[arm64] Pair some pushes and don't use jssp as scratch

Also remove some unused code.

Bug: v8:6644
Change-Id: Id0021b397f366d2f26e990750c4b8c33f0c1cd81
Reviewed-on: https://chromium-review.googlesource.com/806836Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Georgia Kouveli <georgia.kouveli@arm.com>
Cr-Commit-Position: refs/heads/master@{#49868}

src/arm64/code-stubs-arm64.cc

@@ -462,8 +462,12 @@ void CEntryStub::Generate(MacroAssembler* masm) {
   // Retrieve the handler context, SP and FP.
   __ Mov(cp, Operand(pending_handler_context_address));
   __ Ldr(cp, MemOperand(cp));
-  __ Mov(jssp, Operand(pending_handler_sp_address));
-  __ Ldr(jssp, MemOperand(jssp));
+  {
+    UseScratchRegisterScope temps(masm);
+    Register scratch = temps.AcquireX();
+    __ Mov(scratch, Operand(pending_handler_sp_address));
+    __ Ldr(jssp, MemOperand(scratch));
+  }
   __ Mov(csp, jssp);
   __ Mov(fp, Operand(pending_handler_fp_address));
   __ Ldr(fp, MemOperand(fp));

src/arm64/macro-assembler-arm64-inl.h

@@ -1140,22 +1140,6 @@ void MacroAssembler::SmiUntagToFloat(VRegister dst, Register src) {
   Scvtf(dst, src, kSmiShift);
 }
 
-
-void MacroAssembler::SmiTagAndPush(Register src) {
-  STATIC_ASSERT((static_cast<unsigned>(kSmiShift) == kWRegSizeInBits) &&
-                (static_cast<unsigned>(kSmiValueSize) == kWRegSizeInBits) &&
-                (kSmiTag == 0));
-  Push(src.W(), wzr);
-}
-
-
-void MacroAssembler::SmiTagAndPush(Register src1, Register src2) {
-  STATIC_ASSERT((static_cast<unsigned>(kSmiShift) == kWRegSizeInBits) &&
-                (static_cast<unsigned>(kSmiValueSize) == kWRegSizeInBits) &&
-                (kSmiTag == 0));
-  Push(src1.W(), wzr, src2.W(), wzr);
-}
-
 void TurboAssembler::JumpIfSmi(Register value, Label* smi_label,
                                Label* not_smi_label) {
   STATIC_ASSERT((kSmiTagSize == 1) && (kSmiTag == 0));

src/arm64/macro-assembler-arm64.cc

@@ -2976,11 +2976,9 @@ void TurboAssembler::CallRecordWriteStub(
   Register fp_mode_parameter(callable.descriptor().GetRegisterParameter(
       RecordWriteDescriptor::kFPMode));
 
-  Push(object);
-  Push(address);
+  Push(object, address);
 
-  Pop(slot_parameter);
-  Pop(object_parameter);
+  Pop(slot_parameter, object_parameter);
 
   Mov(isolate_parameter, ExternalReference::isolate_address(isolate()));
   Move(remembered_set_parameter, Smi::FromEnum(remembered_set_action));

src/arm64/macro-assembler-arm64.h

@@ -1752,10 +1752,6 @@ class MacroAssembler : public TurboAssembler {
   inline void SmiUntagToDouble(VRegister dst, Register src);
   inline void SmiUntagToFloat(VRegister dst, Register src);
 
-  // Tag and push in one step.
-  inline void SmiTagAndPush(Register src);
-  inline void SmiTagAndPush(Register src1, Register src2);
-
   inline void JumpIfNotSmi(Register value, Label* not_smi_label);
   inline void JumpIfBothSmi(Register value1, Register value2,
                             Label* both_smi_label,

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

@@ -336,14 +336,14 @@ class OutOfLineRecordWrite final : public OutOfLineCode {
         frame()->DidAllocateDoubleRegisters() ? kSaveFPRegs : kDontSaveFPRegs;
     if (must_save_lr_) {
       // We need to save and restore lr if the frame was elided.
-      __ Push(lr);
+      __ Push(lr, padreg);
       unwinding_info_writer_->MarkLinkRegisterOnTopOfStack(__ pc_offset(),
                                                            __ StackPointer());
     }
     __ CallRecordWriteStub(object_, scratch1_, remembered_set_action,
                            save_fp_mode);
     if (must_save_lr_) {
-      __ Pop(lr);
+      __ Pop(padreg, lr);
       unwinding_info_writer_->MarkPopLinkRegisterFromTopOfStack(__ pc_offset());
     }
   }