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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 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
