add a note.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48583 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index 5d7d8c30be6724412dc65ae01f49fd13928f837f..c64d7e0e6e61d9093f667aabd9aa5617f9603c48 100644 (file)
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -772,3 +772,11 @@ ARM, we end up with calls to L___lshrdi3/L___ashldi3 in f, which is
 badness.  PPC64 misses f, f5 and f6.  CellSPU aborts in isel.
 
 //===---------------------------------------------------------------------===//
+
+We do a number of simplifications in simplify libcalls to strength reduce
+standard library functions, but we don't currently merge them together.  For
+example, it is useful to merge memcpy(a,b,strlen(b)) -> strcpy.  This can only
+be done safely if "b" isn't modified between the strlen and memcpy of course.
+
+//===---------------------------------------------------------------------===//
+