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

src/compiler/ia32/code-generator-ia32.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 "src/compilation-info.h"
 #include "src/compiler/code-generator-impl.h"
 #include "src/compiler/gap-resolver.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 631 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:
       __ mov(i.OutputRegister(), esp);
       break;
     case kArchFramePointer:
       __ mov(i.OutputRegister(), ebp);
       break;
     case kArchParentFramePointer:
       if (frame_access_state()->has_frame()) {
         __ mov(i.OutputRegister(), Operand(ebp, 0));
@@ skipping 1311 matching lines @@
     DCHECK(!info()->is_osr());
     int pushed = 0;
     for (int i = Register::kNumRegisters - 1; i >= 0; i--) {
       if (!((1 << i) & saves)) continue;
       __ push(Register::from_code(i));
       ++pushed;
     }
   }
 }
 
-
-void CodeGenerator::AssembleReturn() {
+void CodeGenerator::AssembleReturn(InstructionOperand* pop) {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
 
   const RegList saves = descriptor->CalleeSavedRegisters();
   // Restore registers.
   if (saves != 0) {
     for (int i = 0; i < Register::kNumRegisters; i++) {
       if (!((1 << i) & saves)) continue;
       __ pop(Register::from_code(i));
     }
   }
 
+  // Might need ecx for scratch if pop_size is too big or if there is a variable
+  // pop count.
+  DCHECK_EQ(0u, descriptor->CalleeSavedRegisters() & ecx.bit());
+  size_t pop_size = descriptor->StackParameterCount() * kPointerSize;
+  IA32OperandConverter g(this, nullptr);
   if (descriptor->IsCFunctionCall()) {
     AssembleDeconstructFrame();
   } else if (frame_access_state()->has_frame()) {
-    // Canonicalize JSFunction return sites for now.
-    if (return_label_.is_bound()) {
-      __ jmp(&return_label_);
-      return;
+    // Canonicalize JSFunction return sites for now if they always have the same
+    // number of return args.
+    if (pop->IsImmediate() && g.ToConstant(pop).ToInt32() == 0) {
+      if (return_label_.is_bound()) {
+        __ jmp(&return_label_);
+        return;
+      } else {
+        __ bind(&return_label_);
+        AssembleDeconstructFrame();
+      }
     } else {
-      __ bind(&return_label_);
       AssembleDeconstructFrame();
     }
   }
-  size_t pop_size = descriptor->StackParameterCount() * kPointerSize;
-  // Might need ecx for scratch if pop_size is too big.
+  DCHECK_EQ(0u, descriptor->CalleeSavedRegisters() & edx.bit());
   DCHECK_EQ(0u, descriptor->CalleeSavedRegisters() & ecx.bit());
-  __ Ret(static_cast<int>(pop_size), ecx);
+  if (pop->IsImmediate()) {
+    DCHECK_EQ(Constant::kInt32, g.ToConstant(pop).type());
+    pop_size += g.ToConstant(pop).ToInt32() * kPointerSize;
+    __ Ret(static_cast<int>(pop_size), ecx);
+  } else {
+    Register pop_reg = g.ToRegister(pop);
+    Register scratch_reg = pop_reg.is(ecx) ? edx : ecx;
+    __ pop(scratch_reg);
+    __ lea(esp, Operand(esp, pop_reg, times_4, static_cast<int>(pop_size)));
+    __ jmp(scratch_reg);
+  }
 }
 
 
 void CodeGenerator::AssembleMove(InstructionOperand* source,
                                  InstructionOperand* destination) {
   IA32OperandConverter 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 232 matching lines @@
     int padding_size = last_lazy_deopt_pc_ + space_needed - current_pc;
     __ Nop(padding_size);
   }
 }
 
 #undef __
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8