[LLVM][WebAssembly] Implement branch hinting proposal

clang/include/clang/Options/Options.td

@@ -5468,6 +5468,8 @@ def mharden_sls_EQ : Joined<["-"], "mharden-sls=">, Group<m_Group>,
 
 def matomics : Flag<["-"], "matomics">, Group<m_wasm_Features_Group>;
 def mno_atomics : Flag<["-"], "mno-atomics">, Group<m_wasm_Features_Group>;
+def mbranch_hinting : Flag<["-"], "mbranch-hinting">, Group<m_wasm_Features_Group>;
+def mno_branch_hinting : Flag<["-"], "mno-branch-hinting">, Group<m_wasm_Features_Group>;
 def mbulk_memory : Flag<["-"], "mbulk-memory">, Group<m_wasm_Features_Group>;
 def mno_bulk_memory : Flag<["-"], "mno-bulk-memory">, Group<m_wasm_Features_Group>;
 def mbulk_memory_opt : Flag<["-"], "mbulk-memory-opt">, Group<m_wasm_Features_Group>;

clang/lib/Basic/Targets/WebAssembly.cpp

@@ -53,6 +53,7 @@ bool WebAssemblyTargetInfo::setABI(const std::string &Name) {
 bool WebAssemblyTargetInfo::hasFeature(StringRef Feature) const {
   return llvm::StringSwitch<bool>(Feature)
       .Case("atomics", HasAtomics)
+      .Case("branch-hinting", HasBranchHinting)
       .Case("bulk-memory", HasBulkMemory)
       .Case("bulk-memory-opt", HasBulkMemoryOpt)
       .Case("call-indirect-overlong", HasCallIndirectOverlong)
@@ -87,6 +88,8 @@ void WebAssemblyTargetInfo::getTargetDefines(const LangOptions &Opts,
   defineCPUMacros(Builder, "wasm", /*Tuning=*/false);
   if (HasAtomics)
     Builder.defineMacro("__wasm_atomics__");
+  if (HasBranchHinting)
+    Builder.defineMacro("__wasm_branch_hinting__");
   if (HasBulkMemory)
     Builder.defineMacro("__wasm_bulk_memory__");
   if (HasBulkMemoryOpt)
@@ -191,6 +194,7 @@ bool WebAssemblyTargetInfo::initFeatureMap(
   auto addBleedingEdgeFeatures = [&]() {
     addGenericFeatures();
     Features["atomics"] = true;
+    Features["branch-hinting"] = true;
     Features["exception-handling"] = true;
     Features["extended-const"] = true;
     Features["fp16"] = true;
@@ -223,6 +227,14 @@ bool WebAssemblyTargetInfo::handleTargetFeatures(
       HasAtomics = false;
       continue;
     }
+    if (Feature == "+branch-hinting") {
+      HasBranchHinting = true;
+      continue;
+    }
+    if (Feature == "-branch-hinting") {
+      HasBranchHinting = false;
+      continue;
+    }
     if (Feature == "+bulk-memory") {
       HasBulkMemory = true;
       continue;

clang/lib/Basic/Targets/WebAssembly.h

@@ -58,6 +58,7 @@ class LLVM_LIBRARY_VISIBILITY WebAssemblyTargetInfo : public TargetInfo {
   } SIMDLevel = NoSIMD;
 
   bool HasAtomics = false;
+  bool HasBranchHinting = false;
   bool HasBulkMemory = false;
   bool HasBulkMemoryOpt = false;
   bool HasCallIndirectOverlong = false;