Add a 'dynamic' parameter to the objectsize intrinsic
This is meant to be used with clang's __builtin_dynamic_object_size.
When 'true' is passed to this parameter, the intrinsic has the
potential to be folded into instructions that will be evaluated
at run time. When 'false', the objectsize intrinsic behaviour is
unchanged.
rdar://32212419
Differential revision: https://reviews.llvm.org/D56761
llvm-svn: 352664
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 27f5e0c..85c04f1 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -15575,40 +15575,40 @@
::
- declare i32 @llvm.objectsize.i32(i8* <object>, i1 <min>, i1 <nullunknown>)
- declare i64 @llvm.objectsize.i64(i8* <object>, i1 <min>, i1 <nullunknown>)
+ declare i32 @llvm.objectsize.i32(i8* <object>, i1 <min>, i1 <nullunknown>, i1 <dynamic>)
+ declare i64 @llvm.objectsize.i64(i8* <object>, i1 <min>, i1 <nullunknown>, i1 <dynamic>)
Overview:
"""""""""
-The ``llvm.objectsize`` intrinsic is designed to provide information to
-the optimizers to determine at compile time whether a) an operation
-(like memcpy) will overflow a buffer that corresponds to an object, or
-b) that a runtime check for overflow isn't necessary. An object in this
-context means an allocation of a specific class, structure, array, or
-other object.
+The ``llvm.objectsize`` intrinsic is designed to provide information to the
+optimizer to determine whether a) an operation (like memcpy) will overflow a
+buffer that corresponds to an object, or b) that a runtime check for overflow
+isn't necessary. An object in this context means an allocation of a specific
+class, structure, array, or other object.
Arguments:
""""""""""
-The ``llvm.objectsize`` intrinsic takes three arguments. The first argument is
-a pointer to or into the ``object``. The second argument determines whether
-``llvm.objectsize`` returns 0 (if true) or -1 (if false) when the object size
-is unknown. The third argument controls how ``llvm.objectsize`` acts when
-``null`` in address space 0 is used as its pointer argument. If it's ``false``,
+The ``llvm.objectsize`` intrinsic takes four arguments. The first argument is a
+pointer to or into the ``object``. The second argument determines whether
+``llvm.objectsize`` returns 0 (if true) or -1 (if false) when the object size is
+unknown. The third argument controls how ``llvm.objectsize`` acts when ``null``
+in address space 0 is used as its pointer argument. If it's ``false``,
``llvm.objectsize`` reports 0 bytes available when given ``null``. Otherwise, if
the ``null`` is in a non-zero address space or if ``true`` is given for the
-third argument of ``llvm.objectsize``, we assume its size is unknown.
+third argument of ``llvm.objectsize``, we assume its size is unknown. The fourth
+argument to ``llvm.objectsize`` determines if the value should be evaluated at
+runtime.
-The second and third arguments only accept constants.
+The second, third, and fourth arguments only accept constants.
Semantics:
""""""""""
-The ``llvm.objectsize`` intrinsic is lowered to a constant representing
-the size of the object concerned. If the size cannot be determined at
-compile time, ``llvm.objectsize`` returns ``i32/i64 -1 or 0`` (depending
-on the ``min`` argument).
+The ``llvm.objectsize`` intrinsic is lowered to a value representing the size of
+the object concerned. If the size cannot be determined, ``llvm.objectsize``
+returns ``i32/i64 -1 or 0`` (depending on the ``min`` argument).
'``llvm.expect``' Intrinsic
^^^^^^^^^^^^^^^^^^^^^^^^^^^