Adds native/leaf runtime call stub and redirection on MIPS.

runtime/vm/stub_code_mips.cc

Index: runtime/vm/stub_code_mips.cc
===================================================================
--- runtime/vm/stub_code_mips.cc	(revision 20794)
+++ runtime/vm/stub_code_mips.cc	(working copy)
@@ -100,8 +100,91 @@
 }
 
 
+// Input parameters:
+//   RA : return address.
+//   SP : address of return value.
+//   T5 : address of the native function to call.
+//   A2 : address of first argument in argument array.
+//   A1 : argc_tag including number of arguments and function kind.
 void StubCode::GenerateCallNativeCFunctionStub(Assembler* assembler) {
-  __ Unimplemented("CallNativeCFunction stub");
+  const intptr_t isolate_offset = NativeArguments::isolate_offset();
+  const intptr_t argc_tag_offset = NativeArguments::argc_tag_offset();
+  const intptr_t argv_offset = NativeArguments::argv_offset();
+  const intptr_t retval_offset = NativeArguments::retval_offset();
+
+  __ addiu(SP, SP, Immediate(-2 * kWordSize));
+  __ sw(RA, Address(SP, 1 * kWordSize));
+  __ sw(FP, Address(SP, 0 * kWordSize));
+  __ mov(FP, SP);
+
+  // Load current Isolate pointer from Context structure into A0.
+  __ lw(A0, FieldAddress(CTX, Context::isolate_offset()));
+
+  // Save exit frame information to enable stack walking as we are about
+  // to transition to native code.
+  __ sw(SP, Address(A0, Isolate::top_exit_frame_info_offset()));
+
+  // Save current Context pointer into Isolate structure.
+  __ sw(CTX, Address(A0, Isolate::top_context_offset()));
+
+  // Cache Isolate pointer into CTX while executing native code.
+  __ mov(CTX, A0);
+
+  // Reserve space for the native arguments structure passed on the stack (the
+  // outgoing pointer parameter to the native arguments structure is passed in
+  // R0) and align frame before entering the C++ world.
+  __ ReserveAlignedFrameSpace(sizeof(NativeArguments));
+
+  // Initialize NativeArguments structure and call native function.
+  // Registers A0, A1, A2, and A3 are used.
+
+  ASSERT(isolate_offset == 0 * kWordSize);
+  // Set isolate in NativeArgs: A0 already contains CTX.
+
+  // There are no native calls to closures, so we do not need to set the tag
+  // bits kClosureFunctionBit and kInstanceFunctionBit in argc_tag_.
+  ASSERT(argc_tag_offset == 1 * kWordSize);
+  // Set argc in NativeArguments: T1 already contains argc.
+
+  ASSERT(argv_offset == 2 * kWordSize);
+  // Set argv in NativeArguments: T2 already contains argv.
+
+  ASSERT(retval_offset == 3 * kWordSize);
+  __ addiu(A3, FP, Immediate(2 * kWordSize));  // Set retval in NativeArgs.
+
+  // TODO(regis): Should we pass the structure by value as in runtime calls?
+  // It would require changing Dart API for native functions.
+  // For now, space is reserved on the stack and we pass a pointer to it.
+  __ addiu(SP, SP, Immediate(-4 * kWordSize));
+  __ sw(A3, Address(SP, 3 * kWordSize));
+  __ sw(A2, Address(SP, 2 * kWordSize));
+  __ sw(A1, Address(SP, 1 * kWordSize));
+  __ sw(A0, Address(SP, 0 * kWordSize));
+
+  __ mov(A0, SP);  // Pass the pointer to the NativeArguments.
+
+  // Call native function or redirection via simulator.
+  __ jalr(T5);
+
+  // Reset exit frame information in Isolate structure.
+  __ LoadImmediate(A2, 0);
+  __ sw(A2, Address(CTX, Isolate::top_exit_frame_info_offset()));
+
+  // Load Context pointer from Isolate structure into R2.
+  __ lw(A2, Address(CTX, Isolate::top_context_offset()));
+
+  // Reset Context pointer in Isolate structure.
+  __ LoadImmediate(A3, reinterpret_cast<intptr_t>(Object::null()));
+  __ sw(A3, Address(CTX, Isolate::top_context_offset()));
+
+  // Cache Context pointer into CTX while executing Dart code.
+  __ mov(CTX, A2);
+
+  __ mov(SP, FP);
+  __ lw(RA, Address(SP, 1 * kWordSize));
+  __ lw(FP, Address(SP, 0 * kWordSize));
+  __ addiu(SP, SP, Immediate(2 * kWordSize));
+  __ Ret();
 }