Change target string to Target object in the TE compiler and interpreter

include/tvm/target/target.h

@@ -31,6 +31,7 @@
 #include <tvm/target/target_kind.h>
 
 #include <string>
+#include <unordered_map>
 #include <unordered_set>
 #include <vector>
 
@@ -203,5 +204,6 @@ void CheckAndUpdateHostConsistency(Map<Integer, Target>* target, Target* host);
  * \param host The Target typed object for target host to be updated
  */
 void CheckAndUpdateHostConsistency(Map<Target, IRModule>* target, Target* host);
+
 }  // namespace tvm
 #endif  // TVM_TARGET_TARGET_H_

src/relay/backend/aot_executor_codegen.cc

@@ -669,11 +669,10 @@ class AOTExecutorCodegen : public ExprVisitor {
     ret.lowered_funcs = lowered_module.per_target_module;
     ret.external_mods = lowered_module.external_mods;
 
-    auto target_host_str = target_host_->str();
-    if (ret.lowered_funcs.find(target_host_str) != ret.lowered_funcs.end()) {
-      ret.lowered_funcs[target_host_str]->Update(mod_run);
+    if (ret.lowered_funcs.find(target_host_) != ret.lowered_funcs.end()) {
+      ret.lowered_funcs[target_host_]->Update(mod_run);
     } else {
-      ret.lowered_funcs.Set(target_host_str, mod_run);
+      ret.lowered_funcs.Set(target_host_, mod_run);
     }
 
     std::vector<String> input_var_names(input_vars_.size());
@@ -778,7 +777,7 @@ class AOTExecutorCodegenModule : public runtime::ModuleNode {
     return (*it).second.first;
   }
 
-  Map<String, IRModule> get_irmodule() { return this->output_.lowered_funcs; }
+  Map<Target, IRModule> get_irmodule() { return this->output_.lowered_funcs; }
 
   std::shared_ptr<AOTExecutorCodegen> codegen_;
   LoweredOutput output_;

src/relay/backend/build_module.cc

@@ -92,8 +92,8 @@ struct ExecutorCodegen {
     return CallFunc<Array<tvm::runtime::Module>>("get_external_modules", nullptr);
   }
 
-  Map<String, IRModule> GetIRModule() {
-    return CallFunc<Map<String, IRModule>>("get_irmodule", nullptr);
+  Map<Target, IRModule> GetIRModule() {
+    return CallFunc<Map<Target, IRModule>>("get_irmodule", nullptr);
   }
 
   runtime::Metadata GetMetadata() { return CallFunc<runtime::Metadata>("get_metadata"); }
@@ -491,8 +491,9 @@ class RelayBuildModule : public runtime::ModuleNode {
     auto lowered_funcs = executor_codegen_->GetIRModule();
 
     // No need to build for external functions.
-    if (lowered_funcs.find("ext_dev") != lowered_funcs.end()) {
-      lowered_funcs.Set("ext_dev", IRModule());
+    Target ext_dev("ext_dev");
+    if (lowered_funcs.find(ext_dev) != lowered_funcs.end()) {
+      lowered_funcs.Set(ext_dev, IRModule());
     }
 
     // Generate a placeholder function that attaches linked params as its arguments.
@@ -510,11 +511,11 @@ class RelayBuildModule : public runtime::ModuleNode {
       DictAttrs attrs{dict};
       auto prim = tir::PrimFunc(Array<tir::Var>(), tir::SeqStmt(Array<tir::Stmt>()), VoidType(),
                                 Map<tir::Var, tir::Buffer>(), attrs);
-      if (lowered_funcs.find(target_host->str()) == lowered_funcs.end()) {
-        lowered_funcs.Set(target_host->str(), IRModule(Map<GlobalVar, BaseFunc>({})));
+      if (lowered_funcs.find(target_host) == lowered_funcs.end()) {
+        lowered_funcs.Set(target_host, IRModule(Map<GlobalVar, BaseFunc>({})));
       }
-      lowered_funcs[target_host->str()]->Add(
-          GlobalVar(::tvm::runtime::symbol::tvm_lookup_linked_param), prim);
+      lowered_funcs[target_host]->Add(GlobalVar(::tvm::runtime::symbol::tvm_lookup_linked_param),
+                                      prim);
     }
 
     // When there is no lowered_funcs due to reasons such as optimization.

src/relay/backend/interpreter.cc

@@ -53,7 +53,11 @@ namespace {
 struct PairHash {
   template <typename T1, typename T2>
   std::size_t operator()(const std::pair<T1, T2>& k) const {
-    return std::hash<T1>()(k.first) ^ std::hash<T2>()(k.second);
+    return dmlc::HashCombine(std::hash<T1>()(k.first), std::hash<T2>()(k.second));
+  }
+  template <typename T2>
+  std::size_t operator()(const std::pair<Target, T2>& k) const {
+    return dmlc::HashCombine(ObjectHash()(k.first), std::hash<T2>()(k.second));
   }
 };
 
@@ -289,7 +293,7 @@ class Interpreter : public ExprFunctor<ObjectRef(const Expr& n)>,
                     PatternFunctor<bool(const Pattern& p, const ObjectRef& v)> {
  public:
   // TODO(mbs): Collapse mod and per_target_module once IRModule subsumes LoweredModule.
-  Interpreter(IRModule mod, Map<String, IRModule> per_target_module, Device device, Target target)
+  Interpreter(IRModule mod, Map<Target, IRModule> per_target_module, Device device, Target target)
       : mod_(mod),
         per_target_module_(per_target_module),
         device_(device),
@@ -373,7 +377,7 @@ class Interpreter : public ExprFunctor<ObjectRef(const Expr& n)>,
    */
   PackedFunc TIRToPackedFunc(const GlobalVar& tir_fn_var, const Array<GlobalVar>& all_tir_fn_vars,
                              Target target) {
-    std::pair<std::string, std::string> packed_func_key(target->str(), tir_fn_var->name_hint);
+    std::pair<Target, std::string> packed_func_key(target, tir_fn_var->name_hint);
     auto packed_itr = compiled_packed_funcs_.find(packed_func_key);
     if (packed_itr != compiled_packed_funcs_.end()) {
       // Already compiled.
@@ -382,8 +386,11 @@ class Interpreter : public ExprFunctor<ObjectRef(const Expr& n)>,
 
     // Project out just the function(s) we need.
     IRModule lowered_projected_mod;
-    auto mod_itr = per_target_module_.find(target->str());
-    ICHECK(mod_itr != per_target_module_.end())
+    std::unordered_map<Target, IRModule, backend::TargetStrHash, backend::TargetStrEqual>
+        per_target_module_std_map =
+            backend::TargetModuleMapToTargetStrModuleMap(per_target_module_);
+    auto mod_itr = per_target_module_std_map.find(target);
+    ICHECK(mod_itr != per_target_module_std_map.end())
         << "No target module for target '" << target->str() << "'";
     const IRModule& target_module = (*mod_itr).second;
     for (const auto& var : all_tir_fn_vars) {
@@ -407,7 +414,7 @@ class Interpreter : public ExprFunctor<ObjectRef(const Expr& n)>,
       PackedFunc packed_func = runtime_module.GetFunction(var->name_hint);
       ICHECK(packed_func != nullptr) << "No packed function for global var '" << var->name_hint
                                      << "' in compiled module for target '" << target->str() << "'";
-      compiled_packed_funcs_.emplace(std::make_pair(target->str(), var->name_hint), packed_func);
+      compiled_packed_funcs_.emplace(std::make_pair(target, var->name_hint), packed_func);
     }
 
     // Return just what we need for this call.
@@ -874,11 +881,10 @@ class Interpreter : public ExprFunctor<ObjectRef(const Expr& n)>,
   // Map from target key to lowered TIR functions derived from mod_.
   // Note that primitives are implicitly executed on target_, while shape functions are implicitly
   // executed on the default 'cpu' host. Thus this map has at most two entries.
-  Map<String, IRModule> per_target_module_;
+  Map<Target, IRModule> per_target_module_;
   // Cached packed functions for the primitives and shape functions, keyed by target and
   // global var name.
-  std::unordered_map<std::pair<std::string, std::string>, PackedFunc, PairHash>
-      compiled_packed_funcs_;
+  std::unordered_map<std::pair<Target, std::string>, PackedFunc, PairHash> compiled_packed_funcs_;
   // Unique device on which primitives (but not shape functions) will be executed.
   // (For simplicity we only run the interpreter on a single device.)
   Device device_;
@@ -895,7 +901,7 @@ class Interpreter : public ExprFunctor<ObjectRef(const Expr& n)>,
  * rewritten \p mod and target-specific modules containing bindings for all TIR primitive
  * functions needed by the rewritten module.
  */
-std::pair<IRModule, Map<String, IRModule>> Prepare(IRModule mod, Device device, Target target) {
+std::pair<IRModule, Map<Target, IRModule>> Prepare(IRModule mod, Device device, Target target) {
   // Run minimal transforms on module to establish invariants needed by interpreter.
   transform::Sequential seq({transform::SimplifyInference(),
                              // FuseOps will mark wrapped calls to prim-ops with the 'Primitive'
@@ -1014,7 +1020,7 @@ TypedPackedFunc<ObjectRef(Array<Expr>)> EvalFunction(IRModule mod, Expr expr, De
     // and can just eval it directly.
     expr_to_eval = expr;
   }
-  std::pair<IRModule, Map<String, IRModule>> main_and_lowered =
+  std::pair<IRModule, Map<Target, IRModule>> main_and_lowered =
       Prepare(mod_with_expr, device, target);
   std::shared_ptr<Interpreter> intrp = std::make_shared<Interpreter>(
       /*mod=*/main_and_lowered.first, /*per_target_module=*/main_and_lowered.second, device,
@@ -1057,7 +1063,7 @@ ObjectRef Eval(Expr expr, Map<GlobalTypeVar, TypeData> type_definitions,
                std::unordered_set<String> import_set, Device device, Target target) {
   std::pair<IRModule, GlobalVar> mod_and_global =
       IRModule::FromExprInContext(expr, /*global_funcs=*/{}, type_definitions, import_set);
-  std::pair<IRModule, Map<String, IRModule>> main_and_lowered =
+  std::pair<IRModule, Map<Target, IRModule>> main_and_lowered =
       Prepare(mod_and_global.first, device, target);
   Interpreter intrp(
       /*mod=*/main_and_lowered.first, /*per_target_module=*/main_and_lowered.second, device,

src/relay/backend/te_compiler.cc

@@ -85,32 +85,33 @@ class TECompilerImpl : public TECompilerNode {
     return LowerShapeFuncInternal(key)->cached_func;
   }
 
-  Map<String, IRModule> GetLoweredFunctions() {
-    Map<String, IRModule> lowered_functions;
+  Map<Target, IRModule> GetLoweredFunctions() {
+    std::unordered_map<Target, IRModule, backend::TargetStrHash, backend::TargetStrEqual>
+        lowered_functions;
     for (const auto& it : cache_) {
       auto source_func = it.first;
       auto lowered_func = it.second;
       auto target = source_func->target;
 
-      if (!lowered_functions.count(target->str())) {
-        lowered_functions.Set(target->str(), IRModule(Map<GlobalVar, BaseFunc>({})));
+      if (!lowered_functions.count(target)) {
+        lowered_functions[target] = IRModule(Map<GlobalVar, BaseFunc>({}));
       }
 
-      lowered_functions[target->str()]->Update(lowered_func->cached_func->funcs);
+      lowered_functions[target]->Update(lowered_func->cached_func->funcs);
     }
 
     for (const auto& it : shape_func_cache_) {
       auto source_func = it.first;
       auto lowered_func = it.second;
       auto target = source_func->target;
 
-      if (!lowered_functions.count(target->str())) {
-        lowered_functions.Set(target->str(), IRModule(Map<GlobalVar, BaseFunc>({})));
+      if (!lowered_functions.count(target)) {
+        lowered_functions[target] = IRModule(Map<GlobalVar, BaseFunc>({}));
       }
 
-      lowered_functions[target->str()]->Update(lowered_func->cached_func->funcs);
+      lowered_functions[target]->Update(lowered_func->cached_func->funcs);
     }
-    return lowered_functions;
+    return backend::TargetStrModuleMapToTargetModuleMap(lowered_functions);
   }
 
   Array<tvm::runtime::Module> LowerExternalFunctions() {
@@ -884,7 +885,7 @@ IRModule LoweredModuleToIRModule(LoweredModule mod) {
 
   // Annotate the per-target functions with their target and add them to the unified module
   for (const auto& kv : mod.per_target_module) {
-    const String target = kv.first;
+    const Target target = kv.first;
     const IRModule target_module = kv.second;
 
     // Right now, per-target functions are TIR functions, which don't have type definitions, so
@@ -926,15 +927,15 @@ LoweredModule IRModuleToLoweredModule(IRModule mod) {
     main_mod->AddTypeDef(kv.first, kv.second);
   }
 
-  Map<String, IRModule> per_target_modules;
+  Map<Target, IRModule> per_target_modules;
   for (const auto& kv : mod->functions) {
     const GlobalVar& var = kv.first;
     const BaseFunc& func = kv.second;
     if (func->IsInstance<relay::FunctionNode>()) {
       main_mod->Add(var, func);
     } else if (func->IsInstance<tir::PrimFuncNode>()) {
       // Extract target
-      Optional<String> target = func->GetAttr<String>(tvm::attr::kTarget);
+      Optional<Target> target = func->GetAttr<Target>(tvm::attr::kTarget);
       ICHECK(target) << "Target should be set at this point";
 
       // Put the function in per_target_modules

src/relay/backend/te_compiler.h

@@ -97,7 +97,7 @@ class TECompilerNode : public Object {
   virtual CachedFunc Lower(const CCacheKey& key, const String mod_name) = 0;
 
   /* Return all functions which have been lowered by the compiler, keyed by target. */
-  virtual Map<String, IRModule> GetLoweredFunctions() = 0;
+  virtual Map<Target, IRModule> GetLoweredFunctions() = 0;
 
   /*!
    * \brief Just in time compile to get a PackedFunc.
@@ -144,7 +144,7 @@ struct LoweredModule {
   /*! \brief The module which contains the Relay code. */
   IRModule main_module;
   /*! \brief The module which contains per target code. */
-  Map<String, IRModule> per_target_module;
+  Map<Target, IRModule> per_target_module;
   /*! \brief The external runtime modules which must be combined with the lowered code. */
   Array<tvm::runtime::Module> external_mods;
   // TODO(@electriclilies): THis might need to become a map

src/relay/backend/utils.cc

@@ -187,6 +187,24 @@ Array<Pass> GetPassPrefix(const Map<tvm::Integer, tvm::Target>& targets, bool is
   return pass_seqs;
 }
 
+std::unordered_map<Target, IRModule, TargetStrHash, TargetStrEqual>
+TargetModuleMapToTargetStrModuleMap(Map<Target, IRModule> input_map) {
+  std::unordered_map<Target, IRModule, TargetStrHash, TargetStrEqual> std_map;
+  for (auto kv : input_map) {
+    std_map[kv.first] = kv.second;
+  }
+  return std_map;
+}
+
+Map<Target, IRModule> TargetStrModuleMapToTargetModuleMap(
+    std::unordered_map<Target, IRModule, TargetStrHash, TargetStrEqual> input_map) {
+  Map<Target, IRModule> tvm_map;
+  for (auto kv : input_map) {
+    tvm_map.Set(kv.first, kv.second);
+  }
+  return tvm_map;
+}
+
 }  // namespace backend
 }  // namespace relay
 }  // namespace tvm

src/relay/backend/utils.h

@@ -139,7 +139,7 @@ int64_t CalculateRelayExprSizeBytes(const Type& expr_type);
  */
 struct LoweredOutput {
   std::string graph_json;
-  Map<String, IRModule> lowered_funcs;
+  Map<Target, IRModule> lowered_funcs;
   Array<tvm::runtime::Module> external_mods;
   Map<String, FunctionInfo> function_metadata;
   std::unordered_map<std::string, std::pair<int, const tvm::runtime::NDArray>> params;
@@ -427,6 +427,60 @@ inline bool IsCompileEngineCacheDisabled() {
  */
 Array<Pass> GetPassPrefix(const Map<tvm::Integer, tvm::Target>& targets, bool is_vm);
 
+/*! \brief Target hash function */
+struct TargetStrHash {
+  /*!
+   * \brief Calculate the hash code of a Target based on the string value of the Target.
+   Note that this hash should NOT be used in new usecases, equality of targets based on their
+   value is not well-defined.
+   This will be removed when maps from Targets to IRModules are removed from the codebase.
+   * \param target The Target to hash
+   * \return String hash of the target
+   */
+  size_t operator()(const Target& target) const {
+    return String::HashBytes(target->str().c_str(), target->str().size());
+  }
+};
+
+/*! \brief Target equality function based on the string value of Target
+Note that this equality function should NOT be used in new usecases, equality of targets based on
+their value is not well-defined. This will be removed when maps from Targets to IRModules are
+removed from the codebase.*/
+struct TargetStrEqual {
+  /*!
+   * \brief Check if the two Targets are equal
+   * \param target One Target
+   * \param other_target The other Target
+   * \return String equality of the targets
+   */
+  const bool operator()(const Target& target, const Target& other_target) const {
+    TargetStrHash target_hash = TargetStrHash();
+    return target_hash(target) == target_hash(other_target);
+  }
+};
+
+/*!
+ * \brief Convert a Map<Target, IRModule> to std::unordered_map<Target, IRmodule, TargetStrHash,
+ * TargetStrEqual> Target equality is currently based on pointer equality, which is a problem since
+ * we have a lot of Map<Target, IRModule> in the codebase. This function converts the map to a
+ * version that is keyed based on string value of the Target instead. Note that once we remove
+ * Map<Target, IRModule>, this function will be removed.
+ * \param input_map The map to convert
+ * \return The converted map
+ */
+std::unordered_map<Target, IRModule, TargetStrHash, TargetStrEqual>
+TargetModuleMapToTargetStrModuleMap(Map<Target, IRModule> input_map);
+
+/*!
+ * \brief Convert a std::unordered_map<Target, IRmodule, TargetStrHash, TargetStrEqual> to
+ * Map<Target, IRModule> This function is a helper that undoes TargetModuleMapToTargetStr. Note that
+ * once we remove Map<Target, IRModule>, this function will be removed.
+ * \param input_map The map to convert
+ * \return The converted map
+ */
+Map<Target, IRModule> TargetStrModuleMapToTargetModuleMap(
+    std::unordered_map<Target, IRModule, TargetStrHash, TargetStrEqual> input_map);
+
 }  // namespace backend
 }  // namespace relay
 }  // namespace tvm