ARM64: Ensure stricter alignment when loading and storing register pairs

The impetus for this change is the fact that loads that cross a 64 byte
boundary and stores that cross a 16 byte boundary are a performance issue
on Cortex-A57 and A72.

Change-Id: I81263dc72272192ad2d190b741a955f175880461
diff --git a/compiler/optimizing/optimizing_cfi_test_expected.inc b/compiler/optimizing/optimizing_cfi_test_expected.inc
index 764160a..05eb063 100644
--- a/compiler/optimizing/optimizing_cfi_test_expected.inc
+++ b/compiler/optimizing/optimizing_cfi_test_expected.inc
@@ -32,21 +32,21 @@
 // 0x00000012: .cfi_def_cfa_offset: 64
 
 static constexpr uint8_t expected_asm_kArm64[] = {
-    0xE0, 0x0F, 0x1C, 0xF8, 0xF4, 0xD7, 0x02, 0xA9, 0xFE, 0x1F, 0x00, 0xF9,
-    0xE8, 0xA7, 0x01, 0x6D, 0xE8, 0xA7, 0x41, 0x6D, 0xF4, 0xD7, 0x42, 0xA9,
-    0xFE, 0x1F, 0x40, 0xF9, 0xFF, 0x03, 0x01, 0x91, 0xC0, 0x03, 0x5F, 0xD6,
+    0xE0, 0x0F, 0x1C, 0xF8, 0xF4, 0x17, 0x00, 0xF9, 0xF5, 0x7B, 0x03, 0xA9,
+    0xE8, 0xA7, 0x01, 0x6D, 0xE8, 0xA7, 0x41, 0x6D, 0xF4, 0x17, 0x40, 0xF9,
+    0xF5, 0x7B, 0x43, 0xA9, 0xFF, 0x03, 0x01, 0x91, 0xC0, 0x03, 0x5F, 0xD6,
 };
 static constexpr uint8_t expected_cfi_kArm64[] = {
-    0x44, 0x0E, 0x40, 0x44, 0x94, 0x06, 0x95, 0x04, 0x44, 0x9E, 0x02, 0x44,
+    0x44, 0x0E, 0x40, 0x44, 0x94, 0x06, 0x44, 0x95, 0x04, 0x9E, 0x02, 0x44,
     0x05, 0x48, 0x0A, 0x05, 0x49, 0x08, 0x0A, 0x44, 0x06, 0x48, 0x06, 0x49,
-    0x44, 0xD4, 0xD5, 0x44, 0xDE, 0x44, 0x0E, 0x00, 0x44, 0x0B, 0x0E, 0x40,
+    0x44, 0xD4, 0x44, 0xD5, 0xDE, 0x44, 0x0E, 0x00, 0x44, 0x0B, 0x0E, 0x40,
 };
 // 0x00000000: str x0, [sp, #-64]!
 // 0x00000004: .cfi_def_cfa_offset: 64
-// 0x00000004: stp x20, x21, [sp, #40]
+// 0x00000004: str x20, [sp, #40]
 // 0x00000008: .cfi_offset: r20 at cfa-24
-// 0x00000008: .cfi_offset: r21 at cfa-16
-// 0x00000008: str lr, [sp, #56]
+// 0x00000008: stp x21, lr, [sp, #48]
+// 0x0000000c: .cfi_offset: r21 at cfa-16
 // 0x0000000c: .cfi_offset: r30 at cfa-8
 // 0x0000000c: stp d8, d9, [sp, #24]
 // 0x00000010: .cfi_offset_extended: r72 at cfa-40
@@ -55,10 +55,10 @@
 // 0x00000010: ldp d8, d9, [sp, #24]
 // 0x00000014: .cfi_restore_extended: r72
 // 0x00000014: .cfi_restore_extended: r73
-// 0x00000014: ldp x20, x21, [sp, #40]
+// 0x00000014: ldr x20, [sp, #40]
 // 0x00000018: .cfi_restore: r20
-// 0x00000018: .cfi_restore: r21
-// 0x00000018: ldr lr, [sp, #56]
+// 0x00000018: ldp x21, lr, [sp, #48]
+// 0x0000001c: .cfi_restore: r21
 // 0x0000001c: .cfi_restore: r30
 // 0x0000001c: add sp, sp, #0x40 (64)
 // 0x00000020: .cfi_def_cfa_offset: 0