#. Named values are represented as a string of characters with their
prefix. For example, ``%foo``, ``@DivisionByZero``,
``%a.really.long.identifier``. The actual regular expression used is
- '``[%@][a-zA-Z$._][a-zA-Z$._0-9]*``'. Identifiers which require other
+ '``[%@][-a-zA-Z$._][-a-zA-Z$._0-9]*``'. Identifiers that require other
characters in their names can be surrounded with quotes. Special
characters may be escaped using ``"\xx"`` where ``xx`` is the ASCII
code for the character in hexadecimal. In this way, any character can
- be used in a name value, even quotes themselves.
+ be used in a name value, even quotes themselves. The ``"\01"`` prefix
+ can be used on global variables to suppress mangling.
#. Unnamed values are represented as an unsigned numeric value with
their prefix. For example, ``%12``, ``@2``, ``%44``.
#. Constants, which are described in the section Constants_ below.
#. Unnamed temporaries are created when the result of a computation is
not assigned to a named value.
#. Unnamed temporaries are numbered sequentially (using a per-function
- incrementing counter, starting with 0). Note that basic blocks are
- included in this numbering. For example, if the entry basic block is not
- given a label name, then it will get number 0.
+ incrementing counter, starting with 0). Note that basic blocks and unnamed
+ function parameters are included in this numbering. For example, if the
+ entry basic block is not given a label name and all function parameters are
+ named, then it will get number 0.
It also shows a convention that we follow in this document. When
demonstrating instructions, we will follow an instruction with a comment
}
; Named metadata
- !1 = metadata !{i32 42}
- !foo = !{!1, null}
+ !0 = !{i32 42, null, !"string"}
+ !foo = !{!0}
This example is made up of a :ref:`global variable <globalvars>` named
"``.str``", an external declaration of the "``puts``" function, a
LLVM IR allows you to specify both "identified" and "literal" :ref:`structure
types <t_struct>`. Literal types are uniqued structurally, but identified types
are never uniqued. An :ref:`opaque structural type <t_opaque>` can also be used
-to forward declare a type which is not yet available.
+to forward declare a type that is not yet available.
An example of a identified structure specification is:
[@<GlobalVarName> =] [Linkage] [Visibility] [DLLStorageClass] [ThreadLocal]
[unnamed_addr] [AddrSpace] [ExternallyInitialized]
<global | constant> <Type> [<InitializerConstant>]
- [, section "name"] [, align <Alignment>]
+ [, section "name"] [, comdat [($name)]]
+ [, align <Alignment>]
For example, the following defines a global in a numbered address space
with an initializer, section, and alignment:
attributes <paramattrs>`), optional :ref:`function attributes <fnattrs>`,
an optional section, an optional alignment,
an optional :ref:`comdat <langref_comdats>`,
-an optional :ref:`garbage collector name <gc>`, an optional :ref:`prefix <prefixdata>`, an opening
+an optional :ref:`garbage collector name <gc>`, an optional :ref:`prefix <prefixdata>`,
+an optional :ref:`prologue <prologuedata>`, an opening
curly brace, a list of basic blocks, and a closing curly brace.
LLVM function declarations consist of the "``declare``" keyword, an
an optional ``unnamed_addr`` attribute, a return type, an optional
:ref:`parameter attribute <paramattrs>` for the return type, a function
name, a possibly empty list of arguments, an optional alignment, an optional
-:ref:`garbage collector name <gc>` and an optional :ref:`prefix <prefixdata>`.
+:ref:`garbage collector name <gc>`, an optional :ref:`prefix <prefixdata>`,
+and an optional :ref:`prologue <prologuedata>`.
A function definition contains a list of basic blocks, forming the CFG (Control
Flow Graph) for the function. Each basic block may optionally start with a label
define [linkage] [visibility] [DLLStorageClass]
[cconv] [ret attrs]
<ResultType> @<FunctionName> ([argument list])
- [unnamed_addr] [fn Attrs] [section "name"] [comdat $<ComdatName>]
- [align N] [gc] [prefix Constant] { ... }
+ [unnamed_addr] [fn Attrs] [section "name"] [comdat [($name)]]
+ [align N] [gc] [prefix Constant] [prologue Constant] { ... }
+
+The argument list is a comma seperated sequence of arguments where each
+argument is of the following form
+
+Syntax::
+
+ <type> [parameter Attrs] [name]
+
.. _langref_aliases:
Syntax::
- @<Name> = [
Visibility] [DLLStorageClass] [ThreadLocal] [unnamed_addr] alias [Linkage] <AliaseeTy> @<Aliasee>
+ @<Name> = [
Linkage] [Visibility] [DLLStorageClass] [ThreadLocal] [unnamed_addr] alias <AliaseeTy> @<Aliasee>
The linkage must be one of ``private``, ``internal``, ``linkonce``, ``weak``,
``linkonce_odr``, ``weak_odr``, ``external``. Note that some system linkers
Comdat IR provides access to COFF and ELF object file COMDAT functionality.
-Comdats have a name which represents the COMDAT key. All global objects which
+Comdats have a name which represents the COMDAT key. All global objects that
specify this key will only end up in the final object file if the linker chooses
that key over some other key. Aliases are placed in the same COMDAT that their
aliasee computes to, if any.
.. code-block:: llvm
$foo = comdat largest
- @foo = global i32 2, comdat $foo
+ @foo = global i32 2, comdat($foo)
- define void @bar() comdat $foo {
+ define void @bar() comdat($foo) {
ret void
}
+As a syntactic sugar the ``$name`` can be omitted if the name is the same as
+the global name:
+
+.. code-block:: llvm
+
+ $foo = comdat any
+ @foo = global i32 2, comdat
+
+
In a COFF object file, this will create a COMDAT section with selection kind
``IMAGE_COMDAT_SELECT_LARGEST`` containing the contents of the ``@foo`` symbol
and another COMDAT section with selection kind
``IMAGE_COMDAT_SELECT_ASSOCIATIVE`` which is associated with the first COMDAT
-section and contains the contents of the ``@baz`` symbol.
+section and contains the contents of the ``@bar`` symbol.
There are some restrictions on the properties of the global object.
It, or an alias to it, must have the same name as the COMDAT group when
$foo = comdat any
$bar = comdat any
- @g1 = global i32 42, section "sec", comdat $foo
- @g2 = global i32 42, section "sec", comdat $bar
+ @g1 = global i32 42, section "sec", comdat($foo)
+ @g2 = global i32 42, section "sec", comdat($bar)
From the object file perspective, this requires the creation of two sections
with the same name. This is necessary because both globals belong to different
Syntax::
; Some unnamed metadata nodes, which are referenced by the named metadata.
- !0 = metadata !{metadata !"zero"}
- !1 = metadata !{metadata !"one"}
- !2 = metadata !{metadata !"two"}
+ !0 = !{!"zero"}
+ !1 = !{!"one"}
+ !2 = !{!"two"}
; A named metadata.
!name = !{!0, !1, !2}
the first parameter. This is not a valid attribute for return
values.
+``align <n>``
+ This indicates that the pointer value may be assumed by the optimizer to
+ have the specified alignment.
+
+ Note that this attribute has additional semantics when combined with the
+ ``byval`` attribute.
+
.. _noalias:
``noalias``
- This indicates that pointer values :ref:`based <pointeraliasing>` on
- the argument or return value do not alias pointer values which are
- not *based* on it, ignoring certain "irrelevant" dependencies. For a
- call to the parent function, dependencies between memory references
- from before or after the call and from those during the call are
- "irrelevant" to the ``noalias`` keyword for the arguments and return
- value used in that call. The caller shares the responsibility with
- the callee for ensuring that these requirements are met. For further
- details, please see the discussion of the NoAlias response in :ref:`alias
- analysis <Must, May, or No>`.
+ This indicates that objects accessed via pointer values
+ :ref:`based <pointeraliasing>` on the argument or return value are not also
+ accessed, during the execution of the function, via pointer values not
+ *based* on the argument or return value. The attribute on a return value
+ also has additional semantics described below. The caller shares the
+ responsibility with the callee for ensuring that these requirements are met.
+ For further details, please see the discussion of the NoAlias response in
+ :ref:`alias analysis <Must, May, or No>`.
Note that this definition of ``noalias`` is intentionally similar
- to the definition of ``restrict`` in C99 for function arguments,
- though it is slightly weaker.
+ to the definition of ``restrict`` in C99 for function arguments.
For function return values, C99's ``restrict`` is not meaningful,
- while LLVM's ``noalias`` is.
+ while LLVM's ``noalias`` is. Furthermore, the semantics of the ``noalias``
+ attribute on return values are stronger than the semantics of the attribute
+ when used on function arguments. On function return values, the ``noalias``
+ attribute indicates that the function acts like a system memory allocation
+ function, returning a pointer to allocated storage disjoint from the
+ storage for any other object accessible to the caller.
+
``nocapture``
This indicates that the callee does not make any copies of the
pointer that outlive the callee itself. This is not a valid
define void @f() gc "name" { ... }
The compiler declares the supported values of *name*. Specifying a
-collector which will cause the compiler to alter its output in order to
+collector will cause the compiler to alter its output in order to
support the named garbage collection algorithm.
.. _prefixdata:
Prefix Data
-----------
-Prefix data is data associated with a function which the code generator
-will emit immediately before the function body. The purpose of this feature
-is to allow frontends to associate language-specific runtime metadata with
-specific functions and make it available through the function pointer while
-still allowing the function pointer to be called. To access the data for a
-given function, a program may bitcast the function pointer to a pointer to
-the constant's type. This implies that the IR symbol points to the start
-of the prefix data.
+Prefix data is data associated with a function which the code
+generator will emit immediately before the function's entrypoint.
+The purpose of this feature is to allow frontends to associate
+language-specific runtime metadata with specific functions and make it
+available through the function pointer while still allowing the
+function pointer to be called.
+
+To access the data for a given function, a program may bitcast the
+function pointer to a pointer to the constant's type and dereference
+index -1. This implies that the IR symbol points just past the end of
+the prefix data. For instance, take the example of a function annotated
+with a single ``i32``,
+
+.. code-block:: llvm
+
+ define void @f() prefix i32 123 { ... }
+
+The prefix data can be referenced as,
-To maintain the semantics of ordinary function calls, the prefix data must
+.. code-block:: llvm
+
+ %0 = bitcast *void () @f to *i32
+ %a = getelementptr inbounds *i32 %0, i32 -1
+ %b = load i32* %a
+
+Prefix data is laid out as if it were an initializer for a global variable
+of the prefix data's type. The function will be placed such that the
+beginning of the prefix data is aligned. This means that if the size
+of the prefix data is not a multiple of the alignment size, the
+function's entrypoint will not be aligned. If alignment of the
+function's entrypoint is desired, padding must be added to the prefix
+data.
+
+A function may have prefix data but no body. This has similar semantics
+to the ``available_externally`` linkage in that the data may be used by the
+optimizers but will not be emitted in the object file.
+
+.. _prologuedata:
+
+Prologue Data
+-------------
+
+The ``prologue`` attribute allows arbitrary code (encoded as bytes) to
+be inserted prior to the function body. This can be used for enabling
+function hot-patching and instrumentation.
+
+To maintain the semantics of ordinary function calls, the prologue data must
have a particular format. Specifically, it must begin with a sequence of
bytes which decode to a sequence of machine instructions, valid for the
module's target, which transfer control to the point immediately succeeding
-the prefix data, without performing any other visible action. This allows
+the prologue data, without performing any other visible action. This allows
the inliner and other passes to reason about the semantics of the function
-definition without needing to reason about the prefix data. Obviously this
-makes the format of the prefix data highly target dependent.
+definition without needing to reason about the prologue data. Obviously this
+makes the format of the prologue data highly target dependent.
-Prefix data is laid out as if it were an initializer for a global variable
-of the prefix data's type. No padding is automatically placed between the
-prefix data and the function body. If padding is required, it must be part
-of the prefix data.
-
-A trivial example of valid prefix data for the x86 architecture is ``i8 144``,
+A trivial example of valid prologue data for the x86 architecture is ``i8 144``,
which encodes the ``nop`` instruction:
.. code-block:: llvm
- define void @f() prefix i8 144 { ... }
+ define void @f() prologue i8 144 { ... }
-Generally prefix data can be formed by encoding a relative branch instruction
-which skips the metadata, as in this example of valid prefix data for the
+Generally prologue data can be formed by encoding a relative branch instruction
+which skips the metadata, as in this example of valid prologue data for the
x86_64 architecture, where the first two bytes encode ``jmp .+10``:
.. code-block:: llvm
%0 = type <{ i8, i8, i8* }>
- define void @f() prefix %0 <{ i8 235, i8 8, i8* @md}> { ... }
+ define void @f() prologue %0 <{ i8 235, i8 8, i8* @md}> { ... }
-A function may have prefix data but no body. This has similar semantics
+A function may have prologue data but no body. This has similar semantics
to the ``available_externally`` linkage in that the data may be used by the
optimizers but will not be emitted in the object file.
This indicates that the callee function at a call site should be
recognized as a built-in function, even though the function's declaration
uses the ``nobuiltin`` attribute. This is only valid at call sites for
- direct calls to functions which are declared with the ``nobuiltin``
+ direct calls to functions that are declared with the ``nobuiltin``
attribute.
``cold``
This attribute indicates that this function is rarely called. When
- If R is volatile, the result is target-dependent. (Volatile is
supposed to give guarantees which can support ``sig_atomic_t`` in
- C/C++, and may be used for accesses to addresses which do not behave
+ C/C++, and may be used for accesses to addresses that do not behave
like normal memory. It does not generally provide cross-thread
synchronization.)
- Otherwise, if there is no write to the same byte that happens before
address. This corresponds to the C++0x/C1x ``memory_order_acq_rel``.
``seq_cst`` (sequentially consistent)
In addition to the guarantees of ``acq_rel`` (``acquire`` for an
- operation which only reads, ``release`` for an operation which only
+ operation that only reads, ``release`` for an operation that only
writes), there is a global total order on all
sequentially-consistent operations on all addresses, which is
consistent with the *happens-before* partial order and with the
dramatically change results in floating point (e.g. reassociate). This
flag implies all the others.
+.. _uselistorder:
+
+Use-list Order Directives
+-------------------------
+
+Use-list directives encode the in-memory order of each use-list, allowing the
+order to be recreated. ``<order-indexes>`` is a comma-separated list of
+indexes that are assigned to the referenced value's uses. The referenced
+value's use-list is immediately sorted by these indexes.
+
+Use-list directives may appear at function scope or global scope. They are not
+instructions, and have no effect on the semantics of the IR. When they're at
+function scope, they must appear after the terminator of the final basic block.
+
+If basic blocks have their address taken via ``blockaddress()`` expressions,
+``uselistorder_bb`` can be used to reorder their use-lists from outside their
+function's scope.
+
+:Syntax:
+
+::
+
+ uselistorder <ty> <value>, { <order-indexes> }
+ uselistorder_bb @function, %block { <order-indexes> }
+
+:Examples:
+
+::
+
+ define void @foo(i32 %arg1, i32 %arg2) {
+ entry:
+ ; ... instructions ...
+ bb:
+ ; ... instructions ...
+
+ ; At function scope.
+ uselistorder i32 %arg1, { 1, 0, 2 }
+ uselistorder label %bb, { 1, 0 }
+ }
+
+ ; At global scope.
+ uselistorder i32* @global, { 1, 2, 0 }
+ uselistorder i32 7, { 1, 0 }
+ uselistorder i32 (i32) @bar, { 1, 0 }
+ uselistorder_bb @foo, %bb, { 5, 1, 3, 2, 0, 4 }
+
.. _typesystem:
Type System
< <# elements> x <elementtype> >
The number of elements is a constant integer value larger than 0;
-elementtype may be any integer or floating point type, or a pointer to
-these types. Vectors of size zero are not allowed.
+elementtype may be any integer, floating point or pointer type. Vectors
+of size zero are not allowed.
:Examples:
square brackets (``[]``)). For example:
"``[ i32 42, i32 11, i32 74 ]``". Array constants must have
:ref:`array type <t_array>`, and the number and types of elements must
- match those specified by the type.
+ match those specified by the type. As a special case, character array
+ constants may also be represented as a double-quoted string using the ``c``
+ prefix. For example: "``c"Hello World\0A\00"``".
**Vector constants**
Vector constants are represented with notation similar to vector
type definitions (a comma separated list of elements, surrounded by
having to print large zero initializers (e.g. for large arrays) and
is always exactly equivalent to using explicit zero initializers.
**Metadata node**
- A metadata node is a structure-like constant with :ref:`metadata
- type <t_metadata>`. For example:
- "``metadata !{ i32 0, metadata !"test" }``". Unlike other
- constants that are meant to be interpreted as part of the
- instruction stream, metadata is a place to attach additional
+ A metadata node is a constant tuple without types. For example:
+ "``!{!0, !{!2, !0}, !"test"}``". Metadata can reference constant values,
+ for example: "``!{!0, i32 0, i8* @global, i64 (i64)* @function, !"str"}``".
+ Unlike other typed constants that are meant to be interpreted as part of
+ the instruction stream, metadata is a place to attach additional
information such as debug info.
Global Variable and Function Addresses
%C = xor %B, %B
%D = undef
- %E = icmp lt %D, 4
+ %E = icmp slt %D, 4
%F = icmp gte %D, 4
Safe:
Poison values are similar to :ref:`undef values <undefvalues>`, however
they also represent the fact that an instruction or constant expression
-which cannot evoke side effects has nevertheless detected a condition
-which results in undefined behavior.
+that cannot evoke side effects has nevertheless detected a condition
+that results in undefined behavior.
There is currently no way of representing a poison value in the IR; they
only exist when produced by operations such as :ref:`add <i_add>` with
successor.
- Dependence is transitive.
-Poison Values have the same behavior as :ref:`undef values <undefvalues>`,
-with the additional affect that any instruction which has a *dependence*
+Poison values have the same behavior as :ref:`undef values <undefvalues>`,
+with the additional effect that any instruction that has a *dependence*
on a poison value has undefined behavior.
Here are some examples:
.. _metadata:
-Metadata Nodes and Metadata Strings
------------------------------------
+Metadata
+========
LLVM IR allows metadata to be attached to instructions in the program
that can convey extra information about the code to the optimizers and
code generator. One example application of metadata is source-level
debug information. There are two metadata primitives: strings and nodes.
-All metadata has the ``metadata`` type and is identified in syntax by a
-preceding exclamation point ('``!``').
+
+Metadata does not have a type, and is not a value. If referenced from a
+``call`` instruction, it uses the ``metadata`` type.
+
+All metadata are identified in syntax by a exclamation point ('``!``').
+
+Metadata Nodes and Metadata Strings
+-----------------------------------
A metadata string is a string surrounded by double quotes. It can
contain any character by escaping non-printable characters with
.. code-block:: llvm
- !{ metadata !"test\00", i32 10}
+ !{ !"test\00", i32 10}
+
+Metadata nodes that aren't uniqued use the ``distinct`` keyword. For example:
+
+.. code-block:: llvm
+
+ !0 = distinct !{!"test\00", i32 10}
+
+``distinct`` nodes are useful when nodes shouldn't be merged based on their
+content. They can also occur when transformations cause uniquing collisions
+when metadata operands change.
A :ref:`named metadata <namedmetadatastructure>` is a collection of
metadata nodes, which can be looked up in the module symbol table. For
.. code-block:: llvm
- !foo = metadata !{!4, !3}
+ !foo = !{!4, !3}
Metadata can be used as function arguments. Here ``llvm.dbg.value``
function is using two metadata arguments:
More information about specific metadata nodes recognized by the
optimizers and code generator is found below.
+Specialized Metadata Nodes
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Specialized metadata nodes are custom data structures in metadata (as opposed
+to generic tuples). Their fields are labelled, and can be specified in any
+order.
+
+MDLocation
+""""""""""
+
+``MDLocation`` nodes represent source debug locations. The ``scope:`` field is
+mandatory.
+
+.. code-block:: llvm
+
+ !0 = !MDLocation(line: 2900, column: 42, scope: !1, inlinedAt: !2)
+
'``tbaa``' Metadata
^^^^^^^^^^^^^^^^^^^
.. code-block:: llvm
- !0 = metadata !{ metadata !"an example type tree" }
- !1 = metadata !{ metadata !"int", metadata !0 }
- !2 = metadata !{ metadata !"float", metadata !0 }
- !3 = metadata !{ metadata !"const float", metadata !2, i64 1 }
+ !0 = !{ !"an example type tree" }
+ !1 = !{ !"int", !0 }
+ !2 = !{ !"float", !0 }
+ !3 = !{ !"const float", !2, i64 1 }
The first field is an identity field. It can be any value, usually a
metadata string, which uniquely identifies the type. The most important
.. code-block:: llvm
- !4 = metadata !{ i64 0, i64 4, metadata !1, i64 8, i64 4, metadata !2 }
+ !4 = !{ i64 0, i64 4, !1, i64 8, i64 4, !2 }
This describes a struct with two fields. The first is at offset 0 bytes
with size 4 bytes, and has tbaa tag !1. The second is at offset 8 bytes
4 byte gap between the two fields. This gap represents padding which
does not carry useful data and need not be preserved.
+'``noalias``' and '``alias.scope``' Metadata
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+``noalias`` and ``alias.scope`` metadata provide the ability to specify generic
+noalias memory-access sets. This means that some collection of memory access
+instructions (loads, stores, memory-accessing calls, etc.) that carry
+``noalias`` metadata can specifically be specified not to alias with some other
+collection of memory access instructions that carry ``alias.scope`` metadata.
+Each type of metadata specifies a list of scopes where each scope has an id and
+a domain. When evaluating an aliasing query, if for some some domain, the set
+of scopes with that domain in one instruction's ``alias.scope`` list is a
+subset of (or qual to) the set of scopes for that domain in another
+instruction's ``noalias`` list, then the two memory accesses are assumed not to
+alias.
+
+The metadata identifying each domain is itself a list containing one or two
+entries. The first entry is the name of the domain. Note that if the name is a
+string then it can be combined accross functions and translation units. A
+self-reference can be used to create globally unique domain names. A
+descriptive string may optionally be provided as a second list entry.
+
+The metadata identifying each scope is also itself a list containing two or
+three entries. The first entry is the name of the scope. Note that if the name
+is a string then it can be combined accross functions and translation units. A
+self-reference can be used to create globally unique scope names. A metadata
+reference to the scope's domain is the second entry. A descriptive string may
+optionally be provided as a third list entry.
+
+For example,
+
+.. code-block:: llvm
+
+ ; Two scope domains:
+ !0 = !{!0}
+ !1 = !{!1}
+
+ ; Some scopes in these domains:
+ !2 = !{!2, !0}
+ !3 = !{!3, !0}
+ !4 = !{!4, !1}
+
+ ; Some scope lists:
+ !5 = !{!4} ; A list containing only scope !4
+ !6 = !{!4, !3, !2}
+ !7 = !{!3}
+
+ ; These two instructions don't alias:
+ %0 = load float* %c, align 4, !alias.scope !5
+ store float %0, float* %arrayidx.i, align 4, !noalias !5
+
+ ; These two instructions also don't alias (for domain !1, the set of scopes
+ ; in the !alias.scope equals that in the !noalias list):
+ %2 = load float* %c, align 4, !alias.scope !5
+ store float %2, float* %arrayidx.i2, align 4, !noalias !6
+
+ ; These two instructions don't alias (for domain !0, the set of scopes in
+ ; the !noalias list is not a superset of, or equal to, the scopes in the
+ ; !alias.scope list):
+ %2 = load float* %c, align 4, !alias.scope !6
+ store float %0, float* %arrayidx.i, align 4, !noalias !7
+
'``fpmath``' Metadata
^^^^^^^^^^^^^^^^^^^^^
.. code-block:: llvm
- !0 = metadata !{ float 2.5 } ; maximum acceptable inaccuracy is 2.5 ULPs
+ !0 = !{ float 2.5 } ; maximum acceptable inaccuracy is 2.5 ULPs
'``range``' Metadata
^^^^^^^^^^^^^^^^^^^^
%d = invoke i8 @bar() to label %cont
unwind label %lpad, !range !3 ; Can only be -2, -1, 3, 4 or 5
...
- !0 = metadata !{ i8 0, i8 2 }
- !1 = metadata !{ i8 255, i8 2 }
- !2 = metadata !{ i8 0, i8 2, i8 3, i8 6 }
- !3 = metadata !{ i8 -2, i8 0, i8 3, i8 6 }
+ !0 = !{ i8 0, i8 2 }
+ !1 = !{ i8 255, i8 2 }
+ !2 = !{ i8 0, i8 2, i8 3, i8 6 }
+ !3 = !{ i8 -2, i8 0, i8 3, i8 6 }
'``llvm.loop``'
^^^^^^^^^^^^^^^
.. code-block:: llvm
- !0 = metadata !{ metadata !0 }
- !1 = metadata !{ metadata !1 }
+ !0 = !{!0}
+ !1 = !{!1}
The loop identifier metadata can be used to specify additional
per-loop metadata. Any operands after the first operand can be treated
br i1 %exitcond, label %._crit_edge, label %.lr.ph, !llvm.loop !0
...
- !0 = metadata !{ metadata !0, metadata !1 }
- !1 = metadata !{ metadata !"llvm.loop.unroll.count", i32 4 }
+ !0 = !{!0, !1}
+ !1 = !{!"llvm.loop.unroll.count", i32 4}
'``llvm.loop.vectorize``' and '``llvm.loop.interleave``'
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. code-block:: llvm
- !0 = metadata !{ metadata !"llvm.loop.interleave.count", i32 4 }
+ !0 = !{!"llvm.loop.interleave.count", i32 4}
Note that setting ``llvm.loop.interleave.count`` to 1 disables interleaving
multiple iterations of the loop. If ``llvm.loop.interleave.count`` is set to 0
then the interleave count will be determined automatically.
'``llvm.loop.vectorize.enable``' Metadata
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
This metadata selectively enables or disables vectorization for the loop. The
first operand is the string ``llvm.loop.vectorize.enable`` and the second operand
.. code-block:: llvm
- !0 = metadata !{ metadata !"llvm.loop.vectorize.enable", i1 0 }
- !1 = metadata !{ metadata !"llvm.loop.vectorize.enable", i1 1 }
+ !0 = !{!"llvm.loop.vectorize.enable", i1 0}
+ !1 = !{!"llvm.loop.vectorize.enable", i1 1}
'``llvm.loop.vectorize.width``' Metadata
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. code-block:: llvm
- !0 = metadata !{ metadata !"llvm.loop.vectorize.width", i32 4 }
+ !0 = !{!"llvm.loop.vectorize.width", i32 4}
Note that setting ``llvm.loop.vectorize.width`` to 1 disables
vectorization of the loop. If ``llvm.loop.vectorize.width`` is set to
optimization hints and the unrolling will only be performed if the
optimizer believes it is safe to do so.
-'``llvm.loop.unroll.enable``' Metadata
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
-This metadata either disables loop unrolling or suggests that the loop
-be unrolled fully. The first operand is the string
-``llvm.loop.unroll.enable`` and the second operand is a bit. If the
-bit operand value is 0 loop unrolling is disabled. A value of 1
-indicates that the loop should be fully unrolled. For example:
-
-.. code-block:: llvm
-
- !0 = metadata !{ metadata !"llvm.loop.unroll.enable", i1 0 }
- !1 = metadata !{ metadata !"llvm.loop.unroll.enable", i1 1 }
-
'``llvm.loop.unroll.count``' Metadata
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
.. code-block:: llvm
- !0 = metadata !{ metadata !"llvm.loop.unroll.count", i32 4 }
+ !0 = !{!"llvm.loop.unroll.count", i32 4}
If the trip count of the loop is less than the unroll count the loop
will be partially unrolled.
-If a loop has both a ``llvm.loop.unroll.enable`` metadata and
-``llvm.loop.unroll.count`` metadata the behavior depends upon the
-value of the ``llvm.loop.unroll.enable`` operand. If the value is 0,
-the loop will not be unrolled. If the value is 1, the loop will be
-unrolled with a factor determined by the ``llvm.loop.unroll.count``
-operand effectively ignoring the ``llvm.loop.unroll.enable`` metadata.
+'``llvm.loop.unroll.disable``' Metadata
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This metadata either disables loop unrolling. The metadata has a single operand
+which is the string ``llvm.loop.unroll.disable``. For example:
+
+.. code-block:: llvm
+
+ !0 = !{!"llvm.loop.unroll.disable"}
+
+'``llvm.loop.unroll.full``' Metadata
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This metadata either suggests that the loop should be unrolled fully. The
+metadata has a single operand which is the string ``llvm.loop.unroll.disable``.
+For example:
+
+.. code-block:: llvm
+
+ !0 = !{!"llvm.loop.unroll.full"}
'``llvm.mem``'
^^^^^^^^^^^^^^^
for.end:
...
- !0 = metadata !{ metadata !0 }
+ !0 = !{!0}
It is also possible to have nested parallel loops. In that case the
memory accesses refer to a list of loop identifier metadata nodes instead of
outer.for.end: ; preds = %for.body
...
- !0 = metadata !{ metadata !1, metadata !2 } ; a list of loop identifiers
- !1 = metadata !{ metadata !1 } ; an identifier for the inner loop
- !2 = metadata !{ metadata !2 } ; an identifier for the outer loop
+ !0 = !{!1, !2} ; a list of loop identifiers
+ !1 = !{!1} ; an identifier for the inner loop
+ !2 = !{!2} ; an identifier for the outer loop
Module Flags Metadata
=====================
.. code-block:: llvm
- !0 = metadata !{ i32 1, metadata !"foo", i32 1 }
- !1 = metadata !{ i32 4, metadata !"bar", i32 37 }
- !2 = metadata !{ i32 2, metadata !"qux", i32 42 }
- !3 = metadata !{ i32 3, metadata !"qux",
- metadata !{
- metadata !"foo", i32 1
+ !0 = !{ i32 1, !"foo", i32 1 }
+ !1 = !{ i32 4, !"bar", i32 37 }
+ !2 = !{ i32 2, !"qux", i32 42 }
+ !3 = !{ i32 3, !"qux",
+ !{
+ !"foo", i32 1
}
}
!llvm.module.flags = !{ !0, !1, !2, !3 }
::
- metadata !{ metadata !"foo", i32 1 }
+ !{ !"foo", i32 1 }
The behavior is to emit an error if the ``llvm.module.flags`` does not
contain a flag with the ID ``!"foo"`` that has the value '1' after linking is
linker options, presumably to link against ``libz`` and the ``Cocoa``
framework::
- !0 = metadata !{ i32 6, metadata !"Linker Options",
- metadata !{
- metadata !{ metadata !"-lz" },
- metadata !{ metadata !"-framework", metadata !"Cocoa" } } }
+ !0 = !{ i32 6, !"Linker Options",
+ !{
+ !{ !"-lz" },
+ !{ !"-framework", !"Cocoa" } } }
!llvm.module.flags = !{ !0 }
The metadata encoding as lists of lists of options, as opposed to a collapsed
enum is the smallest type which can represent all of its values::
!llvm.module.flags = !{!0, !1}
- !0 = metadata !{i32 1, metadata !"short_wchar", i32 1}
- !1 = metadata !{i32 1, metadata !"short_enum", i32 0}
+ !0 = !{i32 1, !"short_wchar", i32 1}
+ !1 = !{i32 1, !"short_enum", i32 0}
.. _intrinsicglobalvariables:
%agg1 = insertvalue {i32, float} undef, i32 1, 0 ; yields {i32 1, float undef}
%agg2 = insertvalue {i32, float} %agg1, float %val, 1 ; yields {i32 1, float %val}
- %agg3 = insertvalue {i32, {float}} %agg1, float %val, 1, 0 ; yields {i32 1, float %val}
+ %agg3 = insertvalue {i32, {float}} undef, float %val, 1, 0 ; yields {i32 undef, {float %val}}
.. _memoryops:
::
- <result> = load [volatile] <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>][, !invariant.load !<index>]
+ <result> = load [volatile] <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>][, !invariant.load !<index>][, !nonnull !<index>]
<result> = load atomic [volatile] <ty>* <pointer> [singlethread] <ordering>, align <alignment>
!<index> = !{ i32 1 }
The optional ``!invariant.load`` metadata must reference a single
metadata name ``<index>`` corresponding to a metadata node with no
entries. The existence of the ``!invariant.load`` metadata on the
-instruction tells the optimizer and code generator that this load
-address points to memory which does not change value during program
-execution. The optimizer may then move this load around, for example, by
-hoisting it out of loops using loop invariant code motion.
+instruction tells the optimizer and code generator that the address
+operand to this load points to memory which can be assumed unchanged.
+Being invariant does not imply that a location is dereferenceable,
+but it does imply that once the location is known dereferenceable
+its value is henceforth unchanging.
+
+The optional ``!nonnull`` metadata must reference a single
+metadata name ``<index>`` corresponding to a metadata node with no
+entries. The existence of the ``!nonnull`` metadata on the
+instruction tells the optimizer that the value loaded is known to
+never be null. This is analogous to the ''nonnull'' attribute
+on parameters and return values. This metadata can only be applied
+to loads of a pointer type.
Semantics:
""""""""""
- The calling conventions of the caller and callee must match.
- All ABI-impacting function attributes, such as sret, byval, inreg,
returned, and inalloca, must match.
+ - The callee must be varargs iff the caller is varargs. Bitcasting a
+ non-varargs function to the appropriate varargs type is legal so
+ long as the non-varargs prefixes obey the other rules.
Tail call optimization for calls marked ``tail`` is guaranteed to occur if
the following conditions are met:
.. code-block:: llvm
+ ; This struct is different for every platform. For most platforms,
+ ; it is merely an i8*.
+ %struct.va_list = type { i8* }
+
+ ; For Unix x86_64 platforms, va_list is the following struct:
+ ; %struct.va_list = type { i32, i32, i8*, i8* }
+
define i32 @test(i32 %X, ...) {
; Initialize variable argument processing
- %ap = alloca i8*
- %ap2 = bitcast i8** %ap to i8*
+ %ap = alloca %struct.va_list
+ %ap2 = bitcast %struct.va_list* %ap to i8*
call void @llvm.va_start(i8* %ap2)
; Read a single integer argument
- %tmp = va_arg i8** %ap, i32
+ %tmp = va_arg i8* %ap2, i32
; Demonstrate usage of llvm.va_copy and llvm.va_end
%aq = alloca i8*
other aggressive transformations, so the value returned may not be that
of the obvious source-language caller.
+'``llvm.frameallocate``' and '``llvm.framerecover``' Intrinsics
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+ declare i8* @llvm.frameallocate(i32 %size)
+ declare i8* @llvm.framerecover(i8* %func, i8* %fp)
+
+Overview:
+"""""""""
+
+The '``llvm.frameallocate``' intrinsic allocates stack memory at some fixed
+offset from the frame pointer, and the '``llvm.framerecover``'
+intrinsic applies that offset to a live frame pointer to recover the address of
+the allocation. The offset is computed during frame layout of the caller of
+``llvm.frameallocate``.
+
+Arguments:
+""""""""""
+
+The ``size`` argument to '``llvm.frameallocate``' must be a constant integer
+indicating the amount of stack memory to allocate. As with allocas, allocating
+zero bytes is legal, but the result is undefined.
+
+The ``func`` argument to '``llvm.framerecover``' must be a constant
+bitcasted pointer to a function defined in the current module. The code
+generator cannot determine the frame allocation offset of functions defined in
+other modules.
+
+The ``fp`` argument to '``llvm.framerecover``' must be a frame
+pointer of a call frame that is currently live. The return value of
+'``llvm.frameaddress``' is one way to produce such a value, but most platforms
+also expose the frame pointer through stack unwinding mechanisms.
+
+Semantics:
+""""""""""
+
+These intrinsics allow a group of functions to access one stack memory
+allocation in an ancestor stack frame. The memory returned from
+'``llvm.frameallocate``' may be allocated prior to stack realignment, so the
+memory is only aligned to the ABI-required stack alignment. Each function may
+only call '``llvm.frameallocate``' one or zero times from the function entry
+block. The frame allocation intrinsic inhibits inlining, as any frame
+allocations in the inlined function frame are likely to be at a different
+offset from the one used by '``llvm.framerecover``' called with the
+uninlined function.
+
.. _int_read_register:
.. _int_write_register:
declare i64 @llvm.read_register.i64(metadata)
declare void @llvm.write_register.i32(metadata, i32 @value)
declare void @llvm.write_register.i64(metadata, i64 @value)
- !0 = metadata !{metadata !"sp\00"}
+ !0 = !{!"sp\00"}
Overview:
"""""""""
This instrinsic does *not* empty the instruction pipeline. Modifications
of the current function are outside the scope of the intrinsic.
+'``llvm.instrprof_increment``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+ declare void @llvm.instrprof_increment(i8* <name>, i64 <hash>,
+ i32 <num-counters>, i32 <index>)
+
+Overview:
+"""""""""
+
+The '``llvm.instrprof_increment``' intrinsic can be emitted by a
+frontend for use with instrumentation based profiling. These will be
+lowered by the ``-instrprof`` pass to generate execution counts of a
+program at runtime.
+
+Arguments:
+""""""""""
+
+The first argument is a pointer to a global variable containing the
+name of the entity being instrumented. This should generally be the
+(mangled) function name for a set of counters.
+
+The second argument is a hash value that can be used by the consumer
+of the profile data to detect changes to the instrumented source, and
+the third is the number of counters associated with ``name``. It is an
+error if ``hash`` or ``num-counters`` differ between two instances of
+``instrprof_increment`` that refer to the same name.
+
+The last argument refers to which of the counters for ``name`` should
+be incremented. It should be a value between 0 and ``num-counters``.
+
+Semantics:
+""""""""""
+
+This intrinsic represents an increment of a profiling counter. It will
+cause the ``-instrprof`` pass to generate the appropriate data
+structures and the code to increment the appropriate value, in a
+format that can be written out by a compiler runtime and consumed via
+the ``llvm-profdata`` tool.
+
Standard C Library Intrinsics
-----------------------------
declare float @llvm.fabs.f32(float %Val)
declare double @llvm.fabs.f64(double %Val)
- declare x86_fp80 @llvm.fabs.f80(x86_fp80 %Val)
+ declare x86_fp80 @llvm.fabs.f80(x86_fp80 %Val)
declare fp128 @llvm.fabs.f128(fp128 %Val)
- declare ppc_fp128 @llvm.fabs.ppcf128(ppc_fp128 %Val)
+ declare ppc_fp128 @llvm.fabs.ppcf128(ppc_fp128 %Val)
Overview:
"""""""""
This function returns the same values as the libm ``fabs`` functions
would, and handles error conditions in the same way.
+'``llvm.minnum.*``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+This is an overloaded intrinsic. You can use ``llvm.minnum`` on any
+floating point or vector of floating point type. Not all targets support
+all types however.
+
+::
+
+ declare float @llvm.minnum.f32(float %Val0, float %Val1)
+ declare double @llvm.minnum.f64(double %Val0, double %Val1)
+ declare x86_fp80 @llvm.minnum.f80(x86_fp80 %Val0, x86_fp80 %Val1)
+ declare fp128 @llvm.minnum.f128(fp128 %Val0, fp128 %Val1)
+ declare ppc_fp128 @llvm.minnum.ppcf128(ppc_fp128 %Val0, ppc_fp128 %Val1)
+
+Overview:
+"""""""""
+
+The '``llvm.minnum.*``' intrinsics return the minimum of the two
+arguments.
+
+
+Arguments:
+""""""""""
+
+The arguments and return value are floating point numbers of the same
+type.
+
+Semantics:
+""""""""""
+
+Follows the IEEE-754 semantics for minNum, which also match for libm's
+fmin.
+
+If either operand is a NaN, returns the other non-NaN operand. Returns
+NaN only if both operands are NaN. If the operands compare equal,
+returns a value that compares equal to both operands. This means that
+fmin(+/-0.0, +/-0.0) could return either -0.0 or 0.0.
+
+'``llvm.maxnum.*``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+This is an overloaded intrinsic. You can use ``llvm.maxnum`` on any
+floating point or vector of floating point type. Not all targets support
+all types however.
+
+::
+
+ declare float @llvm.maxnum.f32(float %Val0, float %Val1l)
+ declare double @llvm.maxnum.f64(double %Val0, double %Val1)
+ declare x86_fp80 @llvm.maxnum.f80(x86_fp80 %Val0, x86_fp80 %Val1)
+ declare fp128 @llvm.maxnum.f128(fp128 %Val0, fp128 %Val1)
+ declare ppc_fp128 @llvm.maxnum.ppcf128(ppc_fp128 %Val0, ppc_fp128 %Val1)
+
+Overview:
+"""""""""
+
+The '``llvm.maxnum.*``' intrinsics return the maximum of the two
+arguments.
+
+
+Arguments:
+""""""""""
+
+The arguments and return value are floating point numbers of the same
+type.
+
+Semantics:
+""""""""""
+Follows the IEEE-754 semantics for maxNum, which also match for libm's
+fmax.
+
+If either operand is a NaN, returns the other non-NaN operand. Returns
+NaN only if both operands are NaN. If the operands compare equal,
+returns a value that compares equal to both operands. This means that
+fmax(+/-0.0, +/-0.0) could return either -0.0 or 0.0.
+
'``llvm.copysign.*``' Intrinsic
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
""""""""""
The first argument is the value to be counted. This argument may be of
-any integer type, or a vectory with integer element type. The return
+any integer type, or a vector with integer element type. The return
type must match the first argument type.
The second argument must be a constant and is a flag to indicate whether
""""""""""
The first argument is the value to be counted. This argument may be of
-any integer type, or a vectory with integer element type. The return
+any integer type, or a vector with integer element type. The return
type must match the first argument type.
The second argument must be a constant and is a flag to indicate whether
after performing the required machine specific adjustments. The pointer
returned can then be :ref:`bitcast and executed <int_trampoline>`.
+Masked Vector Load and Store Intrinsics
+---------------------------------------
+
+LLVM provides intrinsics for predicated vector load and store operations. The predicate is specified by a mask operand, which holds one bit per vector element, switching the associated vector lane on or off. The memory addresses corresponding to the "off" lanes are not accessed. When all bits of the mask are on, the intrinsic is identical to a regular vector load or store. When all bits are off, no memory is accessed.
+
+.. _int_mload:
+
+'``llvm.masked.load.*``' Intrinsics
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+This is an overloaded intrinsic. The loaded data is a vector of any integer or floating point data type.
+
+::
+
+ declare <16 x float> @llvm.masked.load.v16f32 (<16 x float>* <ptr>, i32 <alignment>, <16 x i1> <mask>, <16 x float> <passthru>)
+ declare <2 x double> @llvm.masked.load.v2f64 (<2 x double>* <ptr>, i32 <alignment>, <2 x i1> <mask>, <2 x double> <passthru>)
+
+Overview:
+"""""""""
+
+Reads a vector from memory according to the provided mask. The mask holds a bit for each vector lane, and is used to prevent memory accesses to the masked-off lanes. The masked-off lanes in the result vector are taken from the corresponding lanes in the passthru operand.
+
+
+Arguments:
+""""""""""
+
+The first operand is the base pointer for the load. The second operand is the alignment of the source location. It must be a constant integer value. The third operand, mask, is a vector of boolean 'i1' values with the same number of elements as the return type. The fourth is a pass-through value that is used to fill the masked-off lanes of the result. The return type, underlying type of the base pointer and the type of passthru operand are the same vector types.
+
+
+Semantics:
+""""""""""
+
+The '``llvm.masked.load``' intrinsic is designed for conditional reading of selected vector elements in a single IR operation. It is useful for targets that support vector masked loads and allows vectorizing predicated basic blocks on these targets. Other targets may support this intrinsic differently, for example by lowering it into a sequence of branches that guard scalar load operations.
+The result of this operation is equivalent to a regular vector load instruction followed by a 'select' between the loaded and the passthru values, predicated on the same mask. However, using this intrinsic prevents exceptions on memory access to masked-off lanes.
+
+
+::
+
+ %res = call <16 x float> @llvm.masked.load.v16f32 (<16 x float>* %ptr, i32 4, <16 x i1>%mask, <16 x float> %passthru)
+
+ ;; The result of the two following instructions is identical aside from potential memory access exception
+ %loadlal = load <16 x float>* %ptr, align 4
+ %res = select <16 x i1> %mask, <16 x float> %loadlal, <16 x float> %passthru
+
+.. _int_mstore:
+
+'``llvm.masked.store.*``' Intrinsics
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+This is an overloaded intrinsic. The data stored in memory is a vector of any integer or floating point data type.
+
+::
+
+ declare void @llvm.masked.store.v8i32 (<8 x i32> <value>, <8 x i32> * <ptr>, i32 <alignment>, <8 x i1> <mask>)
+ declare void @llvm.masked.store.v16f32(<16 x i32> <value>, <16 x i32>* <ptr>, i32 <alignment>, <16 x i1> <mask>)
+
+Overview:
+"""""""""
+
+Writes a vector to memory according to the provided mask. The mask holds a bit for each vector lane, and is used to prevent memory accesses to the masked-off lanes.
+
+Arguments:
+""""""""""
+
+The first operand is the vector value to be written to memory. The second operand is the base pointer for the store, it has the same underlying type as the value operand. The third operand is the alignment of the destination location. The fourth operand, mask, is a vector of boolean values. The types of the mask and the value operand must have the same number of vector elements.
+
+
+Semantics:
+""""""""""
+
+The '``llvm.masked.store``' intrinsics is designed for conditional writing of selected vector elements in a single IR operation. It is useful for targets that support vector masked store and allows vectorizing predicated basic blocks on these targets. Other targets may support this intrinsic differently, for example by lowering it into a sequence of branches that guard scalar store operations.
+The result of this operation is equivalent to a load-modify-store sequence. However, using this intrinsic prevents exceptions and data races on memory access to masked-off lanes.
+
+::
+
+ call void @llvm.masked.store.v16f32(<16 x float> %value, <16 x float>* %ptr, i32 4, <16 x i1> %mask)
+
+ ;; The result of the following instructions is identical aside from potential data races and memory access exceptions
+ %oldval = load <16 x float>* %ptr, align 4
+ %res = select <16 x i1> %mask, <16 x float> %value, <16 x float> %oldval
+ store <16 x float> %res, <16 x float>* %ptr, align 4
+
+
Memory Use Markers
------------------
This intrinsic is lowered to the ``val``.
+'``llvm.assume``' Intrinsic
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Syntax:
+"""""""
+
+::
+
+ declare void @llvm.assume(i1 %cond)
+
+Overview:
+"""""""""
+
+The ``llvm.assume`` allows the optimizer to assume that the provided
+condition is true. This information can then be used in simplifying other parts
+of the code.
+
+Arguments:
+""""""""""
+
+The condition which the optimizer may assume is always true.
+
+Semantics:
+""""""""""
+
+The intrinsic allows the optimizer to assume that the provided condition is
+always true whenever the control flow reaches the intrinsic call. No code is
+generated for this intrinsic, and instructions that contribute only to the
+provided condition are not used for code generation. If the condition is
+violated during execution, the behavior is undefined.
+
+Note that the optimizer might limit the transformations performed on values
+used by the ``llvm.assume`` intrinsic in order to preserve the instructions
+only used to form the intrinsic's input argument. This might prove undesirable
+if the extra information provided by the ``llvm.assume`` intrinsic does not cause
+sufficient overall improvement in code quality. For this reason,
+``llvm.assume`` should not be used to document basic mathematical invariants
+that the optimizer can otherwise deduce or facts that are of little use to the
+optimizer.
+
'``llvm.donothing``' Intrinsic
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Overview:
"""""""""
-The ``llvm.donothing`` intrinsic doesn't perform any operation. It's the
-only intrinsic that can be called with an invoke instruction.
+The ``llvm.donothing`` intrinsic doesn't perform any operation. It's one of only
+two intrinsics (besides ``llvm.experimental.patchpoint``) that can be called
+with an invoke instruction.
Arguments:
""""""""""
projects / oota-llvm.git / blobdiff