Add a missed optimization

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24495 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index 354439bfdb0c98e0b14782ef49eb036057af9358..c9f23d598be5be31d889b4501ec6ebc422217f82 100644 (file)
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -73,3 +73,12 @@ Another useful one would be  ~0ULL >> X and ~0ULL << X.
 Should support emission of the bswap instruction, probably by adding a new
 DAG node for byte swapping.  Also useful on PPC which has byte-swapping loads.
 
+//===---------------------------------------------------------------------===//
+
+Compile this:
+_Bool f(_Bool a) { return a!=1; }
+
+into:
+        movzbl  %dil, %eax
+        xorl    $1, %eax
+        ret