PPC: [turbofan] Frame elision for code stubs.

Port 53d51c52

Includes fixes required for embedded constant pools.

Original commit message:
    Removed Frame::needs_frame and the function-wide logic using it in
    favor of FrameAccessState::has_frame, which can be set on a more
    granular level, and driving it block by block.

R=mtrofin@chromium.org, joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com, rmcilroy@chromium.org
BUG=v8:4533
LOG=N

Review URL: https://codereview.chromium.org/1843273002

Cr-Commit-Position: refs/heads/master@{#35166}

src/compiler/code-generator.cc

@@ -153,9 +153,11 @@ Handle<Code> CodeGenerator::GenerateCode() {
         }
       }
 
-      for (int i = block->code_start(); i < block->code_end(); ++i) {
-        Instruction* instr = code()->InstructionAt(i);
-        AssembleInstruction(instr, block);
+      if (FLAG_enable_embedded_constant_pool && !block->needs_frame()) {
+        ConstantPoolUnavailableScope constant_pool_unavailable(masm());
+        AssembleBlock(block);
+      } else {
+        AssembleBlock(block);
       }
     }
   }
@@ -300,6 +302,13 @@ bool CodeGenerator::IsMaterializableFromRoot(
   return false;
 }
 
+void CodeGenerator::AssembleBlock(const InstructionBlock* block) {
+  for (int i = block->code_start(); i < block->code_end(); ++i) {
+    Instruction* instr = code()->InstructionAt(i);
+    AssembleInstruction(instr, block);
+  }
+}
+
 void CodeGenerator::AssembleInstruction(Instruction* instr,
                                         const InstructionBlock* block) {
   AssembleGaps(instr);

src/compiler/code-generator.h

@@ -84,6 +84,9 @@ class CodeGenerator final : public GapResolver::Assembler {
   bool IsMaterializableFromRoot(Handle<HeapObject> object,
                                 Heap::RootListIndex* index_return);
 
+  // Assemble instructions for the specified block.
+  void AssembleBlock(const InstructionBlock* block);
+
   // Assemble code for the specified instruction.
   void AssembleInstruction(Instruction* instr, const InstructionBlock* block);
   void AssembleSourcePosition(Instruction* instr);

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

@@ -187,7 +187,8 @@ 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) {
@@ -201,7 +202,7 @@ 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.
       __ mflr(scratch1_);
       __ Push(scratch1_);
@@ -215,7 +216,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
       __ add(scratch1_, object_, offset_);
     }
     __ CallStub(&stub);
-    if (!frame()->needs_frame()) {
+    if (must_save_lr_) {
       // We need to save and restore lr if the frame was elided.
       __ Pop(scratch1_);
       __ mtlr(scratch1_);
@@ -230,6 +231,7 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
   Register const scratch0_;
   Register const scratch1_;
   RecordWriteMode const mode_;
+  bool must_save_lr_;
 };
 
 
@@ -670,6 +672,11 @@ Condition FlagsConditionToCondition(FlagsCondition condition, ArchOpcode op) {
     DCHECK_EQ(LeaveRC, i.OutputRCBit());                      \
   } while (0)
 
+void CodeGenerator::AssembleDeconstructFrame() {
+  __ LeaveFrame(StackFrame::MANUAL);
+}
+
+void CodeGenerator::AssembleSetupStackPointer() {}
 
 void CodeGenerator::AssembleDeconstructActivationRecord(int stack_param_delta) {
   int sp_slot_delta = TailCallFrameStackSlotDelta(stack_param_delta);
@@ -686,7 +693,7 @@ void CodeGenerator::AssemblePrepareTailCall(int stack_param_delta) {
     __ Add(sp, sp, sp_slot_delta * kPointerSize, r0);
     frame_access_state()->IncreaseSPDelta(-sp_slot_delta);
   }
-  if (frame()->needs_frame()) {
+  if (frame_access_state()->has_frame()) {
     __ RestoreFrameStateForTailCall();
   }
   frame_access_state()->SetFrameAccessToSP();
@@ -867,7 +874,7 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       DCHECK_EQ(LeaveRC, i.OutputRCBit());
       break;
     case kArchParentFramePointer:
-      if (frame_access_state()->frame()->needs_frame()) {
+      if (frame_access_state()->has_frame()) {
         __ LoadP(i.OutputRegister(), MemOperand(fp, 0));
       } else {
         __ mr(i.OutputRegister(), fp);
@@ -1707,7 +1714,7 @@ void CodeGenerator::AssembleDeoptimizerCall(
 
 void CodeGenerator::AssemblePrologue() {
   CallDescriptor* descriptor = linkage()->GetIncomingDescriptor();
-  if (frame()->needs_frame()) {
+  if (frame_access_state()->has_frame()) {
     if (descriptor->IsCFunctionCall()) {
       __ function_descriptor();
       __ mflr(r0);
@@ -1723,18 +1730,11 @@ void CodeGenerator::AssemblePrologue() {
       __ Prologue(this->info()->GeneratePreagedPrologue(), ip);
     } else {
       StackFrame::Type type = info()->GetOutputStackFrameType();
-      if (!ABI_CALL_VIA_IP &&
-          info()->output_code_kind() == Code::WASM_FUNCTION) {
-        // TODO(mbrandy): Restrict only to the wasm wrapper case.
-        __ StubPrologue(type);
-      } else {
-        __ StubPrologue(type, ip);
-      }
+      // TODO(mbrandy): Detect cases where ip is the entrypoint (for
+      // efficient intialization of the constant pool pointer register).
+      __ StubPrologue(type);
     }
-  } else {
-    frame()->SetElidedFrameSizeInSlots(0);
   }
-  frame_access_state()->SetFrameAccessToDefault();
 
   int stack_shrink_slots = frame()->GetSpillSlotCount();
   if (info()->is_osr()) {
@@ -1803,20 +1803,18 @@ void CodeGenerator::AssembleReturn() {
   }
 
   if (descriptor->IsCFunctionCall()) {
-    __ LeaveFrame(StackFrame::MANUAL, pop_count * kPointerSize);
-  } else if (frame()->needs_frame()) {
+    AssembleDeconstructFrame();
+  } else if (frame_access_state()->has_frame()) {
     // Canonicalize JSFunction return sites for now.
     if (return_label_.is_bound()) {
       __ b(&return_label_);
       return;
     } else {
       __ bind(&return_label_);
-      __ LeaveFrame(StackFrame::MANUAL, pop_count * kPointerSize);
+      AssembleDeconstructFrame();
     }
-  } else {
-    __ Drop(pop_count);
   }
-  __ Ret();
+  __ Ret(pop_count);
 }
 
 

src/ppc/macro-assembler-ppc.cc

@@ -992,8 +992,11 @@ void MacroAssembler::LoadConstantPoolPointerRegister() {
 
 void MacroAssembler::StubPrologue(StackFrame::Type type, Register base,
                                   int prologue_offset) {
-  LoadSmiLiteral(r11, Smi::FromInt(type));
-  PushCommonFrame(r11);
+  {
+    ConstantPoolUnavailableScope constant_pool_unavailable(this);
+    LoadSmiLiteral(r11, Smi::FromInt(type));
+    PushCommonFrame(r11);
+  }
   if (FLAG_enable_embedded_constant_pool) {
     if (!base.is(no_reg)) {
       // base contains prologue address