[GUFA] Optimize functions not taken by reference better (#5085)

This moves the logic to add connections from signatures to functions from the top level
into the RefFunc logic. That way we only add those connections to functions that
actually have a RefFunc, which avoids us thinking that a function without one can be
reached by a call_ref of its type.

Has a small but non-zero benefit on j2wasm.

1 files changed, 14 insertions, 21 deletions

diff --git a/src/ir/possible-contents.cpp b/src/ir/possible-contents.cpp
index 4755c9904..fd186a74f 100644
--- a/src/ir/possible-contents.cpp
+++ b/src/ir/possible-contents.cpp
@@ -418,6 +418,20 @@ struct InfoCollector
     addRoot(
       curr,
       PossibleContents::literal(Literal(curr->func, curr->type.getHeapType())));
+
+    // The presence of a RefFunc indicates the function may be called
+    // indirectly, so add the relevant connections for this particular function.
+    // We do so here in the RefFunc so that we only do it for functions that
+    // actually have a RefFunc.
+    auto* func = getModule()->getFunction(curr->func);
+    for (Index i = 0; i < func->getParams().size(); i++) {
+      info.links.push_back(
+        {SignatureParamLocation{func->type, i}, LocalLocation{func, i, 0}});
+    }
+    for (Index i = 0; i < func->getResults().size(); i++) {
+      info.links.push_back(
+        {ResultLocation{func, i}, SignatureResultLocation{func->type, i}});
+    }
   }
   void visitRefEq(RefEq* curr) {
     addRoot(curr);
@@ -616,9 +630,6 @@ struct InfoCollector
     handleIndirectCall(curr, curr->heapType);
   }
   void visitCallRef(CallRef* curr) {
-    // TODO: Optimize like RefCast etc.: the values reaching us depend on the
-    //       possible values of |target| (which might be nothing, or might be a
-    //       constant function).
     handleIndirectCall(curr, curr->target->type);
   }
 
@@ -1295,24 +1306,6 @@ Flower::Flower(Module& wasm) : wasm(wasm) {
   }
 
 #ifdef POSSIBLE_CONTENTS_DEBUG
-  std::cout << "func phase\n";
-#endif
-
-  // Connect function parameters to their signature, so that any indirect call
-  // of that signature will reach them.
-  // TODO: find which functions are even taken by reference
-  for (auto& func : wasm.functions) {
-    for (Index i = 0; i < func->getParams().size(); i++) {
-      links.insert(getIndexes({SignatureParamLocation{func->type, i},
-                               LocalLocation{func.get(), i, 0}}));
-    }
-    for (Index i = 0; i < func->getResults().size(); i++) {
-      links.insert(getIndexes({ResultLocation{func.get(), i},
-                               SignatureResultLocation{func->type, i}}));
-    }
-  }
-
-#ifdef POSSIBLE_CONTENTS_DEBUG
   std::cout << "struct phase\n";
 #endif