diff options
Diffstat (limited to 'llvm/docs')
| -rw-r--r-- | llvm/docs/LangRef.rst | 80 |
1 files changed, 45 insertions, 35 deletions
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst index df322396702..97ee0e7d358 100644 --- a/llvm/docs/LangRef.rst +++ b/llvm/docs/LangRef.rst @@ -2209,12 +2209,21 @@ For a simpler introduction to the ordering constraints, see the same address in this global order. This corresponds to the C++0x/C1x ``memory_order_seq_cst`` and Java volatile. -.. _singlethread: +.. _syncscope: -If an atomic operation is marked ``singlethread``, it only *synchronizes -with* or participates in modification and seq\_cst total orderings with -other operations running in the same thread (for example, in signal -handlers). +If an atomic operation is marked ``syncscope("singlethread")``, it only +*synchronizes with* and only participates in the seq\_cst total orderings of +other operations running in the same thread (for example, in signal handlers). + +If an atomic operation is marked ``syncscope("<target-scope>")``, where +``<target-scope>`` is a target specific synchronization scope, then it is target +dependent if it *synchronizes with* and participates in the seq\_cst total +orderings of other operations. + +Otherwise, an atomic operation that is not marked ``syncscope("singlethread")`` +or ``syncscope("<target-scope>")`` *synchronizes with* and participates in the +seq\_cst total orderings of other operations that are not marked +``syncscope("singlethread")`` or ``syncscope("<target-scope>")``. .. _fastmath: @@ -7380,7 +7389,7 @@ Syntax: :: <result> = load [volatile] <ty>, <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>][, !invariant.load !<index>][, !invariant.group !<index>][, !nonnull !<index>][, !dereferenceable !<deref_bytes_node>][, !dereferenceable_or_null !<deref_bytes_node>][, !align !<align_node>] - <result> = load atomic [volatile] <ty>, <ty>* <pointer> [singlethread] <ordering>, align <alignment> [, !invariant.group !<index>] + <result> = load atomic [volatile] <ty>, <ty>* <pointer> [syncscope("<target-scope>")] <ordering>, align <alignment> [, !invariant.group !<index>] !<index> = !{ i32 1 } !<deref_bytes_node> = !{i64 <dereferenceable_bytes>} !<align_node> = !{ i64 <value_alignment> } @@ -7401,14 +7410,14 @@ modify the number or order of execution of this ``load`` with other :ref:`volatile operations <volatile>`. If the ``load`` is marked as ``atomic``, it takes an extra :ref:`ordering -<ordering>` and optional ``singlethread`` argument. The ``release`` and -``acq_rel`` orderings are not valid on ``load`` instructions. Atomic loads -produce :ref:`defined <memmodel>` results when they may see multiple atomic -stores. The type of the pointee must be an integer, pointer, or floating-point -type whose bit width is a power of two greater than or equal to eight and less -than or equal to a target-specific size limit. ``align`` must be explicitly -specified on atomic loads, and the load has undefined behavior if the alignment -is not set to a value which is at least the size in bytes of the +<ordering>` and optional ``syncscope("<target-scope>")`` argument. The +``release`` and ``acq_rel`` orderings are not valid on ``load`` instructions. +Atomic loads produce :ref:`defined <memmodel>` results when they may see +multiple atomic stores. The type of the pointee must be an integer, pointer, or +floating-point type whose bit width is a power of two greater than or equal to +eight and less than or equal to a target-specific size limit. ``align`` must be +explicitly specified on atomic loads, and the load has undefined behavior if the +alignment is not set to a value which is at least the size in bytes of the pointee. ``!nontemporal`` does not have any defined semantics for atomic loads. The optional constant ``align`` argument specifies the alignment of the @@ -7509,7 +7518,7 @@ Syntax: :: store [volatile] <ty> <value>, <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>][, !invariant.group !<index>] ; yields void - store atomic [volatile] <ty> <value>, <ty>* <pointer> [singlethread] <ordering>, align <alignment> [, !invariant.group !<index>] ; yields void + store atomic [volatile] <ty> <value>, <ty>* <pointer> [syncscope("<target-scope>")] <ordering>, align <alignment> [, !invariant.group !<index>] ; yields void Overview: """"""""" @@ -7529,14 +7538,14 @@ allowed to modify the number or order of execution of this ``store`` with other structural type <t_opaque>`) can be stored. If the ``store`` is marked as ``atomic``, it takes an extra :ref:`ordering -<ordering>` and optional ``singlethread`` argument. The ``acquire`` and -``acq_rel`` orderings aren't valid on ``store`` instructions. Atomic loads -produce :ref:`defined <memmodel>` results when they may see multiple atomic -stores. The type of the pointee must be an integer, pointer, or floating-point -type whose bit width is a power of two greater than or equal to eight and less -than or equal to a target-specific size limit. ``align`` must be explicitly -specified on atomic stores, and the store has undefined behavior if the -alignment is not set to a value which is at least the size in bytes of the +<ordering>` and optional ``syncscope("<target-scope>")`` argument. The +``acquire`` and ``acq_rel`` orderings aren't valid on ``store`` instructions. +Atomic loads produce :ref:`defined <memmodel>` results when they may see +multiple atomic stores. The type of the pointee must be an integer, pointer, or +floating-point type whose bit width is a power of two greater than or equal to +eight and less than or equal to a target-specific size limit. ``align`` must be +explicitly specified on atomic stores, and the store has undefined behavior if +the alignment is not set to a value which is at least the size in bytes of the pointee. ``!nontemporal`` does not have any defined semantics for atomic stores. The optional constant ``align`` argument specifies the alignment of the @@ -7597,7 +7606,7 @@ Syntax: :: - fence [singlethread] <ordering> ; yields void + fence [syncscope("<target-scope>")] <ordering> ; yields void Overview: """"""""" @@ -7631,17 +7640,17 @@ A ``fence`` which has ``seq_cst`` ordering, in addition to having both ``acquire`` and ``release`` semantics specified above, participates in the global program order of other ``seq_cst`` operations and/or fences. -The optional ":ref:`singlethread <singlethread>`" argument specifies -that the fence only synchronizes with other fences in the same thread. -(This is useful for interacting with signal handlers.) +A ``fence`` instruction can also take an optional +":ref:`syncscope <syncscope>`" argument. Example: """""""" .. code-block:: llvm - fence acquire ; yields void - fence singlethread seq_cst ; yields void + fence acquire ; yields void + fence syncscope("singlethread") seq_cst ; yields void + fence syncscope("agent") seq_cst ; yields void .. _i_cmpxchg: @@ -7653,7 +7662,7 @@ Syntax: :: - cmpxchg [weak] [volatile] <ty>* <pointer>, <ty> <cmp>, <ty> <new> [singlethread] <success ordering> <failure ordering> ; yields { ty, i1 } + cmpxchg [weak] [volatile] <ty>* <pointer>, <ty> <cmp>, <ty> <new> [syncscope("<target-scope>")] <success ordering> <failure ordering> ; yields { ty, i1 } Overview: """"""""" @@ -7682,10 +7691,8 @@ must be at least ``monotonic``, the ordering constraint on failure must be no stronger than that on success, and the failure ordering cannot be either ``release`` or ``acq_rel``. -The optional "``singlethread``" argument declares that the ``cmpxchg`` -is only atomic with respect to code (usually signal handlers) running in -the same thread as the ``cmpxchg``. Otherwise the cmpxchg is atomic with -respect to all other code in the system. +A ``cmpxchg`` instruction can also take an optional +":ref:`syncscope <syncscope>`" argument. The pointer passed into cmpxchg must have alignment greater than or equal to the size in memory of the operand. @@ -7739,7 +7746,7 @@ Syntax: :: - atomicrmw [volatile] <operation> <ty>* <pointer>, <ty> <value> [singlethread] <ordering> ; yields ty + atomicrmw [volatile] <operation> <ty>* <pointer>, <ty> <value> [syncscope("<target-scope>")] <ordering> ; yields ty Overview: """"""""" @@ -7773,6 +7780,9 @@ be a pointer to that type. If the ``atomicrmw`` is marked as order of execution of this ``atomicrmw`` with other :ref:`volatile operations <volatile>`. +A ``atomicrmw`` instruction can also take an optional +":ref:`syncscope <syncscope>`" argument. + Semantics: """""""""" |
