Merge "Don't mention armeabi-v7a-hard." into mnc-mr-docs

</tr>

<tr>

<td><a href="#v7a">{@code armeabi-v7a} ({@code armeabi-v7a-hard)}</a></td>

<td><a href="#v7a">{@code armeabi-v7a}</a></td>

<td>

<li>armeabi</li>

<li>Thumb-2</li>

<li>VFPv3-D16</li>

<li>Other, optional</li></td>

<td>Hard float when specified as {@code armeabi-v7a-hard}.

Incompatible with ARMv5, v6 devices.</td>

<td>Incompatible with ARMv5, v6 devices.</td>

</tr>

<tr>

<a href="{@docRoot}ndk/guides/android_mk.html">{@code Android.mk}</a>

file.</p>

<h3 id="v7a">armeabi-v7a (armeabi-v7a-hard)</h3>

<h3 id="v7a">armeabi-v7a</h3>

<p>This ABI extends armeabi to include several

<a href="http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0406c/index.html">

CPU instruction set extensions</a>. The instruction extensions that this Android-specific

function calls, instead of dedicated floating-point ones. The system can perform all internal

computations using the FP registers. Doing so speeds up the computations greatly.</p>

<p>Although the requirement to use core register pairs produces a modest performance hit, it ensures

compatibility with all existing armeabi binaries. If you need the additional

performance, you can specify your ABI as {@code armeabi-v7a-hard} instead. Doing so

allows you to use hard floats, while still linking with Android native APIs

that use {@code softfp}. For more information, refer to the comments in

{@code $NDK/tests/device/hard-float/jni/android.mk}.</p>

<p class="note"><strong>Note:</strong> You cannot specify {@code APP_ABI} as both

{@code armeabi-v7a} and {@code armeabi-v7a-hard}. In either case, the build system places the

shared libraries in the {@code armeabi-v7a/} directory.</p>

<h3 id="hard">armeabi-v7a-hard</h3>

<p>This variant of the {@code armeabi-v7a} ABI is unique to the NDK. The NDK build

system adds the following flags in addition to those that it uses for the

{@code armeabi-v7a} ABI:</p>

<pre class="no-pretty-print">

TARGET_CFLAGS += -mhard-float -D_NDK_MATH_NO_SOFTFP=1

TARGET_LDFLAGS += -Wl,--no-warn-mismatch -lm_hard

</pre>

<p>The compiler compiles all code with hard-float, and links it with {@code libm_hard.a}.

This math library is the same one as {@code libm.a}, except that it follows hard-float ABI

conventions. In the APK, the generated shared libraries reside in {@code /lib/armeabi-v7a/}.</p>

<h3 id="arm64-v8a">arm64-v8a</h3>

<p>This ABI is for ARMv8-based CPUs that support AArch64. It also includes the NEON and

VFPv4 instruction sets.</p>