<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=Windows-1252">
</head>
<body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">
<br>
<div>
<div>On Nov 25, 2014, at 11:13 AM, Viswanath Puttagunta <<a href="mailto:viswanath.puttagunta@linaro.org">viswanath.puttagunta@linaro.org</a>> wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">On 25 November 2014 at 10:11, Viswanath Puttagunta<br>
<<a href="mailto:viswanath.puttagunta@linaro.org">viswanath.puttagunta@linaro.org</a>> wrote:<br>
<blockquote type="cite"><br>
On 25 November 2014 at 09:39, Jonathan Lennox <<a href="mailto:jonathan@vidyo.com">jonathan@vidyo.com</a>> wrote:<br>
<blockquote type="cite"><br>
On Nov 25, 2014, at 10:07 AM, Viswanath Puttagunta <<a href="mailto:viswanath.puttagunta@linaro.org">viswanath.puttagunta@linaro.org</a>> wrote:<br>
<blockquote type="cite"><br>
<blockquote type="cite">Also is there plans to make the NEON optimisations on ARMv7 run time<br>
detectable like they have in cairo/pixman? For generic distributions<br>
it would nice to be able to be able to enable them as they offer<br>
decent performance improvements but have the code fall back on devices<br>
that don't support NEON.<br>
</blockquote>
Yep, adding support for ARMv8 is the final objective. I did not want to introduce too many changes in the first shot... and hence only introduced for ARMv7. In theory, most of the code (neon intrinsic code) in this patch should remain unchanged for ARMv8. Only
the mechanism by which neon/asimd presence is detected during runtime and the flags used during compile are the only ones that should change. I will work on this once this patch gets reviewed and accepted. I made sure these changes are fairly localized.<br>
<br>
And yes, this patch also supports runtime detection of neon. Actually, most of code to do run time detection of neon was already there in the project before this patch. I just re-used the infrastructure.<br>
</blockquote>
<br>
ARMv8 shouldn’t need Neon detection at all — Neon is a mandatory part of the ARMv8 architecture, unlike ARMv7, where it’s optional.<br>
</blockquote>
As I understand, your statement for ARMv8 is true for AAarch64 mode. But for ARMv8 in AAarch32 mode, neon is still optional (although I haven't heard of an implementation that does not support NEON even in AAarch32 mode). So, for AArch64 mode, I think rtcd
can be disabled. Also, even the neon detection procedure currently in opus will not work on ARMv8 AArch32 mode. Please refer<br>
<a href="http://community.arm.com/groups/android-community/blog/2014/10/10/runtime-detection-of-cpu-features-on-an-armv8-a-cpu">http://community.arm.com/groups/android-community/blog/2014/10/10/runtime-detection-of-cpu-features-on-an-armv8-a-cpu</a><br>
This is one of my todo lists after this patchset gets reviewed and accepted.<br>
<br>
It looks like this is what the configure script is already doing — arm64 sets rtcd_support to no.<br>
</blockquote>
I can't find any evidence of this in configure.ac. Can you please<br>
point me to where rtcd_support is set to no for armv8 (AAarch64)?<br>
</blockquote>
<div><br>
</div>
Tip of git, starting line 202:</div>
<div><br>
</div>
<div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 202 case $host_cpu in</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 203 arm64*|aarch64*)</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 204 dnl Currently we only have asm for fixed-point</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 205 AS_IF([test "$enable_float" != "yes"],[</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 206 cpu_arm64=yes</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 207 AC_DEFINE([OPUS_ARM64_ASM], [], [Make use of ARM64 asm optimization])</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 208 AS_GCC_INLINE_ASSEMBLY(</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 209 [inline_optimization="ARM64"],</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 210 [inline_optimization="disabled"]</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 211 )</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 212 AS_IF([test x"$inline_optimization" = x"ARM64"],[</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 213 AM_CONDITIONAL([OPUS_ARM64_INLINE_ASM],[true])</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 214 AC_DEFINE([OPUS_ARM64_INLINE_ASM], 1,</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 215 [Use ARM64 inline asm optimizations])</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 216 ])</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 217 dnl Don't yet have external asm for arm64</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 218 asm_optimization="disabled"</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 219 dnl Don't need RTCD for arm64</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 220 rtcd_support=no </div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 221 ])</div>
<div style="margin: 0px; font-size: 11px; font-family: Menlo;"> 222 ;;</div>
<div><br>
</div>
<div>This actually should probably be modified to support compilers that have ARM intrinsics but not GCC assembly (e.g. Visual Studio), however.</div>
</div>
</body>
</html>