[NFC] Refactor a generic function for binary reading of a code annotations section (#7593)

This will save code with future annotations like inline hints.

Author: kripken

src/wasm-binary.h

@@ -1699,6 +1699,13 @@ class WasmBinaryReader {
   // Scans ahead in the binary to check certain conditions like
   // needCodeLocations.
   void preScan();
+
+  // Internal helper for reading a code annotation section for a hint that is
+  // expression offset based. Receives the section name, payload length of the
+  // section and a function to read a single hint (receiving the annotation to
+  // update).
+  template<typename ReadFunc>
+  void readExpressionHints(Name sectionName, size_t payloadLen, ReadFunc read);
 };
 
 } // namespace wasm

src/wasm/wasm-binary.cpp

@@ -5211,14 +5211,17 @@ void WasmBinaryReader::readDylink0(size_t payloadLen) {
   }
 }
 
-void WasmBinaryReader::readBranchHints(size_t payloadLen) {
+template<typename ReadFunc>
+void WasmBinaryReader::readExpressionHints(Name sectionName,
+                                           size_t payloadLen,
+                                           ReadFunc read) {
   auto sectionPos = pos;
 
   auto numFuncs = getU32LEB();
   for (Index i = 0; i < numFuncs; i++) {
     auto funcIndex = getU32LEB();
     if (funcIndex >= wasm.functions.size()) {
-      throwError("bad BranchHint function");
+      throwError("bad function in " + sectionName.toString());
     }
 
     auto& func = wasm.functions[funcIndex];
@@ -5243,22 +5246,11 @@ void WasmBinaryReader::readBranchHints(size_t payloadLen) {
 
       auto iter = locationsMap.find(absoluteOffset);
       if (iter == locationsMap.end()) {
-        throwError("bad BranchHint offset");
+        throwError("bad offset in " + sectionName.toString());
       }
       auto* expr = iter->second;
 
-      auto size = getU32LEB();
-      if (size != 1) {
-        throwError("bad BranchHint size");
-      }
-
-      auto likely = getU32LEB();
-      if (likely != 0 && likely != 1) {
-        throwError("bad BranchHint value");
-      }
-
-      // Apply the valid hint.
-      func->codeAnnotations[expr].branchLikely = likely;
+      read(func->codeAnnotations[expr]);
     }
   }
 
@@ -5267,6 +5259,25 @@ void WasmBinaryReader::readBranchHints(size_t payloadLen) {
   }
 }
 
+void WasmBinaryReader::readBranchHints(size_t payloadLen) {
+  readExpressionHints(Annotations::BranchHint,
+                      payloadLen,
+                      [&](Function::CodeAnnotation& annotation) {
+                        auto size = getU32LEB();
+                        if (size != 1) {
+                          throwError("bad BranchHint size");
+                        }
+
+                        auto likely = getU32LEB();
+                        if (likely != 0 && likely != 1) {
+                          throwError("bad BranchHint value");
+                        }
+
+                        // Apply the valid hint.
+                        annotation.branchLikely = likely;
+                      });
+}
+
 Index WasmBinaryReader::readMemoryAccess(Address& alignment, Address& offset) {
   auto rawAlignment = getU32LEB();
   bool hasMemIdx = false;