[llvm] ca243b0 - [LangRef] get.active.lane.mask can produce poison value

[Sjoerd Meijer via llvm-commits]

Author: Sjoerd Meijer
Date: 2020-08-27T08:57:35+01:00
New Revision: ca243b07276aec744d86b5f36b475b8b247615aa

URL: https://github.com/llvm/llvm-project/commit/ca243b07276aec744d86b5f36b475b8b247615aa
DIFF: https://github.com/llvm/llvm-project/commit/ca243b07276aec744d86b5f36b475b8b247615aa.diff

LOG: [LangRef] get.active.lane.mask can produce poison value

We had already specified that second argument `n` of this intrinsic is `n > 0`,
but now add to this that the result is a poison value if this is not the case.

Differential Revision: https://reviews.llvm.org/D86637

Added: 
    

Modified: 
    llvm/docs/LangRef.rst

Removed: 
    


################################################################################
diff  --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 1dfb19555380..157e1945966c 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -16937,9 +16937,9 @@ where ``%m`` is a vector (mask) of active/inactive lanes with its elements
 indexed by ``i``,  and ``%base``, ``%n`` are the two arguments to
 ``llvm.get.active.lane.mask.*``, ``%icmp`` is an integer compare and ``ult``
 the unsigned less-than comparison operator.  Overflow cannot occur in
-``(%base + i)`` and its comparison against ``%n`` with ``%n > 0``, as it is
-performed in integer numbers and not in machine numbers. The above is
-equivalent to:
+``(%base + i)`` and its comparison against ``%n`` as it is performed in integer
+numbers and not in machine numbers.  If ``%n`` is ``0``, then the result a
+poison value. The above is equivalent to:
 
 ::