TableGen: Add !foldl operation

Change-Id: I63d67bf6e0b315e2d3360e47e3b62c9517f38987

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326790 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 10 insertions, 1 deletions

diff --git a/docs/TableGen/LangIntro.rst b/docs/TableGen/LangIntro.rst
index 7437723bf3b..67000fa03c6 100644
--- a/docs/TableGen/LangIntro.rst
+++ b/docs/TableGen/LangIntro.rst
@@ -217,6 +217,15 @@ supported include:
     of a variable that will be substituted by members of 'b' in 'c'.
     This operation is analogous to $(foreach) in GNU make.
 
+``!foldl(start, lst, a, b, expr)``
+    Perform a left-fold over 'lst' with the given starting value. 'a' and 'b'
+    are variable names which will be substituted in 'expr'. If you think of
+    expr as a function f(a,b), the fold will compute
+    'f(...f(f(start, lst[0]), lst[1]), ...), lst[n-1])' for a list of length n.
+    As usual, 'a' will be of the type of 'start', and 'b' will be of the type
+    of elements of 'lst'. These types need not be the same, but 'expr' must be
+    of the same type as 'start'.
+
 ``!head(a)``
     The first element of list 'a.'
 
diff --git a/docs/TableGen/LangRef.rst b/docs/TableGen/LangRef.rst
index 5f7917a5b4b..5da852879d2 100644
--- a/docs/TableGen/LangRef.rst
+++ b/docs/TableGen/LangRef.rst
@@ -98,7 +98,7 @@ wide variety of meanings:
                :!eq     !if      !head    !tail      !con
                :!add    !shl     !sra     !srl       !and
                :!or     !empty   !subst   !foreach   !strconcat
-               :!cast   !listconcat       !size
+               :!cast   !listconcat       !size      !foldl
 
 
 Syntax