From 62cb792c5ee246acc630340fc40d536c985abff3 Mon Sep 17 00:00:00 2001
From: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Date: Mon, 27 Jul 2020 23:38:33 -0400
Subject: [PATCH] [mips][wasm][liftoff] Add direct and indirect tail-calls

Port b64cede5d8d2dd7056812488c6ebe95fe36c29dc
https://crrev.com/c/2289970

Port 5de28709202142f9455ae039b8c9212baa2aa100
https://crrev.com/c/2316304

Change-Id: Ia4e24558b10adef196ab167137a9a5b6db98754b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2321950
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Zhao Jiazhong <zhaojiazhong-hf@loongson.cn>
Cr-Commit-Position: refs/heads/master@{#69089}
---
 .../baseline/mips/liftoff-assembler-mips.h    | 36 +++++++++++++++++++
 .../mips64/liftoff-assembler-mips64.h         | 36 +++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/src/wasm/baseline/mips/liftoff-assembler-mips.h b/src/wasm/baseline/mips/liftoff-assembler-mips.h
index 802074630f..5c0427eb91 100644
--- a/src/wasm/baseline/mips/liftoff-assembler-mips.h
+++ b/src/wasm/baseline/mips/liftoff-assembler-mips.h
@@ -275,6 +275,29 @@ int LiftoffAssembler::PrepareStackFrame() {
   return offset;
 }
 
+void LiftoffAssembler::PrepareTailCall(int num_callee_stack_params,
+                                       int stack_param_delta) {
+  UseScratchRegisterScope temps(this);
+  Register scratch = temps.Acquire();
+
+  // Push the return address and frame pointer to complete the stack frame.
+  Lw(scratch, MemOperand(fp, 4));
+  Push(scratch);
+  Lw(scratch, MemOperand(fp, 0));
+  Push(scratch);
+
+  // Shift the whole frame upwards.
+  int slot_count = num_callee_stack_params + 2;
+  for (int i = slot_count - 1; i >= 0; --i) {
+    Lw(scratch, MemOperand(sp, i * 4));
+    Sw(scratch, MemOperand(fp, (i - stack_param_delta) * 4));
+  }
+
+  // Set the new stack and frame pointer.
+  addiu(sp, fp, -stack_param_delta * 4);
+  Pop(ra, fp);
+}
+
 void LiftoffAssembler::PatchPrepareStackFrame(int offset, int frame_size) {
   // We can't run out of space, just pass anything big enough to not cause the
   // assembler to try to grow the buffer.
@@ -2575,6 +2598,10 @@ void LiftoffAssembler::CallNativeWasmCode(Address addr) {
   Call(addr, RelocInfo::WASM_CALL);
 }
 
+void LiftoffAssembler::TailCallNativeWasmCode(Address addr) {
+  Jump(addr, RelocInfo::WASM_CALL);
+}
+
 void LiftoffAssembler::CallIndirect(const wasm::FunctionSig* sig,
                                     compiler::CallDescriptor* call_descriptor,
                                     Register target) {
@@ -2586,6 +2613,15 @@ void LiftoffAssembler::CallIndirect(const wasm::FunctionSig* sig,
   }
 }
 
+void LiftoffAssembler::TailCallIndirect(Register target) {
+  if (target == no_reg) {
+    Pop(kScratchReg);
+    Jump(kScratchReg);
+  } else {
+    Jump(target);
+  }
+}
+
 void LiftoffAssembler::CallRuntimeStub(WasmCode::RuntimeStubId sid) {
   // A direct call to a wasm runtime stub defined in this module.
   // Just encode the stub index. This will be patched at relocation.
diff --git a/src/wasm/baseline/mips64/liftoff-assembler-mips64.h b/src/wasm/baseline/mips64/liftoff-assembler-mips64.h
index 4c4fa6d255..de6bb6e548 100644
--- a/src/wasm/baseline/mips64/liftoff-assembler-mips64.h
+++ b/src/wasm/baseline/mips64/liftoff-assembler-mips64.h
@@ -240,6 +240,29 @@ int LiftoffAssembler::PrepareStackFrame() {
   return offset;
 }
 
+void LiftoffAssembler::PrepareTailCall(int num_callee_stack_params,
+                                       int stack_param_delta) {
+  UseScratchRegisterScope temps(this);
+  Register scratch = temps.Acquire();
+
+  // Push the return address and frame pointer to complete the stack frame.
+  Ld(scratch, MemOperand(fp, 8));
+  Push(scratch);
+  Ld(scratch, MemOperand(fp, 0));
+  Push(scratch);
+
+  // Shift the whole frame upwards.
+  int slot_count = num_callee_stack_params + 2;
+  for (int i = slot_count - 1; i >= 0; --i) {
+    Ld(scratch, MemOperand(sp, i * 8));
+    Sd(scratch, MemOperand(fp, (i - stack_param_delta) * 8));
+  }
+
+  // Set the new stack and frame pointer.
+  daddiu(sp, fp, -stack_param_delta * 8);
+  Pop(ra, fp);
+}
+
 void LiftoffAssembler::PatchPrepareStackFrame(int offset, int frame_size) {
   // We can't run out of space, just pass anything big enough to not cause the
   // assembler to try to grow the buffer.
@@ -2678,6 +2701,10 @@ void LiftoffAssembler::CallNativeWasmCode(Address addr) {
   Call(addr, RelocInfo::WASM_CALL);
 }
 
+void LiftoffAssembler::TailCallNativeWasmCode(Address addr) {
+  Jump(addr, RelocInfo::WASM_CALL);
+}
+
 void LiftoffAssembler::CallIndirect(const wasm::FunctionSig* sig,
                                     compiler::CallDescriptor* call_descriptor,
                                     Register target) {
@@ -2689,6 +2716,15 @@ void LiftoffAssembler::CallIndirect(const wasm::FunctionSig* sig,
   }
 }
 
+void LiftoffAssembler::TailCallIndirect(Register target) {
+  if (target == no_reg) {
+    Pop(kScratchReg);
+    Jump(kScratchReg);
+  } else {
+    Jump(target);
+  }
+}
+
 void LiftoffAssembler::CallRuntimeStub(WasmCode::RuntimeStubId sid) {
   // A direct call to a wasm runtime stub defined in this module.
   // Just encode the stub index. This will be patched at relocation.