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

src/compiler/mips/code-generator-mips.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/code-generator.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/osr.h"
 #include "src/mips/macro-assembler-mips.h"
@@ skipping 430 matching lines @@
     __ or_(at, at, kScratchReg2);                                              \
     __ Branch(USE_DELAY_SLOT, ool->entry(), eq, at, Operand(zero_reg));        \
     __ cvt_d_l(i.OutputDoubleRegister(), i.OutputDoubleRegister());            \
     __ bind(ool->exit());                                                      \
     __ bind(&done);                                                            \
   } while (0)
 
 
 void CodeGenerator::AssembleDeconstructActivationRecord(int stack_param_delta) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
-  int stack_slots = frame()->GetSpillSlotCount();
-  int stack_pointer_delta = 0;
-  if (descriptor->IsJSFunctionCall() || stack_slots > 0) {
-    __ mov(sp, fp);
-    __ lw(fp, MemOperand(sp, 0 * kPointerSize));
-    __ lw(ra, MemOperand(sp, 1 * kPointerSize));
-    stack_pointer_delta = 2 * kPointerSize;
-  }
-  if (stack_param_delta < 0) {
-    stack_pointer_delta += -stack_param_delta * kPointerSize;
-  }
-  if (stack_pointer_delta != 0) {
-    __ addiu(sp, sp, stack_pointer_delta);
+  int spill_slots = frame()->GetSpillSlotCount();
+  bool has_frame = descriptor->IsJSFunctionCall() || spill_slots > 0;
+  if (has_frame) {
+    if (stack_param_delta != 0) {
+      int total_discarded_slots = frame()->GetTotalFrameSlotCount();
+      // Leave the PC and saved frame pointer on the stack.
+      total_discarded_slots -=
+          StandardFrameConstants::kFixedFrameSizeFromFp / kPointerSize;
+      // Discard only slots that won't be used by new parameters.
+      total_discarded_slots -= stack_param_delta;
+      if (total_discarded_slots > 0) {
+        __ addiu(sp, sp, total_discarded_slots * kPointerSize);
+      }
+    } else {
+      __ mov(sp, fp);
+    }
+    __ Pop(ra, fp);
   }
 }
 
+
+void CodeGenerator::AssemblePrepareTailCall(int stack_param_delta) {
+  if (stack_param_delta > 0) {
+    int total_discarded_slots = frame()->GetTotalFrameSlotCount();
+    // Leave the PC and saved frame pointer on the stack.
+    total_discarded_slots -=
+        StandardFrameConstants::kFixedFrameSizeFromFp / kPointerSize;
+    // Discard only slots that won't be used by new parameters.
+    total_discarded_slots -= stack_param_delta;
+    if (total_discarded_slots < 0) {
+      __ Subu(sp, sp, Operand(-total_discarded_slots * kPointerSize));
+    }
+  }
+}
+
 
 // Assembles an instruction after register allocation, producing machine code.
 void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
   MipsOperandConverter i(this, instr);
   InstructionCode opcode = instr->opcode();
 
   switch (ArchOpcodeField::decode(opcode)) {
     case kArchCallCodeObject: {
       EnsureSpaceForLazyDeopt();
       if (instr->InputAt(0)->IsImmediate()) {
@@ skipping 49 matching lines @@
     case kArchLazyBailout: {
       EnsureSpaceForLazyDeopt();
       RecordCallPosition(instr);
       break;
     }
     case kArchPrepareCallCFunction: {
       int const num_parameters = MiscField::decode(instr->opcode());
       __ PrepareCallCFunction(num_parameters, kScratchReg);
       break;
     }
+    case kArchPrepareTailCall:
+      AssemblePrepareTailCall(i.InputInt32(instr->InputCount() - 1));
+      break;
     case kArchCallCFunction: {
       int const num_parameters = MiscField::decode(instr->opcode());
       if (instr->InputAt(0)->IsImmediate()) {
         ExternalReference ref = i.InputExternalReference(0);
         __ CallCFunction(ref, num_parameters);
       } else {
         Register func = i.InputRegister(0);
         __ CallCFunction(func, num_parameters);
       }
       break;
@@ skipping 1034 matching lines @@
       padding_size -= v8::internal::Assembler::kInstrSize;
     }
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8