[PATCH] D98112: [LangRef] mention that the lifetime intrinsics' description in LangRef isn't everything

[Juneyoung Lee via Phabricator via llvm-commits]

aqjune updated this revision to Diff 328843.
aqjune added a comment.

Forward-declare the dependency on the stack coloring algorithm


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98112/new/

https://reviews.llvm.org/D98112

Files:
  llvm/docs/LangRef.rst


Index: llvm/docs/LangRef.rst
===================================================================
--- llvm/docs/LangRef.rst
+++ llvm/docs/LangRef.rst
@@ -9369,6 +9369,12 @@
 pointer may not be unique. The order in which memory is allocated (ie.,
 which way the stack grows) is not specified.
 
+If the returned pointer is used by :ref:`llvm.lifetime.start <int_lifestart>`,
+the returned object is initially dead.
+See :ref:`llvm.lifetime.start <int_lifestart>` and
+:ref:`llvm.lifetime.end <int_lifeend>` for the precise semantics of
+lifetime-manipulating intrinsics.
+
 Example:
 """"""""
 
@@ -18099,6 +18105,10 @@
 
 If ``ptr`` is a stack-allocated object and it points to the first byte of
 the object, the object is initially marked as dead.
+``ptr`` is conservatively considered as a non-stack-allocated object if
+the stack coloring algorithm that is used in the optimization pipeline cannot
+conclude that ``ptr`` is a stack-allocated object.
+
 After '``llvm.lifetime.start``', the stack object that ``ptr`` points is marked
 as alive and has an uninitialized value.
 The stack object is marked as dead when either
@@ -18114,7 +18124,6 @@
 byte of the object or it is a stack object that is already alive, it simply
 fills all bytes of the object with ``poison``.
 
-
 .. _int_lifeend:
 
 '``llvm.lifetime.end``' Intrinsic
@@ -18145,13 +18154,16 @@
 
 If ``ptr`` is a stack-allocated object and it points to the first byte of the
 object, the object is dead.
+``ptr`` is conservatively considered as a non-stack-allocated object if
+the stack coloring algorithm that is used in the optimization pipeline cannot
+conclude that ``ptr`` is a stack-allocated object.
+
 Calling ``llvm.lifetime.end`` on an already dead alloca is no-op.
 
 If ``ptr`` is a non-stack-allocated object or it does not point to the first
 byte of the object, it is equivalent to simply filling all bytes of the object
 with ``poison``.
 
-
 '``llvm.invariant.start``' Intrinsic
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 


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