Improve type optimization reusing the type argument vector of the instantiator

runtime/vm/intermediate_language_mips.cc

Index: runtime/vm/intermediate_language_mips.cc
===================================================================
--- runtime/vm/intermediate_language_mips.cc	(revision 22056)
+++ runtime/vm/intermediate_language_mips.cc	(working copy)
@@ -1301,11 +1301,10 @@
 
 LocationSummary* InstantiateTypeArgumentsInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
-  const intptr_t kNumTemps = 1;
+  const intptr_t kNumTemps = 0;
   LocationSummary* locs =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kCall);
   locs->set_in(0, Location::RegisterLocation(T0));
-  locs->set_temp(0, Location::RegisterLocation(T1));
   locs->set_out(Location::RegisterLocation(T0));
   return locs;
 }
@@ -1315,52 +1314,41 @@
     FlowGraphCompiler* compiler) {
   __ TraceSimMsg("InstantiateTypeArgumentsInstr");
   Register instantiator_reg = locs()->in(0).reg();
-  Register temp = locs()->temp(0).reg();
   Register result_reg = locs()->out().reg();
 
   // 'instantiator_reg' is the instantiator AbstractTypeArguments object
   // (or null).
-  // If the instantiator is null and if the type argument vector
-  // instantiated from null becomes a vector of dynamic, then use null as
-  // the type arguments.
-  Label type_arguments_instantiated;
-  const intptr_t len = type_arguments().Length();
-  if (type_arguments().IsRawInstantiatedRaw(len)) {
-    __ BranchEqual(instantiator_reg, reinterpret_cast<intptr_t>(Object::null()),
-                   &type_arguments_instantiated);
-  }
-  // Instantiate non-null type arguments.
-  if (type_arguments().IsUninstantiatedIdentity()) {
-    // Check if the instantiator type argument vector is a TypeArguments of a
-    // matching length and, if so, use it as the instantiated type_arguments.
-    // No need to check the instantiator ('instantiator_reg') for null here,
-    // because a null instantiator will have the wrong class (Null instead of
-    // TypeArguments).
-    Label type_arguments_uninstantiated;
-    __ LoadClassId(temp, instantiator_reg);
-    __ BranchNotEqual(temp, kTypeArgumentsCid, &type_arguments_uninstantiated);
-    __ lw(temp, FieldAddress(instantiator_reg, TypeArguments::length_offset()));
-    __ BranchEqual(temp, Smi::RawValue(len), &type_arguments_instantiated);
-    __ Bind(&type_arguments_uninstantiated);
-  }
-  // A runtime call to instantiate the type arguments is required.
-  __ addiu(SP, SP, Immediate(-3 * kWordSize));
-  __ LoadObject(TMP1, Object::ZoneHandle());
-  __ LoadObject(TMP2, type_arguments());
-  __ sw(TMP1, Address(SP, 2 * kWordSize));  // Make room for the result.
-  __ sw(TMP2, Address(SP, 1 * kWordSize));
-  // Push instantiator type arguments.
-  __ sw(instantiator_reg, Address(SP, 0 * kWordSize));
+  if (!type_arguments().IsUninstantiatedIdentity()) {
+    // If the instantiator is null and if the type argument vector
+    // instantiated from null becomes a vector of dynamic, then use null as
+    // the type arguments.
+    Label type_arguments_instantiated;
+    const intptr_t len = type_arguments().Length();
+    if (type_arguments().IsRawInstantiatedRaw(len)) {
+      __ BranchEqual(instantiator_reg,
+                     reinterpret_cast<intptr_t>(Object::null()),
+                     &type_arguments_instantiated);
+    }
+    // Instantiate non-null type arguments.
+    // A runtime call to instantiate the type arguments is required.
+    __ addiu(SP, SP, Immediate(-3 * kWordSize));
+    __ LoadObject(TMP1, Object::ZoneHandle());
+    __ LoadObject(TMP2, type_arguments());
+    __ sw(TMP1, Address(SP, 2 * kWordSize));  // Make room for the result.
+    __ sw(TMP2, Address(SP, 1 * kWordSize));
+    // Push instantiator type arguments.
+    __ sw(instantiator_reg, Address(SP, 0 * kWordSize));
 
-  compiler->GenerateCallRuntime(token_pos(),
-                                deopt_id(),
-                                kInstantiateTypeArgumentsRuntimeEntry,
-                                locs());
-  // Pop instantiated type arguments.
-  __ lw(result_reg, Address(SP, 2 * kWordSize));
-  // Drop instantiator and uninstantiated type arguments.
-  __ addiu(SP, SP, Immediate(3 * kWordSize));
-  __ Bind(&type_arguments_instantiated);
+    compiler->GenerateCallRuntime(token_pos(),
+                                  deopt_id(),
+                                  kInstantiateTypeArgumentsRuntimeEntry,
+                                  locs());
+    // Pop instantiated type arguments.
+    __ lw(result_reg, Address(SP, 2 * kWordSize));
+    // Drop instantiator and uninstantiated type arguments.
+    __ addiu(SP, SP, Immediate(3 * kWordSize));
+    __ Bind(&type_arguments_instantiated);
+  }
   ASSERT(instantiator_reg == result_reg);
   // 'result_reg': Instantiated type arguments.
 }
@@ -1369,12 +1357,11 @@
 LocationSummary*
 ExtractConstructorTypeArgumentsInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
-  const intptr_t kNumTemps = 1;
+  const intptr_t kNumTemps = 0;
   LocationSummary* locs =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   locs->set_out(Location::SameAsFirstInput());
-  locs->set_temp(0, Location::RequiresRegister());
   return locs;
 }
 
@@ -1384,40 +1371,28 @@
   Register instantiator_reg = locs()->in(0).reg();
   Register result_reg = locs()->out().reg();
   ASSERT(instantiator_reg == result_reg);
-  Register temp_reg = locs()->temp(0).reg();
 
   // instantiator_reg is the instantiator type argument vector, i.e. an
   // AbstractTypeArguments object (or null).
-  // If the instantiator is null and if the type argument vector
-  // instantiated from null becomes a vector of dynamic, then use null as
-  // the type arguments.
-  Label type_arguments_instantiated;
-  const intptr_t len = type_arguments().Length();
-  if (type_arguments().IsRawInstantiatedRaw(len)) {
-    __ BranchEqual(instantiator_reg, reinterpret_cast<intptr_t>(Object::null()),
-                   &type_arguments_instantiated);
+  if (!type_arguments().IsUninstantiatedIdentity()) {
+    // If the instantiator is null and if the type argument vector
+    // instantiated from null becomes a vector of dynamic, then use null as
+    // the type arguments.
+    Label type_arguments_instantiated;
+    const intptr_t len = type_arguments().Length();
+    if (type_arguments().IsRawInstantiatedRaw(len)) {
+      __ BranchEqual(instantiator_reg,
+                     reinterpret_cast<intptr_t>(Object::null()),
+                     &type_arguments_instantiated);
+    }
+    // Instantiate non-null type arguments.
+    // In the non-factory case, we rely on the allocation stub to
+    // instantiate the type arguments.
+    __ LoadObject(result_reg, type_arguments());
+    // result_reg: uninstantiated type arguments.
+    __ Bind(&type_arguments_instantiated);
   }
-  // Instantiate non-null type arguments.
-  if (type_arguments().IsUninstantiatedIdentity()) {
-    // Check if the instantiator type argument vector is a TypeArguments of a
-    // matching length and, if so, use it as the instantiated type_arguments.
-    // No need to check instantiator_reg for null here, because a null
-    // instantiator will have the wrong class (Null instead of TypeArguments).
-    Label type_arguments_uninstantiated;
-    __ LoadClassId(temp_reg, instantiator_reg);
-    __ BranchNotEqual(temp_reg, kTypeArgumentsCid,
-                      &type_arguments_uninstantiated);
-    __ lw(temp_reg,
-          FieldAddress(instantiator_reg, TypeArguments::length_offset()));
-    __ BranchEqual(temp_reg, Smi::RawValue(type_arguments().Length()),
-                   &type_arguments_instantiated);
-    __ Bind(&type_arguments_uninstantiated);
-  }
-  // In the non-factory case, we rely on the allocation stub to
-  // instantiate the type arguments.
-  __ LoadObject(result_reg, type_arguments());
-  // result_reg: uninstantiated type arguments.
-  __ Bind(&type_arguments_instantiated);
+  ASSERT(instantiator_reg == result_reg);
   // result_reg: uninstantiated or instantiated type arguments.
 }
 
@@ -1425,12 +1400,11 @@
 LocationSummary*
 ExtractConstructorInstantiatorInstr::MakeLocationSummary() const {
   const intptr_t kNumInputs = 1;
-  const intptr_t kNumTemps = 1;
+  const intptr_t kNumTemps = 0;
   LocationSummary* locs =
       new LocationSummary(kNumInputs, kNumTemps, LocationSummary::kNoCall);
   locs->set_in(0, Location::RequiresRegister());
   locs->set_out(Location::SameAsFirstInput());
-  locs->set_temp(0, Location::RequiresRegister());
   return locs;
 }
 
@@ -1439,50 +1413,30 @@
     FlowGraphCompiler* compiler) {
   Register instantiator_reg = locs()->in(0).reg();
   ASSERT(locs()->out().reg() == instantiator_reg);
-  Register temp_reg = locs()->temp(0).reg();
 
   // instantiator_reg is the instantiator AbstractTypeArguments object
-  // (or null).  If the instantiator is null and if the type argument vector
-  // instantiated from null becomes a vector of dynamic, then use null as
-  // the type arguments and do not pass the instantiator.
-  Label done;
-  const intptr_t len = type_arguments().Length();
-  if (type_arguments().IsRawInstantiatedRaw(len)) {
-    Label instantiator_not_null;
-    __ BranchNotEqual(instantiator_reg,
-        reinterpret_cast<intptr_t>(Object::null()), &instantiator_not_null);
-    // Null was used in VisitExtractConstructorTypeArguments as the
-    // instantiated type arguments, no proper instantiator needed.
-    __ LoadImmediate(instantiator_reg,
-                     Smi::RawValue(StubCode::kNoInstantiator));
-    __ b(&done);
-    __ Bind(&instantiator_not_null);
-  }
-  // Instantiate non-null type arguments.
+  // (or null).
   if (type_arguments().IsUninstantiatedIdentity()) {
-    // TODO(regis): The following emitted code is duplicated in
-    // VisitExtractConstructorTypeArguments above. The reason is that the code
-    // is split between two computations, so that each one produces a
-    // single value, rather than producing a pair of values.
-    // If this becomes an issue, we should expose these tests at the IL level.
-
-    // Check if the instantiator type argument vector is a TypeArguments of a
-    // matching length and, if so, use it as the instantiated type_arguments.
-    // No need to check the instantiator ('instantiator_reg') for null here,
-    // because a null instantiator will have the wrong class (Null instead of
-    // TypeArguments).
-    __ LoadClassId(temp_reg, instantiator_reg);
-    __ BranchNotEqual(temp_reg, kTypeArgumentsCid, &done);
-    __ lw(temp_reg,
-          FieldAddress(instantiator_reg, TypeArguments::length_offset()));
-    __ BranchNotEqual(temp_reg, Smi::RawValue(type_arguments().Length()),
-                      &done);
     // The instantiator was used in VisitExtractConstructorTypeArguments as the
     // instantiated type arguments, no proper instantiator needed.
     __ LoadImmediate(instantiator_reg,
                      Smi::RawValue(StubCode::kNoInstantiator));
+  } else {
+    // If the instantiator is null and if the type argument vector
+    // instantiated from null becomes a vector of dynamic, then use null as
+    // the type arguments and do not pass the instantiator.
+    const intptr_t len = type_arguments().Length();
+    if (type_arguments().IsRawInstantiatedRaw(len)) {
+      Label instantiator_not_null;
+      __ BranchNotEqual(instantiator_reg,
+          reinterpret_cast<intptr_t>(Object::null()), &instantiator_not_null);
+      // Null was used in VisitExtractConstructorTypeArguments as the
+      // instantiated type arguments, no proper instantiator needed.
+      __ LoadImmediate(instantiator_reg,
+                       Smi::RawValue(StubCode::kNoInstantiator));
+      __ Bind(&instantiator_not_null);
+    }
   }
-  __ Bind(&done);
   // instantiator_reg: instantiator or kNoInstantiator.
 }