Add support for int-to-byte in the optimizing compiler.

- Add support for the int-to-byte Dex instruction in the
  optimizing compiler.
- Implement the ARM and Thumb-2 SBFX instructions.
- Generate x86, x86-64 and ARM (but not ARM64) code for
  char to byte, short to byte and int to byte
  HTypeConversion nodes.
- Add related tests to test/422-type-conversion.

Change-Id: Ic8b8911b90d4b5281fad15bcee96bc3ee85dc577
diff --git a/compiler/utils/arm/assembler_thumb2.cc b/compiler/utils/arm/assembler_thumb2.cc
index 053e843..a309e18 100644
--- a/compiler/utils/arm/assembler_thumb2.cc
+++ b/compiler/utils/arm/assembler_thumb2.cc
@@ -264,6 +264,27 @@
 }
 
 
+void Thumb2Assembler::sbfx(Register rd, Register rn, uint32_t lsb, uint32_t width, Condition cond) {
+  CheckCondition(cond);
+  CHECK_LE(lsb, 31U);
+  CHECK(1U <= width && width <= 32U) << width;
+  uint32_t widthminus1 = width - 1;
+  uint32_t imm2 = lsb & (B1 | B0);  // Bits 0-1 of `lsb`.
+  uint32_t imm3 = (lsb & (B4 | B3 | B2)) >> 2;  // Bits 2-4 of `lsb`.
+
+  uint32_t op = 20U /* 0b10100 */;
+  int32_t encoding = B31 | B30 | B29 | B28 | B25 |
+      op << 20 |
+      static_cast<uint32_t>(rn) << 16 |
+      imm3 << 12 |
+      static_cast<uint32_t>(rd) << 8 |
+      imm2 << 6 |
+      widthminus1;
+
+  Emit32(encoding);
+}
+
+
 void Thumb2Assembler::ldr(Register rd, const Address& ad, Condition cond) {
   EmitLoadStore(cond, true, false, false, false, rd, ad);
 }