[turbofan]: Fix tail calls edge cases and add tests

src/compiler/linkage.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/code-stubs.h"
 #include "src/compiler.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/node.h"
 #include "src/compiler/pipeline.h"
@@ skipping 35 matching lines @@
     const CallDescriptor* other) const {
   if (ReturnCount() != other->ReturnCount()) return false;
   for (size_t i = 0; i < ReturnCount(); ++i) {
     if (GetReturnLocation(i) != other->GetReturnLocation(i)) return false;
   }
   return true;
 }
 
 
 bool CallDescriptor::CanTailCall(const Node* node) const {
+  // Determine the number of stack parameters passed in
+  size_t stack_params = 0;
+  for (size_t i = 0; i < InputCount(); ++i) {
+    if (!GetInputLocation(i).is_register()) {
+      ++stack_params;
+    }
+  }
+  // Ensure the input linkage contains the stack parameters in the right order
+  size_t current_stack_param = 0;
+  for (size_t i = 0; i < InputCount(); ++i) {
+    if (!GetInputLocation(i).is_register()) {
+      if (GetInputLocation(i) !=
+          LinkageLocation(static_cast<int>(current_stack_param) -
+                          static_cast<int>(stack_params))) {
+        return false;
+      }
+      ++current_stack_param;
+    }
+  }
   // Tail calling is currently allowed if return locations match and all
   // parameters are either in registers or on the stack but match exactly in
   // number and content.
   CallDescriptor const* other = OpParameter<CallDescriptor const*>(node);
   if (!HasSameReturnLocationsAs(other)) return false;
   size_t current_input = 0;
   size_t other_input = 0;
-  size_t stack_parameter = 0;
   while (true) {
     if (other_input >= other->InputCount()) {
-      while (current_input <= InputCount()) {
+      while (current_input < InputCount()) {
         if (!GetInputLocation(current_input).is_register()) {
           return false;
         }
         ++current_input;
       }
       return true;
     }
     if (current_input >= InputCount()) {
       while (other_input < other->InputCount()) {
         if (!other->GetInputLocation(other_input).is_register()) {
@@ skipping 12 matching lines @@
       continue;
     }
     if (GetInputLocation(current_input) !=
         other->GetInputLocation(other_input)) {
       return false;
     }
     Node* input = node->InputAt(static_cast<int>(other_input));
     if (input->opcode() != IrOpcode::kParameter) {
       return false;
     }
+    // Make sure that the parameter input passed through to the tail call
+    // corresponds to the correct stack slot.
     size_t param_index = ParameterIndexOf(input->op());
-    if (param_index != stack_parameter) {
+    if (param_index != current_input - 1) {
       return false;
     }
-    ++stack_parameter;
     ++current_input;
     ++other_input;
   }
   UNREACHABLE();
   return false;
 }
 
 
 CallDescriptor* Linkage::ComputeIncoming(Zone* zone, CompilationInfo* info) {
   if (info->code_stub() != NULL) {
@@ skipping 149 matching lines @@
 
 CallDescriptor* Linkage::GetSimplifiedCDescriptor(Zone* zone,
                                                   const MachineSignature* sig) {
   UNIMPLEMENTED();
   return NULL;
 }
 #endif  // !V8_TURBOFAN_BACKEND
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8