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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@28176 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index b8ec59ae3642f18b09021fc9391462e748c1211f..af520afe1d88455329dc18a640e3a4c75939d2dd 100644 (file)
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -1166,4 +1166,13 @@ pressure.  The scheduling issue is more pronounced without -static.
 The 2) marked instructions are the lowered form of the 1,undef,3,4 
 shufflevector.  It seems that there should be a better way to do it :)
 
+//===---------------------------------------------------------------------===//
+
+If shorter, we should use things like:
+movzwl %ax, %eax
+instead of:
+andl $65535, %EAX
+
+The former can also be used when the two-addressy nature of the 'and' would
+require a copy to be inserted (in X86InstrInfo::convertToThreeAddress).