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

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

Change-Id: I5cd4c6d86f0f6a966c059715b98db35cc8f9de76
diff --git a/compiler/utils/arm/assembler_arm.h b/compiler/utils/arm/assembler_arm.h
index 911000a..d288b70 100644
--- a/compiler/utils/arm/assembler_arm.h
+++ b/compiler/utils/arm/assembler_arm.h
@@ -421,8 +421,11 @@
   virtual void sdiv(Register rd, Register rn, Register rm, Condition cond = AL) = 0;
   virtual void udiv(Register rd, Register rn, Register rm, Condition cond = AL) = 0;
 
+  // Bit field extract instructions.
   virtual void sbfx(Register rd, Register rn, uint32_t lsb, uint32_t width,
                     Condition cond = AL) = 0;
+  virtual void ubfx(Register rd, Register rn, uint32_t lsb, uint32_t width,
+                    Condition cond = AL) = 0;
 
   // Load/store instructions.
   virtual void ldr(Register rd, const Address& ad, Condition cond = AL) = 0;