a couple of miscellaneous things.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26625 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index 3e2eaef..651d472 100644 (file)
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -566,3 +566,21 @@ LBB_foo_3:      # no_exit
         jb LBB_foo_3    # no_exit
 
 //===---------------------------------------------------------------------===//
+
+Codegen:
+  if (copysign(1.0, x) == copysign(1.0, y))
+into:
+  if (x^y & mask)
+when using SSE.
+
+//===---------------------------------------------------------------------===//
+
+Optimize this into something reasonable:
+ x * copysign(1.0, y) * copysign(1.0, z)
+
+//===---------------------------------------------------------------------===//
+
+Optimize copysign(x, *y) to use an integer load from y.
+
+//===---------------------------------------------------------------------===//
+