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24 | </div> | |
25 | <div class="section"> | |
26 | <div class="titlepage"><div><div><h4 class="title"> | |
27 | <a name="context.econtext.rationale.x86_and_floating_point_env"></a><a class="link" href="x86_and_floating_point_env.html" title="x86 and floating-point env">x86 | |
28 | and floating-point env</a> | |
29 | </h4></div></div></div> | |
30 | <h6> | |
31 | <a name="context.econtext.rationale.x86_and_floating_point_env.h0"></a> | |
32 | <span><a name="context.econtext.rationale.x86_and_floating_point_env.i386"></a></span><a class="link" href="x86_and_floating_point_env.html#context.econtext.rationale.x86_and_floating_point_env.i386">i386</a> | |
33 | </h6> | |
34 | <p> | |
35 | "The FpCsr and the MxCsr register must be saved and restored before | |
36 | any call or return by any procedure that needs to modify them ..." | |
37 | <sup>[<a name="context.econtext.rationale.x86_and_floating_point_env.f0" href="#ftn.context.econtext.rationale.x86_and_floating_point_env.f0" class="footnote">4</a>]</sup>. | |
38 | </p> | |
39 | <h6> | |
40 | <a name="context.econtext.rationale.x86_and_floating_point_env.h1"></a> | |
41 | <span><a name="context.econtext.rationale.x86_and_floating_point_env.x86_64"></a></span><a class="link" href="x86_and_floating_point_env.html#context.econtext.rationale.x86_and_floating_point_env.x86_64">x86_64</a> | |
42 | </h6> | |
43 | <h6> | |
44 | <a name="context.econtext.rationale.x86_and_floating_point_env.h2"></a> | |
45 | <span><a name="context.econtext.rationale.x86_and_floating_point_env.windows"></a></span><a class="link" href="x86_and_floating_point_env.html#context.econtext.rationale.x86_and_floating_point_env.windows">Windows</a> | |
46 | </h6> | |
47 | <p> | |
48 | MxCsr - "A callee that modifies any of the non-volatile fields within | |
49 | MxCsr must restore them before returning to its caller. Furthermore, a | |
50 | caller that has modified any of these fields must restore them to their | |
51 | standard values before invoking a callee ..." <sup>[<a name="context.econtext.rationale.x86_and_floating_point_env.f1" href="#ftn.context.econtext.rationale.x86_and_floating_point_env.f1" class="footnote">5</a>]</sup>. | |
52 | </p> | |
53 | <p> | |
54 | FpCsr - "A callee that modifies any of the fields within FpCsr must | |
55 | restore them before returning to its caller. Furthermore, a caller that | |
56 | has modified any of these fields must restore them to their standard values | |
57 | before invoking a callee ..." <sup>[<a name="context.econtext.rationale.x86_and_floating_point_env.f2" href="#ftn.context.econtext.rationale.x86_and_floating_point_env.f2" class="footnote">6</a>]</sup>. | |
58 | </p> | |
59 | <p> | |
60 | "The MMX and floating-point stack registers (MM0-MM7/ST0-ST7) are | |
61 | preserved across context switches. There is no explicit calling convention | |
62 | for these registers." <sup>[<a name="context.econtext.rationale.x86_and_floating_point_env.f3" href="#ftn.context.econtext.rationale.x86_and_floating_point_env.f3" class="footnote">7</a>]</sup>. | |
63 | </p> | |
64 | <p> | |
65 | "The 64-bit Microsoft compiler does not use ST(0)-ST(7)/MM0-MM7". | |
66 | <sup>[<a name="context.econtext.rationale.x86_and_floating_point_env.f4" href="#ftn.context.econtext.rationale.x86_and_floating_point_env.f4" class="footnote">8</a>]</sup>. | |
67 | </p> | |
68 | <p> | |
69 | "XMM6-XMM15 must be preserved" <sup>[<a name="context.econtext.rationale.x86_and_floating_point_env.f5" href="#ftn.context.econtext.rationale.x86_and_floating_point_env.f5" class="footnote">9</a>]</sup> | |
70 | </p> | |
71 | <h6> | |
72 | <a name="context.econtext.rationale.x86_and_floating_point_env.h3"></a> | |
73 | <span><a name="context.econtext.rationale.x86_and_floating_point_env.sysv"></a></span><a class="link" href="x86_and_floating_point_env.html#context.econtext.rationale.x86_and_floating_point_env.sysv">SysV</a> | |
74 | </h6> | |
75 | <p> | |
76 | "The control bits of the MxCsr register are callee-saved (preserved | |
77 | across calls), while the status bits are caller-saved (not preserved). | |
78 | The x87 status word register is caller-saved, whereas the x87 control word | |
79 | (FpCsr) is callee-saved." <sup>[<a name="context.econtext.rationale.x86_and_floating_point_env.f6" href="#ftn.context.econtext.rationale.x86_and_floating_point_env.f6" class="footnote">10</a>]</sup>. | |
80 | </p> | |
81 | <div class="footnotes"> | |
82 | <br><hr width="100" align="left"> | |
83 | <div class="footnote"><p><sup>[<a name="ftn.context.econtext.rationale.x86_and_floating_point_env.f0" href="#context.econtext.rationale.x86_and_floating_point_env.f0" class="para">4</a>] </sup> | |
84 | 'Calling Conventions', Agner Fog | |
85 | </p></div> | |
86 | <div class="footnote"><p><sup>[<a name="ftn.context.econtext.rationale.x86_and_floating_point_env.f1" href="#context.econtext.rationale.x86_and_floating_point_env.f1" class="para">5</a>] </sup> | |
87 | <a href="http://http://msdn.microsoft.com/en-us/library/yxty7t75.aspx" target="_top">MSDN | |
88 | article 'MxCsr'</a> | |
89 | </p></div> | |
90 | <div class="footnote"><p><sup>[<a name="ftn.context.econtext.rationale.x86_and_floating_point_env.f2" href="#context.econtext.rationale.x86_and_floating_point_env.f2" class="para">6</a>] </sup> | |
91 | <a href="http://http://msdn.microsoft.com/en-us/library/ms235300.aspx" target="_top">MSDN | |
92 | article 'FpCsr'</a> | |
93 | </p></div> | |
94 | <div class="footnote"><p><sup>[<a name="ftn.context.econtext.rationale.x86_and_floating_point_env.f3" href="#context.econtext.rationale.x86_and_floating_point_env.f3" class="para">7</a>] </sup> | |
95 | <a href="http://msdn.microsoft.com/en-us/library/a32tsf7t%28VS.80%29.aspx" target="_top">MSDN | |
96 | article 'Legacy Floating-Point Support'</a> | |
97 | </p></div> | |
98 | <div class="footnote"><p><sup>[<a name="ftn.context.econtext.rationale.x86_and_floating_point_env.f4" href="#context.econtext.rationale.x86_and_floating_point_env.f4" class="para">8</a>] </sup> | |
99 | 'Calling Conventions', Agner Fog | |
100 | </p></div> | |
101 | <div class="footnote"><p><sup>[<a name="ftn.context.econtext.rationale.x86_and_floating_point_env.f5" href="#context.econtext.rationale.x86_and_floating_point_env.f5" class="para">9</a>] </sup> | |
102 | <a href="http://msdn.microsoft.com/en-us/library/9z1stfyw%28v=vs.100%29.aspx" target="_top">MSDN | |
103 | article 'Register Usage'</a> | |
104 | </p></div> | |
105 | <div class="footnote"><p><sup>[<a name="ftn.context.econtext.rationale.x86_and_floating_point_env.f6" href="#context.econtext.rationale.x86_and_floating_point_env.f6" class="para">10</a>] </sup> | |
106 | SysV ABI AMD64 Architecture Processor Supplement Draft Version 0.99.4, | |
107 | 3.2.1 | |
108 | </p></div> | |
109 | </div> | |
110 | </div> | |
111 | <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> | |
112 | <td align="left"></td> | |
113 | <td align="right"><div class="copyright-footer">Copyright © 2014 Oliver Kowalke<p> | |
114 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
115 | file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) | |
116 | </p> | |
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