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) 1988-2013 Free Software Foundation, Inc. 14 15Permission is granted to copy, distribute and/or modify this document 16under the terms of the GNU Free Documentation License, Version 1.3 or 17any later version published by the Free Software Foundation; with the 18Invariant Sections being ``Funding Free Software'', the Front-Cover 19Texts being (a) (see below), and with the Back-Cover Texts being (b) 20(see below). 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The <code>CONST16</code> instruction is currently not a 64standard option from Tensilica. When enabled, <code>CONST16</code> 65instructions are always used in place of the standard <code>L32R</code> 66instructions. The use of <code>CONST16</code> is enabled by default only if 67the <code>L32R</code> instruction is not available. 68 69 <br><dt><code>-mfused-madd</code><dt><code>-mno-fused-madd</code><dd><a name="index-mfused_002dmadd-2327"></a><a name="index-mno_002dfused_002dmadd-2328"></a>Enable or disable use of fused multiply/add and multiply/subtract 70instructions in the floating-point option. This has no effect if the 71floating-point option is not also enabled. Disabling fused multiply/add 72and multiply/subtract instructions forces the compiler to use separate 73instructions for the multiply and add/subtract operations. This may be 74desirable in some cases where strict IEEE 754-compliant results are 75required: the fused multiply add/subtract instructions do not round the 76intermediate result, thereby producing results with <em>more</em> bits of 77precision than specified by the IEEE standard. Disabling fused multiply 78add/subtract instructions also ensures that the program output is not 79sensitive to the compiler's ability to combine multiply and add/subtract 80operations. 81 82 <br><dt><code>-mserialize-volatile</code><dt><code>-mno-serialize-volatile</code><dd><a name="index-mserialize_002dvolatile-2329"></a><a name="index-mno_002dserialize_002dvolatile-2330"></a>When this option is enabled, GCC inserts <code>MEMW</code> instructions before 83<code>volatile</code> memory references to guarantee sequential consistency. 84The default is <samp><span class="option">-mserialize-volatile</span></samp>. Use 85<samp><span class="option">-mno-serialize-volatile</span></samp> to omit the <code>MEMW</code> instructions. 86 87 <br><dt><code>-mforce-no-pic</code><dd><a name="index-mforce_002dno_002dpic-2331"></a>For targets, like GNU/Linux, where all user-mode Xtensa code must be 88position-independent code (PIC), this option disables PIC for compiling 89kernel code. 90 91 <br><dt><code>-mtext-section-literals</code><dt><code>-mno-text-section-literals</code><dd><a name="index-mtext_002dsection_002dliterals-2332"></a><a name="index-mno_002dtext_002dsection_002dliterals-2333"></a>Control the treatment of literal pools. The default is 92<samp><span class="option">-mno-text-section-literals</span></samp>, which places literals in a separate 93section in the output file. This allows the literal pool to be placed 94in a data RAM/ROM, and it also allows the linker to combine literal 95pools from separate object files to remove redundant literals and 96improve code size. With <samp><span class="option">-mtext-section-literals</span></samp>, the literals 97are interspersed in the text section in order to keep them as close as 98possible to their references. This may be necessary for large assembly 99files. 100 101 <br><dt><code>-mtarget-align</code><dt><code>-mno-target-align</code><dd><a name="index-mtarget_002dalign-2334"></a><a name="index-mno_002dtarget_002dalign-2335"></a>When this option is enabled, GCC instructs the assembler to 102automatically align instructions to reduce branch penalties at the 103expense of some code density. The assembler attempts to widen density 104instructions to align branch targets and the instructions following call 105instructions. If there are not enough preceding safe density 106instructions to align a target, no widening is performed. The 107default is <samp><span class="option">-mtarget-align</span></samp>. These options do not affect the 108treatment of auto-aligned instructions like <code>LOOP</code>, which the 109assembler always aligns, either by widening density instructions or 110by inserting NOP instructions. 111 112 <br><dt><code>-mlongcalls</code><dt><code>-mno-longcalls</code><dd><a name="index-mlongcalls-2336"></a><a name="index-mno_002dlongcalls-2337"></a>When this option is enabled, GCC instructs the assembler to translate 113direct calls to indirect calls unless it can determine that the target 114of a direct call is in the range allowed by the call instruction. This 115translation typically occurs for calls to functions in other source 116files. Specifically, the assembler translates a direct <code>CALL</code> 117instruction into an <code>L32R</code> followed by a <code>CALLX</code> instruction. 118The default is <samp><span class="option">-mno-longcalls</span></samp>. This option should be used in 119programs where the call target can potentially be out of range. This 120option is implemented in the assembler, not the compiler, so the 121assembly code generated by GCC still shows direct call 122instructions—look at the disassembled object code to see the actual 123instructions. Note that the assembler uses an indirect call for 124every cross-file call, not just those that really are out of range. 125</dl> 126 127 </body></html> 128 129