Optimize startup be reducing selector lookup.

Move away from looking up selectors at proto initialization time to doing optimized string compares at implementation resolving time.

PiperOrigin-RevId: 623183331

objectivec/GPBDescriptor.m

@@ -51,40 +51,6 @@ - (instancetype)initWithName:(NSString *)name
 static const char kClassNameSuffixKey = 0;
 static const char kFileDescriptorCacheKey = 0;
 
-// Utility function to generate selectors on the fly.
-static SEL SelFromStrings(const char *prefix, const char *middle, const char *suffix,
-                          BOOL takesArg) {
-  if (prefix == NULL && suffix == NULL && !takesArg) {
-    return sel_getUid(middle);
-  }
-  const size_t prefixLen = prefix != NULL ? strlen(prefix) : 0;
-  const size_t middleLen = strlen(middle);
-  const size_t suffixLen = suffix != NULL ? strlen(suffix) : 0;
-  size_t totalLen = prefixLen + middleLen + suffixLen + 1;  // include space for null on end.
-  if (takesArg) {
-    totalLen += 1;
-  }
-  char buffer[totalLen];
-  if (prefix != NULL) {
-    memcpy(buffer, prefix, prefixLen);
-    memcpy(buffer + prefixLen, middle, middleLen);
-    buffer[prefixLen] = (char)toupper(buffer[prefixLen]);
-  } else {
-    memcpy(buffer, middle, middleLen);
-  }
-  if (suffix != NULL) {
-    memcpy(buffer + prefixLen + middleLen, suffix, suffixLen);
-  }
-  if (takesArg) {
-    buffer[totalLen - 2] = ':';
-  }
-  // Always null terminate it.
-  buffer[totalLen - 1] = 0;
-
-  SEL result = sel_getUid(buffer);
-  return result;
-}
-
 static NSArray *NewFieldsArrayForHasIndex(int hasIndex, NSArray *allMessageFields)
     __attribute__((ns_returns_retained));
 
@@ -594,8 +560,6 @@ - (instancetype)initWithName:(const char *)name fields:(NSArray *)fields {
     for (GPBFieldDescriptor *fieldDesc in fields) {
       fieldDesc->containingOneof_ = self;
     }
-
-    caseSel_ = SelFromStrings(NULL, name, "OneOfCase", NO);
   }
   return self;
 }
@@ -682,27 +646,9 @@ - (instancetype)initWithFieldDescription:(void *)description
       coreDesc = description;
     }
     description_ = coreDesc;
-    getSel_ = sel_getUid(coreDesc->name);
-    setSel_ = SelFromStrings("set", coreDesc->name, NULL, YES);
 
     GPBDataType dataType = coreDesc->dataType;
     BOOL isMessage = GPBDataTypeIsMessage(dataType);
-    BOOL isMapOrArray = GPBFieldIsMapOrArray(self);
-
-    if (isMapOrArray) {
-      // map<>/repeated fields get a *Count property (inplace of a has*) to
-      // support checking if there are any entries without triggering
-      // autocreation.
-      hasOrCountSel_ = SelFromStrings(NULL, coreDesc->name, "_Count", NO);
-    } else {
-      // It is a single field; it gets has/setHas selectors if...
-      //  - not in a oneof (negative has index)
-      //  - not clearing on zero
-      if ((coreDesc->hasIndex >= 0) && ((coreDesc->flags & GPBFieldClearHasIvarOnZero) == 0)) {
-        hasOrCountSel_ = SelFromStrings("has", coreDesc->name, NULL, NO);
-        setHasSel_ = SelFromStrings("setHas", coreDesc->name, NULL, YES);
-      }
-    }
 
     // Extra type specific data.
     if (isMessage) {
@@ -719,6 +665,7 @@ - (instancetype)initWithFieldDescription:(void *)description
     }
 
     // Non map<>/repeated fields can have defaults in proto2 syntax.
+    BOOL isMapOrArray = GPBFieldIsMapOrArray(self);
     if (!isMapOrArray && includesDefault) {
       defaultValue_ = ((GPBMessageFieldDescriptionWithDefault *)description)->defaultValue;
       if (dataType == GPBDataTypeBytes) {

objectivec/GPBDescriptor_PackagePrivate.h

@@ -80,6 +80,10 @@ typedef struct GPBFileDescription {
 // Describes a single field in a protobuf as it is represented as an ivar.
 typedef struct GPBMessageFieldDescription {
   // Name of ivar.
+  // Note that we looked into using a SEL here instead (which really is just a C string)
+  // but there is not a way to initialize an SEL with a constant (@selector is not constant) so the
+  // additional code generated to initialize the value is actually bigger in size than just using a
+  // C identifier for large apps.
   const char *name;
   union {
     // className is deprecated and will be removed in favor of clazz.
@@ -235,7 +239,6 @@ typedef NS_OPTIONS(uint32_t, GPBDescriptorInitializationFlags) {
  @package
   const char *name_;
   NSArray *fields_;
-  SEL caseSel_;
 }
 // name must be long lived.
 - (instancetype)initWithName:(const char *)name fields:(NSArray *)fields;
@@ -245,11 +248,6 @@ typedef NS_OPTIONS(uint32_t, GPBDescriptorInitializationFlags) {
  @package
   GPBMessageFieldDescription *description_;
   GPB_UNSAFE_UNRETAINED GPBOneofDescriptor *containingOneof_;
-
-  SEL getSel_;
-  SEL setSel_;
-  SEL hasOrCountSel_;  // *Count for map<>/repeated fields, has* otherwise.
-  SEL setHasSel_;
 }
 @end