[turbofan]: Implement tail calls with more callee than caller parameters

src/compiler/instruction-selector-impl.h

 // 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.
 
 #ifndef V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 #define V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_
 
 #include "src/compiler/instruction.h"
 #include "src/compiler/instruction-selector.h"
 #include "src/compiler/linkage.h"
@@ skipping 110 matching lines @@
     return Use(node, UnallocatedOperand(UnallocatedOperand::FIXED_REGISTER,
                                         reg.code(), GetVReg(node)));
   }
 
   InstructionOperand UseFixed(Node* node, DoubleRegister reg) {
     return Use(node,
                UnallocatedOperand(UnallocatedOperand::FIXED_DOUBLE_REGISTER,
                                   reg.code(), GetVReg(node)));
   }
 
-  InstructionOperand UseExplicit(Register reg) {
+  InstructionOperand UseExplicit(LinkageLocation location) {
     MachineType machine_type = InstructionSequence::DefaultRepresentation();
-    return ExplicitOperand(LocationOperand::REGISTER, machine_type, reg.code());
+    if (location.IsRegister()) {
+      return ExplicitOperand(LocationOperand::REGISTER, machine_type,
+                             location.AsRegister());
+    } else {
+      return ExplicitOperand(LocationOperand::STACK_SLOT, machine_type,
+                             location.GetLocation());
+    }
   }
 
   InstructionOperand UseImmediate(Node* node) {
     return sequence()->AddImmediate(ToConstant(node));
   }
 
   InstructionOperand UseLocation(Node* node, LinkageLocation location,
                                  MachineType type) {
     return Use(node, ToUnallocatedOperand(location, type, GetVReg(node)));
   }
 
+  // Used to force gap moves from the from_location to the to_location
+  // immediately before an instruction.
+  InstructionOperand UseLocation(LinkageLocation to_location,
+                                 LinkageLocation from_location,
+                                 MachineType type) {
+    UnallocatedOperand casted_from_operand =
+        UnallocatedOperand::cast(TempLocation(
+            from_location, static_cast<MachineType>(kTypeAny | kMachPtr)));

[Jarin, 2015/11/20 10:56:09]

Why does not this use the incoming type? As suggested in
instruction-selector.cc, we should perhaps rename the function to
UsePointerLocation and hardcode kMachPtr here.

[danno, 2015/11/20 14:43:23]

Done.

+    selector_->Emit(kArchNop, casted_from_operand);
+    return ToUnallocatedOperand(to_location, type,
+                                casted_from_operand.virtual_register());
+  }
+
   InstructionOperand TempRegister() {
     return UnallocatedOperand(UnallocatedOperand::MUST_HAVE_REGISTER,
                               UnallocatedOperand::USED_AT_START,
                               sequence()->NextVirtualRegister());
   }
 
   InstructionOperand TempDoubleRegister() {
     UnallocatedOperand op = UnallocatedOperand(
         UnallocatedOperand::MUST_HAVE_REGISTER,
         UnallocatedOperand::USED_AT_START, sequence()->NextVirtualRegister());
@@ skipping 186 matching lines @@
   Node* result_;             // Only valid if mode_ == kFlags_set.
   BasicBlock* true_block_;   // Only valid if mode_ == kFlags_branch.
   BasicBlock* false_block_;  // Only valid if mode_ == kFlags_branch.
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_INSTRUCTION_SELECTOR_IMPL_H_