Readme

llvm-svn: 35533

1 files changed, 42 insertions, 1 deletions

diff --git a/llvm/lib/Target/Alpha/README.txt b/llvm/lib/Target/Alpha/README.txt
index c4330351fff..9ae15174c58 100644
--- a/llvm/lib/Target/Alpha/README.txt
+++ b/llvm/lib/Target/Alpha/README.txt
@@ -1 +1,42 @@
-* EMPTY *
+***
+
+add gcc builtins for alpha instructions
+
+
+***
+
+custom expand byteswap into nifty 
+extract/insert/mask byte/word/longword/quadword low/high
+sequences
+
+***
+
+see if any of the extract/insert/mask operations can be added
+
+***
+
+match more interesting things for cmovlbc cmovlbs (move if low bit clear/set)
+
+***
+
+lower srem and urem
+
+remq(i,j):  i - (j * divq(i,j)) if j != 0
+remqu(i,j): i - (j * divqu(i,j)) if j != 0
+reml(i,j):  i - (j * divl(i,j)) if j != 0
+remlu(i,j): i - (j * divlu(i,j)) if j != 0
+
+***
+
+add crazy vector instructions (MVI):
+
+(MIN|MAX)(U|S)(B8|W4) min and max, signed and unsigned, byte and word
+PKWB, UNPKBW pack/unpack word to byte
+PKLB UNPKBL pack/unpack long to byte
+PERR pixel error (sum accross bytes of bytewise abs(i8v8 a - i8v8 b))
+
+cmpbytes bytewise cmpeq of i8v8 a and i8v8 b (not part of MVI extentions)
+
+this has some good examples for other operations that can be synthesised well 
+from these rather meager vector ops (such as saturating add).
+http://www.alphalinux.org/docs/MVI-full.html