[commit: ghc] master: Add a couple of comments (6508697)

[Ian Lynagh]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/6508697f398fa4e9241cec88991772eda86e37b3

>---------------------------------------------------------------

commit 6508697f398fa4e9241cec88991772eda86e37b3
Author: Ian Lynagh <igloo at earth.li>
Date:   Fri Apr 20 18:54:25 2012 +0100

    Add a couple of comments

>---------------------------------------------------------------

 compiler/prelude/primops.txt.pp |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/compiler/prelude/primops.txt.pp b/compiler/prelude/primops.txt.pp
index 4d452c0..037915a 100644
--- a/compiler/prelude/primops.txt.pp
+++ b/compiler/prelude/primops.txt.pp
@@ -269,6 +269,7 @@ primtype Word#
 primop   WordAddOp   "plusWord#"   Dyadic   Word# -> Word# -> Word#
    with commutable = True
 
+-- Returns (# high, low #) (or equivalently, (# carry, low #))
 primop   WordAdd2Op  "plusWord2#"  GenPrimOp
    Word# -> Word# -> (# Word#, Word# #)
    with commutable = True
@@ -278,6 +279,7 @@ primop   WordSubOp   "minusWord#"   Dyadic   Word# -> Word# -> Word#
 primop   WordMulOp   "timesWord#"   Dyadic   Word# -> Word# -> Word#
    with commutable = True
 
+-- Returns (# high, low #)
 primop   WordMul2Op  "timesWord2#"   GenPrimOp
    Word# -> Word# -> (# Word#, Word# #)
    with commutable = True