Update to LLVM 3.5a.
Change-Id: Ifadecab779f128e62e430c2b4f6ddd84953ed617
diff --git a/docs/WritingAnLLVMBackend.rst b/docs/WritingAnLLVMBackend.rst
index 35a2d16..429f52a 100644
--- a/docs/WritingAnLLVMBackend.rst
+++ b/docs/WritingAnLLVMBackend.rst
@@ -238,6 +238,12 @@
* ``getTargetLowering()``
* ``getJITInfo()``
+Some architectures, such as GPUs, do not support jumping to an arbitrary
+program location and implement branching using masked execution and loop using
+special instructions around the loop body. In order to avoid CFG modifications
+that introduce irreducible control flow not handled by such hardware, a target
+must call `setRequiresStructuredCFG(true)` when being initialized.
+
In addition, the ``XXXTargetMachine`` constructor should specify a
``TargetDescription`` string that determines the data layout for the target
machine, including characteristics such as pointer size, alignment, and