commit f60525793a1fd784ce7de82f18e7ad9de242c431
author Aart Bik <ajcbik@google.com> Thu Jul 20 16:47:45 2017 -0700
committer Aart Bik <ajcbik@google.com> Thu Jul 20 17:03:35 2017 -0700
tree 5b63ffbc991a2b80ef8e779b975cf737c6d5ab3c
parent 8fe41cf9c995d321da607fa45ad0e752444696a1

Assume all x86/x86_64 hosts support at least sse4.x/popcount.

Note: a small change with potentially big consequences
      please review carefully

Rationale:

Since all true Android x86/x86_64 devices and all x86/x86_64 hosts support
at least sse4.x/popcount, ideally we would simply drop support for
anything "lower". However, since the emulator running on x86/x86_64
only supports as much as the underlying host (a bad design to start
with!), we cannot do the full drop until emulator support includes
sse4.x/popcount.

This CL is the next best thing to get much more SIMD testing "out there"
It assumes that all x86/x86_64 hosts support at least sse4.x/popcount.
This firstly implies that the ART runtime binary itself may exploit
these features. Secondly, this implies thatthe ART runtime passes these
feature flags to dex2oat and JIT by calling the method
InstructionSetFeatures::FromCppDefines(). Since invoking dex2oat
directly does not pick up these flags, cross-compiling from a
x86/x86_64 host to a x86/x86_64 target should not be affected.

Bug: 63585550

Test: test-art-host and test-art-target (FUGU)

Change-Id: I93736cd7b781e4432f3cea036368e230af3d03d0

build/Android.bp

diff --git a/build/Android.bp b/build/Android.bp
index c5ff486..d617116 100644
--- a/build/Android.bp
+++ b/build/Android.bp
@@ -99,6 +99,15 @@
                 // Bug: 15446488. We don't omit the frame pointer to work around
                 // clang/libunwind bugs that cause SEGVs in run-test-004-ThreadStress.
                 "-fno-omit-frame-pointer",
+                // The build assumes that all our x86/x86_64 hosts (such as buildbots and developer
+                // desktops) support at least sse4.2/popcount. This firstly implies that the ART
+                // runtime binary itself may exploit these features. Secondly, this implies that
+                // the ART runtime passes these feature flags to dex2oat and JIT by calling the
+                // method InstructionSetFeatures::FromCppDefines(). Since invoking dex2oat directly
+                // does not pick up these flags, cross-compiling from a x86/x86_64 host to a
+                // x86/x86_64 target should not be affected.
+                "-msse4.2",
+                "-mpopcnt",
             ],
             host_ldlibs: [
                 "-ldl",