diff options
| author | Yury Gribov <y.gribov@samsung.com> | 2015-12-01 11:40:55 +0000 |
|---|---|---|
| committer | Yury Gribov <y.gribov@samsung.com> | 2015-12-01 11:40:55 +0000 |
| commit | d7dbb66eb8fbcc73891aca2bef750d6e5f1faf98 (patch) | |
| tree | b10e85909d2c0a0500be275e7f4b94850ae95d55 /llvm/docs/LangRef.rst | |
| parent | df55f522bd6eb42e81c5723375ac329dc3aa97be (diff) | |
| download | bcm5719-llvm-d7dbb66eb8fbcc73891aca2bef750d6e5f1faf98.tar.gz bcm5719-llvm-d7dbb66eb8fbcc73891aca2bef750d6e5f1faf98.zip | |
Introduce new @llvm.get.dynamic.area.offset.i{32, 64} intrinsics.
The @llvm.get.dynamic.area.offset.* intrinsic family is used to get the offset
from native stack pointer to the address of the most recent dynamic alloca on
the caller's stack. These intrinsics are intendend for use in combination with
@llvm.stacksave and @llvm.restore to get a pointer to the most recent dynamic
alloca. This is useful, for example, for AddressSanitizer's stack unpoisoning
routines.
Patch by Max Ostapenko.
Differential Revision: http://reviews.llvm.org/D14983
llvm-svn: 254404
Diffstat (limited to 'llvm/docs/LangRef.rst')
| -rw-r--r-- | llvm/docs/LangRef.rst | 42 |
1 files changed, 42 insertions, 0 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index be8e63bf071..36bfb516779 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -9337,6 +9337,48 @@ Semantics: See the description for :ref:`llvm.stacksave <int_stacksave>`. +.. _int_get_dynamic_area_offset: + +'``llvm.get.dynamic.area.offset``' Intrinsic +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Syntax: +""""""" + +:: + + declare i32 @llvm.get.dynamic.area.offset.i32() + declare i64 @llvm.get.dynamic.area.offset.i64() + + Overview: + """"""""" + + The '``llvm.get.dynamic.area.offset.*``' intrinsic family is used to + get the offset from native stack pointer to the address of the most + recent dynamic alloca on the caller's stack. These intrinsics are + intendend for use in combination with + :ref:`llvm.stacksave <int_stacksave>` to get a + pointer to the most recent dynamic alloca. This is useful, for example, + for AddressSanitizer's stack unpoisoning routines. + +Semantics: +"""""""""" + + These intrinsics return a non-negative integer value that can be used to + get the address of the most recent dynamic alloca, allocated by :ref:`alloca <i_alloca>` + on the caller's stack. In particular, for targets where stack grows downwards, + adding this offset to the native stack pointer would get the address of the most + recent dynamic alloca. For targets where stack grows upwards, the situation is a bit more + complicated, because substracting this value from stack pointer would get the address + one past the end of the most recent dynamic alloca. + + Although for most targets `llvm.get.dynamic.area.offset <int_get_dynamic_area_offset>` + returns just a zero, for others, such as PowerPC and PowerPC64, it returns a + compile-time-known constant value. + + The return value type of :ref:`llvm.get.dynamic.area.offset <int_get_dynamic_area_offset>` + must match the target's generic address space's (address space 0) pointer type. + '``llvm.prefetch``' Intrinsic ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
