Optimize AOT's switchable calls for the monomorphic case.

runtime/vm/stub_code_arm.cc

Index: runtime/vm/stub_code_arm.cc
diff --git a/runtime/vm/stub_code_arm.cc b/runtime/vm/stub_code_arm.cc
index 370711b2813f9a8e45e0a84346426875585c5de2..59bd06f30f5af1b8b049ee151b88379cf635bdf6 100644
--- a/runtime/vm/stub_code_arm.cc
+++ b/runtime/vm/stub_code_arm.cc
@@ -1990,10 +1990,11 @@ void StubCode::GenerateOptimizedIdenticalWithNumberCheckStub(
 //  R0: receiver
 //  R9: MegamorphicCache (preserved)
 // Result:
-//  R1: target entry point
 //  CODE_REG: target Code
 //  R4: arguments descriptor
 void StubCode::GenerateMegamorphicLookupStub(Assembler* assembler) {
+  __ NoMonomorphicCheckedEntry();
+
   __ LoadTaggedClassIdMayBeSmi(R0, R0);
   // R0: receiver cid as Smi.
   __ ldr(R2, FieldAddress(R9, MegamorphicCache::buckets_offset()));
@@ -2028,7 +2029,7 @@ void StubCode::GenerateMegamorphicLookupStub(Assembler* assembler) {
   __ ldr(R4, FieldAddress(R9, MegamorphicCache::arguments_descriptor_offset()));
   __ ldr(R1, FieldAddress(R0, Function::entry_point_offset()));
   __ ldr(CODE_REG, FieldAddress(R0, Function::code_offset()));
-  __ Ret();
+  __ bx(R1);
 
   // Probe failed, check if it is a miss.
   __ Bind(&probe_failed);
@@ -2046,10 +2047,11 @@ void StubCode::GenerateMegamorphicLookupStub(Assembler* assembler) {
 //  R0: receiver
 //  R9: ICData (preserved)
 // Result:
-//  R1: target entry point
 //  CODE_REG: target Code object
 //  R4: arguments descriptor
 void StubCode::GenerateICLookupThroughFunctionStub(Assembler* assembler) {
+  __ NoMonomorphicCheckedEntry();
+
   Label loop, found, miss;
   __ ldr(R4, FieldAddress(R9, ICData::arguments_descriptor_offset()));
   __ ldr(R8, FieldAddress(R9, ICData::ic_data_offset()));
@@ -2074,17 +2076,19 @@ void StubCode::GenerateICLookupThroughFunctionStub(Assembler* assembler) {
   __ LoadFromOffset(kWord, R0, R8, target_offset);
   __ ldr(R1, FieldAddress(R0, Function::entry_point_offset()));
   __ ldr(CODE_REG, FieldAddress(R0, Function::code_offset()));
-  __ Ret();
+  __ bx(R1);
 
   __ Bind(&miss);
   __ LoadIsolate(R2);
   __ ldr(CODE_REG, Address(R2, Isolate::ic_miss_code_offset()));
   __ ldr(R1, FieldAddress(CODE_REG, Code::entry_point_offset()));
-  __ Ret();
+  __ bx(R1);
 }
 
 
 void StubCode::GenerateICLookupThroughCodeStub(Assembler* assembler) {
+  __ NoMonomorphicCheckedEntry();
+
   Label loop, found, miss;
   __ ldr(R4, FieldAddress(R9, ICData::arguments_descriptor_offset()));
   __ ldr(R8, FieldAddress(R9, ICData::ic_data_offset()));
@@ -2109,13 +2113,34 @@ void StubCode::GenerateICLookupThroughCodeStub(Assembler* assembler) {
   const intptr_t entry_offset = ICData::EntryPointIndexFor(1) * kWordSize;
   __ ldr(R1, Address(R8, entry_offset));
   __ ldr(CODE_REG, Address(R8, code_offset));
-  __ Ret();
+  __ bx(R1);
 
   __ Bind(&miss);
   __ LoadIsolate(R2);
   __ ldr(CODE_REG, Address(R2, Isolate::ic_miss_code_offset()));
   __ ldr(R1, FieldAddress(CODE_REG, Code::entry_point_offset()));
-  __ Ret();
+  __ bx(R1);
+}
+
+
+// Called from the monomorphic checked entry.
+//  R0: receiver
+void StubCode::GenerateMonomorphicMissStub(Assembler* assembler) {
+  __ EnterStubFrame();
+  __ Push(R0);  // Preserve receiver.
+
+  __ PushObject(Object::null_object());  // Result.
+  __ Push(R0);                           // Arg0: Receiver
+  __ CallRuntime(kMonomorphicMissRuntimeEntry, 1);
+  __ Drop(1);
+  __ Pop(R9);  // result = IC
+
+  __ Pop(R0);  // Restore receiver.
+  __ LeaveStubFrame();
+
+  __ ldr(CODE_REG, Address(THR, Thread::ic_lookup_through_code_stub_offset()));
+  __ ldr(R1, FieldAddress(CODE_REG, Code::checked_entry_point_offset()));
+  __ bx(R1);
 }