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diff --git a/share/doc/gccint/Machine-Modes.html b/share/doc/gccint/Machine-Modes.html new file mode 100644 index 0000000..d7593db --- /dev/null +++ b/share/doc/gccint/Machine-Modes.html @@ -0,0 +1,765 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1988-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). 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In the C code, machine modes are represented by an enumeration +type, <code>machine_mode</code>, defined in <samp>machmode.def</samp>. Each RTL +expression has room for a machine mode and so do certain kinds of tree +expressions (declarations and types, to be precise). +</p> +<p>In debugging dumps and machine descriptions, the machine mode of an RTL +expression is written after the expression code with a colon to separate +them. The letters ‘<samp>mode</samp>’ which appear at the end of each machine mode +name are omitted. For example, <code>(reg:SI 38)</code> is a <code>reg</code> +expression with machine mode <code>SImode</code>. If the mode is +<code>VOIDmode</code>, it is not written at all. +</p> +<p>Here is a table of machine modes. The term “byte” below refers to an +object of <code>BITS_PER_UNIT</code> bits (see <a href="Storage-Layout.html#Storage-Layout">Storage Layout</a>). +</p> +<dl compact="compact"> +<dd><a name="index-BImode"></a> +</dd> +<dt><code>BImode</code></dt> +<dd><p>“Bit” mode represents a single bit, for predicate registers. +</p> +<a name="index-QImode"></a> +</dd> +<dt><code>QImode</code></dt> +<dd><p>“Quarter-Integer” mode represents a single byte treated as an integer. +</p> +<a name="index-HImode"></a> +</dd> +<dt><code>HImode</code></dt> +<dd><p>“Half-Integer” mode represents a two-byte integer. +</p> +<a name="index-PSImode"></a> +</dd> +<dt><code>PSImode</code></dt> +<dd><p>“Partial Single Integer” mode represents an integer which occupies +four bytes but which doesn’t really use all four. On some machines, +this is the right mode to use for pointers. +</p> +<a name="index-SImode"></a> +</dd> +<dt><code>SImode</code></dt> +<dd><p>“Single Integer” mode represents a four-byte integer. +</p> +<a name="index-PDImode"></a> +</dd> +<dt><code>PDImode</code></dt> +<dd><p>“Partial Double Integer” mode represents an integer which occupies +eight bytes but which doesn’t really use all eight. On some machines, +this is the right mode to use for certain pointers. +</p> +<a name="index-DImode"></a> +</dd> +<dt><code>DImode</code></dt> +<dd><p>“Double Integer” mode represents an eight-byte integer. +</p> +<a name="index-TImode"></a> +</dd> +<dt><code>TImode</code></dt> +<dd><p>“Tetra Integer” (?) mode represents a sixteen-byte integer. +</p> +<a name="index-OImode"></a> +</dd> +<dt><code>OImode</code></dt> +<dd><p>“Octa Integer” (?) mode represents a thirty-two-byte integer. +</p> +<a name="index-XImode"></a> +</dd> +<dt><code>XImode</code></dt> +<dd><p>“Hexadeca Integer” (?) mode represents a sixty-four-byte integer. +</p> +<a name="index-QFmode"></a> +</dd> +<dt><code>QFmode</code></dt> +<dd><p>“Quarter-Floating” mode represents a quarter-precision (single byte) +floating point number. +</p> +<a name="index-HFmode"></a> +</dd> +<dt><code>HFmode</code></dt> +<dd><p>“Half-Floating” mode represents a half-precision (two byte) floating +point number. +</p> +<a name="index-TQFmode"></a> +</dd> +<dt><code>TQFmode</code></dt> +<dd><p>“Three-Quarter-Floating” (?) mode represents a three-quarter-precision +(three byte) floating point number. +</p> +<a name="index-SFmode"></a> +</dd> +<dt><code>SFmode</code></dt> +<dd><p>“Single Floating” mode represents a four byte floating point number. +In the common case, of a processor with IEEE arithmetic and 8-bit bytes, +this is a single-precision IEEE floating point number; it can also be +used for double-precision (on processors with 16-bit bytes) and +single-precision VAX and IBM types. +</p> +<a name="index-DFmode"></a> +</dd> +<dt><code>DFmode</code></dt> +<dd><p>“Double Floating” mode represents an eight byte floating point number. +In the common case, of a processor with IEEE arithmetic and 8-bit bytes, +this is a double-precision IEEE floating point number. +</p> +<a name="index-XFmode"></a> +</dd> +<dt><code>XFmode</code></dt> +<dd><p>“Extended Floating” mode represents an IEEE extended floating point +number. This mode only has 80 meaningful bits (ten bytes). Some +processors require such numbers to be padded to twelve bytes, others +to sixteen; this mode is used for either. +</p> +<a name="index-SDmode"></a> +</dd> +<dt><code>SDmode</code></dt> +<dd><p>“Single Decimal Floating” mode represents a four byte decimal +floating point number (as distinct from conventional binary floating +point). +</p> +<a name="index-DDmode"></a> +</dd> +<dt><code>DDmode</code></dt> +<dd><p>“Double Decimal Floating” mode represents an eight byte decimal +floating point number. +</p> +<a name="index-TDmode"></a> +</dd> +<dt><code>TDmode</code></dt> +<dd><p>“Tetra Decimal Floating” mode represents a sixteen byte decimal +floating point number all 128 of whose bits are meaningful. +</p> +<a name="index-TFmode"></a> +</dd> +<dt><code>TFmode</code></dt> +<dd><p>“Tetra Floating” mode represents a sixteen byte floating point number +all 128 of whose bits are meaningful. One common use is the +IEEE quad-precision format. +</p> +<a name="index-QQmode"></a> +</dd> +<dt><code>QQmode</code></dt> +<dd><p>“Quarter-Fractional” mode represents a single byte treated as a signed +fractional number. The default format is “s.7”. +</p> +<a name="index-HQmode"></a> +</dd> +<dt><code>HQmode</code></dt> +<dd><p>“Half-Fractional” mode represents a two-byte signed fractional number. +The default format is “s.15”. +</p> +<a name="index-SQmode"></a> +</dd> +<dt><code>SQmode</code></dt> +<dd><p>“Single Fractional” mode represents a four-byte signed fractional number. +The default format is “s.31”. +</p> +<a name="index-DQmode"></a> +</dd> +<dt><code>DQmode</code></dt> +<dd><p>“Double Fractional” mode represents an eight-byte signed fractional number. +The default format is “s.63”. +</p> +<a name="index-TQmode"></a> +</dd> +<dt><code>TQmode</code></dt> +<dd><p>“Tetra Fractional” mode represents a sixteen-byte signed fractional number. +The default format is “s.127”. +</p> +<a name="index-UQQmode"></a> +</dd> +<dt><code>UQQmode</code></dt> +<dd><p>“Unsigned Quarter-Fractional” mode represents a single byte treated as an +unsigned fractional number. The default format is “.8”. +</p> +<a name="index-UHQmode"></a> +</dd> +<dt><code>UHQmode</code></dt> +<dd><p>“Unsigned Half-Fractional” mode represents a two-byte unsigned fractional +number. The default format is “.16”. +</p> +<a name="index-USQmode"></a> +</dd> +<dt><code>USQmode</code></dt> +<dd><p>“Unsigned Single Fractional” mode represents a four-byte unsigned fractional +number. The default format is “.32”. +</p> +<a name="index-UDQmode"></a> +</dd> +<dt><code>UDQmode</code></dt> +<dd><p>“Unsigned Double Fractional” mode represents an eight-byte unsigned +fractional number. The default format is “.64”. +</p> +<a name="index-UTQmode"></a> +</dd> +<dt><code>UTQmode</code></dt> +<dd><p>“Unsigned Tetra Fractional” mode represents a sixteen-byte unsigned +fractional number. The default format is “.128”. +</p> +<a name="index-HAmode"></a> +</dd> +<dt><code>HAmode</code></dt> +<dd><p>“Half-Accumulator” mode represents a two-byte signed accumulator. +The default format is “s8.7”. +</p> +<a name="index-SAmode"></a> +</dd> +<dt><code>SAmode</code></dt> +<dd><p>“Single Accumulator” mode represents a four-byte signed accumulator. +The default format is “s16.15”. +</p> +<a name="index-DAmode"></a> +</dd> +<dt><code>DAmode</code></dt> +<dd><p>“Double Accumulator” mode represents an eight-byte signed accumulator. +The default format is “s32.31”. +</p> +<a name="index-TAmode"></a> +</dd> +<dt><code>TAmode</code></dt> +<dd><p>“Tetra Accumulator” mode represents a sixteen-byte signed accumulator. +The default format is “s64.63”. +</p> +<a name="index-UHAmode"></a> +</dd> +<dt><code>UHAmode</code></dt> +<dd><p>“Unsigned Half-Accumulator” mode represents a two-byte unsigned accumulator. +The default format is “8.8”. +</p> +<a name="index-USAmode"></a> +</dd> +<dt><code>USAmode</code></dt> +<dd><p>“Unsigned Single Accumulator” mode represents a four-byte unsigned +accumulator. The default format is “16.16”. +</p> +<a name="index-UDAmode"></a> +</dd> +<dt><code>UDAmode</code></dt> +<dd><p>“Unsigned Double Accumulator” mode represents an eight-byte unsigned +accumulator. The default format is “32.32”. +</p> +<a name="index-UTAmode"></a> +</dd> +<dt><code>UTAmode</code></dt> +<dd><p>“Unsigned Tetra Accumulator” mode represents a sixteen-byte unsigned +accumulator. The default format is “64.64”. +</p> +<a name="index-CCmode"></a> +</dd> +<dt><code>CCmode</code></dt> +<dd><p>“Condition Code” mode represents the value of a condition code, which +is a machine-specific set of bits used to represent the result of a +comparison operation. Other machine-specific modes may also be used for +the condition code. (see <a href="Condition-Code.html#Condition-Code">Condition Code</a>). +</p> +<a name="index-BLKmode"></a> +</dd> +<dt><code>BLKmode</code></dt> +<dd><p>“Block” mode represents values that are aggregates to which none of +the other modes apply. In RTL, only memory references can have this mode, +and only if they appear in string-move or vector instructions. On machines +which have no such instructions, <code>BLKmode</code> will not appear in RTL. +</p> +<a name="index-VOIDmode"></a> +</dd> +<dt><code>VOIDmode</code></dt> +<dd><p>Void mode means the absence of a mode or an unspecified mode. +For example, RTL expressions of code <code>const_int</code> have mode +<code>VOIDmode</code> because they can be taken to have whatever mode the context +requires. In debugging dumps of RTL, <code>VOIDmode</code> is expressed by +the absence of any mode. +</p> +<a name="index-QCmode"></a> +<a name="index-HCmode"></a> +<a name="index-SCmode"></a> +<a name="index-DCmode"></a> +<a name="index-XCmode"></a> +<a name="index-TCmode"></a> +</dd> +<dt><code>QCmode, HCmode, SCmode, DCmode, XCmode, TCmode</code></dt> +<dd><p>These modes stand for a complex number represented as a pair of floating +point values. The floating point values are in <code>QFmode</code>, +<code>HFmode</code>, <code>SFmode</code>, <code>DFmode</code>, <code>XFmode</code>, and +<code>TFmode</code>, respectively. +</p> +<a name="index-CQImode"></a> +<a name="index-CHImode"></a> +<a name="index-CSImode"></a> +<a name="index-CDImode"></a> +<a name="index-CTImode"></a> +<a name="index-COImode"></a> +<a name="index-CPSImode"></a> +</dd> +<dt><code>CQImode, CHImode, CSImode, CDImode, CTImode, COImode, CPSImode</code></dt> +<dd><p>These modes stand for a complex number represented as a pair of integer +values. The integer values are in <code>QImode</code>, <code>HImode</code>, +<code>SImode</code>, <code>DImode</code>, <code>TImode</code>, <code>OImode</code>, and <code>PSImode</code>, +respectively. +</p> +<a name="index-BND32mode"></a> +<a name="index-BND64mode"></a> +</dd> +<dt><code>BND32mode BND64mode</code></dt> +<dd><p>These modes stand for bounds for pointer of 32 and 64 bit size respectively. +Mode size is double pointer mode size. +</p></dd> +</dl> + +<p>The machine description defines <code>Pmode</code> as a C macro which expands +into the machine mode used for addresses. Normally this is the mode +whose size is <code>BITS_PER_WORD</code>, <code>SImode</code> on 32-bit machines. +</p> +<p>The only modes which a machine description <i>must</i> support are +<code>QImode</code>, and the modes corresponding to <code>BITS_PER_WORD</code>, +<code>FLOAT_TYPE_SIZE</code> and <code>DOUBLE_TYPE_SIZE</code>. +The compiler will attempt to use <code>DImode</code> for 8-byte structures and +unions, but this can be prevented by overriding the definition of +<code>MAX_FIXED_MODE_SIZE</code>. Alternatively, you can have the compiler +use <code>TImode</code> for 16-byte structures and unions. Likewise, you can +arrange for the C type <code>short int</code> to avoid using <code>HImode</code>. +</p> +<a name="index-mode-classes"></a> +<p>Very few explicit references to machine modes remain in the compiler and +these few references will soon be removed. Instead, the machine modes +are divided into mode classes. These are represented by the enumeration +type <code>enum mode_class</code> defined in <samp>machmode.h</samp>. The possible +mode classes are: +</p> +<dl compact="compact"> +<dd><a name="index-MODE_005fINT"></a> +</dd> +<dt><code>MODE_INT</code></dt> +<dd><p>Integer modes. By default these are <code>BImode</code>, <code>QImode</code>, +<code>HImode</code>, <code>SImode</code>, <code>DImode</code>, <code>TImode</code>, and +<code>OImode</code>. +</p> +<a name="index-MODE_005fPARTIAL_005fINT"></a> +</dd> +<dt><code>MODE_PARTIAL_INT</code></dt> +<dd><p>The “partial integer” modes, <code>PQImode</code>, <code>PHImode</code>, +<code>PSImode</code> and <code>PDImode</code>. +</p> +<a name="index-MODE_005fFLOAT"></a> +</dd> +<dt><code>MODE_FLOAT</code></dt> +<dd><p>Floating point modes. By default these are <code>QFmode</code>, +<code>HFmode</code>, <code>TQFmode</code>, <code>SFmode</code>, <code>DFmode</code>, +<code>XFmode</code> and <code>TFmode</code>. +</p> +<a name="index-MODE_005fDECIMAL_005fFLOAT"></a> +</dd> +<dt><code>MODE_DECIMAL_FLOAT</code></dt> +<dd><p>Decimal floating point modes. By default these are <code>SDmode</code>, +<code>DDmode</code> and <code>TDmode</code>. +</p> +<a name="index-MODE_005fFRACT"></a> +</dd> +<dt><code>MODE_FRACT</code></dt> +<dd><p>Signed fractional modes. By default these are <code>QQmode</code>, <code>HQmode</code>, +<code>SQmode</code>, <code>DQmode</code> and <code>TQmode</code>. +</p> +<a name="index-MODE_005fUFRACT"></a> +</dd> +<dt><code>MODE_UFRACT</code></dt> +<dd><p>Unsigned fractional modes. By default these are <code>UQQmode</code>, <code>UHQmode</code>, +<code>USQmode</code>, <code>UDQmode</code> and <code>UTQmode</code>. +</p> +<a name="index-MODE_005fACCUM"></a> +</dd> +<dt><code>MODE_ACCUM</code></dt> +<dd><p>Signed accumulator modes. By default these are <code>HAmode</code>, +<code>SAmode</code>, <code>DAmode</code> and <code>TAmode</code>. +</p> +<a name="index-MODE_005fUACCUM"></a> +</dd> +<dt><code>MODE_UACCUM</code></dt> +<dd><p>Unsigned accumulator modes. By default these are <code>UHAmode</code>, +<code>USAmode</code>, <code>UDAmode</code> and <code>UTAmode</code>. +</p> +<a name="index-MODE_005fCOMPLEX_005fINT"></a> +</dd> +<dt><code>MODE_COMPLEX_INT</code></dt> +<dd><p>Complex integer modes. (These are not currently implemented). +</p> +<a name="index-MODE_005fCOMPLEX_005fFLOAT"></a> +</dd> +<dt><code>MODE_COMPLEX_FLOAT</code></dt> +<dd><p>Complex floating point modes. By default these are <code>QCmode</code>, +<code>HCmode</code>, <code>SCmode</code>, <code>DCmode</code>, <code>XCmode</code>, and +<code>TCmode</code>. +</p> +<a name="index-MODE_005fCC"></a> +</dd> +<dt><code>MODE_CC</code></dt> +<dd><p>Modes representing condition code values. These are <code>CCmode</code> plus +any <code>CC_MODE</code> modes listed in the <samp><var>machine</var>-modes.def</samp>. +See <a href="Jump-Patterns.html#Jump-Patterns">Jump Patterns</a>, +also see <a href="Condition-Code.html#Condition-Code">Condition Code</a>. +</p> +<a name="index-MODE_005fPOINTER_005fBOUNDS"></a> +</dd> +<dt><code>MODE_POINTER_BOUNDS</code></dt> +<dd><p>Pointer bounds modes. Used to represent values of pointer bounds type. +Operations in these modes may be executed as NOPs depending on hardware +features and environment setup. +</p> +<a name="index-MODE_005fOPAQUE"></a> +</dd> +<dt><code>MODE_OPAQUE</code></dt> +<dd><p>This is a mode class for modes that don’t want to provide operations +other than register moves, memory moves, loads, stores, and +<code>unspec</code>s. They have a size and precision and that’s all. +</p> +<a name="index-MODE_005fRANDOM"></a> +</dd> +<dt><code>MODE_RANDOM</code></dt> +<dd><p>This is a catchall mode class for modes which don’t fit into the above +classes. Currently <code>VOIDmode</code> and <code>BLKmode</code> are in +<code>MODE_RANDOM</code>. +</p></dd> +</dl> + +<a name="index-machine-mode-wrapper-classes"></a> +<p><code>machmode.h</code> also defines various wrapper classes that combine a +<code>machine_mode</code> with a static assertion that a particular +condition holds. The classes are: +</p> +<dl compact="compact"> +<dd><a name="index-scalar_005fint_005fmode"></a> +</dd> +<dt><code>scalar_int_mode</code></dt> +<dd><p>A mode that has class <code>MODE_INT</code> or <code>MODE_PARTIAL_INT</code>. +</p> +<a name="index-scalar_005ffloat_005fmode"></a> +</dd> +<dt><code>scalar_float_mode</code></dt> +<dd><p>A mode that has class <code>MODE_FLOAT</code> or <code>MODE_DECIMAL_FLOAT</code>. +</p> +<a name="index-scalar_005fmode"></a> +</dd> +<dt><code>scalar_mode</code></dt> +<dd><p>A mode that holds a single numerical value. In practice this means +that the mode is a <code>scalar_int_mode</code>, is a <code>scalar_float_mode</code>, +or has class <code>MODE_FRACT</code>, <code>MODE_UFRACT</code>, <code>MODE_ACCUM</code>, +<code>MODE_UACCUM</code> or <code>MODE_POINTER_BOUNDS</code>. +</p> +<a name="index-complex_005fmode"></a> +</dd> +<dt><code>complex_mode</code></dt> +<dd><p>A mode that has class <code>MODE_COMPLEX_INT</code> or <code>MODE_COMPLEX_FLOAT</code>. +</p> +<a name="index-fixed_005fsize_005fmode"></a> +</dd> +<dt><code>fixed_size_mode</code></dt> +<dd><p>A mode whose size is known at compile time. +</p></dd> +</dl> + +<p>Named modes use the most constrained of the available wrapper classes, +if one exists, otherwise they use <code>machine_mode</code>. For example, +<code>QImode</code> is a <code>scalar_int_mode</code>, <code>SFmode</code> is a +<code>scalar_float_mode</code> and <code>BLKmode</code> is a plain +<code>machine_mode</code>. It is possible to refer to any mode as a raw +<code>machine_mode</code> by adding the <code>E_</code> prefix, where <code>E</code> +stands for “enumeration”. For example, the raw <code>machine_mode</code> +names of the modes just mentioned are <code>E_QImode</code>, <code>E_SFmode</code> +and <code>E_BLKmode</code> respectively. +</p> +<p>The wrapper classes implicitly convert to <code>machine_mode</code> and to any +wrapper class that represents a more general condition; for example +<code>scalar_int_mode</code> and <code>scalar_float_mode</code> both convert +to <code>scalar_mode</code> and all three convert to <code>fixed_size_mode</code>. +The classes act like <code>machine_mode</code>s that accept only certain +named modes. +</p> +<a name="index-opt_005fmode"></a> +<p><samp>machmode.h</samp> also defines a template class <code>opt_mode<<var>T</var>></code> +that holds a <code>T</code> or nothing, where <code>T</code> can be either +<code>machine_mode</code> or one of the wrapper classes above. The main +operations on an <code>opt_mode<<var>T</var>></code> <var>x</var> are as follows: +</p> +<dl compact="compact"> +<dt>‘<samp><var>x</var>.exists ()</samp>’</dt> +<dd><p>Return true if <var>x</var> holds a mode rather than nothing. +</p> +</dd> +<dt>‘<samp><var>x</var>.exists (&<var>y</var>)</samp>’</dt> +<dd><p>Return true if <var>x</var> holds a mode rather than nothing, storing the +mode in <var>y</var> if so. <var>y</var> must be assignment-compatible with <var>T</var>. +</p> +</dd> +<dt>‘<samp><var>x</var>.require ()</samp>’</dt> +<dd><p>Assert that <var>x</var> holds a mode rather than nothing and return that mode. +</p> +</dd> +<dt>‘<samp><var>x</var> = <var>y</var></samp>’</dt> +<dd><p>Set <var>x</var> to <var>y</var>, where <var>y</var> is a <var>T</var> or implicitly converts +to a <var>T</var>. +</p></dd> +</dl> + +<p>The default constructor sets an <code>opt_mode<<var>T</var>></code> to nothing. +There is also a constructor that takes an initial value of type <var>T</var>. +</p> +<p>It is possible to use the <samp>is-a.h</samp> accessors on a <code>machine_mode</code> +or machine mode wrapper <var>x</var>: +</p> +<dl compact="compact"> +<dd><a name="index-is_005fa"></a> +</dd> +<dt>‘<samp>is_a <<var>T</var>> (<var>x</var>)</samp>’</dt> +<dd><p>Return true if <var>x</var> meets the conditions for wrapper class <var>T</var>. +</p> +</dd> +<dt>‘<samp>is_a <<var>T</var>> (<var>x</var>, &<var>y</var>)</samp>’</dt> +<dd><p>Return true if <var>x</var> meets the conditions for wrapper class <var>T</var>, +storing it in <var>y</var> if so. <var>y</var> must be assignment-compatible with +<var>T</var>. +</p> +</dd> +<dt>‘<samp>as_a <<var>T</var>> (<var>x</var>)</samp>’</dt> +<dd><p>Assert that <var>x</var> meets the conditions for wrapper class <var>T</var> +and return it as a <var>T</var>. +</p> +</dd> +<dt>‘<samp>dyn_cast <<var>T</var>> (<var>x</var>)</samp>’</dt> +<dd><p>Return an <code>opt_mode<<var>T</var>></code> that holds <var>x</var> if <var>x</var> meets +the conditions for wrapper class <var>T</var> and that holds nothing otherwise. +</p></dd> +</dl> + +<p>The purpose of these wrapper classes is to give stronger static type +checking. For example, if a function takes a <code>scalar_int_mode</code>, +a caller that has a general <code>machine_mode</code> must either check or +assert that the code is indeed a scalar integer first, using one of +the functions above. +</p> +<p>The wrapper classes are normal C++ classes, with user-defined +constructors. Sometimes it is useful to have a POD version of +the same type, particularly if the type appears in a <code>union</code>. +The template class <code>pod_mode<<var>T</var>></code> provides a POD version +of wrapper class <var>T</var>. It is assignment-compatible with <var>T</var> +and implicitly converts to both <code>machine_mode</code> and <var>T</var>. +</p> +<p>Here are some C macros that relate to machine modes: +</p> +<dl compact="compact"> +<dd><a name="index-GET_005fMODE"></a> +</dd> +<dt><code>GET_MODE (<var>x</var>)</code></dt> +<dd><p>Returns the machine mode of the RTX <var>x</var>. +</p> +<a name="index-PUT_005fMODE"></a> +</dd> +<dt><code>PUT_MODE (<var>x</var>, <var>newmode</var>)</code></dt> +<dd><p>Alters the machine mode of the RTX <var>x</var> to be <var>newmode</var>. +</p> +<a name="index-NUM_005fMACHINE_005fMODES"></a> +</dd> +<dt><code>NUM_MACHINE_MODES</code></dt> +<dd><p>Stands for the number of machine modes available on the target +machine. This is one greater than the largest numeric value of any +machine mode. +</p> +<a name="index-GET_005fMODE_005fNAME"></a> +</dd> +<dt><code>GET_MODE_NAME (<var>m</var>)</code></dt> +<dd><p>Returns the name of mode <var>m</var> as a string. +</p> +<a name="index-GET_005fMODE_005fCLASS"></a> +</dd> +<dt><code>GET_MODE_CLASS (<var>m</var>)</code></dt> +<dd><p>Returns the mode class of mode <var>m</var>. +</p> +<a name="index-GET_005fMODE_005fWIDER_005fMODE"></a> +</dd> +<dt><code>GET_MODE_WIDER_MODE (<var>m</var>)</code></dt> +<dd><p>Returns the next wider natural mode. For example, the expression +<code>GET_MODE_WIDER_MODE (QImode)</code> returns <code>HImode</code>. +</p> +<a name="index-GET_005fMODE_005fSIZE"></a> +</dd> +<dt><code>GET_MODE_SIZE (<var>m</var>)</code></dt> +<dd><p>Returns the size in bytes of a datum of mode <var>m</var>. +</p> +<a name="index-GET_005fMODE_005fBITSIZE"></a> +</dd> +<dt><code>GET_MODE_BITSIZE (<var>m</var>)</code></dt> +<dd><p>Returns the size in bits of a datum of mode <var>m</var>. +</p> +<a name="index-GET_005fMODE_005fIBIT"></a> +</dd> +<dt><code>GET_MODE_IBIT (<var>m</var>)</code></dt> +<dd><p>Returns the number of integral bits of a datum of fixed-point mode <var>m</var>. +</p> +<a name="index-GET_005fMODE_005fFBIT"></a> +</dd> +<dt><code>GET_MODE_FBIT (<var>m</var>)</code></dt> +<dd><p>Returns the number of fractional bits of a datum of fixed-point mode <var>m</var>. +</p> +<a name="index-GET_005fMODE_005fMASK"></a> +</dd> +<dt><code>GET_MODE_MASK (<var>m</var>)</code></dt> +<dd><p>Returns a bitmask containing 1 for all bits in a word that fit within +mode <var>m</var>. This macro can only be used for modes whose bitsize is +less than or equal to <code>HOST_BITS_PER_INT</code>. +</p> +<a name="index-GET_005fMODE_005fALIGNMENT"></a> +</dd> +<dt><code>GET_MODE_ALIGNMENT (<var>m</var>)</code></dt> +<dd><p>Return the required alignment, in bits, for an object of mode <var>m</var>. +</p> +<a name="index-GET_005fMODE_005fUNIT_005fSIZE"></a> +</dd> +<dt><code>GET_MODE_UNIT_SIZE (<var>m</var>)</code></dt> +<dd><p>Returns the size in bytes of the subunits of a datum of mode <var>m</var>. +This is the same as <code>GET_MODE_SIZE</code> except in the case of complex +modes. For them, the unit size is the size of the real or imaginary +part. +</p> +<a name="index-GET_005fMODE_005fNUNITS"></a> +</dd> +<dt><code>GET_MODE_NUNITS (<var>m</var>)</code></dt> +<dd><p>Returns the number of units contained in a mode, i.e., +<code>GET_MODE_SIZE</code> divided by <code>GET_MODE_UNIT_SIZE</code>. +</p> +<a name="index-GET_005fCLASS_005fNARROWEST_005fMODE"></a> +</dd> +<dt><code>GET_CLASS_NARROWEST_MODE (<var>c</var>)</code></dt> +<dd><p>Returns the narrowest mode in mode class <var>c</var>. +</p></dd> +</dl> + +<p>The following 3 variables are defined on every target. They can be +used to allocate buffers that are guaranteed to be large enough to +hold any value that can be represented on the target. The first two +can be overridden by defining them in the target’s mode.def file, +however, the value must be a constant that can determined very early +in the compilation process. The third symbol cannot be overridden. +</p> +<dl compact="compact"> +<dd><a name="index-BITS_005fPER_005fUNIT"></a> +</dd> +<dt><code>BITS_PER_UNIT</code></dt> +<dd><p>The number of bits in an addressable storage unit (byte). If you do +not define this, the default is 8. +</p> +<a name="index-MAX_005fBITSIZE_005fMODE_005fANY_005fINT"></a> +</dd> +<dt><code>MAX_BITSIZE_MODE_ANY_INT</code></dt> +<dd><p>The maximum bitsize of any mode that is used in integer math. This +should be overridden by the target if it uses large integers as +containers for larger vectors but otherwise never uses the contents to +compute integer values. +</p> +<a name="index-MAX_005fBITSIZE_005fMODE_005fANY_005fMODE"></a> +</dd> +<dt><code>MAX_BITSIZE_MODE_ANY_MODE</code></dt> +<dd><p>The bitsize of the largest mode on the target. The default value is +the largest mode size given in the mode definition file, which is +always correct for targets whose modes have a fixed size. Targets +that might increase the size of a mode beyond this default should define +<code>MAX_BITSIZE_MODE_ANY_MODE</code> to the actual upper limit in +<samp><var>machine</var>-modes.def</samp>. +</p></dd> +</dl> + +<a name="index-byte_005fmode"></a> +<a name="index-word_005fmode"></a> +<p>The global variables <code>byte_mode</code> and <code>word_mode</code> contain modes +whose classes are <code>MODE_INT</code> and whose bitsizes are either +<code>BITS_PER_UNIT</code> or <code>BITS_PER_WORD</code>, respectively. On 32-bit +machines, these are <code>QImode</code> and <code>SImode</code>, respectively. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="Constants.html#Constants" accesskey="n" rel="next">Constants</a>, Previous: <a href="Flags.html#Flags" accesskey="p" rel="previous">Flags</a>, Up: <a href="RTL.html#RTL" accesskey="u" rel="up">RTL</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |