[llvm-branch-commits] [llvm] e7e6335 - ReleaseNotes: Add updates in LangRef related with undef/poison

[Juneyoung Lee via llvm-branch-commits]

Author: Juneyoung Lee
Date: 2020-09-08T11:40:24+09:00
New Revision: e7e6335763cafe06988a6c06ed50af0b4ec28d8b

URL: https://github.com/llvm/llvm-project/commit/e7e6335763cafe06988a6c06ed50af0b4ec28d8b
DIFF: https://github.com/llvm/llvm-project/commit/e7e6335763cafe06988a6c06ed50af0b4ec28d8b.diff

LOG: ReleaseNotes: Add updates in LangRef related with undef/poison

Added: 
    

Modified: 
    llvm/docs/ReleaseNotes.rst

Removed: 
    


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diff  --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index cbc8c0859c7b..0d5e0137bbc4 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -101,6 +101,18 @@ Changes to the LLVM IR
   where ``uint64_t`` was used to denote the size in bits of a IR type
   we have partially migrated the codebase to using ``llvm::TypeSize``.
 
+* Branching on ``undef``/``poison`` is undefined behavior. It is needed for
+  correctly analyzing value ranges based on branch conditions. This is
+  consistent with MSan's behavior as well.
+
+* ``memset``/``memcpy``/``memmove`` can take ``undef``/``poison`` pointer(s)
+  if the size to fill is zero.
+
+* Passing ``undef``/``poison`` to a standard I/O library function call
+  (`printf`/`fputc`/...) is undefined behavior. The new ``noundef`` attribute
+  is attached to the functions' arguments. The full list is available at
+  ``llvm::inferLibFuncAttributes``.
+
 Changes to building LLVM
 ------------------------
 
@@ -305,6 +317,10 @@ Changes to the Go bindings
 Changes to the DAG infrastructure
 ---------------------------------
 
+* A SelDag-level freeze instruction has landed. It is simply lowered as a copy
+  operation to MachineIR, but to make it fully correct either IMPLICIT_DEF
+  should be fixed or the equivalent FREEZE operation should be added to
+  MachineIR.
 
 Changes to the Debug Info
 ---------------------------------