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author | Yonghong Song <yhs@fb.com> | 2019-09-19 02:59:43 +0000 |
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committer | Yonghong Song <yhs@fb.com> | 2019-09-19 02:59:43 +0000 |
commit | bf89fb7d86986de60e99a96104c2cc97b3d56230 (patch) | |
tree | bbcd189ce0c95278a082df3cbac623aaee74b1fc /docs/LanguageExtensions.rst | |
parent | a1445cd0340006d7635101c4c2b27ae51328642c (diff) | |
download | clang-bf89fb7d86986de60e99a96104c2cc97b3d56230.tar.gz |
[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
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@372294 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs/LanguageExtensions.rst')
-rw-r--r-- | docs/LanguageExtensions.rst | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/docs/LanguageExtensions.rst b/docs/LanguageExtensions.rst index 80c960909f..9826c41c35 100644 --- a/docs/LanguageExtensions.rst +++ b/docs/LanguageExtensions.rst @@ -2353,12 +2353,14 @@ and other similar allocation libraries, and are only available in C++. 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**: |