| <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <html> |
| <!-- Copyright (C) 1988-2015 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). A copy of the license is included in the section entitled |
| "GNU Free Documentation License". |
| |
| (a) The FSF's Front-Cover Text is: |
| |
| A GNU Manual |
| |
| (b) The FSF's Back-Cover Text is: |
| |
| You have freedom to copy and modify this GNU Manual, like GNU |
| software. Copies published by the Free Software Foundation raise |
| funds for GNU development. --> |
| <!-- Created by GNU Texinfo 5.2, http://www.gnu.org/software/texinfo/ --> |
| <head> |
| <title>GNU Compiler Collection (GCC) Internals: Named Address Spaces</title> |
| |
| <meta name="description" content="GNU Compiler Collection (GCC) Internals: Named Address Spaces"> |
| <meta name="keywords" content="GNU Compiler Collection (GCC) Internals: Named Address Spaces"> |
| <meta name="resource-type" content="document"> |
| <meta name="distribution" content="global"> |
| <meta name="Generator" content="makeinfo"> |
| <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> |
| <link href="index.html#Top" rel="start" title="Top"> |
| <link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> |
| <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> |
| <link href="Target-Macros.html#Target-Macros" rel="up" title="Target Macros"> |
| <link href="Misc.html#Misc" rel="next" title="Misc"> |
| <link href="C_002b_002b-ABI.html#C_002b_002b-ABI" rel="prev" title="C++ ABI"> |
| <style type="text/css"> |
| <!-- |
| a.summary-letter {text-decoration: none} |
| blockquote.smallquotation {font-size: smaller} |
| div.display {margin-left: 3.2em} |
| div.example {margin-left: 3.2em} |
| div.indentedblock {margin-left: 3.2em} |
| div.lisp {margin-left: 3.2em} |
| div.smalldisplay {margin-left: 3.2em} |
| div.smallexample {margin-left: 3.2em} |
| div.smallindentedblock {margin-left: 3.2em; font-size: smaller} |
| div.smalllisp {margin-left: 3.2em} |
| kbd {font-style:oblique} |
| pre.display {font-family: inherit} |
| pre.format {font-family: inherit} |
| pre.menu-comment {font-family: serif} |
| pre.menu-preformatted {font-family: serif} |
| pre.smalldisplay {font-family: inherit; font-size: smaller} |
| pre.smallexample {font-size: smaller} |
| pre.smallformat {font-family: inherit; font-size: smaller} |
| pre.smalllisp {font-size: smaller} |
| span.nocodebreak {white-space:nowrap} |
| span.nolinebreak {white-space:nowrap} |
| span.roman {font-family:serif; font-weight:normal} |
| span.sansserif {font-family:sans-serif; font-weight:normal} |
| ul.no-bullet {list-style: none} |
| --> |
| </style> |
| |
| |
| </head> |
| |
| <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> |
| <a name="Named-Address-Spaces"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Misc.html#Misc" accesskey="n" rel="next">Misc</a>, Previous: <a href="C_002b_002b-ABI.html#C_002b_002b-ABI" accesskey="p" rel="prev">C++ ABI</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</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> |
| <hr> |
| <a name="Adding-support-for-named-address-spaces"></a> |
| <h3 class="section">17.30 Adding support for named address spaces</h3> |
| <a name="index-named-address-spaces"></a> |
| |
| <p>The draft technical report of the ISO/IEC JTC1 S22 WG14 N1275 |
| standards committee, <cite>Programming Languages - C - Extensions to |
| support embedded processors</cite>, specifies a syntax for embedded |
| processors to specify alternate address spaces. You can configure a |
| GCC port to support section 5.1 of the draft report to add support for |
| address spaces other than the default address space. These address |
| spaces are new keywords that are similar to the <code>volatile</code> and |
| <code>const</code> type attributes. |
| </p> |
| <p>Pointers to named address spaces can have a different size than |
| pointers to the generic address space. |
| </p> |
| <p>For example, the SPU port uses the <code>__ea</code> address space to refer |
| to memory in the host processor, rather than memory local to the SPU |
| processor. Access to memory in the <code>__ea</code> address space involves |
| issuing DMA operations to move data between the host processor and the |
| local processor memory address space. Pointers in the <code>__ea</code> |
| address space are either 32 bits or 64 bits based on the |
| <samp>-mea32</samp> or <samp>-mea64</samp> switches (native SPU pointers are |
| always 32 bits). |
| </p> |
| <p>Internally, address spaces are represented as a small integer in the |
| range 0 to 15 with address space 0 being reserved for the generic |
| address space. |
| </p> |
| <p>To register a named address space qualifier keyword with the C front end, |
| the target may call the <code>c_register_addr_space</code> routine. For example, |
| the SPU port uses the following to declare <code>__ea</code> as the keyword for |
| named address space #1: |
| </p><div class="smallexample"> |
| <pre class="smallexample">#define ADDR_SPACE_EA 1 |
| c_register_addr_space ("__ea", ADDR_SPACE_EA); |
| </pre></div> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fADDR_005fSPACE_005fPOINTER_005fMODE"></a>Target Hook: <em>enum machine_mode</em> <strong>TARGET_ADDR_SPACE_POINTER_MODE</strong> <em>(addr_space_t <var>address_space</var>)</em></dt> |
| <dd><p>Define this to return the machine mode to use for pointers to |
| <var>address_space</var> if the target supports named address spaces. |
| The default version of this hook returns <code>ptr_mode</code> for the |
| generic address space only. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fADDR_005fSPACE_005fADDRESS_005fMODE"></a>Target Hook: <em>enum machine_mode</em> <strong>TARGET_ADDR_SPACE_ADDRESS_MODE</strong> <em>(addr_space_t <var>address_space</var>)</em></dt> |
| <dd><p>Define this to return the machine mode to use for addresses in |
| <var>address_space</var> if the target supports named address spaces. |
| The default version of this hook returns <code>Pmode</code> for the |
| generic address space only. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fADDR_005fSPACE_005fVALID_005fPOINTER_005fMODE"></a>Target Hook: <em>bool</em> <strong>TARGET_ADDR_SPACE_VALID_POINTER_MODE</strong> <em>(enum machine_mode <var>mode</var>, addr_space_t <var>as</var>)</em></dt> |
| <dd><p>Define this to return nonzero if the port can handle pointers |
| with machine mode <var>mode</var> to address space <var>as</var>. This target |
| hook is the same as the <code>TARGET_VALID_POINTER_MODE</code> target hook, |
| except that it includes explicit named address space support. The default |
| version of this hook returns true for the modes returned by either the |
| <code>TARGET_ADDR_SPACE_POINTER_MODE</code> or <code>TARGET_ADDR_SPACE_ADDRESS_MODE</code> |
| target hooks for the given address space. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fADDR_005fSPACE_005fLEGITIMATE_005fADDRESS_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_ADDR_SPACE_LEGITIMATE_ADDRESS_P</strong> <em>(enum machine_mode <var>mode</var>, rtx <var>exp</var>, bool <var>strict</var>, addr_space_t <var>as</var>)</em></dt> |
| <dd><p>Define this to return true if <var>exp</var> is a valid address for mode |
| <var>mode</var> in the named address space <var>as</var>. The <var>strict</var> |
| parameter says whether strict addressing is in effect after reload has |
| finished. This target hook is the same as the |
| <code>TARGET_LEGITIMATE_ADDRESS_P</code> target hook, except that it includes |
| explicit named address space support. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fADDR_005fSPACE_005fLEGITIMIZE_005fADDRESS"></a>Target Hook: <em>rtx</em> <strong>TARGET_ADDR_SPACE_LEGITIMIZE_ADDRESS</strong> <em>(rtx <var>x</var>, rtx <var>oldx</var>, enum machine_mode <var>mode</var>, addr_space_t <var>as</var>)</em></dt> |
| <dd><p>Define this to modify an invalid address <var>x</var> to be a valid address |
| with mode <var>mode</var> in the named address space <var>as</var>. This target |
| hook is the same as the <code>TARGET_LEGITIMIZE_ADDRESS</code> target hook, |
| except that it includes explicit named address space support. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fADDR_005fSPACE_005fSUBSET_005fP"></a>Target Hook: <em>bool</em> <strong>TARGET_ADDR_SPACE_SUBSET_P</strong> <em>(addr_space_t <var>subset</var>, addr_space_t <var>superset</var>)</em></dt> |
| <dd><p>Define this to return whether the <var>subset</var> named address space is |
| contained within the <var>superset</var> named address space. Pointers to |
| a named address space that is a subset of another named address space |
| will be converted automatically without a cast if used together in |
| arithmetic operations. Pointers to a superset address space can be |
| converted to pointers to a subset address space via explicit casts. |
| </p></dd></dl> |
| |
| <dl> |
| <dt><a name="index-TARGET_005fADDR_005fSPACE_005fCONVERT"></a>Target Hook: <em>rtx</em> <strong>TARGET_ADDR_SPACE_CONVERT</strong> <em>(rtx <var>op</var>, tree <var>from_type</var>, tree <var>to_type</var>)</em></dt> |
| <dd><p>Define this to convert the pointer expression represented by the RTL |
| <var>op</var> with type <var>from_type</var> that points to a named address |
| space to a new pointer expression with type <var>to_type</var> that points |
| to a different named address space. When this hook it called, it is |
| guaranteed that one of the two address spaces is a subset of the other, |
| as determined by the <code>TARGET_ADDR_SPACE_SUBSET_P</code> target hook. |
| </p></dd></dl> |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="Misc.html#Misc" accesskey="n" rel="next">Misc</a>, Previous: <a href="C_002b_002b-ABI.html#C_002b_002b-ABI" accesskey="p" rel="prev">C++ ABI</a>, Up: <a href="Target-Macros.html#Target-Macros" accesskey="u" rel="up">Target Macros</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> |
