rustc_codegen_llvm: move should_use_new_llvm_pass_manager function to llvm_util

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -3,7 +3,7 @@ use crate::back::write::{
 };
 use crate::llvm::archive_ro::ArchiveRO;
 use crate::llvm::{self, build_string, False, True};
-use crate::{LlvmCodegenBackend, ModuleLlvm};
+use crate::{llvm_util, LlvmCodegenBackend, ModuleLlvm};
 use rustc_codegen_ssa::back::lto::{LtoModuleCodegen, SerializedModule, ThinModule, ThinShared};
 use rustc_codegen_ssa::back::symbol_export;
 use rustc_codegen_ssa::back::write::{
@@ -596,7 +596,10 @@ pub(crate) fn run_pass_manager(
     //      tools/lto/LTOCodeGenerator.cpp
     debug!("running the pass manager");
     unsafe {
-        if write::should_use_new_llvm_pass_manager(cgcx, config) {
+        if llvm_util::should_use_new_llvm_pass_manager(
+            &config.new_llvm_pass_manager,
+            &cgcx.target_arch,
+        ) {
             let opt_stage = if thin { llvm::OptStage::ThinLTO } else { llvm::OptStage::FatLTO };
             let opt_level = config.opt_level.unwrap_or(config::OptLevel::No);
             write::optimize_with_new_llvm_pass_manager(

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -413,21 +413,6 @@ fn get_pgo_sample_use_path(config: &ModuleConfig) -> Option<CString> {
         .map(|path_buf| CString::new(path_buf.to_string_lossy().as_bytes()).unwrap())
 }
 
-pub(crate) fn should_use_new_llvm_pass_manager(
-    cgcx: &CodegenContext<LlvmCodegenBackend>,
-    config: &ModuleConfig,
-) -> bool {
-    // The new pass manager is enabled by default for LLVM >= 13.
-    // This matches Clang, which also enables it since Clang 13.
-
-    // FIXME: There are some perf issues with the new pass manager
-    // when targeting s390x, so it is temporarily disabled for that
-    // arch, see https://github.com/rust-lang/rust/issues/89609
-    config
-        .new_llvm_pass_manager
-        .unwrap_or_else(|| cgcx.target_arch != "s390x" && llvm_util::get_version() >= (13, 0, 0))
-}
-
 pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     diag_handler: &Handler,
@@ -531,7 +516,10 @@ pub(crate) unsafe fn optimize(
     }
 
     if let Some(opt_level) = config.opt_level {
-        if should_use_new_llvm_pass_manager(cgcx, config) {
+        if llvm_util::should_use_new_llvm_pass_manager(
+            &config.new_llvm_pass_manager,
+            &cgcx.target_arch,
+        ) {
             let opt_stage = match cgcx.lto {
                 Lto::Fat => llvm::OptStage::PreLinkFatLTO,
                 Lto::Thin | Lto::ThinLocal => llvm::OptStage::PreLinkThinLTO,

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -415,3 +415,13 @@ pub fn tune_cpu(sess: &Session) -> Option<&str> {
     let name = sess.opts.debugging_opts.tune_cpu.as_ref()?;
     Some(handle_native(name))
 }
+
+pub(crate) fn should_use_new_llvm_pass_manager(user_opt: &Option<bool>, target_arch: &str) -> bool {
+    // The new pass manager is enabled by default for LLVM >= 13.
+    // This matches Clang, which also enables it since Clang 13.
+
+    // FIXME: There are some perf issues with the new pass manager
+    // when targeting s390x, so it is temporarily disabled for that
+    // arch, see https://github.com/rust-lang/rust/issues/89609
+    user_opt.unwrap_or_else(|| target_arch != "s390x" && llvm_util::get_version() >= (13, 0, 0))
+}