<ol>
<li><a href="#linkage_private">'<tt>private</tt>' Linkage</a></li>
<li><a href="#linkage_linker_private">'<tt>linker_private</tt>' Linkage</a></li>
+ <li><a href="#linkage_linker_private_weak">'<tt>linker_private_weak</tt>' Linkage</a></li>
<li><a href="#linkage_internal">'<tt>internal</tt>' Linkage</a></li>
<li><a href="#linkage_available_externally">'<tt>available_externally</tt>' Linkage</a></li>
<li><a href="#linkage_linkonce">'<tt>linkonce</tt>' Linkage</a></li>
<dl>
<dt><tt><b><a name="linkage_private">private</a></b></tt></dt>
- <dd>Global values with private linkage are only directly accessible by objects
- in the current module. In particular, linking code into a module with an
- private global value may cause the private to be renamed as necessary to
- avoid collisions. Because the symbol is private to the module, all
- references can be updated. This doesn't show up in any symbol table in the
- object file.</dd>
+ <dd>Global values with "<tt>private</tt>" linkage are only directly accessible
+ by objects in the current module. In particular, linking code into a
+ module with an private global value may cause the private to be renamed as
+ necessary to avoid collisions. Because the symbol is private to the
+ module, all references can be updated. This doesn't show up in any symbol
+ table in the object file.</dd>
<dt><tt><b><a name="linkage_linker_private">linker_private</a></b></tt></dt>
- <dd>Similar to private, but the symbol is passed through the assembler and
- removed by the linker after evaluation. Note that (unlike private
- symbols) linker_private symbols are subject to coalescing by the linker:
- weak symbols get merged and redefinitions are rejected. However, unlike
- normal strong symbols, they are removed by the linker from the final
- linked image (executable or dynamic library).</dd>
+ <dd>Similar to <tt>private</tt>, but the symbol is passed through the
+ assembler and evaluated by the linker. Unlike normal strong symbols, they
+ are removed by the linker from the final linked image (executable or
+ dynamic library).</dd>
+
+ <dt><tt><b><a name="linkage_linker_private_weak">linker_private_weak</a></b></tt></dt>
+ <dd>Similar to "<tt>linker_private</tt>", but the symbol is weak. Note that
+ <tt>linker_private_weak</tt> symbols are subject to coalescing by the
+ linker. The symbols are removed by the linker from the final linked image
+ (executable or dynamic library).</dd>
<dt><tt><b><a name="linkage_internal">internal</a></b></tt></dt>
<dd>Similar to private, but the value shows as a local symbol
<dt><tt><b><a name="linkage_weak_odr">weak_odr</a></b></tt></dt>
<dd>Some languages allow differing globals to be merged, such as two functions
with different semantics. Other languages, such as <tt>C++</tt>, ensure
- that only equivalent globals are ever merged (the "one definition rule" -
- "ODR"). Such languages can use the <tt>linkonce_odr</tt>
+ that only equivalent globals are ever merged (the "one definition rule"
+ — "ODR"). Such languages can use the <tt>linkonce_odr</tt>
and <tt>weak_odr</tt> linkage types to indicate that the global will only
be merged with equivalent globals. These linkage types are otherwise the
same as their non-<tt>odr</tt> versions.</dd>
generator that usually indicates a desired alignment for the synthesized
stack slot.</dd>
- <dt><tt><b>sret</b></tt></dt>
+ <dt><tt><b><a name="sret">sret</a></b></tt></dt>
<dd>This indicates that the pointer parameter specifies the address of a
structure that is the return value of the function in the source program.
This pointer must be guaranteed by the caller to be valid: loads and
may only be applied to the first parameter. This is not a valid attribute
for return values. </dd>
- <dt><tt><b>noalias</b></tt></dt>
- <dd>This indicates that the pointer does not alias any global or any other
- parameter. The caller is responsible for ensuring that this is the
- case. On a function return value, <tt>noalias</tt> additionally indicates
- that the pointer does not alias any other pointers visible to the
- caller. For further details, please see the discussion of the NoAlias
- response in
- <a href="http://llvm.org/docs/AliasAnalysis.html#MustMayNo">alias
- analysis</a>.</dd>
-
- <dt><tt><b>nocapture</b></tt></dt>
+ <dt><tt><b><a name="noalias">noalias</a></b></tt></dt>
+ <dd>This indicates that pointer values
+ <a href="#pointeraliasing"><i>based</i></a> on the argument or return
+ value do not alias pointer values which are not <i>based</i> 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 <tt>noalias</tt> 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
+ <a href="AliasAnalysis.html#MustMayNo">alias analysis</a>.<br>
+<br>
+ Note that this definition of <tt>noalias<tt> is intentionally
+ similar to the definition of <tt>restrict<tt> in C99 for function
+ arguments, though it is slightly weaker.
+<br>
+ For function return values, C99's <tt>restrict</tt> is not meaningful,
+ while LLVM's <tt>noalias</tt> is.
+ </dd>
+
+ <dt><tt><b><a name="nocapture">nocapture</a></b></tt></dt>
<dd>This indicates that the callee does not make any copies of the pointer
that outlive the callee itself. This is not a valid attribute for return
values.</dd>
- <dt><tt><b>nest</b></tt></dt>
+ <dt><tt><b><a name="nest">nest</a></b></tt></dt>
<dd>This indicates that the pointer parameter can be excised using the
<a href="#int_trampoline">trampoline intrinsics</a>. This is not a valid
attribute for return values.</dd>
this function is desirable (such as the "inline" keyword in C/C++). It
is just a hint; it imposes no requirements on the inliner.</dd>
+ <dt><tt><b>naked</b></tt></dt>
+ <dd>This attribute disables prologue / epilogue emission for the function.
+ This can have very system-specific consequences.</dd>
+
+ <dt><tt><b>noimplicitfloat</b></tt></dt>
+ <dd>This attributes disables implicit floating point instructions.</dd>
+
<dt><tt><b>noinline</b></tt></dt>
<dd>This attribute indicates that the inliner should never inline this
function in any situation. This attribute may not be used together with
the <tt>alwaysinline</tt> attribute.</dd>
- <dt><tt><b>optsize</b></tt></dt>
- <dd>This attribute suggests that optimization passes and code generator passes
- make choices that keep the code size of this function low, and otherwise
- do optimizations specifically to reduce code size.</dd>
+ <dt><tt><b>noredzone</b></tt></dt>
+ <dd>This attribute indicates that the code generator should not use a red
+ zone, even if the target-specific ABI normally permits it.</dd>
<dt><tt><b>noreturn</b></tt></dt>
<dd>This function attribute indicates that the function never returns
unwind or exceptional control flow. If the function does unwind, its
runtime behavior is undefined.</dd>
+ <dt><tt><b>optsize</b></tt></dt>
+ <dd>This attribute suggests that optimization passes and code generator passes
+ make choices that keep the code size of this function low, and otherwise
+ do optimizations specifically to reduce code size.</dd>
+
<dt><tt><b>readnone</b></tt></dt>
<dd>This attribute indicates that the function computes its result (or decides
to unwind an exception) based strictly on its arguments, without
function that doesn't have an <tt>sspreq</tt> attribute or which has
an <tt>ssp</tt> attribute, then the resulting function will have
an <tt>sspreq</tt> attribute.</dd>
-
- <dt><tt><b>noredzone</b></tt></dt>
- <dd>This attribute indicates that the code generator should not use a red
- zone, even if the target-specific ABI normally permits it.</dd>
-
- <dt><tt><b>noimplicitfloat</b></tt></dt>
- <dd>This attributes disables implicit floating point instructions.</dd>
-
- <dt><tt><b>naked</b></tt></dt>
- <dd>This attribute disables prologue / epilogue emission for the function.
- This can have very system-specific consequences.</dd>
</dl>
</div>
<dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
<dd>This specifies the alignment for a floating point type of a given bit
- <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
- (double).</dd>
+ <i>size</i>. Only values of <i>size</i> that are supported by the target
+ will work. 32 (float) and 64 (double) are supported on all targets;
+ 80 or 128 (different flavors of long double) are also supported on some
+ targets.
<dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
<dd>This specifies the alignment for an aggregate type of a given bit
according to the following rules:</p>
<ul>
- <li>A pointer value formed from a
- <tt><a href="#i_getelementptr">getelementptr</a></tt> instruction
- is associated with the addresses associated with the first operand
- of the <tt>getelementptr</tt>.</li>
+ <li>A pointer value is associated with the addresses associated with
+ any value it is <i>based</i> on.
<li>An address of a global variable is associated with the address
range of the variable's storage.</li>
<li>The result value of an allocation instruction is associated with
the address range of the allocated storage.</li>
<li>A null pointer in the default address-space is associated with
no address.</li>
- <li>A pointer value formed by an
- <tt><a href="#i_inttoptr">inttoptr</a></tt> is associated with all
- address ranges of all pointer values that contribute (directly or
- indirectly) to the computation of the pointer's value.</li>
- <li>The result value of a
- <tt><a href="#i_bitcast">bitcast</a></tt> is associated with all
- addresses associated with the operand of the <tt>bitcast</tt>.</li>
<li>An integer constant other than zero or a pointer value returned
from a function not defined within LLVM may be associated with address
ranges allocated through mechanisms other than those provided by
LLVM. Such ranges shall not overlap with any ranges of addresses
allocated by mechanisms provided by LLVM.</li>
- </ul>
+</ul>
+
+<p>A pointer value is <i>based</i> on another pointer value according
+ to the following rules:</p>
+
+<ul>
+ <li>A pointer value formed from a
+ <tt><a href="#i_getelementptr">getelementptr</a></tt> operation
+ is <i>based</i> on the first operand of the <tt>getelementptr</tt>.</li>
+ <li>The result value of a
+ <tt><a href="#i_bitcast">bitcast</a></tt> is <i>based</i> on the operand
+ of the <tt>bitcast</tt>.</li>
+ <li>A pointer value formed by an
+ <tt><a href="#i_inttoptr">inttoptr</a></tt> is <i>based</i> on all
+ pointer values that contribute (directly or indirectly) to the
+ computation of the pointer's value.</li>
+ <li>The "<i>based</i> on" relationship is transitive.</li>
+</ul>
+
+<p>Note that this definition of <i>"based"</i> is intentionally
+ similar to the definition of <i>"based"</i> in C99, though it is
+ slightly weaker.</p>
<p>LLVM IR does not associate types with memory. The result type of a
<tt><a href="#i_load">load</a></tt> merely indicates the size and
alignment of the memory from which to load, as well as the
-interpretation of the value. The first operand of a
+interpretation of the value. The first operand type of a
<tt><a href="#i_store">store</a></tt> similarly only indicates the size
and alignment of the store.</p>
<li>An instruction with externally visible side effects depends on the most
recent preceding instruction with externally visible side effects, following
- the order in the IR. (This includes volatile loads and stores.)</li>
+ the order in the IR. (This includes
+ <a href="#volatile">volatile operations</a>.)</li>
<li>An instruction <i>control-depends</i> on a
<a href="#terminators">terminator instruction</a>
<dd>Perform the <a href="#i_shufflevector">shufflevector operation</a> on
constants.</dd>
+ <dt><b><tt>extractvalue (VAL, IDX0, IDX1, ...)</tt></b></dt>
+ <dd>Perform the <a href="#i_extractvalue">extractvalue operation</a> on
+ constants. The index list is interpreted in a similar manner as indices in
+ a '<a href="#i_getelementptr">getelementptr</a>' operation. At least one
+ index value must be specified.</dd>
+
+ <dt><b><tt>insertvalue (VAL, ELT, IDX0, IDX1, ...)</tt></b></dt>
+ <dd>Perform the <a href="#i_insertvalue">insertvalue operation</a> on
+ constants. The index list is interpreted in a similar manner as indices in
+ a '<a href="#i_getelementptr">getelementptr</a>' operation. At least one
+ index value must be specified.</dd>
+
<dt><b><tt>OPCODE (LHS, RHS)</tt></b></dt>
<dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
be any of the <a href="#binaryops">binary</a>
<div class="doc_text">
<p>This intrinsic makes it possible to excise one parameter, marked with
- the <tt>nest</tt> attribute, from a function. The result is a callable
+ the <a href="#nest"><tt>nest</tt></a> attribute, from a function.
+ The result is a callable
function pointer lacking the nest parameter - the caller does not need to
provide a value for it. Instead, the value to use is stored in advance in a
"trampoline", a block of memory usually allocated on the stack, which also
projects / oota-llvm.git / blobdiff