diff options
Diffstat (limited to 'llvm/docs/LangRef.rst')
| -rw-r--r-- | llvm/docs/LangRef.rst | 38 |
1 files changed, 24 insertions, 14 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index bac13cc..d8cd3b8 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -26,7 +26,7 @@ readable assembly language representation. This allows LLVM to provide a powerful intermediate representation for efficient compiler transformations and analysis, while providing a natural means to debug and visualize the transformations. The three different forms of LLVM are -all equivalent. This document describes the human readable +all equivalent. This document describes the human-readable representation and notation. The LLVM representation aims to be light-weight and low-level while @@ -413,6 +413,8 @@ added in the future: - On AArch64 the callee preserves all general purpose registers, except X0-X8 and X16-X18. Not allowed with ``nest``. + - On RISC-V the callee preserve x5-x31 except x6, x7 and x28 registers. + The idea behind this convention is to support calls to runtime functions that have a hot path and a cold path. The hot path is usually a small piece of code that doesn't use many registers. The cold path might need to call out to @@ -21287,7 +21289,7 @@ Semantics: On some architectures the address of the code to be executed needs to be different than the address where the trampoline is actually stored. This intrinsic returns the executable address corresponding to ``tramp`` -after performing the required machine specific adjustments. The pointer +after performing the required machine-specific adjustments. The pointer returned can then be :ref:`bitcast and executed <int_trampoline>`. @@ -26653,16 +26655,20 @@ object's lifetime. Arguments: """""""""" -The first argument is a constant integer representing the size of the -object, or -1 if it is variable sized. The second argument is a pointer -to an ``alloca`` instruction. +The first argument is a constant integer, which is ignored and will be removed +in the future. + +The second argument is either a pointer to an ``alloca`` instruction or +a ``poison`` value. Semantics: """""""""" -The stack-allocated object that ``ptr`` points to is initially marked as dead. -After '``llvm.lifetime.start``', the stack object is marked as alive and has an -uninitialized value. +If ``ptr`` is a ``poison`` value, the intrinsic has no effect. + +Otherwise, the stack-allocated object that ``ptr`` points to is initially +marked as dead. After '``llvm.lifetime.start``', the stack object is marked as +alive and has an uninitialized value. The stack object is marked as dead when either :ref:`llvm.lifetime.end <int_lifeend>` to the alloca is executed or the function returns. @@ -26693,15 +26699,19 @@ The '``llvm.lifetime.end``' intrinsic specifies the end of a Arguments: """""""""" -The first argument is a constant integer representing the size of the -object, or -1 if it is variable sized. The second argument is a pointer -to an ``alloca`` instruction. +The first argument is a constant integer, which is ignored and will be removed +in the future. + +The second argument is either a pointer to an ``alloca`` instruction or +a ``poison`` value. Semantics: """""""""" -The stack-allocated object that ``ptr`` points to becomes dead after the call -to this intrinsic. +If ``ptr`` is a ``poison`` value, the intrinsic has no effect. + +Otherwise, the stack-allocated object that ``ptr`` points to becomes dead after +the call to this intrinsic. Calling ``llvm.lifetime.end`` on an already dead alloca is no-op. @@ -29378,7 +29388,7 @@ None. Semantics: """""""""" -This intrinsic is lowered to the target dependent trap instruction. If +This intrinsic is lowered to the target-dependent trap instruction. If the target does not have a trap instruction, this intrinsic will be lowered to a call of the ``abort()`` function. |