1<html lang="en"> 2<head> 3<title>Xtensa Options - Using the GNU Compiler Collection (GCC)</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Using the GNU Compiler Collection (GCC)"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Submodel-Options.html#Submodel-Options" title="Submodel Options"> 9<link rel="prev" href="Xstormy16-Options.html#Xstormy16-Options" title="Xstormy16 Options"> 10<link rel="next" href="zSeries-Options.html#zSeries-Options" title="zSeries Options"> 11<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 12<!-- 13Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 141998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 152010 Free Software Foundation, Inc. 16 17Permission is granted to copy, distribute and/or modify this document 18under the terms of the GNU Free Documentation License, Version 1.3 or 19any later version published by the Free Software Foundation; with the 20Invariant Sections being ``Funding Free Software'', the Front-Cover 21Texts being (a) (see below), and with the Back-Cover Texts being (b) 22(see below). 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The <code>CONST16</code> instruction is currently not a 66standard option from Tensilica. When enabled, <code>CONST16</code> 67instructions are always used in place of the standard <code>L32R</code> 68instructions. The use of <code>CONST16</code> is enabled by default only if 69the <code>L32R</code> instruction is not available. 70 71 <br><dt><code>-mfused-madd</code><dt><code>-mno-fused-madd</code><dd><a name="index-mfused_002dmadd-2152"></a><a name="index-mno_002dfused_002dmadd-2153"></a>Enable or disable use of fused multiply/add and multiply/subtract 72instructions in the floating-point option. This has no effect if the 73floating-point option is not also enabled. Disabling fused multiply/add 74and multiply/subtract instructions forces the compiler to use separate 75instructions for the multiply and add/subtract operations. This may be 76desirable in some cases where strict IEEE 754-compliant results are 77required: the fused multiply add/subtract instructions do not round the 78intermediate result, thereby producing results with <em>more</em> bits of 79precision than specified by the IEEE standard. Disabling fused multiply 80add/subtract instructions also ensures that the program output is not 81sensitive to the compiler's ability to combine multiply and add/subtract 82operations. 83 84 <br><dt><code>-mserialize-volatile</code><dt><code>-mno-serialize-volatile</code><dd><a name="index-mserialize_002dvolatile-2154"></a><a name="index-mno_002dserialize_002dvolatile-2155"></a>When this option is enabled, GCC inserts <code>MEMW</code> instructions before 85<code>volatile</code> memory references to guarantee sequential consistency. 86The default is <samp><span class="option">-mserialize-volatile</span></samp>. Use 87<samp><span class="option">-mno-serialize-volatile</span></samp> to omit the <code>MEMW</code> instructions. 88 89 <br><dt><code>-mforce-no-pic</code><dd><a name="index-mforce_002dno_002dpic-2156"></a>For targets, like GNU/Linux, where all user-mode Xtensa code must be 90position-independent code (PIC), this option disables PIC for compiling 91kernel code. 92 93 <br><dt><code>-mtext-section-literals</code><dt><code>-mno-text-section-literals</code><dd><a name="index-mtext_002dsection_002dliterals-2157"></a><a name="index-mno_002dtext_002dsection_002dliterals-2158"></a>Control the treatment of literal pools. The default is 94<samp><span class="option">-mno-text-section-literals</span></samp>, which places literals in a separate 95section in the output file. This allows the literal pool to be placed 96in a data RAM/ROM, and it also allows the linker to combine literal 97pools from separate object files to remove redundant literals and 98improve code size. With <samp><span class="option">-mtext-section-literals</span></samp>, the literals 99are interspersed in the text section in order to keep them as close as 100possible to their references. This may be necessary for large assembly 101files. 102 103 <br><dt><code>-mtarget-align</code><dt><code>-mno-target-align</code><dd><a name="index-mtarget_002dalign-2159"></a><a name="index-mno_002dtarget_002dalign-2160"></a>When this option is enabled, GCC instructs the assembler to 104automatically align instructions to reduce branch penalties at the 105expense of some code density. The assembler attempts to widen density 106instructions to align branch targets and the instructions following call 107instructions. If there are not enough preceding safe density 108instructions to align a target, no widening will be performed. The 109default is <samp><span class="option">-mtarget-align</span></samp>. These options do not affect the 110treatment of auto-aligned instructions like <code>LOOP</code>, which the 111assembler will always align, either by widening density instructions or 112by inserting no-op instructions. 113 114 <br><dt><code>-mlongcalls</code><dt><code>-mno-longcalls</code><dd><a name="index-mlongcalls-2161"></a><a name="index-mno_002dlongcalls-2162"></a>When this option is enabled, GCC instructs the assembler to translate 115direct calls to indirect calls unless it can determine that the target 116of a direct call is in the range allowed by the call instruction. This 117translation typically occurs for calls to functions in other source 118files. Specifically, the assembler translates a direct <code>CALL</code> 119instruction into an <code>L32R</code> followed by a <code>CALLX</code> instruction. 120The default is <samp><span class="option">-mno-longcalls</span></samp>. This option should be used in 121programs where the call target can potentially be out of range. This 122option is implemented in the assembler, not the compiler, so the 123assembly code generated by GCC will still show direct call 124instructions—look at the disassembled object code to see the actual 125instructions. Note that the assembler will use an indirect call for 126every cross-file call, not just those that really will be out of range. 127</dl> 128 129 </body></html> 130 131