[wasm-split] Disallow mixing --profile, --keep-funcs, and --split-funcs (#4187)

Previously the set of functions to keep was initially empty, then the profile
added new functions to keep, then the --keep-funcs functions were added, then
the --split-funcs functions were removed. This method of composing these
different options was arbitrary and not necessarily intuitive, and it prevented
reasonable workflows from working. For example, providing only a --split-funcs
list would result in all functions being split out not matter which functions
were listed.

To make the behavior of these options, and --split-funcs in particular, more
intuitive, disallow mixing them and when --split-funcs is used, split out only
the listed functions.

1 files changed, 24 insertions, 21 deletions

diff --git a/src/tools/wasm-split/wasm-split.cpp b/src/tools/wasm-split/wasm-split.cpp
index b1ae153c9..2be368994 100644
--- a/src/tools/wasm-split/wasm-split.cpp
+++ b/src/tools/wasm-split/wasm-split.cpp
@@ -173,7 +173,7 @@ void splitModule(const WasmSplitOptions& options) {
   std::set<Name> keepFuncs;
 
   if (options.profileFile.size()) {
-    // Use the profile to initialize `keepFuncs`.
+    // Use the profile to set `keepFuncs`.
     uint64_t hash = hashFile(options.inputFiles[0]);
     ProfileData profile = readProfile(options.profileFile);
     if (profile.hash != hash) {
@@ -193,29 +193,32 @@ void splitModule(const WasmSplitOptions& options) {
     if (i != profile.timestamps.size()) {
       Fatal() << "Unexpected extra profile data";
     }
-  }
-
-  // Add in the functions specified with --keep-funcs
-  for (auto& func : options.keepFuncs) {
-    if (!options.quiet && wasm.getFunctionOrNull(func) == nullptr) {
-      std::cerr << "warning: function " << func << " does not exist\n";
+  } else if (options.keepFuncs.size()) {
+    // Use the explicitly provided `keepFuncs`.
+    for (auto& func : options.keepFuncs) {
+      if (!options.quiet && wasm.getFunctionOrNull(func) == nullptr) {
+        std::cerr << "warning: function " << func << " does not exist\n";
+      }
+      keepFuncs.insert(func);
     }
-    keepFuncs.insert(func);
-  }
-
-  // Remove the functions specified with --remove-funcs
-  for (auto& func : options.splitFuncs) {
-    auto* function = wasm.getFunctionOrNull(func);
-    if (!options.quiet && function == nullptr) {
-      std::cerr << "warning: function " << func << " does not exist\n";
+  } else if (options.splitFuncs.size()) {
+    // Use the explicitly provided `splitFuncs`.
+    for (auto& func : wasm.functions) {
+      keepFuncs.insert(func->name);
     }
-    if (function && function->imported()) {
-      if (!options.quiet) {
-        std::cerr << "warning: cannot split out imported function " << func
-                  << "\n";
+    for (auto& func : options.splitFuncs) {
+      auto* function = wasm.getFunctionOrNull(func);
+      if (!options.quiet && function == nullptr) {
+        std::cerr << "warning: function " << func << " does not exist\n";
+      }
+      if (function && function->imported()) {
+        if (!options.quiet) {
+          std::cerr << "warning: cannot split out imported function " << func
+                    << "\n";
+        }
+      } else {
+        keepFuncs.erase(func);
       }
-    } else {
-      keepFuncs.erase(func);
     }
   }