[regexp] Store named captures on the regexp result

This implements storing named captures on the regexp result object.
For instance, /(?<a>.)/u.exec("b") will return a result such that:

result.group.a  // "b"

https://tc39.github.io/proposal-regexp-named-groups/

BUG=v8:5437

Review-Url: https://codereview.chromium.org/2630233003
Cr-Original-Original-Original-Commit-Position: refs/heads/master@{#42532}
Committed: https://chromium.googlesource.com/v8/v8/+/70000946eb2a9155679528702a766219a1fcf154
Review-Url: https://codereview.chromium.org/2630233003
Cr-Original-Original-Commit-Position: refs/heads/master@{#42570}
Committed: https://chromium.googlesource.com/v8/v8/+/ee94fa11ed63477393c6534c352ebac6e502396c
Review-Url: https://codereview.chromium.org/2630233003
Cr-Original-Commit-Position: refs/heads/master@{#42676}
Committed: https://chromium.googlesource.com/v8/v8/+/8bf52534f6bf86821a1589dcbcb7335052c1f94f
Review-Url: https://codereview.chromium.org/2630233003
Cr-Commit-Position: refs/heads/master@{#42838}

src/builtins/builtins-regexp.cc

@@ -33,8 +33,9 @@ class RegExpBuiltinsAssembler : public CodeStubAssembler {
   void StoreLastIndex(Node* context, Node* regexp, Node* value,
                       bool is_fastpath);
 
-  Node* ConstructNewResultFromMatchInfo(Node* context, Node* match_info,
-                                        Node* string);
+  Node* ConstructNewResultFromMatchInfo(Node* const context, Node* const regexp,
+                                        Node* const match_info,
+                                        Node* const string);
 
   Node* RegExpPrototypeExecBodyWithoutResult(Node* const context,
                                              Node* const regexp,
@@ -141,10 +142,10 @@ void RegExpBuiltinsAssembler::StoreLastIndex(Node* context, Node* regexp,
   }
 }
 
-Node* RegExpBuiltinsAssembler::ConstructNewResultFromMatchInfo(Node* context,
-                                                               Node* match_info,
-                                                               Node* string) {
-  Label out(this);
+Node* RegExpBuiltinsAssembler::ConstructNewResultFromMatchInfo(
+    Node* const context, Node* const regexp, Node* const match_info,
+    Node* const string) {
+  Label named_captures(this), out(this);
 
   Node* const num_indices = SmiUntag(LoadFixedArrayElement(
       match_info, RegExpMatchInfo::kNumberOfCapturesIndex));
@@ -164,7 +165,8 @@ Node* RegExpBuiltinsAssembler::ConstructNewResultFromMatchInfo(Node* context,
 
   StoreFixedArrayElement(result_elements, 0, first, SKIP_WRITE_BARRIER);
 
-  GotoIf(SmiEqual(num_results, SmiConstant(Smi::FromInt(1))), &out);
+  // If no captures exist we can skip named capture handling as well.
+  GotoIf(SmiEqual(num_results, SmiConstant(1)), &out);
 
   // Store all remaining captures.
   Node* const limit = IntPtrAdd(
@@ -187,7 +189,7 @@ Node* RegExpBuiltinsAssembler::ConstructNewResultFromMatchInfo(Node* context,
     Node* const start = LoadFixedArrayElement(match_info, from_cursor);
 
     Label next_iter(this);
-    GotoIf(SmiEqual(start, SmiConstant(Smi::FromInt(-1))), &next_iter);
+    GotoIf(SmiEqual(start, SmiConstant(-1)), &next_iter);
 
     Node* const from_cursor_plus1 = IntPtrAdd(from_cursor, IntPtrConstant(1));
     Node* const end = LoadFixedArrayElement(match_info, from_cursor_plus1);
@@ -199,7 +201,83 @@ Node* RegExpBuiltinsAssembler::ConstructNewResultFromMatchInfo(Node* context,
     Bind(&next_iter);
     var_from_cursor.Bind(IntPtrAdd(from_cursor, IntPtrConstant(2)));
     var_to_cursor.Bind(IntPtrAdd(to_cursor, IntPtrConstant(1)));
-    Branch(UintPtrLessThan(var_from_cursor.value(), limit), &loop, &out);
+    Branch(UintPtrLessThan(var_from_cursor.value(), limit), &loop,
+           &named_captures);
+  }
+
+  Bind(&named_captures);
+  {
+    // We reach this point only if captures exist, implying that this is an
+    // IRREGEXP JSRegExp.
+
+    CSA_ASSERT(this, HasInstanceType(regexp, JS_REGEXP_TYPE));
+    CSA_ASSERT(this, SmiGreaterThan(num_results, SmiConstant(1)));
+
+    // Preparations for named capture properties. Exit early if the result does
+    // not have any named captures to minimize performance impact.
+
+    Node* const data = LoadObjectField(regexp, JSRegExp::kDataOffset);
+    CSA_ASSERT(this, SmiEqual(LoadFixedArrayElement(data, JSRegExp::kTagIndex),
+                              SmiConstant(JSRegExp::IRREGEXP)));
+
+    // The names fixed array associates names at even indices with a capture
+    // index at odd indices.
+    Node* const names =
+        LoadFixedArrayElement(data, JSRegExp::kIrregexpCaptureNameMapIndex);
+    GotoIf(SmiEqual(names, SmiConstant(0)), &out);
+
+    // Allocate a new object to store the named capture properties.
+    // TODO(jgruber): Could be optimized by adding the object map to the heap
+    // root list.
+
+    Node* const native_context = LoadNativeContext(context);
+    Node* const map = LoadContextElement(
+        native_context, Context::SLOW_OBJECT_WITH_NULL_PROTOTYPE_MAP);
+    Node* const properties =
+        AllocateNameDictionary(NameDictionary::kInitialCapacity);
+
+    Node* const group_object = AllocateJSObjectFromMap(map, properties);
+
+    // Store it on the result as a 'group' property.
+
+    {
+      Node* const name = HeapConstant(isolate()->factory()->group_string());
+      CallRuntime(Runtime::kCreateDataProperty, context, result, name,
+                  group_object);
+    }
+
+    // One or more named captures exist, add a property for each one.
+
+    CSA_ASSERT(this, HasInstanceType(names, FIXED_ARRAY_TYPE));
+    Node* const names_length = LoadAndUntagFixedArrayBaseLength(names);
+    CSA_ASSERT(this, IntPtrGreaterThan(names_length, IntPtrConstant(0)));
+
+    Variable var_i(this, MachineType::PointerRepresentation());
+    var_i.Bind(IntPtrConstant(0));
+
+    Variable* vars[] = {&var_i};
+    const int vars_count = sizeof(vars) / sizeof(vars[0]);
+    Label loop(this, vars_count, vars);
+
+    Goto(&loop);
+    Bind(&loop);
+    {
+      Node* const i = var_i.value();
+      Node* const i_plus_1 = IntPtrAdd(i, IntPtrConstant(1));
+      Node* const i_plus_2 = IntPtrAdd(i_plus_1, IntPtrConstant(1));
+
+      Node* const name = LoadFixedArrayElement(names, i);
+      Node* const index = LoadFixedArrayElement(names, i_plus_1);
+      Node* const capture =
+          LoadFixedArrayElement(result_elements, SmiUntag(index));
+
+      CallRuntime(Runtime::kCreateDataProperty, context, group_object, name,
+                  capture);
+
+      var_i.Bind(i_plus_2);
+      Branch(IntPtrGreaterThanOrEqual(var_i.value(), names_length), &out,
+             &loop);
+    }
   }
 
   Bind(&out);
@@ -352,7 +430,7 @@ Node* RegExpBuiltinsAssembler::RegExpPrototypeExecBody(Node* const context,
   {
     Node* const match_indices = indices_or_null;
     Node* const result =
-        ConstructNewResultFromMatchInfo(context, match_indices, string);
+        ConstructNewResultFromMatchInfo(context, regexp, match_indices, string);
     var_result.Bind(result);
     Goto(&out);
   }
@@ -2510,7 +2588,7 @@ TF_BUILTIN(RegExpInternalMatch, RegExpBuiltinsAssembler) {
   Bind(&if_matched);
   {
     Node* result =
-        ConstructNewResultFromMatchInfo(context, match_indices, string);
+        ConstructNewResultFromMatchInfo(context, regexp, match_indices, string);
     Return(result);
   }
 }

src/heap-symbols.h

@@ -88,6 +88,7 @@
   V(get_string, "get")                                             \
   V(get_space_string, "get ")                                      \
   V(global_string, "global")                                       \
+  V(group_string, "group")                                         \
   V(has_string, "has")                                             \
   V(hour_string, "hour")                                           \
   V(ignoreCase_string, "ignoreCase")                               \

test/mjsunit/harmony/regexp-named-captures.js

@@ -18,15 +18,15 @@ assertThrows("/(?<ab>a)\\k<a>/u");  // Invalid reference.
 assertThrows("/\\k<a>(?<ab>a)/u");  // Invalid reference.
 
 // Fallback behavior in non-unicode mode.
-assertThrows("/(?<>a)/");
-assertThrows("/(?<aa)/");
-assertThrows("/(?<42a>a)/");
-assertThrows("/(?<:a>a)/");
-assertThrows("/(?<a:>a)/");
-assertThrows("/(?<a>a)(?<a>a)/");
-assertThrows("/(?<a>a)(?<b>b)(?<a>a)/");
-assertThrows("/(?<a>a)\\k<ab>/");
-assertThrows("/(?<ab>a)\\k<a>/");
+assertThrows("/(?<>a)/", SyntaxError);
+assertThrows("/(?<aa)/", SyntaxError);
+assertThrows("/(?<42a>a)/", SyntaxError);
+assertThrows("/(?<:a>a)/", SyntaxError);
+assertThrows("/(?<a:>a)/", SyntaxError);
+assertThrows("/(?<a>a)(?<a>a)/", SyntaxError);
+assertThrows("/(?<a>a)(?<b>b)(?<a>a)/", SyntaxError);
+assertThrows("/(?<a>a)\\k<ab>/", SyntaxError);
+assertThrows("/(?<ab>a)\\k<a>/", SyntaxError);
 
 assertEquals(["k<a>"], "xxxk<a>xxx".match(/\k<a>/));
 assertEquals(["k<a"], "xxxk<a>xxx".match(/\k<a/));
@@ -74,3 +74,25 @@ assertEquals(["bab", "b"], "bab".match(/(?<a>\k<a>\w)../u));
 // Reference before group.
 assertEquals(["bab", "b"], "bab".match(/\k<a>(?<a>b)\w\k<a>/u));
 assertEquals(["bab", "b", "a"], "bab".match(/(?<b>b)\k<a>(?<a>a)\k<b>/u));
+
+// Reference properties.
+assertEquals("a", /(?<a>a)(?<b>b)\k<a>/u.exec("aba").group.a);
+assertEquals("b", /(?<a>a)(?<b>b)\k<a>/u.exec("aba").group.b);
+assertEquals(undefined, /(?<a>a)(?<b>b)\k<a>/u.exec("aba").group.c);
+assertEquals(undefined, /(?<a>a)(?<b>b)\k<a>|(?<c>c)/u.exec("aba").group.c);
+
+// Unicode names.
+assertEquals("a", /(?<π>a)/u.exec("bab").group.π);
+assertEquals("a", /(?<\u{03C0}>a)/u.exec("bab").group.\u03C0);
+assertEquals("a", /(?<$>a)/u.exec("bab").group.$);
+assertEquals("a", /(?<_>a)/u.exec("bab").group._);
+assertEquals("a", /(?<$𐒤>a)/u.exec("bab").group.$𐒤);
+assertEquals("a", /(?<_\u200C>a)/u.exec("bab").group._\u200C);
+assertEquals("a", /(?<_\u200D>a)/u.exec("bab").group._\u200D);
+assertEquals("a", /(?<ಠ_ಠ>a)/u.exec("bab").group.ಠ_ಠ);
+assertThrows('/(?<❤>a)/u', SyntaxError);
+assertThrows('/(?<𐒤>a)/u', SyntaxError);  // ID_Continue but not ID_Start.
+
+// The '__proto__' property on the groups object.
+assertEquals(undefined, /(?<a>.)/u.exec("a").group.__proto__);
+assertEquals("a", /(?<__proto__>a)/u.exec("a").group.__proto__);

test/mjsunit/mjsunit.status

@@ -156,6 +156,9 @@
   # desugaring regexp property class relies on ICU.
   'harmony/regexp-property-*': [PASS, ['no_i18n == True', FAIL]],
 
+  # noi18n build cannot parse characters in supplementary plane.
+  'harmony/regexp-named-captures': [PASS, ['no_i18n == True', FAIL]],
+
   # Allocates a large array buffer, which TSAN sometimes cannot handle.
   'regress/regress-599717': [PASS, ['tsan', SKIP]],