[CLANG][BPF] change __builtin_preserve_access_index() signature
The clang intrinsic __builtin_preserve_access_index() currently
has signature:
const void * __builtin_preserve_access_index(const void * ptr)
This may cause compiler warning when:
- parameter type is "volatile void *" or "const volatile void *", or
- the assign-to type of the intrinsic does not have "const" qualifier.
Further, this signature does not allow dereference of the
builtin result pointer as it is a "const void *" type, which
adds extra step for the user to do type casting.
Let us change the signature to:
PointerT __builtin_preserve_access_index(PointerT ptr)
such that the result and argument types are the same.
With this, directly dereferencing the builtin return value
becomes possible.
Differential Revision: https://reviews.llvm.org/D67734
llvm-svn: 372294
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 80c9609..9826c41 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2353,12 +2353,14 @@
array subscript access and structure/union member access are relocatable
under bpf compile-once run-everywhere framework. Debuginfo (typically
with ``-g``) is needed, otherwise, the compiler will exit with an error.
+The return type for the intrinsic is the same as the type of the
+argument, and must be a pointer type.
**Syntax**:
.. code-block:: c
- const void * __builtin_preserve_access_index(const void * ptr)
+ PointerT __builtin_preserve_access_index(PointerT ptr)
**Example of Use**: