[Strings] Add experimental StringNew variants (#5459)

string.from_code_point makes a string from an int code point.

string.new_utf8*_try makes a utf8 string and returns null on a UTF8 encoding
error rather than trap.

1 files changed, 35 insertions, 25 deletions

diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 829025a2c..6bbd82476 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2990,43 +2990,53 @@ Expression* SExpressionWasmBuilder::makeRefAs(Element& s, RefAsOp op) {
   return Builder(wasm).makeRefAs(op, value);
 }
 
-Expression* SExpressionWasmBuilder::makeStringNew(Element& s, StringNewOp op) {
+Expression*
+SExpressionWasmBuilder::makeStringNew(Element& s, StringNewOp op, bool try_) {
   size_t i = 1;
   Expression* length = nullptr;
-  if (op == StringNewWTF8) {
-    std::string_view str = s[i++]->str().str;
-    if (str == "utf8") {
-      op = StringNewUTF8;
-    } else if (str == "wtf8") {
-      op = StringNewWTF8;
-    } else if (str == "replace") {
-      op = StringNewReplace;
-    } else {
-      throw ParseException("bad string.new op", s.line, s.col);
+  if (op == StringNewWTF8 || op == StringNewUTF8) {
+    if (!try_) {
+      std::string_view str = s[i++]->str().str;
+      if (str == "utf8") {
+        op = StringNewUTF8;
+      } else if (str == "wtf8") {
+        op = StringNewWTF8;
+      } else if (str == "replace") {
+        op = StringNewReplace;
+      } else {
+        throw ParseException("bad string.new op", s.line, s.col);
+      }
     }
     length = parseExpression(s[i + 1]);
-    return Builder(wasm).makeStringNew(op, parseExpression(s[i]), length);
+    return Builder(wasm).makeStringNew(op, parseExpression(s[i]), length, try_);
   } else if (op == StringNewWTF16) {
     length = parseExpression(s[i + 1]);
-    return Builder(wasm).makeStringNew(op, parseExpression(s[i]), length);
-  } else if (op == StringNewWTF8Array) {
-    std::string_view str = s[i++]->str().str;
-    if (str == "utf8") {
-      op = StringNewUTF8Array;
-    } else if (str == "wtf8") {
-      op = StringNewWTF8Array;
-    } else if (str == "replace") {
-      op = StringNewReplaceArray;
-    } else {
-      throw ParseException("bad string.new op", s.line, s.col);
+    return Builder(wasm).makeStringNew(op, parseExpression(s[i]), length, try_);
+  } else if (op == StringNewWTF8Array || op == StringNewUTF8Array) {
+    if (!try_) {
+      std::string_view str = s[i++]->str().str;
+      if (str == "utf8") {
+        op = StringNewUTF8Array;
+      } else if (str == "wtf8") {
+        op = StringNewWTF8Array;
+      } else if (str == "replace") {
+        op = StringNewReplaceArray;
+      } else {
+        throw ParseException("bad string.new op", s.line, s.col);
+      }
     }
     auto* start = parseExpression(s[i + 1]);
     auto* end = parseExpression(s[i + 2]);
-    return Builder(wasm).makeStringNew(op, parseExpression(s[i]), start, end);
+    return Builder(wasm).makeStringNew(
+      op, parseExpression(s[i]), start, end, try_);
   } else if (op == StringNewWTF16Array) {
     auto* start = parseExpression(s[i + 1]);
     auto* end = parseExpression(s[i + 2]);
-    return Builder(wasm).makeStringNew(op, parseExpression(s[i]), start, end);
+    return Builder(wasm).makeStringNew(
+      op, parseExpression(s[i]), start, end, try_);
+  } else if (op == StringNewFromCodePoint) {
+    return Builder(wasm).makeStringNew(
+      op, parseExpression(s[i]), nullptr, try_);
   } else {
     throw ParseException("bad string.new op", s.line, s.col);
   }