[turbofan] Better and more sane support for tail calls

test/unittests/compiler/linkage-tail-call-unittest.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/node.h"
 #include "test/unittests/test-utils.h"
 
@@ skipping 37 matching lines @@
   }
 };
 
 
 TEST_F(LinkageTailCall, EmptyToEmpty) {
   LocationSignature locations(0, 0, nullptr);
   CallDescriptor* desc = NewStandardCallDescriptor(&locations);
   CommonOperatorBuilder common(zone());
   const Operator* op = common.Call(desc);
   Node* const node = Node::New(zone(), 1, op, 0, nullptr, false);
-  EXPECT_TRUE(desc->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, SameReturn) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0)};
   LocationSignature locations1(1, 0, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Callee
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations1);
 
   CommonOperatorBuilder common(zone());
   const Operator* op = common.Call(desc2);
   Node* const node = Node::New(zone(), 1, op, 0, nullptr, false);
-  EXPECT_TRUE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, DifferingReturn) {
   // Caller
   LinkageLocation location_array1[] = {RegisterLocation(0)};
   LocationSignature locations1(1, 0, location_array1);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Callee
   LinkageLocation location_array2[] = {RegisterLocation(1)};
   LocationSignature locations2(1, 0, location_array2);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations2);
 
   CommonOperatorBuilder common(zone());
   const Operator* op = common.Call(desc2);
   Node* const node = Node::New(zone(), 1, op, 0, nullptr, false);
-  EXPECT_FALSE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_FALSE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MoreRegisterParametersCallee) {
   // Caller
   LinkageLocation location_array1[] = {RegisterLocation(0)};
   LocationSignature locations1(1, 0, location_array1);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Callee
   LinkageLocation location_array2[] = {RegisterLocation(0),
                                        RegisterLocation(0)};
   LocationSignature locations2(1, 1, location_array2);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations2);
 
   CommonOperatorBuilder common(zone());
   const Operator* op = common.Call(desc2);
   Node* const node = Node::New(zone(), 1, op, 0, nullptr, false);
-  EXPECT_TRUE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MoreRegisterParametersCaller) {
   // Caller
   LinkageLocation location_array1[] = {RegisterLocation(0),
                                        RegisterLocation(0)};
   LocationSignature locations1(1, 1, location_array1);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Callee
   LinkageLocation location_array2[] = {RegisterLocation(0)};
   LocationSignature locations2(1, 0, location_array2);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations2);
 
   CommonOperatorBuilder common(zone());
   const Operator* op = common.Call(desc2);
   Node* const node = Node::New(zone(), 1, op, 0, nullptr, false);
-  EXPECT_TRUE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MoreRegisterAndStackParametersCallee) {
   // Caller
   LinkageLocation location_array1[] = {RegisterLocation(0)};
   LocationSignature locations1(1, 0, location_array1);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Callee
   LinkageLocation location_array2[] = {RegisterLocation(0), RegisterLocation(0),
                                        RegisterLocation(1), StackLocation(1)};
   LocationSignature locations2(1, 3, location_array2);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations2);
 
   CommonOperatorBuilder common(zone());
   const Operator* op = common.Call(desc2);
   Node* const node = Node::New(zone(), 1, op, 0, nullptr, false);
-  EXPECT_FALSE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_FALSE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(1, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MoreRegisterAndStackParametersCaller) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0), RegisterLocation(0),
                                       RegisterLocation(1), StackLocation(1)};
   LocationSignature locations1(1, 3, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Callee
   LinkageLocation location_array2[] = {RegisterLocation(0)};
   LocationSignature locations2(1, 0, location_array2);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations2);
 
   CommonOperatorBuilder common(zone());
   const Operator* op = common.Call(desc2);
   Node* const node = Node::New(zone(), 1, op, 0, nullptr, false);
-  EXPECT_FALSE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(-1, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MatchingStackParameters) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0), StackLocation(3),
                                       StackLocation(2), StackLocation(1)};
   LocationSignature locations1(1, 3, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Caller
   LocationSignature locations2(1, 3, location_array);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations1);
 
   CommonOperatorBuilder common(zone());
   Node* p0 = Node::New(zone(), 0, nullptr, 0, nullptr, false);
   Node* p1 = Node::New(zone(), 0, common.Parameter(0), 0, nullptr, false);
   Node* p2 = Node::New(zone(), 0, common.Parameter(1), 0, nullptr, false);
   Node* p3 = Node::New(zone(), 0, common.Parameter(2), 0, nullptr, false);
   Node* parameters[] = {p0, p1, p2, p3};
   const Operator* op = common.Call(desc2);
   Node* const node =
       Node::New(zone(), 1, op, arraysize(parameters), parameters, false);
-  EXPECT_TRUE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, NonMatchingStackParameters) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0), StackLocation(3),
                                       StackLocation(2), StackLocation(1)};
   LocationSignature locations1(1, 3, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Caller
   LocationSignature locations2(1, 3, location_array);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations1);
 
   CommonOperatorBuilder common(zone());
   Node* p0 = Node::New(zone(), 0, nullptr, 0, nullptr, false);
   Node* p1 = Node::New(zone(), 0, common.Parameter(0), 0, nullptr, false);
   Node* p2 = Node::New(zone(), 0, common.Parameter(2), 0, nullptr, false);
   Node* p3 = Node::New(zone(), 0, common.Parameter(1), 0, nullptr, false);
   Node* parameters[] = {p0, p1, p2, p3};
   const Operator* op = common.Call(desc2);
   Node* const node =
       Node::New(zone(), 1, op, arraysize(parameters), parameters, false);
-  EXPECT_FALSE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MatchingStackParametersExtraCallerRegisters) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0), StackLocation(3),
                                       StackLocation(2),    StackLocation(1),
                                       RegisterLocation(0), RegisterLocation(1)};
   LocationSignature locations1(1, 5, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Caller
   LocationSignature locations2(1, 3, location_array);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations1);
 
   CommonOperatorBuilder common(zone());
   Node* p0 = Node::New(zone(), 0, nullptr, 0, nullptr, false);
   Node* p1 = Node::New(zone(), 0, common.Parameter(0), 0, nullptr, false);
   Node* p2 = Node::New(zone(), 0, common.Parameter(1), 0, nullptr, false);
   Node* p3 = Node::New(zone(), 0, common.Parameter(2), 0, nullptr, false);
   Node* parameters[] = {p0, p1, p2, p3};
   const Operator* op = common.Call(desc2);
   Node* const node =
       Node::New(zone(), 1, op, arraysize(parameters), parameters, false);
-  EXPECT_TRUE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MatchingStackParametersExtraCalleeRegisters) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0), StackLocation(3),
                                       StackLocation(2),    StackLocation(1),
                                       RegisterLocation(0), RegisterLocation(1)};
   LocationSignature locations1(1, 3, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Caller
   LocationSignature locations2(1, 5, location_array);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations1);
 
   CommonOperatorBuilder common(zone());
   Node* p0 = Node::New(zone(), 0, nullptr, 0, nullptr, false);
   Node* p1 = Node::New(zone(), 0, common.Parameter(0), 0, nullptr, false);
   Node* p2 = Node::New(zone(), 0, common.Parameter(1), 0, nullptr, false);
   Node* p3 = Node::New(zone(), 0, common.Parameter(2), 0, nullptr, false);
   Node* p4 = Node::New(zone(), 0, common.Parameter(3), 0, nullptr, false);
   Node* parameters[] = {p0, p1, p2, p3, p4};
   const Operator* op = common.Call(desc2);
   Node* const node =
       Node::New(zone(), 1, op, arraysize(parameters), parameters, false);
-  EXPECT_TRUE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(0, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MatchingStackParametersExtraCallerRegistersAndStack) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0), StackLocation(3),
                                       StackLocation(2),    StackLocation(1),
                                       RegisterLocation(0), StackLocation(4)};
   LocationSignature locations1(1, 5, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Caller
   LocationSignature locations2(1, 3, location_array);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations2);
 
   CommonOperatorBuilder common(zone());
   Node* p0 = Node::New(zone(), 0, nullptr, 0, nullptr, false);
   Node* p1 = Node::New(zone(), 0, common.Parameter(0), 0, nullptr, false);
   Node* p2 = Node::New(zone(), 0, common.Parameter(1), 0, nullptr, false);
   Node* p3 = Node::New(zone(), 0, common.Parameter(2), 0, nullptr, false);
   Node* p4 = Node::New(zone(), 0, common.Parameter(3), 0, nullptr, false);
   Node* parameters[] = {p0, p1, p2, p3, p4};
   const Operator* op = common.Call(desc2);
   Node* const node =
       Node::New(zone(), 1, op, arraysize(parameters), parameters, false);
-  EXPECT_FALSE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_TRUE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(-1, stack_param_delta);
 }
 
 
 TEST_F(LinkageTailCall, MatchingStackParametersExtraCalleeRegistersAndStack) {
   // Caller
   LinkageLocation location_array[] = {RegisterLocation(0), StackLocation(3),
                                       StackLocation(2),    RegisterLocation(0),
                                       RegisterLocation(1), StackLocation(4)};
   LocationSignature locations1(1, 3, location_array);
   CallDescriptor* desc1 = NewStandardCallDescriptor(&locations1);
 
   // Caller
   LocationSignature locations2(1, 5, location_array);
   CallDescriptor* desc2 = NewStandardCallDescriptor(&locations2);
 
   CommonOperatorBuilder common(zone());
   Node* p0 = Node::New(zone(), 0, nullptr, 0, nullptr, false);
   Node* p1 = Node::New(zone(), 0, common.Parameter(0), 0, nullptr, false);
   Node* p2 = Node::New(zone(), 0, common.Parameter(1), 0, nullptr, false);
   Node* p3 = Node::New(zone(), 0, common.Parameter(2), 0, nullptr, false);
   Node* p4 = Node::New(zone(), 0, common.Parameter(3), 0, nullptr, false);
   Node* parameters[] = {p0, p1, p2, p3, p4};
   const Operator* op = common.Call(desc2);
   Node* const node =
       Node::New(zone(), 1, op, arraysize(parameters), parameters, false);
-  EXPECT_FALSE(desc1->CanTailCall(node));
+  int stack_param_delta = 0;
+  EXPECT_FALSE(desc1->CanTailCall(node, &stack_param_delta));
+  EXPECT_EQ(1, stack_param_delta);
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8