6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-07-12 00:29:33 +00:00
Code Issues Projects Releases Wiki Activity

Make document HTML-4.01 (Strict) compliant.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13497 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Misha Brukman 2004-05-12 18:31:21 +00:00
parent f6acb51bf3
commit 85234aca74
1 changed files with 180 additions and 261 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

441
docs/TableGenFundamentals.html
View File

@ -9,42 +9,44 @@
<div class="doc_title">TableGen Fundamentals</div>
<div class="doc_text">
<ul>
<li><a href="#introduction">Introduction</a></li>
<li><a href="#introduction">Introduction</a>
<ol>
<li><a href="#concepts">Basic concepts</a></li>
<li><a href="#example">An example record</a></li>
<li><a href="#running">Running TableGen</a></li>
</ol>
<li><a href="#syntax">TableGen syntax</a></li>
</ol></li>
<li><a href="#syntax">TableGen syntax</a>
<ol>
<li><a href="#primitives">TableGen primitives</a></li>
<li><a href="#primitives">TableGen primitives</a>
<ol>
<li><a href="#comments">TableGen comments</a></li>
<li><a href="#types">The TableGen type system</a></li>
<li><a href="#values">TableGen values and expressions</a></li>
</ol>
<li><a href="#classesdefs">Classes and definitions</a></li>
</ol></li>
<li><a href="#classesdefs">Classes and definitions</a>
<ol>
<li><a href="#valuedef">Value definitions</a></li>
<li><a href="#recordlet">'let' expressions</a></li>
<li><a href="#templateargs">Class template arguments</a></li>
</ol>
<li><a href="#filescope">File scope entities</a></li>
</ol></li>
<li><a href="#filescope">File scope entities</a>
<ol>
<li><a href="#include">File inclusion</a></li>
<li><a href="#globallet">'let' expressions</a></li>
</ol>
</ol>
<li><a href="#backends">TableGen backends</a></li>
</ol></li>
</ol></li>
<li><a href="#backends">TableGen backends</a>
<ol>
<li><a href="#">todo</a></li>
</ol>
<li><a href="#codegenerator">The LLVM code generator</a></li>
</ol></li>
<li><a href="#codegenerator">The LLVM code generator</a>
<ol>
<li><a href="#">todo</a></li>
</ol>
</ol></li>
</ul>
</div>
<!-- *********************************************************************** -->
<div class="doc_section"><a name="introduction">Introduction</a></div>
@ -62,72 +64,56 @@ makes it easier to structure domain specific information.</p>
<p>The core part of TableGen <a href="#syntax">parses a file</a>, instantiates
the declarations, and hands the result off to a domain-specific "<a
href="#backends">TableGen backend</a>" for processing. The current major user
of TableGen is the <a href="#codegenerator">LLVM code generator</a>.
</p>
of TableGen is the <a href="#codegenerator">LLVM code generator</a>.</p>
<p>
Note that if you work on TableGen much, and use emacs or vim, that you can find
an emacs "TableGen mode" and a vim language file in <tt>llvm/utils/emacs</tt>
and <tt>llvm/utils/vim</tt> directory of your LLVM distribution, respectively.
</p>
<p>Note that if you work on TableGen much, and use emacs or vim, that you can
find an emacs "TableGen mode" and a vim language file in
<tt>llvm/utils/emacs</tt> and <tt>llvm/utils/vim</tt> directory of your LLVM
distribution, respectively.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="running">Basic concepts</a>
</div>
<div class="doc_subsection"><a name="running">Basic concepts</a></div>
<div class="doc_text">
<p>
TableGen files consist of two key parts: 'classes' and 'definitions', both of
which are considered 'records'.
</p>
<p>TableGen files consist of two key parts: 'classes' and 'definitions', both
of which are considered 'records'.</p>
<p>
<b>TableGen records</b> have a unique name, a list of values, and a list of
<p><b>TableGen records</b> have a unique name, a list of values, and a list of
superclasses. The list of values is main data that TableGen builds for each
record, it is this that holds the domain specific information for the
application. The interpretation of this data is left to a specific <a
href="#backends">TableGen backend</a>, but the structure and format rules are
taken care of and fixed by TableGen.
</p>
taken care of and fixed by TableGen.</p>
<p>
<b>TableGen definitions</b> are the concrete form of 'records'. These generally
do not have any undefined values, and are marked with the '<tt>def</tt>'
keyword.
</p>
<p><b>TableGen definitions</b> are the concrete form of 'records'. These
generally do not have any undefined values, and are marked with the
'<tt>def</tt>' keyword.</p>
<p>
<b>TableGen classes</b> are abstract records that are used to build and describe
other records. These 'classes' allow the end-user to build abstractions for
either the domain they are targetting (such as "Register", "RegisterClass", and
"Instruction" in the LLVM code generator) or for the implementor to help factor
out common properties of records (such as "FPInst", which is used to represent
floating point instructions in the X86 backend). TableGen keeps track of all of
the classes that are used to build up a definition, so the backend can find all
definitions of a particular class, such as "Instruction".
</p>
<p><b>TableGen classes</b> are abstract records that are used to build and
describe other records. These 'classes' allow the end-user to build
abstractions for either the domain they are targetting (such as "Register",
"RegisterClass", and "Instruction" in the LLVM code generator) or for the
implementor to help factor out common properties of records (such as "FPInst",
which is used to represent floating point instructions in the X86 backend).
TableGen keeps track of all of the classes that are used to build up a
definition, so the backend can find all definitions of a particular class, such
as "Instruction".</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="example">An example record</a>
</div>
<div class="doc_subsection"><a name="example">An example record</a></div>
<div class="doc_text">
<p>
With no other arguments, TableGen parses the specified file and prints out all
of the classes, then all of the definitions. This is a good way to see what the
various definitions expand to fully. Running this on the <tt>X86.td</tt> file
prints this (at the time of this writing):
</p>
<p>With no other arguments, TableGen parses the specified file and prints out
all of the classes, then all of the definitions. This is a good way to see what
the various definitions expand to fully. Running this on the <tt>X86.td</tt>
file prints this (at the time of this writing):</p>
<p>
<pre>
...
<b>def</b> ADDrr8 { <i>// Instruction X86Inst I2A8 Pattern</i>
@ -153,64 +139,53 @@ prints this (at the time of this writing):
<b>bits</b>&lt;3&gt; FPFormBits = { 0, 0, 0 };
}
...
</pre><p>
</pre>
<p>
This definition corresponds to an 8-bit register-register add instruction in the
X86. The string after the '<tt>def</tt>' string indicates the name of the
<p>This definition corresponds to an 8-bit register-register add instruction in
the X86. The string after the '<tt>def</tt>' string indicates the name of the
record ("<tt>ADDrr8</tt>" in this case), and the comment at the end of the line
indicates the superclasses of the definition. The body of the record contains
all of the data that TableGen assembled for the record, indicating that the
instruction is part of the "X86" namespace, should be printed as "<tt>add</tt>"
in the assembly file, it is a two-address instruction, has a particular
encoding, etc. The contents and semantics of the information in the record is
specific to the needs of the X86 backend, and is only shown as an example.
</p>
specific to the needs of the X86 backend, and is only shown as an example.</p>
<p>
As you can see, a lot of information is needed for every instruction supported
by the code generator, and specifying it all manually would be unmaintainble,
prone to bugs, and tiring to do in the first place. Because we are using
TableGen, all of the information was derived from the following definition:
</p>
<p>As you can see, a lot of information is needed for every instruction
supported by the code generator, and specifying it all manually would be
unmaintainble, prone to bugs, and tiring to do in the first place. Because we
are using TableGen, all of the information was derived from the following
definition:</p>
<p><pre>
<pre>
<b>def</b> ADDrr8 : I2A8&lt;"add", 0x00, MRMDestReg&gt;,
Pattern&lt;(set R8, (plus R8, R8))&gt;;
</pre></p>
</pre>
<p>
This definition makes use of the custom I2A8 (two address instruction with 8-bit
operand) class, which is defined in the X86-specific TableGen file to factor out
the common features that instructions of its class share. A key feature of
TableGen is that it allows the end-user to define the abstractions they prefer
to use when describing their information.
</p>
<p>This definition makes use of the custom I2A8 (two address instruction with
8-bit operand) class, which is defined in the X86-specific TableGen file to
factor out the common features that instructions of its class share. A key
feature of TableGen is that it allows the end-user to define the abstractions
they prefer to use when describing their information.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="running">Running TableGen</a>
</div>
<div class="doc_subsection"><a name="running">Running TableGen</a></div>
<div class="doc_text">
<p>
TableGen runs just like any other LLVM tool. The first (optional) argument
<p>TableGen runs just like any other LLVM tool. The first (optional) argument
specifies the file to read. If a filename is not specified, <tt>tblgen</tt>
reads from standard input.
</p>
reads from standard input.</p>
<p>
To be useful, one of the <a href="#backends">TableGen backends</a> must be used.
These backends are selectable on the command line (type '<tt>tblgen --help</tt>'
for a list). For example, to get a list of all of the definitions that subclass
a particular type (which can be useful for building up an enum list of these
records), use the <tt>--print-enums</tt> option:
</p>
<p>To be useful, one of the <a href="#backends">TableGen backends</a> must be
used. These backends are selectable on the command line (type '<tt>tblgen
--help</tt>' for a list). For example, to get a list of all of the definitions
that subclass a particular type (which can be useful for building up an enum
list of these records), use the <tt>--print-enums</tt> option:</p>
<p><pre>
<pre>
$ tblgen X86.td -print-enums -class=Register
AH, AL, AX, BH, BL, BP, BX, CH, CL, CX, DH, DI, DL, DX,
EAX, EBP, EBX, ECX, EDI, EDX, ESI, ESP, FP0, FP1, FP2, FP3, FP4, FP5, FP6,
@ -220,18 +195,14 @@ $ tblgen X86.td -print-enums -class=Instruction
ADCrr32, ADDri16, ADDri16b, ADDri32, ADDri32b, ADDri8, ADDrr16, ADDrr32,
ADDrr8, ADJCALLSTACKDOWN, ADJCALLSTACKUP, ANDri16, ANDri16b, ANDri32, ANDri32b,
ANDri8, ANDrr16, ANDrr32, ANDrr8, BSWAPr32, CALLm32, CALLpcrel32, ...
</pre></p>
</pre>
<p>
The default backend prints out all of the records, as described <a
href="#example">above</a>.
</p>
<p>The default backend prints out all of the records, as described <a
href="#example">above</a>.</p>
<p>
If you plan to use TableGen for some purpose, you will most likely have to <a
href="#backends">write a backend</a> that extracts the information specific to
what you need and formats it in the appropriate way.
</p>
<p>If you plan to use TableGen for some purpose, you will most likely have to
<a href="#backends">write a backend</a> that extracts the information specific
to what you need and formats it in the appropriate way.</p>
</div>
@ -241,54 +212,39 @@ what you need and formats it in the appropriate way.
<!-- *********************************************************************** -->
<div class="doc_text">
<p>
TableGen doesn't care about the meaning of data (that is up to the backend to
define), but it does care about syntax, and it enforces a simple type system.
<p>TableGen doesn't care about the meaning of data (that is up to the backend
to define), but it does care about syntax, and it enforces a simple type system.
This section describes the syntax and the constructs allowed in a TableGen file.
</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="primitives">TableGen primitives</tt></a>
</div>
<div class="doc_subsection"><a name="primitives">TableGen primitives</a></div>
<!----------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="comments">TableGen comments</tt></a>
</div>
<!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"><a name="comments">TableGen comments</a></div>
<div class="doc_text">
<p>TableGen supports BCPL style "<tt>//</tt>" comments, which run to the end of
the line, and it also supports <b>nestable</b> "<tt>/* */</tt>" comments.</p>
</div>
<!----------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="types">The TableGen type system</tt></a>
<!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection"><a name="types">The TableGen type system</a>
</div>
<div class="doc_text">
<p>
TableGen files are strongly typed, in a simple (but complete) type-system.
<p>TableGen files are strongly typed, in a simple (but complete) type-system.
These types are used to perform automatic conversions, check for errors, and to
help interface designers constrain the input that they allow. Every <a
href="#valuedef">value definition</a> is required to have an associated type.
</p>
<p>
TableGen supports a mixture of very low-level types (such as <tt>bit</tt>) and
very high-level types (such as <tt>dag</tt>). This flexibility is what allows
it to describe a wide range of information conveniently and compactly. The
TableGen types are:
</p>
<p>TableGen supports a mixture of very low-level types (such as <tt>bit</tt>)
and very high-level types (such as <tt>dag</tt>). This flexibility is what
allows it to describe a wide range of information conveniently and compactly.
The TableGen types are:</p>
<p>
<ul>
<li>"<tt><b>bit</b></tt>" - A 'bit' is a boolean value that can hold either 0 or
1.</li>
@ -319,29 +275,25 @@ remember why this is distinct from string!</li>
<li>"<tt><b>dag</b></tt>" - This type represents a nestable directed graph of
elements.</li>
</ul>
</p>
<p>
To date, these types have been sufficient for describing things that TableGen
has been used for, but it is straight-forward to extend this list if needed.
</p>
<p>To date, these types have been sufficient for describing things that
TableGen has been used for, but it is straight-forward to extend this list if
needed.</p>
</div>
<!----------------------------------------------------------------------------->
<!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="values">TableGen values and expressions</tt></a>
<a name="values">TableGen values and expressions</a>
</div>
<div>
<p>
TableGen allows for a pretty reasonable number of different expression forms
<p>TableGen allows for a pretty reasonable number of different expression forms
when building up values. These forms allow the TableGen file to be written in a
natural syntax and flavor for the application. The current expression forms
supported include:
</p>
supported include:</p>
<p><ul>
<ul>
<li>? - Uninitialized field.</li>
<li>0b1001011 - Binary integer value.</li>
<li>07654321 - Octal integer value (indicated by a leading 0).</li>
@ -360,27 +312,20 @@ supported include:
definition, the remaining elements in the list may be arbitrary other values,
including nested 'dag' values.</li>
</ul></p>
</ul>
<p>
Note that all of the values have rules specifying how they convert to values
<p>Note that all of the values have rules specifying how they convert to values
for different types. These rules allow you to assign a value like "7" to a
"bits&lt;4&gt;" value, for example.
</p>
"bits&lt;4&gt;" value, for example.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="classesdefs">Classes and definitions</tt></a>
<div class="doc_subsection"><a name="classesdefs">Classes and definitions</a>
</div>
<div>
<p>
As mentioned in the <a href="#concepts">intro</a>, classes and definitions
<p>As mentioned in the <a href="#concepts">intro</a>, classes and definitions
(collectively known as 'records') in TableGen are the main high-level unit of
information that TableGen collects. Records are defined with a <tt>def</tt> or
<tt>class</tt> keyword, the record name, and an optional list of "<a
@ -389,87 +334,78 @@ they are specified as a comma seperated list that starts with a colon character
(":"). If <a href="#valuedef">value definitions</a> or <a href="#recordlet">let
expressions</a> are needed for the class, they are enclosed in curly braces
("{}"); otherwise, the record ends with a semicolon. Here is a simple TableGen
file:
</p>
file:</p>
<p><pre>
<pre>
<b>class</b> C { <b>bit</b> V = 1; }
<b>def</b> X : C;
<b>def</b> Y : C {
<b>string</b> Greeting = "hello";
}
</pre></p>
</pre>
<p>
This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of which
derive from the <tt>C</tt> class. Because of this, they both get the <tt>V</tt>
bit value. The <tt>Y</tt> definition also gets the Greeting member as well.
</p>
<p>This example defines two definitions, <tt>X</tt> and <tt>Y</tt>, both of
which derive from the <tt>C</tt> class. Because of this, they both get the
<tt>V</tt> bit value. The <tt>Y</tt> definition also gets the Greeting member
as well.</p>
<p>
In general, classes are useful for collecting together the commonality between a
group of records and isolating it in a single place. Also, classes permit the
specification of default values for their subclasses, allowing the subclasses to
override them as they wish.
</p>
<p>In general, classes are useful for collecting together the commonality
between a group of records and isolating it in a single place. Also, classes
permit the specification of default values for their subclasses, allowing the
subclasses to override them as they wish.</p>
</div>
<!----------------------------------------------------------------------------->
<!---------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="valuedef">Value definitions</tt></a>
<a name="valuedef">Value definitions</a>
</div>
<div class="doc_text">
<p>
Value definitions define named entries in records. A value must be defined
<p>Value definitions define named entries in records. A value must be defined
before it can be referred to as the operand for another value definition or
before the value is reset with a <a href="#recordlet">let expression</a>. A
value is defined by specifying a <a href="#types">TableGen type</a> and a name.
If an initial value is available, it may be specified after the type with an
equal sign. Value definitions require terminating semicolons.
equal sign. Value definitions require terminating semicolons.</p>
</div>
<!----------------------------------------------------------------------------->
<!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="recordlet">'let' expressions</tt></a>
<a name="recordlet">'let' expressions</a>
</div>
<div class="doc_text">
<p>
A record-level let expression is used to change the value of a value definition
in a record. This is primarily useful when a superclass defines a value that a
derived class or definition wants to override. Let expressions consist of the
'<tt>let</tt>' keyword followed by a value name, an equal sign ("="), and a new
value. For example, a new class could be added to the example above, redefining
the <tt>V</tt> field for all of its subclasses:</p>
<p>A record-level let expression is used to change the value of a value
definition in a record. This is primarily useful when a superclass defines a
value that a derived class or definition wants to override. Let expressions
consist of the '<tt>let</tt>' keyword followed by a value name, an equal sign
("="), and a new value. For example, a new class could be added to the example
above, redefining the <tt>V</tt> field for all of its subclasses:</p>
<p><pre>
<pre>
<b>class</b> D : C { let V = 0; }
<b>def</b> Z : D;
</pre></p>
</pre>
<p>
In this case, the <tt>Z</tt> definition will have a zero value for its "V"
<p>In this case, the <tt>Z</tt> definition will have a zero value for its "V"
value, despite the fact that it derives (indirectly) from the <tt>C</tt> class,
because the <tt>D</tt> class overrode its value.
</p>
because the <tt>D</tt> class overrode its value.</p>
</div>
<!----------------------------------------------------------------------------->
<!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="templateargs">Class template arguments</tt></a>
<a name="templateargs">Class template arguments</a>
</div>
<div class="doc_text">
<p>
TableGen permits the definition of parameterized classes as well as normal
<p>TableGen permits the definition of parameterized classes as well as normal
concrete classes. Parameterized TableGen classes specify a list of variable
bindings (which may optionally have defaults) that are bound when used. Here is
a simple example:</p>
<p><pre>
<pre>
<b>class</b> FPFormat&lt;<b>bits</b>&lt;3&gt; val&gt; {
<b>bits</b>&lt;3&gt; Value = val;
}
@ -479,17 +415,16 @@ a simple example:</p>
<b>def</b> OneArgFPRW : FPFormat&lt;3&gt;;
<b>def</b> TwoArgFP : FPFormat&lt;4&gt;;
<b>def</b> SpecialFP : FPFormat&lt;5&gt;;
</pre></p>
</pre>
<p>
In this case, template arguments are used as a space efficient way to specify a
list of "enumeration values", each with a "Value" field set to the specified
<p>In this case, template arguments are used as a space efficient way to specify
a list of "enumeration values", each with a "Value" field set to the specified
integer.</p>
<p>The more esoteric forms of <a href="#values">TableGen expressions</a> are
useful in conjunction with template arguments. As an example:</p>
<p><pre>
<pre>
<b>class</b> ModRefVal&lt;<b>bits</b>&lt;2&gt; val&gt; {
<b>bits</b>&lt;2&gt; Value = val;
}
@ -512,15 +447,14 @@ useful in conjunction with template arguments. As an example:</p>
<b>def</b> bork : Value&lt;Mod&gt;;
<b>def</b> zork : Value&lt;Ref&gt;;
<b>def</b> hork : Value&lt;ModRef&gt;;
</pre></p>
</pre>
<p>
This is obviously a contrived example, but it shows how template arguments can
be used to decouple the interface provided to the user of the class from the
<p>This is obviously a contrived example, but it shows how template arguments
can be used to decouple the interface provided to the user of the class from the
actual internal data representation expected by the class. In this case,
running <tt>tblgen</tt> on the example prints the following definitions:</p>
<p><pre>
<pre>
<b>def</b> bork { <i>// Value</i>
bit isMod = 1;
bit isRef = 0;
@ -533,61 +467,54 @@ running <tt>tblgen</tt> on the example prints the following definitions:</p>
bit isMod = 0;
bit isRef = 1;
}
</pre></p>
</pre>
<p>
This shows that TableGen was able to dig into the argument and extract a piece
of information that was requested by the designer of the "Value" class. For
more realistic examples, please see existing users of TableGen, such as the X86
backend.</p>
<p> This shows that TableGen was able to dig into the argument and extract a
piece of information that was requested by the designer of the "Value" class.
For more realistic examples, please see existing users of TableGen, such as the
X86 backend.</p>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="filescope">File scope entities</tt></a>
<a name="filescope">File scope entities</a>
</div>
<!----------------------------------------------------------------------------->
<!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="include">File inclusion</tt></a>
<a name="include">File inclusion</a>
</div>
<div class="doc_text">
<p>
TableGen supports the '<tt>include</tt>' token, which textually substitutes the
specified file in place of the include directive. The filename should be
<p>TableGen supports the '<tt>include</tt>' token, which textually substitutes
the specified file in place of the include directive. The filename should be
specified as a double quoted string immediately after the '<tt>include</tt>'
keyword. Example:
keyword. Example:</p>
<p><pre>
<pre>
<b>include</b> "foo.td"
</pre></p>
</pre>
</div>
<!----------------------------------------------------------------------------->
<!-- -------------------------------------------------------------------------->
<div class="doc_subsubsection">
<a name="globallet">'let' expressions</tt></a>
<a name="globallet">'let' expressions</a>
</div>
<div class="doc_text">
<p>
"let" expressions at file scope are similar to <a href="#recordlet">"let"
<p> "let" expressions at file scope are similar to <a href="#recordlet">"let"
expressions within a record</a>, except they can specify a value binding for
multiple records at a time, and may be useful in certain other cases.
File-scope let expressions are really just another way that TableGen allows the
end-user to factor out commonality from the records.
</p>
end-user to factor out commonality from the records.</p>
<p>
File-scope "let" expressions take a comma-seperated list of bindings to apply,
and one of more records to bind the values in. Here are some examples:
</p>
<p>File-scope "let" expressions take a comma-seperated list of bindings to
apply, and one of more records to bind the values in. Here are some
examples:</p>
<p><pre>
<pre>
<b>let</b> isTerminator = 1, isReturn = 1 <b>in</b>
<b>def</b> RET : X86Inst&lt;"ret", 0xC3, RawFrm, NoArg&gt;;
@ -598,56 +525,48 @@ and one of more records to bind the values in. Here are some examples:
<b>def</b> CALLr32 : X86Inst&lt;"call", 0xFF, MRMS2r, Arg32&gt;;
<b>def</b> CALLm32 : X86Inst&lt;"call", 0xFF, MRMS2m, Arg32&gt;;
}
</pre></p>
</pre>
<p>
File-scope "let" expressions are often useful when a couple of definitions need
to be added to several records, and the records do not otherwise need to be
opened, as in the case with the CALL* instructions above.
</p>
<p>File-scope "let" expressions are often useful when a couple of definitions
need to be added to several records, and the records do not otherwise need to be
opened, as in the case with the CALL* instructions above.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section"><a name="backends">TableGen backends</a></div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>
How they work, how to write one. This section should not contain details about
any particular backend, except maybe -print-enums as an example. This should
highlight the APIs in TableGen/Record.h.
</p>
<p>How they work, how to write one. This section should not contain details
about any particular backend, except maybe -print-enums as an example. This
should highlight the APIs in <tt>TableGen/Record.h</tt>.</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section"><a name="codegenerator">The LLVM code generator</a></div>
<div class="doc_section"><a name="codegenerator">The LLVM code generator</a>
</div>
<!-- *********************************************************************** -->
<div class="doc_text">
<p>
This is just a temporary, convenient, place to put stuff about the code
<p>This is just a temporary, convenient, place to put stuff about the code
generator before it gets its own document. This should describe all of the
tablegen backends used by the code generator and the classes/definitions they
expect.
</p>
expect.</p>
</div>
<!-- *********************************************************************** -->
<hr>
<div class="doc_footer">
<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a>
<br>
<address>
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
<a href="http://validator.w3.org/check/referer"><img
src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>
<a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
<a href="http://llvm.cs.uiuc.edu">LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
</div>
</address>
</body>
</html>