Add support for long-to-double in the optimizing compiler.

- Add support for the long-to-double Dex instruction in the
  optimizing compiler.
- Enable requests of temporary FPU (double) registers during
  code generation.
- Fix art::x86::X86Assembler::LoadLongConstant and extend
  it to int64_t values.
- Have art::x86_64::X86_64Assembler::cvtsi2sd work with
  64-bit operands.
- Generate x86, x86-64 and ARM (but not ARM64) code for
  long to double HTypeConversion nodes.
- Add related tests to test/422-type-conversion.

Change-Id: Ie73d9e5e25bd2e15f585c371e8fc2dcb83438ccd
diff --git a/compiler/utils/x86/assembler_x86.cc b/compiler/utils/x86/assembler_x86.cc
index a297ea3..dbad386 100644
--- a/compiler/utils/x86/assembler_x86.cc
+++ b/compiler/utils/x86/assembler_x86.cc
@@ -1318,13 +1318,19 @@
 }
 
 
+void X86Assembler::LoadLongConstant(XmmRegister dst, int64_t value) {
+  // TODO: Need to have a code constants table.
+  pushl(Immediate(High32Bits(value)));
+  pushl(Immediate(Low32Bits(value)));
+  movsd(dst, Address(ESP, 0));
+  addl(ESP, Immediate(2 * sizeof(int32_t)));
+}
+
+
 void X86Assembler::LoadDoubleConstant(XmmRegister dst, double value) {
   // TODO: Need to have a code constants table.
   int64_t constant = bit_cast<int64_t, double>(value);
-  pushl(Immediate(High32Bits(constant)));
-  pushl(Immediate(Low32Bits(constant)));
-  movsd(dst, Address(ESP, 0));
-  addl(ESP, Immediate(2 * sizeof(intptr_t)));
+  LoadLongConstant(dst, constant);
 }