PPC/s390: [codegen] Remove PrepareForTailCall

Port ec717160

Original Commit Message:

    This is no longer used, tail calls are dealt with inside of
    VisiTailCall.

R=zhin@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: I44cac6f77ce79d47806b3f504c3bad1d88475a25
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3055307Reviewed-by: Zhi An Ng <zhin@chromium.org>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#75945}

src/codegen/ppc/macro-assembler-ppc.cc

@@ -1385,54 +1385,6 @@ void TurboAssembler::MovFromFloatParameter(const DoubleRegister dst) {
   Move(dst, d1);
 }
 
-void TurboAssembler::PrepareForTailCall(Register callee_args_count,
-                                        Register caller_args_count,
-                                        Register scratch0, Register scratch1) {
-  DCHECK(!AreAliased(callee_args_count, caller_args_count, scratch0, scratch1));
-
-  // Calculate the end of destination area where we will put the arguments
-  // after we drop current frame. We add kSystemPointerSize to count the
-  // receiver argument which is not included into formal parameters count.
-  Register dst_reg = scratch0;
-  ShiftLeftU64(dst_reg, caller_args_count, Operand(kSystemPointerSizeLog2));
-  add(dst_reg, fp, dst_reg);
-  AddS64(dst_reg, dst_reg,
-         Operand(StandardFrameConstants::kCallerSPOffset + kSystemPointerSize),
-         scratch0);
-
-  Register src_reg = caller_args_count;
-  // Calculate the end of source area. +kSystemPointerSize is for the receiver.
-  ShiftLeftU64(src_reg, callee_args_count, Operand(kSystemPointerSizeLog2));
-  add(src_reg, sp, src_reg);
-  AddS64(src_reg, src_reg, Operand(kSystemPointerSize), scratch0);
-
-  if (FLAG_debug_code) {
-    CmpU64(src_reg, dst_reg);
-    Check(lt, AbortReason::kStackAccessBelowStackPointer);
-  }
-
-  // Restore caller's frame pointer and return address now as they will be
-  // overwritten by the copying loop.
-  RestoreFrameStateForTailCall();
-
-  // Now copy callee arguments to the caller frame going backwards to avoid
-  // callee arguments corruption (source and destination areas could overlap).
-
-  // Both src_reg and dst_reg are pointing to the word after the one to copy,
-  // so they must be pre-decremented in the loop.
-  Register tmp_reg = scratch1;
-  Label loop;
-  addi(tmp_reg, callee_args_count, Operand(1));  // +1 for receiver
-  mtctr(tmp_reg);
-  bind(&loop);
-  LoadU64WithUpdate(tmp_reg, MemOperand(src_reg, -kSystemPointerSize));
-  StoreU64WithUpdate(tmp_reg, MemOperand(dst_reg, -kSystemPointerSize));
-  bdnz(&loop);
-
-  // Leave current frame.
-  mr(sp, dst_reg);
-}
-
 void MacroAssembler::LoadStackLimit(Register destination, StackLimitKind kind) {
   DCHECK(root_array_available());
   Isolate* isolate = this->isolate();

src/codegen/ppc/macro-assembler-ppc.h

@@ -419,10 +419,6 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
                             Register scratch);
   void PrepareCallCFunction(int num_reg_arguments, Register scratch);
 
-  void PrepareForTailCall(Register callee_args_count,
-                          Register caller_args_count, Register scratch0,
-                          Register scratch1);
-
   // There are two ways of passing double arguments on ARM, depending on
   // whether soft or hard floating point ABI is used. These functions
   // abstract parameter passing for the three different ways we call

src/codegen/s390/macro-assembler-s390.cc

@@ -1578,55 +1578,6 @@ void TurboAssembler::MovFromFloatParameter(const DoubleRegister dst) {
   Move(dst, d0);
 }
 
-void TurboAssembler::PrepareForTailCall(Register callee_args_count,
-                                        Register caller_args_count,
-                                        Register scratch0, Register scratch1) {
-  DCHECK(!AreAliased(callee_args_count, caller_args_count, scratch0, scratch1));
-
-  // Calculate the end of destination area where we will put the arguments
-  // after we drop current frame. We AddS64 kSystemPointerSize to count the
-  // receiver argument which is not included into formal parameters count.
-  Register dst_reg = scratch0;
-  ShiftLeftU64(dst_reg, caller_args_count, Operand(kSystemPointerSizeLog2));
-  AddS64(dst_reg, fp, dst_reg);
-  AddS64(dst_reg, dst_reg,
-         Operand(StandardFrameConstants::kCallerSPOffset + kSystemPointerSize));
-
-  Register src_reg = caller_args_count;
-  // Calculate the end of source area. +kSystemPointerSize is for the receiver.
-  ShiftLeftU64(src_reg, callee_args_count, Operand(kSystemPointerSizeLog2));
-  AddS64(src_reg, sp, src_reg);
-  AddS64(src_reg, src_reg, Operand(kSystemPointerSize));
-
-  if (FLAG_debug_code) {
-    CmpU64(src_reg, dst_reg);
-    Check(lt, AbortReason::kStackAccessBelowStackPointer);
-  }
-
-  // Restore caller's frame pointer and return address now as they will be
-  // overwritten by the copying loop.
-  RestoreFrameStateForTailCall();
-
-  // Now copy callee arguments to the caller frame going backwards to avoid
-  // callee arguments corruption (source and destination areas could overlap).
-
-  // Both src_reg and dst_reg are pointing to the word after the one to copy,
-  // so they must be pre-decremented in the loop.
-  Register tmp_reg = scratch1;
-  Label loop;
-  AddS64(tmp_reg, callee_args_count, Operand(1));  // +1 for receiver
-  mov(r1, tmp_reg);
-  bind(&loop);
-  LoadU64(tmp_reg, MemOperand(src_reg, -kSystemPointerSize));
-  StoreU64(tmp_reg, MemOperand(dst_reg, -kSystemPointerSize));
-  lay(src_reg, MemOperand(src_reg, -kSystemPointerSize));
-  lay(dst_reg, MemOperand(dst_reg, -kSystemPointerSize));
-  BranchOnCount(r1, &loop);
-
-  // Leave current frame.
-  mov(sp, dst_reg);
-}
-
 MemOperand MacroAssembler::StackLimitAsMemOperand(StackLimitKind kind) {
   DCHECK(root_array_available());
   Isolate* isolate = this->isolate();

src/codegen/s390/macro-assembler-s390.h

@@ -812,10 +812,6 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
 #endif
   }
 
-  void PrepareForTailCall(Register callee_args_count,
-                          Register caller_args_count, Register scratch0,
-                          Register scratch1);
-
   // ---------------------------------------------------------------------------
   // Runtime calls