[turbofan] Frame elision for code stubs

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 54fe76c3d1762889a3a703f040764614417431ac..7125263fd5158dc39c3f18dea4688d94d2c773e5 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -279,7 +279,8 @@ 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) {
@@ -293,7 +294,7 @@ 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 lr if the frame was elided.
       __ Push(lr);
     }
@@ -301,7 +302,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
                          remembered_set_action, save_fp_mode);
     __ Add(scratch1_, object_, index_);
     __ CallStub(&stub);
-    if (!frame()->needs_frame()) {
+    if (must_save_lr_) {
       __ Pop(lr);
     }
   }
@@ -313,6 +314,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
   Register const scratch0_;
   Register const scratch1_;
   RecordWriteMode const mode_;
+  bool must_save_lr_;
 };
 
 
@@ -466,6 +468,15 @@ Condition FlagsConditionToCondition(FlagsCondition condition) {
     }                                                                       \
   } while (0)
 
+void CodeGenerator::AssembleDeconstructFrame() {
+  const CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
+  if (descriptor->IsCFunctionCall() || descriptor->UseNativeStack()) {
+    __ Mov(csp, fp);
+  } else {
+    __ Mov(jssp, fp);
+  }
+  __ Pop(fp, lr);
+}
 
 void CodeGenerator::AssembleDeconstructActivationRecord(int stack_param_delta) {
   int sp_slot_delta = TailCallFrameStackSlotDelta(stack_param_delta);
@@ -482,7 +493,7 @@ void CodeGenerator::AssemblePrepareTailCall(int stack_param_delta) {
     __ Claim(-sp_slot_delta);
     frame_access_state()->IncreaseSPDelta(-sp_slot_delta);
   }
-  if (frame()->needs_frame()) {
+  if (frame_access_state()->has_frame()) {
     __ Ldr(lr, MemOperand(fp, StandardFrameConstants::kCallerPCOffset));
     __ Ldr(fp, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
   }
@@ -664,7 +675,7 @@ 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()) {
         __ ldr(i.OutputRegister(), MemOperand(fp, 0));
       } else {
         __ mov(i.OutputRegister(), fp);
@@ -1464,22 +1475,24 @@ void CodeGenerator::AssembleDeoptimizerCall(
   __ Call(deopt_entry, RelocInfo::RUNTIME_ENTRY);
 }
 
+void CodeGenerator::SetupStackPointer() {

[danno, 2016/03/24 12:53:05]

If wonder if this should be called AssemblePrologue if what is currently
AssemblePrologue become AssembleConstructFrame

[Mircea Trofin, 2016/03/24 17:46:11]

Possibly. I want to restructure AssemblePrologue because it does a few things,
including mutating the Frame (in
some cases). I'd prefer doing this rename with that restructuring.

+  const CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
+  if (descriptor->UseNativeStack() || descriptor->IsCFunctionCall()) {
+    __ SetStackPointer(csp);
+  } else {
+    __ SetStackPointer(jssp);
+  }
+}
 
 void CodeGenerator::AssemblePrologue() {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
   frame()->AlignFrame(16);

[danno, 2016/03/24 12:53:05]

Shouldn't you remove this now?

[Mircea Trofin, 2016/03/24 17:46:11]

Done.

   int stack_shrink_slots = frame()->GetSpillSlotCount();
-  if (frame()->needs_frame()) {
+  if (frame_access_state()->has_frame()) {
     if (descriptor->IsJSFunctionCall()) {
       DCHECK(!descriptor->UseNativeStack());
-      __ SetStackPointer(jssp);
       __ Prologue(this->info()->GeneratePreagedPrologue());
     } else {
-      if (descriptor->UseNativeStack() || descriptor->IsCFunctionCall()) {
-        __ SetStackPointer(csp);
-      } else {
-        __ SetStackPointer(jssp);
-      }
       if (descriptor->IsCFunctionCall()) {
         __ Push(lr, fp);
         __ Mov(fp, masm_.StackPointer());
@@ -1489,15 +1502,8 @@ void CodeGenerator::AssemblePrologue() {
                         frame()->GetTotalFrameSlotCount());
       }
     }
-  } else {
-    if (descriptor->UseNativeStack()) {
-      __ SetStackPointer(csp);
-    } else {
-      __ SetStackPointer(jssp);
-    }
-    frame()->SetElidedFrameSizeInSlots(0);
   }
-  frame_access_state()->SetFrameAccessToDefault();
+
   if (info()->is_osr()) {
     // TurboFan OSR-compiled functions cannot be entered directly.
     __ Abort(kShouldNotDirectlyEnterOsrFunction);
@@ -1558,22 +1564,14 @@ void CodeGenerator::AssembleReturn() {
 
   int pop_count = static_cast<int>(descriptor->StackParameterCount());
   if (descriptor->IsCFunctionCall()) {
-    __ Mov(csp, fp);
-    __ Pop(fp, lr);
-  } else if (frame()->needs_frame()) {
-    // Canonicalize JSFunction return sites for now.
+    AssembleDeconstructFrame();
+  } else if (frame_access_state()->has_frame()) {
     if (return_label_.is_bound()) {
       __ B(&return_label_);
       return;
     } else {
       __ Bind(&return_label_);
-      if (descriptor->UseNativeStack()) {
-        __ Mov(csp, fp);
-        pop_count += (pop_count & 1);  // align
-      } else {
-        __ Mov(jssp, fp);
-      }
-      __ Pop(fp, lr);
+      AssembleDeconstructFrame();
     }
   } else if (descriptor->UseNativeStack()) {
     pop_count += (pop_count & 1);  // align