[turbofan] Better and more sane support for tail calls

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

Index: test/unittests/compiler/linkage-tail-call-unittest.cc
diff --git a/test/unittests/compiler/linkage-tail-call-unittest.cc b/test/unittests/compiler/linkage-tail-call-unittest.cc
index 5d24a3bd1da6963f2a5984eac10899205e9e6ca7..814f5efb8e684cd68a25b7a2ef6afa7fae19bb6e 100644
--- a/test/unittests/compiler/linkage-tail-call-unittest.cc
+++ b/test/unittests/compiler/linkage-tail-call-unittest.cc
@@ -55,7 +55,9 @@ TEST_F(LinkageTailCall, EmptyToEmpty) {
   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);
 }
 
 
@@ -71,7 +73,9 @@ TEST_F(LinkageTailCall, SameReturn) {
   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);
 }
 
 
@@ -89,7 +93,9 @@ TEST_F(LinkageTailCall, DifferingReturn) {
   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);
 }
 
 
@@ -108,7 +114,9 @@ TEST_F(LinkageTailCall, MoreRegisterParametersCallee) {
   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);
 }
 
 
@@ -127,7 +135,9 @@ TEST_F(LinkageTailCall, MoreRegisterParametersCaller) {
   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);
 }
 
 
@@ -146,7 +156,9 @@ TEST_F(LinkageTailCall, MoreRegisterAndStackParametersCallee) {
   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);
 }
 
 
@@ -165,7 +177,9 @@ TEST_F(LinkageTailCall, MoreRegisterAndStackParametersCaller) {
   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);
 }
 
 
@@ -189,7 +203,9 @@ TEST_F(LinkageTailCall, MatchingStackParameters) {
   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);
 }
 
 
@@ -213,7 +229,9 @@ TEST_F(LinkageTailCall, NonMatchingStackParameters) {
   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);
 }
 
 
@@ -238,7 +256,9 @@ TEST_F(LinkageTailCall, MatchingStackParametersExtraCallerRegisters) {
   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);
 }
 
 
@@ -264,7 +284,9 @@ TEST_F(LinkageTailCall, MatchingStackParametersExtraCalleeRegisters) {
   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);
 }
 
 
@@ -290,7 +312,9 @@ TEST_F(LinkageTailCall, MatchingStackParametersExtraCallerRegistersAndStack) {
   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);
 }
 
 
@@ -316,7 +340,9 @@ TEST_F(LinkageTailCall, MatchingStackParametersExtraCalleeRegistersAndStack) {
   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