Work around excessive stack space in non optimized builds during deco…

…des. Progress on: apple#1034
thomasvl · Aug 11, 2020 · 5061489 · 5061489
1 parent 55d6fde
commit 5061489
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Showing 3 changed files with 10 additions and 4 deletions.
diff --git a/Sources/protoc-gen-swift/MessageFieldGenerator.swift b/Sources/protoc-gen-swift/MessageFieldGenerator.swift
@@ -181,7 +181,7 @@ class MessageFieldGenerator: FieldGeneratorBase, FieldGenerator {
             traitsArg = ""
         }
 
-        p.print("case \(number): try decoder.\(decoderMethod)(\(traitsArg)value: &\(storedProperty))\n")
+        p.print("case \(number): try { try decoder.\(decoderMethod)(\(traitsArg)value: &\(storedProperty)) }()\n")
     }
 
     func generateTraverse(printer p: inout CodePrinter) {

diff --git a/Sources/protoc-gen-swift/MessageGenerator.swift b/Sources/protoc-gen-swift/MessageGenerator.swift
@@ -283,14 +283,19 @@ class MessageGenerator {
         p.print("while let \(varName) = try decoder.nextFieldNumber() {\n")
         p.indent()
         if !fields.isEmpty {
-          p.print("switch fieldNumber {\n")
+
+          p.print(
+              "// The use of inline closures is to circumvents an issue where the compiler\n",
+              "// allocates stack space for every case branch when no optimizations are\n",
+              "// enabled. https://github.com/apple/swift-protobuf/issues/1034\n",
+              "switch fieldNumber {\n")
           for f in fieldsSortedByNumber {
             f.generateDecodeFieldCase(printer: &p)
           }
           if isExtensible {
             p.print("case \(descriptor.swiftExtensionRangeExpressions):\n")
             p.indent()
-            p.print("try decoder.decodeExtensionField(values: &_protobuf_extensionFieldValues, messageType: \(swiftFullName).self, fieldNumber: fieldNumber)\n")
+            p.print("try { try decoder.decodeExtensionField(values: &_protobuf_extensionFieldValues, messageType: \(swiftFullName).self, fieldNumber: fieldNumber) }()\n")
             p.outdent()
           }
           p.print("default: break\n")

diff --git a/Sources/protoc-gen-swift/OneofGenerator.swift b/Sources/protoc-gen-swift/OneofGenerator.swift
@@ -310,7 +310,7 @@ class OneofGenerator {
     }
 
     func generateDecodeFieldCase(printer p: inout CodePrinter, field: MemberFieldGenerator) {
-        p.print("case \(field.number):\n")
+        p.print("case \(field.number): try {\n")
         p.indent()
 
         if field.isGroupOrMessage {
@@ -335,6 +335,7 @@ class OneofGenerator {
           "try decoder.decodeSingular\(field.protoGenericType)Field(value: &v)\n",
           "if let v = v {\(storedProperty) = \(field.dottedSwiftName)(v)}\n")
         p.outdent()
+        p.print("}()\n")
     }
 
     func generateTraverse(printer p: inout CodePrinter, field: MemberFieldGenerator) {