918,7 +1918,7 @@ which is a pointer to an integer on the
*Inserting instructions*
-There are essentially two ways to insert an ``Instruction`` into an existing
+There are essentially three ways to insert an ``Instruction`` into an existing
sequence of instructions that form a ``BasicBlock``:
* Insertion into an explicit instruction list
@@ -1988,6 +1988,41 @@ sequence of instructions that form a ``B
which is much cleaner, especially if you're creating a lot of instructions and
adding them to ``BasicBlock``\ s.
+* Insertion using an instance of ``IRBuilder``
+
+ Inserting several ``Instuction``\ s can be quite laborious using the previous
+ methods. The ``IRBuilder`` is a convenience class that can be used to add
+ several instructions to the end of a ``BasicBlock`` or before a particular
+ ``Instruction``. It also supports constant folding and renaming named
+ registers (see ``IRBuilder``'s template arguments).
+
+ The example below demonstrates a very simple use of the ``IRBuilder`` where
+ three instructions are inserted before the instruction ``pi``. The first two
+ instructions are Call instructions and third instruction multiplies the return
+ value of the two calls.
+
+ .. code-block:: c++
+
+ Instruction *pi = ...;
+ IRBuilder<> Builder(pi);
+ CallInst* callOne = Builder.CreateCall(...);
+ CallInst* callTwo = Builder.CreateCall(...);
+ Value* result = Builder.CreateMul(callOne, callTwo);
+
+ The example below is similar to the above example except that the created
+ ``IRBuilder`` inserts instructions at the end of the ``BasicBlock`` ``pb``.
+
+ .. code-block:: c++
+
+ BasicBlock *pb = ...;
+ IRBuilder<> Builder(pb);
+ CallInst* callOne = Builder.CreateCall(...);
+ CallInst* callTwo = Builder.CreateCall(...);
+ Value* result = Builder.CreateMul(callOne, callTwo);
+
+ See :doc:`tutorial/LangImpl3` for a practical use of the ``IRBuilder``.
+
+
.. _schanges_deleting:
Deleting Instructions
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