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

src/compiler/instruction-selector-impl.h

Index: src/compiler/instruction-selector-impl.h
diff --git a/src/compiler/instruction-selector-impl.h b/src/compiler/instruction-selector-impl.h
index 8543aa0b19604dec163c9801a210ec686d0ee691..9916f14028cb69901f7b398c67e0d2d86ce8fd80 100644
--- a/src/compiler/instruction-selector-impl.h
+++ b/src/compiler/instruction-selector-impl.h
@@ -128,9 +128,15 @@ class OperandGenerator {
                                   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) {
@@ -142,6 +148,19 @@ class OperandGenerator {
     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,