[riscv64][codegen] Remove PrepareForTailCall

Port: ec717160
Bug: v8:11879
Change-Id: I1e2f1d712a14fee383227c5a2b479cf00dde9e9c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3062031Reviewed-by: Ji Qiu <qiuji@iscas.ac.cn>
Reviewed-by: Brice Dobry <brice.dobry@futurewei.com>
Commit-Queue: Ji Qiu <qiuji@iscas.ac.cn>
Auto-Submit: Ji Qiu <qiuji@iscas.ac.cn>
Cr-Commit-Position: refs/heads/master@{#76151}

src/codegen/riscv64/macro-assembler-riscv64.cc

@@ -3612,52 +3612,6 @@ void TurboAssembler::MovToFloatParameters(DoubleRegister src1,
 // -----------------------------------------------------------------------------
 // JavaScript invokes.
 
-void TurboAssembler::PrepareForTailCall(Register callee_args_count,
-                                        Register caller_args_count,
-                                        Register scratch0, Register 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;
-  CalcScaledAddress(dst_reg, fp, caller_args_count, kSystemPointerSizeLog2);
-  Add64(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.
-  CalcScaledAddress(src_reg, sp, callee_args_count, kSystemPointerSizeLog2);
-  Add64(src_reg, src_reg, Operand(kSystemPointerSize));
-
-  if (FLAG_debug_code) {
-    Check(Uless, AbortReason::kStackAccessBelowStackPointer, src_reg,
-          Operand(dst_reg));
-  }
-
-  // Restore caller's frame pointer and return address now as they will be
-  // overwritten by the copying loop.
-  Ld(ra, MemOperand(fp, StandardFrameConstants::kCallerPCOffset));
-  Ld(fp, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
-
-  // 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, entry;
-  Branch(&entry);
-  bind(&loop);
-  Sub64(src_reg, src_reg, Operand(kSystemPointerSize));
-  Sub64(dst_reg, dst_reg, Operand(kSystemPointerSize));
-  Ld(tmp_reg, MemOperand(src_reg));
-  Sd(tmp_reg, MemOperand(dst_reg));
-  bind(&entry);
-  Branch(&loop, ne, sp, Operand(src_reg));
-
-  // Leave current frame.
-  Mv(sp, dst_reg);
-}
-
 void MacroAssembler::LoadStackLimit(Register destination, StackLimitKind kind) {
   DCHECK(root_array_available());
   Isolate* isolate = this->isolate();

src/codegen/riscv64/macro-assembler-riscv64.h

@@ -479,15 +479,6 @@ class V8_EXPORT_PRIVATE TurboAssembler : public TurboAssemblerBase {
 
   void SmiUntag(Register reg) { SmiUntag(reg, reg); }
 
-  // Removes current frame and its arguments from the stack preserving
-  // the arguments and a return address pushed to the stack for the next call.
-  // Both |callee_args_count| and |caller_args_count| do not include
-  // receiver. |callee_args_count| is not modified. |caller_args_count|
-  // is trashed.
-  void PrepareForTailCall(Register callee_args_count,
-                          Register caller_args_count, Register scratch0,
-                          Register scratch1);
-
   int CalculateStackPassedDWords(int num_gp_arguments, int num_fp_arguments);
 
   // Before calling a C-function from generated code, align arguments on stack.