| <!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>Using the GNU Compiler Collection (GCC): S/390 and zSeries Options</title> |
| |
| <meta name="description" content="Using the GNU Compiler Collection (GCC): S/390 and zSeries Options"> |
| <meta name="keywords" content="Using the GNU Compiler Collection (GCC): S/390 and zSeries Options"> |
| <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="Submodel-Options.html#Submodel-Options" rel="up" title="Submodel Options"> |
| <link href="Score-Options.html#Score-Options" rel="next" title="Score Options"> |
| <link href="RX-Options.html#RX-Options" rel="prev" title="RX Options"> |
| <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="S_002f390-and-zSeries-Options"></a> |
| <div class="header"> |
| <p> |
| Next: <a href="Score-Options.html#Score-Options" accesskey="n" rel="next">Score Options</a>, Previous: <a href="RX-Options.html#RX-Options" accesskey="p" rel="prev">RX Options</a>, Up: <a href="Submodel-Options.html#Submodel-Options" accesskey="u" rel="up">Submodel Options</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="S_002f390-and-zSeries-Options-1"></a> |
| <h4 class="subsection">3.17.40 S/390 and zSeries Options</h4> |
| <a name="index-S_002f390-and-zSeries-Options"></a> |
| |
| <p>These are the ‘<samp>-m</samp>’ options defined for the S/390 and zSeries architecture. |
| </p> |
| <dl compact="compact"> |
| <dt><code>-mhard-float</code></dt> |
| <dt><code>-msoft-float</code></dt> |
| <dd><a name="index-mhard_002dfloat-5"></a> |
| <a name="index-msoft_002dfloat-10"></a> |
| <p>Use (do not use) the hardware floating-point instructions and registers |
| for floating-point operations. When <samp>-msoft-float</samp> is specified, |
| functions in <samp>libgcc.a</samp> are used to perform floating-point |
| operations. When <samp>-mhard-float</samp> is specified, the compiler |
| generates IEEE floating-point instructions. This is the default. |
| </p> |
| </dd> |
| <dt><code>-mhard-dfp</code></dt> |
| <dt><code>-mno-hard-dfp</code></dt> |
| <dd><a name="index-mhard_002ddfp-1"></a> |
| <a name="index-mno_002dhard_002ddfp-1"></a> |
| <p>Use (do not use) the hardware decimal-floating-point instructions for |
| decimal-floating-point operations. When <samp>-mno-hard-dfp</samp> is |
| specified, functions in <samp>libgcc.a</samp> are used to perform |
| decimal-floating-point operations. When <samp>-mhard-dfp</samp> is |
| specified, the compiler generates decimal-floating-point hardware |
| instructions. This is the default for <samp>-march=z9-ec</samp> or higher. |
| </p> |
| </dd> |
| <dt><code>-mlong-double-64</code></dt> |
| <dt><code>-mlong-double-128</code></dt> |
| <dd><a name="index-mlong_002ddouble_002d64-1"></a> |
| <a name="index-mlong_002ddouble_002d128-1"></a> |
| <p>These switches control the size of <code>long double</code> type. A size |
| of 64 bits makes the <code>long double</code> type equivalent to the <code>double</code> |
| type. This is the default. |
| </p> |
| </dd> |
| <dt><code>-mbackchain</code></dt> |
| <dt><code>-mno-backchain</code></dt> |
| <dd><a name="index-mbackchain"></a> |
| <a name="index-mno_002dbackchain"></a> |
| <p>Store (do not store) the address of the caller’s frame as backchain pointer |
| into the callee’s stack frame. |
| A backchain may be needed to allow debugging using tools that do not understand |
| DWARF 2 call frame information. |
| When <samp>-mno-packed-stack</samp> is in effect, the backchain pointer is stored |
| at the bottom of the stack frame; when <samp>-mpacked-stack</samp> is in effect, |
| the backchain is placed into the topmost word of the 96/160 byte register |
| save area. |
| </p> |
| <p>In general, code compiled with <samp>-mbackchain</samp> is call-compatible with |
| code compiled with <samp>-mmo-backchain</samp>; however, use of the backchain |
| for debugging purposes usually requires that the whole binary is built with |
| <samp>-mbackchain</samp>. Note that the combination of <samp>-mbackchain</samp>, |
| <samp>-mpacked-stack</samp> and <samp>-mhard-float</samp> is not supported. In order |
| to build a linux kernel use <samp>-msoft-float</samp>. |
| </p> |
| <p>The default is to not maintain the backchain. |
| </p> |
| </dd> |
| <dt><code>-mpacked-stack</code></dt> |
| <dt><code>-mno-packed-stack</code></dt> |
| <dd><a name="index-mpacked_002dstack"></a> |
| <a name="index-mno_002dpacked_002dstack"></a> |
| <p>Use (do not use) the packed stack layout. When <samp>-mno-packed-stack</samp> is |
| specified, the compiler uses the all fields of the 96/160 byte register save |
| area only for their default purpose; unused fields still take up stack space. |
| When <samp>-mpacked-stack</samp> is specified, register save slots are densely |
| packed at the top of the register save area; unused space is reused for other |
| purposes, allowing for more efficient use of the available stack space. |
| However, when <samp>-mbackchain</samp> is also in effect, the topmost word of |
| the save area is always used to store the backchain, and the return address |
| register is always saved two words below the backchain. |
| </p> |
| <p>As long as the stack frame backchain is not used, code generated with |
| <samp>-mpacked-stack</samp> is call-compatible with code generated with |
| <samp>-mno-packed-stack</samp>. Note that some non-FSF releases of GCC 2.95 for |
| S/390 or zSeries generated code that uses the stack frame backchain at run |
| time, not just for debugging purposes. Such code is not call-compatible |
| with code compiled with <samp>-mpacked-stack</samp>. Also, note that the |
| combination of <samp>-mbackchain</samp>, |
| <samp>-mpacked-stack</samp> and <samp>-mhard-float</samp> is not supported. In order |
| to build a linux kernel use <samp>-msoft-float</samp>. |
| </p> |
| <p>The default is to not use the packed stack layout. |
| </p> |
| </dd> |
| <dt><code>-msmall-exec</code></dt> |
| <dt><code>-mno-small-exec</code></dt> |
| <dd><a name="index-msmall_002dexec"></a> |
| <a name="index-mno_002dsmall_002dexec"></a> |
| <p>Generate (or do not generate) code using the <code>bras</code> instruction |
| to do subroutine calls. |
| This only works reliably if the total executable size does not |
| exceed 64k. The default is to use the <code>basr</code> instruction instead, |
| which does not have this limitation. |
| </p> |
| </dd> |
| <dt><code>-m64</code></dt> |
| <dt><code>-m31</code></dt> |
| <dd><a name="index-m64-2"></a> |
| <a name="index-m31"></a> |
| <p>When <samp>-m31</samp> is specified, generate code compliant to the |
| GNU/Linux for S/390 ABI. When <samp>-m64</samp> is specified, generate |
| code compliant to the GNU/Linux for zSeries ABI. This allows GCC in |
| particular to generate 64-bit instructions. For the ‘<samp>s390</samp>’ |
| targets, the default is <samp>-m31</samp>, while the ‘<samp>s390x</samp>’ |
| targets default to <samp>-m64</samp>. |
| </p> |
| </dd> |
| <dt><code>-mzarch</code></dt> |
| <dt><code>-mesa</code></dt> |
| <dd><a name="index-mzarch"></a> |
| <a name="index-mesa"></a> |
| <p>When <samp>-mzarch</samp> is specified, generate code using the |
| instructions available on z/Architecture. |
| When <samp>-mesa</samp> is specified, generate code using the |
| instructions available on ESA/390. Note that <samp>-mesa</samp> is |
| not possible with <samp>-m64</samp>. |
| When generating code compliant to the GNU/Linux for S/390 ABI, |
| the default is <samp>-mesa</samp>. When generating code compliant |
| to the GNU/Linux for zSeries ABI, the default is <samp>-mzarch</samp>. |
| </p> |
| </dd> |
| <dt><code>-mmvcle</code></dt> |
| <dt><code>-mno-mvcle</code></dt> |
| <dd><a name="index-mmvcle"></a> |
| <a name="index-mno_002dmvcle"></a> |
| <p>Generate (or do not generate) code using the <code>mvcle</code> instruction |
| to perform block moves. When <samp>-mno-mvcle</samp> is specified, |
| use a <code>mvc</code> loop instead. This is the default unless optimizing for |
| size. |
| </p> |
| </dd> |
| <dt><code>-mdebug</code></dt> |
| <dt><code>-mno-debug</code></dt> |
| <dd><a name="index-mdebug-1"></a> |
| <a name="index-mno_002ddebug"></a> |
| <p>Print (or do not print) additional debug information when compiling. |
| The default is to not print debug information. |
| </p> |
| </dd> |
| <dt><code>-march=<var>cpu-type</var></code></dt> |
| <dd><a name="index-march-10"></a> |
| <p>Generate code that runs on <var>cpu-type</var>, which is the name of a |
| system representing a certain processor type. Possible values for |
| <var>cpu-type</var> are ‘<samp>g5</samp>’, ‘<samp>g6</samp>’, ‘<samp>z900</samp>’, ‘<samp>z990</samp>’, |
| ‘<samp>z9-109</samp>’, ‘<samp>z9-ec</samp>’, ‘<samp>z10</samp>’, ‘<samp>z196</samp>’, and |
| ‘<samp>zEC12</samp>’. When generating code using the instructions available |
| on z/Architecture, the default is <samp>-march=z900</samp>. Otherwise, |
| the default is <samp>-march=g5</samp>. |
| </p> |
| </dd> |
| <dt><code>-mtune=<var>cpu-type</var></code></dt> |
| <dd><a name="index-mtune-12"></a> |
| <p>Tune to <var>cpu-type</var> everything applicable about the generated code, |
| except for the ABI and the set of available instructions. |
| The list of <var>cpu-type</var> values is the same as for <samp>-march</samp>. |
| The default is the value used for <samp>-march</samp>. |
| </p> |
| </dd> |
| <dt><code>-mtpf-trace</code></dt> |
| <dt><code>-mno-tpf-trace</code></dt> |
| <dd><a name="index-mtpf_002dtrace"></a> |
| <a name="index-mno_002dtpf_002dtrace"></a> |
| <p>Generate code that adds (does not add) in TPF OS specific branches to trace |
| routines in the operating system. This option is off by default, even |
| when compiling for the TPF OS. |
| </p> |
| </dd> |
| <dt><code>-mfused-madd</code></dt> |
| <dt><code>-mno-fused-madd</code></dt> |
| <dd><a name="index-mfused_002dmadd-3"></a> |
| <a name="index-mno_002dfused_002dmadd-3"></a> |
| <p>Generate code that uses (does not use) the floating-point multiply and |
| accumulate instructions. These instructions are generated by default if |
| hardware floating point is used. |
| </p> |
| </dd> |
| <dt><code>-mwarn-framesize=<var>framesize</var></code></dt> |
| <dd><a name="index-mwarn_002dframesize"></a> |
| <p>Emit a warning if the current function exceeds the given frame size. Because |
| this is a compile-time check it doesn’t need to be a real problem when the program |
| runs. It is intended to identify functions that most probably cause |
| a stack overflow. It is useful to be used in an environment with limited stack |
| size e.g. the linux kernel. |
| </p> |
| </dd> |
| <dt><code>-mwarn-dynamicstack</code></dt> |
| <dd><a name="index-mwarn_002ddynamicstack"></a> |
| <p>Emit a warning if the function calls <code>alloca</code> or uses dynamically-sized |
| arrays. This is generally a bad idea with a limited stack size. |
| </p> |
| </dd> |
| <dt><code>-mstack-guard=<var>stack-guard</var></code></dt> |
| <dt><code>-mstack-size=<var>stack-size</var></code></dt> |
| <dd><a name="index-mstack_002dguard"></a> |
| <a name="index-mstack_002dsize"></a> |
| <p>If these options are provided the S/390 back end emits additional instructions in |
| the function prologue that trigger a trap if the stack size is <var>stack-guard</var> |
| bytes above the <var>stack-size</var> (remember that the stack on S/390 grows downward). |
| If the <var>stack-guard</var> option is omitted the smallest power of 2 larger than |
| the frame size of the compiled function is chosen. |
| These options are intended to be used to help debugging stack overflow problems. |
| The additionally emitted code causes only little overhead and hence can also be |
| used in production-like systems without greater performance degradation. The given |
| values have to be exact powers of 2 and <var>stack-size</var> has to be greater than |
| <var>stack-guard</var> without exceeding 64k. |
| In order to be efficient the extra code makes the assumption that the stack starts |
| at an address aligned to the value given by <var>stack-size</var>. |
| The <var>stack-guard</var> option can only be used in conjunction with <var>stack-size</var>. |
| </p> |
| </dd> |
| <dt><code>-mhotpatch=<var>pre-halfwords</var>,<var>post-halfwords</var></code></dt> |
| <dd><a name="index-mhotpatch"></a> |
| <p>If the hotpatch option is enabled, a “hot-patching” function |
| prologue is generated for all functions in the compilation unit. |
| The funtion label is prepended with the given number of two-byte |
| NOP instructions (<var>pre-halfwords</var>, maximum 1000000). After |
| the label, 2 * <var>post-halfwords</var> bytes are appended, using the |
| largest NOP like instructions the architecture allows (maximum |
| 1000000). |
| </p> |
| <p>If both arguments are zero, hotpatching is disabled. |
| </p> |
| <p>This option can be overridden for individual functions with the |
| <code>hotpatch</code> attribute. |
| </p></dd> |
| </dl> |
| |
| <hr> |
| <div class="header"> |
| <p> |
| Next: <a href="Score-Options.html#Score-Options" accesskey="n" rel="next">Score Options</a>, Previous: <a href="RX-Options.html#RX-Options" accesskey="p" rel="prev">RX Options</a>, Up: <a href="Submodel-Options.html#Submodel-Options" accesskey="u" rel="up">Submodel Options</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> |
