Readme note

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27152 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index 91bdb538e94ae09fd61c4fb6ef9bca1ea2cc4568..58a864e01cc2e62080c378c1451e73307ed7a2bb 100644 (file)
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -542,6 +542,13 @@ Currently the load folding imull has a higher complexity than the LEA32 pattern.
 
 //===---------------------------------------------------------------------===//
 
+We are currently lowering large (1MB+) memmove/memcpy to rep/stosl and rep/movsl
+We should leave these as libcalls for everything over a much lower threshold,
+since libc is hand tuned for medium and large mem ops (avoiding RFO for large
+stores, TLB preheating, etc)
+
+//===---------------------------------------------------------------------===//
+
 Lower memcpy / memset to a series of SSE 128 bit move instructions when it's
 feasible.