Reland "[wasm-gc] Liftoff support part 5: i31"

This is a reland of a3ce2f6da2
(No changes; was reverted because a dependency was reverted.)

Original change's description:
> [wasm-gc] Liftoff support part 5: i31
>
> This implements support for i31.get_s and i31.get_u.
>
> Bug: v8:7748
> Change-Id: Icbfddbc2ff46b4eb6bf3edf7b3a794f9797361d4
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2595309
> Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
> Reviewed-by: Clemens Backes <clemensb@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#71808}

Bug: v8:7748
Change-Id: Id8e66cab285d2a36fcd712b92a522e83dea93193
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2617089
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71984}

src/wasm/baseline/arm/liftoff-assembler-arm.h

@@ -703,11 +703,13 @@ void LiftoffAssembler::StoreTaggedPointer(Register dst_addr,
                                           LiftoffRegister src,
                                           LiftoffRegList pinned) {
   STATIC_ASSERT(kTaggedSize == kInt32Size);
+  {
     // Store the value.
     UseScratchRegisterScope temps(this);
     MemOperand dst_op =
         liftoff::GetMemOp(this, &temps, dst_addr, offset_reg, offset_imm);
     str(src.gp(), dst_op);
+  }
   // The write barrier.
   Label write_barrier;
   Label exit;

src/wasm/baseline/ia32/liftoff-assembler-ia32.h

@@ -71,6 +71,7 @@ inline void Load(LiftoffAssembler* assm, LiftoffRegister dst, Register base,
     case ValueType::kI32:
     case ValueType::kOptRef:
     case ValueType::kRef:
+    case ValueType::kRtt:
       assm->mov(dst.gp(), src);
       break;
     case ValueType::kI64:

src/wasm/baseline/liftoff-compiler.cc

@@ -4136,6 +4136,9 @@ class LiftoffCompiler {
     __ PushRegister(kWasmI32, len);
   }
 
+  // 1 bit Smi tag, 31 bits Smi shift, 1 bit i31ref high-bit truncation.
+  constexpr static int kI31To32BitSmiShift = 33;
+
   void I31New(FullDecoder* decoder, const Value& input, Value* result) {
     LiftoffRegister src = __ PopToRegister();
     LiftoffRegister dst = __ GetUnusedRegister(kGpReg, {src}, {});
@@ -4144,20 +4147,33 @@ class LiftoffCompiler {
       __ emit_i32_shli(dst.gp(), src.gp(), kSmiTagSize);
     } else {
       DCHECK(SmiValuesAre32Bits());
-      // 1 bit Smi tag, 31 bits Smi shift, 1 bit i31ref high-bit truncation.
-      constexpr int kI31To32BitSmiShift = 33;
       __ emit_i64_shli(dst, src, kI31To32BitSmiShift);
     }
     __ PushRegister(kWasmI31Ref, dst);
   }
 
   void I31GetS(FullDecoder* decoder, const Value& input, Value* result) {
-    // TODO(7748): Implement.
-    unsupported(decoder, kGC, "i31.get_s");
+    LiftoffRegister src = __ PopToRegister();
+    LiftoffRegister dst = __ GetUnusedRegister(kGpReg, {src}, {});
+    if (SmiValuesAre31Bits()) {
+      __ emit_i32_sari(dst.gp(), src.gp(), kSmiTagSize);
+    } else {
+      DCHECK(SmiValuesAre32Bits());
+      __ emit_i64_sari(dst, src, kI31To32BitSmiShift);
     }
+    __ PushRegister(kWasmI32, dst);
+  }
+
   void I31GetU(FullDecoder* decoder, const Value& input, Value* result) {
-    // TODO(7748): Implement.
-    unsupported(decoder, kGC, "i31.get_u");
+    LiftoffRegister src = __ PopToRegister();
+    LiftoffRegister dst = __ GetUnusedRegister(kGpReg, {src}, {});
+    if (SmiValuesAre31Bits()) {
+      __ emit_i32_shri(dst.gp(), src.gp(), kSmiTagSize);
+    } else {
+      DCHECK(SmiValuesAre32Bits());
+      __ emit_i64_shri(dst, src, kI31To32BitSmiShift);
+    }
+    __ PushRegister(kWasmI32, dst);
   }
 
   void RttCanon(FullDecoder* decoder, const HeapTypeImmediate<validate>& imm,

src/wasm/baseline/x64/liftoff-assembler-x64.h

@@ -91,6 +91,7 @@ inline void Load(LiftoffAssembler* assm, LiftoffRegister dst, Operand src,
     case ValueType::kI64:
     case ValueType::kOptRef:
     case ValueType::kRef:
+    case ValueType::kRtt:
       assm->movq(dst.gp(), src);
       break;
     case ValueType::kF32:

test/cctest/wasm/test-gc.cc

@@ -42,6 +42,7 @@ class WasmGCTester {
         flag_liftoff_only(
             &v8::internal::FLAG_liftoff_only,
             execution_tier == TestExecutionTier::kLiftoff ? true : false),
+        flag_tierup(&v8::internal::FLAG_wasm_tier_up, false),
         zone(&allocator, ZONE_NAME),
         builder_(&zone),
         isolate_(CcTest::InitIsolateOnce()),
@@ -182,6 +183,7 @@ class WasmGCTester {
   const FlagScope<bool> flag_typedfuns;
   const FlagScope<bool> flag_liftoff;
   const FlagScope<bool> flag_liftoff_only;
+  const FlagScope<bool> flag_tierup;
 
   v8::internal::AccountingAllocator allocator;
   Zone zone;
@@ -1091,8 +1093,9 @@ WASM_COMPILED_EXEC_TEST(RefTestCastNull) {
   tester.CheckHasThrown(kRefCastNull, 0);
 }
 
-TEST(BasicI31) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(BasicI31) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
   const byte kSigned = tester.DefineFunction(
       tester.sigs.i_i(), {},
       {WASM_I31_GET_S(WASM_I31_NEW(WASM_LOCAL_GET(0))), kExprEnd});
@@ -1112,8 +1115,9 @@ TEST(BasicI31) {
   tester.CheckResult(kUnsigned, 0x7FFFFFFF, 0x7FFFFFFF);
 }
 
-TEST(I31Casts) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(I31Casts) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
   const byte struct_type = tester.DefineStruct({F(wasm::kWasmI32, true)});
   const byte i31_rtt =
       tester.AddGlobal(ValueType::Rtt(HeapType::kI31, 1), false,
@@ -1173,8 +1177,9 @@ TEST(I31Casts) {
 
 // This flushed out a few bugs, so it serves as a regression test. It can also
 // be modified (made to run longer) to measure performance of casts.
-TEST(CastsBenchmark) {
-  WasmGCTester tester;
+WASM_COMPILED_EXEC_TEST(CastsBenchmark) {
+  WasmGCTester tester(execution_tier);
+  FLAG_experimental_liftoff_extern_ref = true;
   const byte SuperType = tester.DefineStruct({F(wasm::kWasmI32, true)});
   const byte SubType =
       tester.DefineStruct({F(wasm::kWasmI32, true), F(wasm::kWasmI32, true)});