doc: update install docs for 387->softfloat transition

Fixes #41861

Change-Id: I7aa9370c7762986ee07ba6ff7f6ebda067559f06
Reviewed-on: https://go-review.googlesource.com/c/go/+/260757
Trust: Keith Randall <khr@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
This commit is contained in:
Keith Randall 2020-10-08 08:42:11 -07:00
parent 8f26b57f9a
commit 2be7788f83

View file

@ -666,16 +666,13 @@ For example, you should not set <code>$GOHOSTARCH</code> to
<code>arm</code> on an x86 system.
</p>
<li><code>$GO386</code> (for <code>386</code> only, default is auto-detected
if built on either <code>386</code> or <code>amd64</code>, <code>387</code> otherwise)
<li><code>$GO386</code> (for <code>386</code> only, defaults to <code>sse2</code>)
<p>
This controls the code generated by gc to use either the 387 floating-point unit
(set to <code>387</code>) or SSE2 instructions (set to <code>sse2</code>) for
floating point computations.
This variable controls how gc implements floating point computations.
</p>
<ul>
<li><code>GO386=387</code>: use x87 for floating point operations; should support all x86 chips (Pentium MMX or later).</li>
<li><code>GO386=sse2</code>: use SSE2 for floating point operations; has better performance than 387, but only available on Pentium 4/Opteron/Athlon 64 or later.</li>
<li><code>GO386=softfloat</code>: use software floating point operations; should support all x86 chips (Pentium MMX or later).</li>
<li><code>GO386=sse2</code>: use SSE2 for floating point operations; has better performance but only available on Pentium 4/Opteron/Athlon 64 or later.</li>
</ul>
</li>