TableGen: some LangRef doc fixes
Summary: Change-Id: I1442e2daa09cab727a01d8c31893b50e644a5cd3
Reviewers: tra, simon_tatham, craig.topper
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D47530
Change-Id: I397655dd18b7ff978c1affa3174740d9c1a82594
llvm-svn: 333901
diff --git a/llvm/docs/TableGen/LangIntro.rst b/llvm/docs/TableGen/LangIntro.rst
index b77dad0..ea46550 100644
--- a/llvm/docs/TableGen/LangIntro.rst
+++ b/llvm/docs/TableGen/LangIntro.rst
@@ -152,8 +152,8 @@
``foreach <var> = [ <list> ] in <def>``
Replicate <body> or <def>, replacing instances of <var> with each value
in <list>. <var> is scoped at the level of the ``foreach`` loop and must
- not conflict with any other object introduced in <body> or <def>. Currently
- only ``def``\s are expanded within <body>.
+ not conflict with any other object introduced in <body> or <def>. Only
+ ``def``\s and ``defm``\s are expanded within <body>.
``foreach <var> = 0-15 in ...``
@@ -348,6 +348,23 @@
despite the fact that it derives (indirectly) from the ``C`` class, because the
``D`` class overrode its value.
+References between variables in a record are substituted late, which gives
+``let`` expressions unusual power. Consider this admittedly silly example:
+
+.. code-block:: text
+
+ class A<int x> {
+ int Y = x;
+ int Yplus1 = !add(Y, 1);
+ int xplus1 = !add(x, 1);
+ }
+ def Z : A<5> {
+ let Y = 10;
+ }
+
+The value of ``Z.xplus1`` will be 6, but the value of ``Z.Yplus1`` is 11. Use
+this power wisely.
+
.. _template arguments:
Class template arguments