Define behavior of "stack-probe-size" attribute when inlining.

Also document the attribute, since "probe-stack" already is.

Reviewed By: majnemer

Differential Revision: https://reviews.llvm.org/D34528

llvm-svn: 306069

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index ef8178efa3b..2a0812ab930 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -1511,6 +1511,21 @@ example:
     On an argument, this attribute indicates that the function does not write
     through this pointer argument, even though it may write to the memory that
     the pointer points to.
+``"stack-probe-size"``
+    This attribute controls the behavior of stack probes: either
+    the ``"probe-stack"`` attribute, or ABI-required stack probes, if any.
+    It defines the size of the guard region. It ensures that if the function
+    may use more stack space than the size of the guard region, stack probing
+    sequence will be emitted. It takes one required integer value, which
+    is 4096 by default.
+
+    If a function that has a ``"stack-probe-size"`` attribute is inlined into
+    a function with another ``"stack-probe-size"`` attribute, the resulting
+    function has the ``"stack-probe-size"`` attribute that has the lower
+    numeric value. If a function that has a ``"stack-probe-size"`` attribute is
+    inlined into a function that has no ``"stack-probe-size"`` attribute
+    at all, the resulting function has the ``"stack-probe-size"`` attribute
+    of the callee.
 ``writeonly``
     On a function, this attribute indicates that the function may write to but
     does not read from memory.