Revert "Revert "Fast ART x86 interpreter""

This reverts commit 2d093a1213cc2f85b5e5e02782332657c479eb94.

Disable x86 mterp compilation on Mac host builds (but keep enabled
for all target builds).

Change-Id: Ie355279f166d2964a786646ee53f065b7e0f5ede
diff --git a/runtime/interpreter/mterp/x86/entry.S b/runtime/interpreter/mterp/x86/entry.S
new file mode 100644
index 0000000..a24ef70
--- /dev/null
+++ b/runtime/interpreter/mterp/x86/entry.S
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/*
+ * Interpreter entry point.
+ */
+
+    .text
+    .global ExecuteMterpImpl
+    .type   ExecuteMterpImpl, %function
+
+/*
+ * On entry:
+ *  0  Thread* self
+ *  1  code_item
+ *  2  ShadowFrame
+ *  3  JValue* result_register
+ *
+ */
+
+ExecuteMterpImpl:
+    .cfi_startproc
+    /* Allocate frame */
+    subl    $$FRAME_SIZE, %esp
+    .cfi_adjust_cfa_offset FRAME_SIZE
+
+    /* Spill callee save regs */
+    movl    %ebp, EBP_SPILL(%esp)
+    movl    %edi, EDI_SPILL(%esp)
+    movl    %esi, ESI_SPILL(%esp)
+    movl    %ebx, EBX_SPILL(%esp)
+
+    /* Load ShadowFrame pointer */
+    movl    IN_ARG2(%esp), %edx
+
+    /* Remember the return register */
+    movl    IN_ARG3(%esp), %eax
+    movl    %eax, SHADOWFRAME_RESULT_REGISTER_OFFSET(%edx)
+
+    /* Remember the code_item */
+    movl    IN_ARG1(%esp), %ecx
+    movl    %ecx, SHADOWFRAME_CODE_ITEM_OFFSET(%edx)
+
+    /* set up "named" registers */
+    movl    SHADOWFRAME_NUMBER_OF_VREGS_OFFSET(%edx), %eax
+    leal    SHADOWFRAME_VREGS_OFFSET(%edx), rFP
+    leal    (rFP, %eax, 4), rREFS
+    movl    SHADOWFRAME_DEX_PC_OFFSET(%edx), %eax
+    lea     CODEITEM_INSNS_OFFSET(%ecx), rPC
+    lea     (rPC, %eax, 2), rPC
+    EXPORT_PC
+
+    /* Starting ibase */
+    REFRESH_IBASE
+
+    /* start executing the instruction at rPC */
+    FETCH_INST
+    GOTO_NEXT
+    /* NOTE: no fallthrough */