[turbofan] Frame elision for code stubs

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

Index: src/compiler/mips/code-generator-mips.cc
diff --git a/src/compiler/mips/code-generator-mips.cc b/src/compiler/mips/code-generator-mips.cc
index 26074af6275f76c43b0b8924235e6075f07776d6..941659e4bb77266ca8d053cd436f8d0b307b5e98 100644
--- a/src/compiler/mips/code-generator-mips.cc
+++ b/src/compiler/mips/code-generator-mips.cc
@@ -224,7 +224,8 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
         value_(value),
         scratch0_(scratch0),
         scratch1_(scratch1),
-        mode_(mode) {}
+        mode_(mode),
+        must_save_lr_(!gen->frame_access_state()->has_frame()) {}
 
   void Generate() final {
     if (mode_ > RecordWriteMode::kValueIsPointer) {
@@ -238,7 +239,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
                                              : OMIT_REMEMBERED_SET;
     SaveFPRegsMode const save_fp_mode =
         frame()->DidAllocateDoubleRegisters() ? kSaveFPRegs : kDontSaveFPRegs;
-    if (!frame()->needs_frame()) {
+    if (must_save_lr_) {
       // We need to save and restore ra if the frame was elided.
       __ Push(ra);
     }
@@ -246,7 +247,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
                          remembered_set_action, save_fp_mode);
     __ Addu(scratch1_, object_, index_);
     __ CallStub(&stub);
-    if (!frame()->needs_frame()) {
+    if (must_save_lr_) {
       __ Pop(ra);
     }
   }
@@ -258,6 +259,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
   Register const scratch0_;
   Register const scratch1_;
   RecordWriteMode const mode_;
+  bool must_save_lr_;
 };
 
 
@@ -470,6 +472,13 @@ FPUCondition FlagsConditionToConditionCmpFPU(bool& predicate,
     __ bind(&done);                                                           \
   }
 
+void CodeGenerator::AssembleDeconstructFrame() {
+  __ mov(sp, fp);
+  __ Pop(ra, fp);
+}
+
+void CodeGenerator::AssembleSetupStackPointer() {}
+
 void CodeGenerator::AssembleDeconstructActivationRecord(int stack_param_delta) {
   int sp_slot_delta = TailCallFrameStackSlotDelta(stack_param_delta);
   if (sp_slot_delta > 0) {
@@ -485,7 +494,7 @@ void CodeGenerator::AssemblePrepareTailCall(int stack_param_delta) {
     __ Subu(sp, sp, Operand(-sp_slot_delta * kPointerSize));
     frame_access_state()->IncreaseSPDelta(-sp_slot_delta);
   }
-  if (frame()->needs_frame()) {
+  if (frame_access_state()->has_frame()) {
     __ lw(ra, MemOperand(fp, StandardFrameConstants::kCallerPCOffset));
     __ lw(fp, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
   }
@@ -645,7 +654,7 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ mov(i.OutputRegister(), fp);
       break;
     case kArchParentFramePointer:
-      if (frame_access_state()->frame()->needs_frame()) {
+      if (frame_access_state()->has_frame()) {
         __ lw(i.OutputRegister(), MemOperand(fp, 0));
       } else {
         __ mov(i.OutputRegister(), fp);
@@ -1564,7 +1573,7 @@ void CodeGenerator::AssembleDeoptimizerCall(
 void CodeGenerator::AssemblePrologue() {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   int stack_shrink_slots = frame()->GetSpillSlotCount();
-  if (frame()->needs_frame()) {
+  if (frame_access_state()->has_frame()) {
     if (descriptor->IsCFunctionCall()) {
       __ Push(ra, fp);
       __ mov(fp, sp);
@@ -1573,10 +1582,7 @@ void CodeGenerator::AssemblePrologue() {
     } else {
       __ StubPrologue(info()->GetOutputStackFrameType());
     }
-  } else {
-    frame()->SetElidedFrameSizeInSlots(0);
   }
-  frame_access_state()->SetFrameAccessToDefault();
 
   if (info()->is_osr()) {
     // TurboFan OSR-compiled functions cannot be entered directly.
@@ -1638,17 +1644,15 @@ void CodeGenerator::AssembleReturn() {
   }
 
   if (descriptor->IsCFunctionCall()) {
-    __ mov(sp, fp);
-    __ Pop(ra, fp);
-  } else if (frame()->needs_frame()) {
+    AssembleDeconstructFrame();
+  } else if (frame_access_state()->has_frame()) {
     // Canonicalize JSFunction return sites for now.
     if (return_label_.is_bound()) {
       __ Branch(&return_label_);
       return;
     } else {
       __ bind(&return_label_);
-      __ mov(sp, fp);
-      __ Pop(ra, fp);
+      AssembleDeconstructFrame();
     }
   }
   if (pop_count != 0) {