Revert changes of GetPassPrefix interface.

Author: ibsidorenko

src/relay/backend/build_module.cc

@@ -328,7 +328,7 @@ class RelayBuildModule : public runtime::ModuleNode {
     backend::BindParamsInModule(relay_module, params_);
 
     Array<Pass> pass_seqs =
-        GetPassPrefix(/*homogeneous target=*/config_->optional_homogeneous_target, /*is_vm=*/false);
+        GetPassPrefix(/*is_homogenous=*/config_->primitive_targets.size() == 1, /*is_vm=*/false);
     transform::PassContext pass_ctx = PassContext::Current();
 
     if (config_->optional_homogeneous_target.defined()) {

src/relay/backend/task_extraction.cc

@@ -36,7 +36,7 @@ Array<meta_schedule::ExtractedTask> ExtractTask(IRModule mod, Target target,
   backend::FTECompilerTIRConverter tir_converter = backend::GetTIRConverter();
   backend::BindParamsInModule(mod, params);
   // is_vm=true for backward compatibility
-  Array<Pass> pass_seqs = relay::backend::GetPassPrefix(target, /*is_vm=*/true);
+  Array<Pass> pass_seqs = relay::backend::GetPassPrefix(/*is_homogenous=*/true, /*is_vm=*/true);
   pass_seqs.push_back(transform::FuseOps());
 
   mod = transform::Sequential(pass_seqs)(std::move(mod));

src/relay/backend/utils.cc

@@ -219,15 +219,13 @@ ExecutorCodegenMetadata::ExecutorCodegenMetadata(
 
 TVM_REGISTER_NODE_TYPE(ExecutorCodegenMetadataNode);
 
-Array<Pass> GetPassPrefix(Target homogeneous_target, bool is_vm) {
+Array<Pass> GetPassPrefix(bool is_homogeneous, bool is_vm) {
   Array<Pass> pass_seqs;
   // TODO(mbs): Would be nice to get spans on all diagnostics, but since they arg forgotton
   // by most passes there's little utility in including this now. Plus we'd need to only do
   // this if there's no existing spans to work from.
   // pass_seqs.push_back(parser::AnnotateSpans());
   Array<runtime::String> entry_functions{"main"};
-  // Can be undefined in case of heterogeneous execution
-  bool is_homogeneous = homogeneous_target.defined();
   pass_seqs.push_back(transform::RemoveUnusedFunctions(entry_functions));
   pass_seqs.push_back(transform::ToBasicBlockNormalForm());
   // Run all dialect legalization passes.

src/relay/backend/utils.h

@@ -676,11 +676,11 @@ inline IRModule PrimFuncToIRModule(tir::PrimFunc f) {
  * difference. This function unifies the shared optimization pass prefix between vm and graph
  * runtime, and returns the pass prefix given the backend type.
  *
- * \param homogeneous_target Execution target (can be undefined in case of heterogeneous execution).
+ * \param is_homogeneous True if all primitives are to be executed on the same device and target.
  * \param is_vm True if passes are to be used for the vm executor.
  * \return An array of passes.
  */
-Array<Pass> GetPassPrefix(Target homogeneous_target, bool is_vm);
+Array<Pass> GetPassPrefix(bool is_homogeneous, bool is_vm);
 
 /*! \brief Target hash function */
 struct TargetStrHash {

src/relay/backend/vm/compiler.cc

@@ -1054,7 +1054,7 @@ transform::Sequential VMCompiler::FuseAndLowerOperators(const CompilationConfig&
 IRModule VMCompiler::OptimizeModuleImpl(IRModule mod) {
   backend::BindParamsInModule(mod, params_);
   Array<Pass> pass_seqs = relay::backend::GetPassPrefix(
-      /*homogeneous target=*/config_->optional_homogeneous_target, /*is_vm=*/true);
+      /*is_homogeneous=*/config_->optional_homogeneous_target.defined(), /*is_vm=*/true);
 
   // Always plan devices so the remaining passes don't need to distinguish homogeneous vs
   // heterogeneous execution.