Revert "Revert "ART: Mterp for arm64""

Looks like some of our assemblers disagree on valid arm64 assembly syntax
Force use of clang for art runtime.  In a subsequent CL, will use form
that both gcc and clang accept.

This reverts commit 43f3fb960bce978df699c8a68a972be2a0d0d221.

Change-Id: Ice83072171ab502c43d492e2238b446c4814ea67
diff --git a/runtime/interpreter/mterp/arm64/fcmp.S b/runtime/interpreter/mterp/arm64/fcmp.S
new file mode 100644
index 0000000..a45e789
--- /dev/null
+++ b/runtime/interpreter/mterp/arm64/fcmp.S
@@ -0,0 +1,20 @@
+%default {"wide":"", "r1":"s1", "r2":"s2", "default_val":"-1","cond":"le"}
+    /*
+     * Compare two floating-point values.  Puts 0, 1, or -1 into the
+     * destination register based on the results of the comparison.
+     */
+    /* op vAA, vBB, vCC */
+    FETCH w0, 1                         // w0<- CCBB
+    lsr     w4, wINST, #8               // w4<- AA
+    and     w2, w0, #255                // w2<- BB
+    lsr     w3, w0, #8                  // w3<- CC
+    GET_VREG$wide $r1, w2
+    GET_VREG$wide $r2, w3
+    mov     w0, #$default_val
+    fcmp $r1, $r2
+    csneg w0, w0, w0, $cond
+    csel w0, wzr, w0, eq
+    FETCH_ADVANCE_INST 2                // advance rPC, load rINST
+    GET_INST_OPCODE ip                  // extract opcode from rINST
+    SET_VREG w0, w4                     // vAA<- w0
+    GOTO_OPCODE ip                      // jump to next instruction