Adds mrc instruction to arm simulator, assembler, disassembler.

runtime/vm/assembler_arm_test.cc

Index: runtime/vm/assembler_arm_test.cc
===================================================================
--- runtime/vm/assembler_arm_test.cc	(revision 19404)
+++ runtime/vm/assembler_arm_test.cc	(working copy)
@@ -5,8 +5,10 @@
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM)
 
+#include "vm/assembler_macros.h"
 #include "vm/assembler.h"
 #include "vm/os.h"
+#include "vm/simulator.h"
 #include "vm/unit_test.h"
 #include "vm/virtual_memory.h"
 
@@ -1361,6 +1363,27 @@
   EXPECT_EQ(42, EXECUTE_TEST_CODE_INT32(Tst, test->entry()));
 }
 
+
+// If we are in the simulator, check that HasDiv returns the expected result

[regis, 2013/03/04 21:54:52]

You can run this test even if we are running on real hardware.

[srdjan, 2013/03/04 22:02:17]

ditto

+#ifdef USING_SIMULATOR

[regis, 2013/03/04 21:54:52]

We prefer the form #if defined(USING_SIMULATOR), which makes it easier to add
terms.
I may have missed some in my previous submits. I'll check.

+ASSEMBLER_TEST_GENERATE(HasDiv, assembler) {
+  AssemblerMacros::HasDiv(assembler, R0);
+  __ mov(PC, ShifterOperand(LR));
+}
+
+
+ASSEMBLER_TEST_RUN(HasDiv, test) {
+  EXPECT(test != NULL);
+  typedef int (*Tst)();
+  if (FLAG_sim_has_int_div) {

[regis, 2013/03/04 21:54:52]

A flag is problematic to maintain when running tests.
Instead of a flag, add a new static integer_division_supported() in class
CPUFeatures. See assembler_arm.h.
This call will be used to decide what instructions to emit on real hardware.
Now, if we want to test mrc under the simulator, the tests should set the
feature directly in CPUFeatures, thereby telling the simulator what to do. Let's
discuss if this explanation is not clear.

+    EXPECT_LT(0, EXECUTE_TEST_CODE_INT32(Tst, test->entry()));
+  } else {
+    EXPECT_EQ(0, EXECUTE_TEST_CODE_INT32(Tst, test->entry()));
+  }
+}
+#endif

[regis, 2013/03/04 21:54:52]

We like to repeat the #if as a comment, unless they are very close to each
other:
#endif  // defined(USING_SIMULATOR) 

+
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM