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

This reverts commit a3ce2f6d.

Reason for revert: speculative revert due to waterfall unhappiness (looks like bot weirdness though?)

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}

TBR=jkummerow@chromium.org,clemensb@chromium.org

Change-Id: I5050f16fdaf355d178935f523a9bec516302d2a1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:7748
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2596337Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71810}

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

@@ -703,13 +703,11 @@ 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

@@ -71,7 +71,6 @@ 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

@@ -4063,9 +4063,6 @@ 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}, {});
@@ -4074,33 +4071,20 @@ 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) {
-    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);
+    // TODO(7748): Implement.
+    unsupported(decoder, kGC, "i31.get_s");
   }
-
   void I31GetU(FullDecoder* decoder, const Value& input, Value* result) {
-    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);
+    // TODO(7748): Implement.
+    unsupported(decoder, kGC, "i31.get_u");
   }
 
   void RttCanon(FullDecoder* decoder, const HeapTypeImmediate<validate>& imm,

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

@@ -90,7 +90,6 @@ 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

@@ -42,7 +42,6 @@ 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()),
@@ -183,7 +182,6 @@ 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;
@@ -1088,9 +1086,8 @@ TEST(RefTestCastNull) {
   tester.CheckHasThrown(kRefCastNull, 0);
 }
 
-WASM_COMPILED_EXEC_TEST(BasicI31) {
-  WasmGCTester tester(execution_tier);
-  FLAG_experimental_liftoff_extern_ref = true;
+TEST(BasicI31) {
+  WasmGCTester tester;
   const byte kSigned = tester.DefineFunction(
       tester.sigs.i_i(), {},
       {WASM_I31_GET_S(WASM_I31_NEW(WASM_GET_LOCAL(0))), kExprEnd});
@@ -1110,9 +1107,8 @@ WASM_COMPILED_EXEC_TEST(BasicI31) {
   tester.CheckResult(kUnsigned, 0x7FFFFFFF, 0x7FFFFFFF);
 }
 
-WASM_COMPILED_EXEC_TEST(I31Casts) {
-  WasmGCTester tester(execution_tier);
-  FLAG_experimental_liftoff_extern_ref = true;
+TEST(I31Casts) {
+  WasmGCTester tester;
   const byte struct_type = tester.DefineStruct({F(wasm::kWasmI32, true)});
   const byte i31_rtt =
       tester.AddGlobal(ValueType::Rtt(HeapType::kI31, 1), false,
@@ -1172,9 +1168,8 @@ WASM_COMPILED_EXEC_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.
-WASM_COMPILED_EXEC_TEST(CastsBenchmark) {
-  WasmGCTester tester(execution_tier);
-  FLAG_experimental_liftoff_extern_ref = true;
+TEST(CastsBenchmark) {
+  WasmGCTester tester;
   const byte SuperType = tester.DefineStruct({F(wasm::kWasmI32, true)});
   const byte SubType =
       tester.DefineStruct({F(wasm::kWasmI32, true), F(wasm::kWasmI32, true)});