[turbofan] Support variable size argument popping in TF-generated functions

src/compiler/x64/code-generator-x64.cc

 // Copyright 2013 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 <limits>
+
 #include "src/compilation-info.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/wasm/wasm-module.h"
 #include "src/x64/assembler-x64.h"
 #include "src/x64/macro-assembler-x64.h"
 
 namespace v8 {
@@ skipping 897 matching lines @@
       int deopt_state_id =
           BuildTranslation(instr, -1, 0, OutputFrameStateCombine::Ignore());
       Deoptimizer::BailoutType bailout_type =
           Deoptimizer::BailoutType(MiscField::decode(instr->opcode()));
       CodeGenResult result = AssembleDeoptimizerCall(
           deopt_state_id, bailout_type, current_source_position_);
       if (result != kSuccess) return result;
       break;
     }
     case kArchRet:
-      AssembleReturn();
+      AssembleReturn(instr->InputAt(0));
       break;
     case kArchStackPointer:
       __ movq(i.OutputRegister(), rsp);
       break;
     case kArchFramePointer:
       __ movq(i.OutputRegister(), rbp);
       break;
     case kArchParentFramePointer:
       if (frame_access_state()->has_frame()) {
         __ movq(i.OutputRegister(), Operand(rbp, 0));
@@ skipping 1508 matching lines @@
 
   const RegList saves = descriptor->CalleeSavedRegisters();
   if (saves != 0) {  // Save callee-saved registers.
     for (int i = Register::kNumRegisters - 1; i >= 0; i--) {
       if (!((1 << i) & saves)) continue;
       __ pushq(Register::from_code(i));
     }
   }
 }
 
-
-void CodeGenerator::AssembleReturn() {
+void CodeGenerator::AssembleReturn(InstructionOperand* pop) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
 
   // Restore registers.
   const RegList saves = descriptor->CalleeSavedRegisters();
   if (saves != 0) {
     for (int i = 0; i < Register::kNumRegisters; i++) {
       if (!((1 << i) & saves)) continue;
       __ popq(Register::from_code(i));
     }
   }
@@ skipping 20 matching lines @@
   } else if (frame_access_state()->has_frame()) {
     // Canonicalize JSFunction return sites for now.
     if (return_label_.is_bound()) {
       __ jmp(&return_label_);
       return;
     } else {
       __ bind(&return_label_);
       AssembleDeconstructFrame();
     }
   }
+  // Might need rcx for scratch if pop_size is too big or if there is a variable
+  // pop count.
+  DCHECK_EQ(0u, descriptor->CalleeSavedRegisters() & rcx.bit());
   size_t pop_size = descriptor->StackParameterCount() * kPointerSize;
-  // Might need rcx for scratch if pop_size is too big.
-  DCHECK_EQ(0u, descriptor->CalleeSavedRegisters() & rcx.bit());
-  __ Ret(static_cast<int>(pop_size), rcx);
+  X64OperandConverter g(this, nullptr);
+  if (pop->IsImmediate()) {
+    DCHECK_EQ(Constant::kInt32, g.ToConstant(pop).type());
+    pop_size += g.ToConstant(pop).ToInt32() * kPointerSize;
+    CHECK_LT(pop_size, std::numeric_limits<int>::max());
+    __ Ret(static_cast<int>(pop_size), rcx);
+  } else {
+    Register reg = g.ToRegister(pop);
+    __ popq(rcx);
+    CHECK_LT(pop_size, std::numeric_limits<int>::max());
+    __ leaq(rsp, Operand(rsp, reg, times_8, static_cast<int>(pop_size)));
+    __ jmp(rcx);
+  }
 }
 
 
 void CodeGenerator::AssembleMove(InstructionOperand* source,
                                  InstructionOperand* destination) {
   X64OperandConverter g(this, nullptr);
   // Dispatch on the source and destination operand kinds.  Not all
   // combinations are possible.
   if (source->IsRegister()) {
     DCHECK(destination->IsRegister() || destination->IsStackSlot());
@@ skipping 247 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8