ReleaseNotes: The fast-math-flags changes

By Sanjay Patel!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_60@325776 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/ReleaseNotes.rst b/docs/ReleaseNotes.rst
index a0df1890987641d5936b3d819df3083612b1eec5..6dcca287fe1f065b25809f6dc0e9ff1565a67d6a 100644 (file)
--- a/docs/ReleaseNotes.rst
+++ b/docs/ReleaseNotes.rst
@@ -74,6 +74,15 @@ Non-comprehensive list of changes in this release
 Changes to the LLVM IR
 ----------------------
 
+* The fast-math-flags (FMF) have been updated. Previously, the 'fast' flag
+  indicated that floating-point reassociation was allowed and all other flags
+  were set too. The 'fast' flag still exists, but there is a new flag called
+  'reassoc' to indicate specifically that reassociation is allowed. A new bit
+  called 'afn' was also added to selectively allow approximations for common
+  mathlib functions like square-root. The new flags provide more flexibility
+  to enable/disable specific floating-point optimizations. Making the
+  optimizer respond appropriately to these flags is an ongoing effort.
+
 Changes to the AArch64 Target
 -----------------------------