[stringrefs] Implement string.is_usv_sequence

Bug: v8:12868
Change-Id: I2f12858db1956a3b14b95341f1459df8abc03db0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3702797
Commit-Queue: Andy Wingo <wingo@igalia.com>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81188}

src/builtins/wasm.tq

@@ -840,6 +840,12 @@ builtin WasmStringEqual(a: String, b: String): int32 {
   if (StringEqual(context, a, b) == True) return 1;
   return 0;
 }
+builtin WasmStringIsUSVSequence(str: String): int32 {
+  if (IsOneByteStringInstanceType(str.instanceType)) return 1;
+  const length = runtime::WasmStringMeasureUtf8(LoadContextFromFrame(), str);
+  if (Signed(ChangeNumberToUint32(length)) < 0) return 0;
+  return 1;
+}
 transitioning builtin WasmStringViewWtf16GetCodeUnit(
     string: String, offset: uint32): uint32 {
   try {

src/compiler/wasm-compiler.cc

@@ -5832,6 +5832,14 @@ Node* WasmGraphBuilder::StringEqual(Node* a, CheckForNull a_null_check, Node* b,
   return done.PhiAt(0);
 }
 
+Node* WasmGraphBuilder::StringIsUSVSequence(Node* str, CheckForNull null_check,
+                                            wasm::WasmCodePosition position) {
+  if (null_check == kWithNullCheck) str = AssertNotNull(str, position);
+
+  return gasm_->CallBuiltin(Builtin::kWasmStringIsUSVSequence,
+                            Operator::kNoDeopt, str);
+}
+
 Node* WasmGraphBuilder::StringViewWtf16GetCodeUnit(
     Node* string, CheckForNull null_check, Node* offset,
     wasm::WasmCodePosition position) {

src/compiler/wasm-compiler.h

@@ -558,6 +558,8 @@ class WasmGraphBuilder {
                      wasm::WasmCodePosition position);
   Node* StringEqual(Node* a, CheckForNull a_null_check, Node* b,
                     CheckForNull b_null_check, wasm::WasmCodePosition position);
+  Node* StringIsUSVSequence(Node* str, CheckForNull null_check,
+                            wasm::WasmCodePosition position);
   Node* StringViewWtf16GetCodeUnit(Node* string, CheckForNull null_check,
                                    Node* offset,
                                    wasm::WasmCodePosition position);

src/wasm/baseline/liftoff-compiler.cc

@@ -6246,6 +6246,26 @@ class LiftoffCompiler {
     __ PushRegister(kI32, result_reg);
   }
 
+  void StringIsUSVSequence(FullDecoder* decoder, const Value& str,
+                           Value* result) {
+    LiftoffRegList pinned;
+
+    LiftoffRegister str_reg = pinned.set(__ PopToRegister(pinned));
+    MaybeEmitNullCheck(decoder, str_reg.gp(), pinned, str.type);
+    LiftoffAssembler::VarState str_var(kRef, str_reg, 0);
+
+    CallRuntimeStub(WasmCode::kWasmStringIsUSVSequence,
+                    MakeSig::Returns(kI32).Params(kRef),
+                    {
+                        str_var,
+                    },
+                    decoder->position());
+    RegisterDebugSideTableEntry(decoder, DebugSideTableBuilder::kDidSpill);
+
+    LiftoffRegister result_reg(kReturnRegister0);
+    __ PushRegister(kI32, result_reg);
+  }
+
   void StringAsWtf8(FullDecoder* decoder, const Value& str, Value* result) {
     UNIMPLEMENTED();
   }

src/wasm/function-body-decoder-impl.h

@@ -1146,6 +1146,7 @@ struct ControlBase : public PcForErrors<validate> {
     const Value& str, const Value& address)                                    \
   F(StringConcat, const Value& head, const Value& tail, Value* result)         \
   F(StringEq, const Value& a, const Value& b, Value* result)                   \
+  F(StringIsUSVSequence, const Value& str, Value* result)                      \
   F(StringAsWtf8, const Value& str, Value* result)                             \
   F(StringViewWtf8Advance, const Value& view, const Value& pos,                \
     const Value& bytes, Value* result)                                         \
@@ -5243,6 +5244,15 @@ class WasmFullDecoder : public WasmDecoder<validate, decoding_mode> {
         Push(result);
         return opcode_length;
       }
+      case kExprStringIsUSVSequence: {
+        NON_CONST_ONLY
+        Value str = Peek(0, 0, kWasmStringRef);
+        Value result = CreateValue(kWasmI32);
+        CALL_INTERFACE_IF_OK_AND_REACHABLE(StringIsUSVSequence, str, &result);
+        Drop(1);
+        Push(result);
+        return opcode_length;
+      }
       case kExprStringAsWtf8: {
         NON_CONST_ONLY
         Value str = Peek(0, 0, kWasmStringRef);

src/wasm/graph-builder-interface.cc

@@ -1460,6 +1460,12 @@ class WasmGraphBuildingInterface {
                               NullCheckFor(b.type), decoder->position());
   }
 
+  void StringIsUSVSequence(FullDecoder* decoder, const Value& str,
+                           Value* result) {
+    result->node = builder_->StringIsUSVSequence(
+        str.node, NullCheckFor(str.type), decoder->position());
+  }
+
   void StringAsWtf8(FullDecoder* decoder, const Value& str, Value* result) {
     UNIMPLEMENTED();
   }

src/wasm/wasm-code-manager.h

@@ -132,6 +132,7 @@ struct WasmModule;
   V(WasmStringEncodeWtf16)               \
   V(WasmStringConcat)                    \
   V(WasmStringEqual)                     \
+  V(WasmStringIsUSVSequence)             \
   V(WasmStringViewWtf16GetCodeUnit)      \
   V(WasmStringViewWtf16Encode)           \
   V(WasmStringViewWtf16Slice)

test/mjsunit/wasm/stringrefs-exec.js

@@ -518,6 +518,34 @@ function HasIsolatedSurrogate(str) {
                WebAssembly.RuntimeError, "dereferencing a null pointer");
 })();
 
+(function TestStringIsUSVSequence() {
+  let builder = new WasmModuleBuilder();
+
+  builder.addFunction("is_usv_sequence", kSig_i_w)
+    .exportFunc()
+    .addBody([
+      kExprLocalGet, 0,
+      kGCPrefix, kExprStringIsUsvSequence
+    ]);
+
+  builder.addFunction("is_usv_sequence_null", kSig_i_v)
+    .exportFunc()
+    .addBody([
+      kExprRefNull, kStringRefCode,
+      kGCPrefix, kExprStringIsUsvSequence
+    ]);
+
+  let instance = builder.instantiate();
+
+  for (let str of interestingStrings) {
+    assertEquals(HasIsolatedSurrogate(str) ? 0 : 1,
+                 instance.exports.is_usv_sequence(str));
+  }
+
+  assertThrows(() => instance.exports.is_usv_sequence_null(),
+               WebAssembly.RuntimeError, "dereferencing a null pointer");
+})();
+
 (function TestStringViewWtf16() {
   let builder = new WasmModuleBuilder();