Rollup merge of #96215 - nikic:legacy-pm-removal, r=nagisa

Drop support for legacy PM with LLVM 15

LLVM 15 already removes some of the legacy PM APIs we're using. This patch forces use of NewPM with LLVM 15 (with `-Z new-llvm-pass-manager=no` throwing a warning) and stubs out various FFI methods with a report_fatal_error on LLVM 15.

For LLVMPassManagerBuilderPopulateLTOPassManager() I went with adding our own wrapper, as the alternative would be to muck about with weak symbols, which seems to be non-trivial as far as cross-platform support is concerned (std has `weak!` for this purpose, but only as an internal utility.)

Fixes #96072.
Fixes #96362.

4 files changed, 29 insertions, 24 deletions

diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index 7a747a9cdee..3f5957bdb6e 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -625,7 +625,7 @@ pub(crate) fn run_pass_manager(
             if thin {
                 llvm::LLVMRustPassManagerBuilderPopulateThinLTOPassManager(b, pm);
             } else {
-                llvm::LLVMPassManagerBuilderPopulateLTOPassManager(
+                llvm::LLVMRustPassManagerBuilderPopulateLTOPassManager(
                     b, pm, /* Internalize = */ False, /* RunInliner = */ True,
                 );
             }
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 7ef3b12cd08..99e30531c22 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -523,6 +523,12 @@ pub(crate) unsafe fn optimize(
     let module_name = module.name.clone();
     let module_name = Some(&module_name[..]);
 
+    if let Some(false) = config.new_llvm_pass_manager && llvm_util::get_version() >= (15, 0, 0) {
+        diag_handler.warn(
+            "ignoring `-Z new-llvm-pass-manager=no`, which is no longer supported with LLVM 15",
+        );
+    }
+
     if config.emit_no_opt_bc {
         let out = cgcx.output_filenames.temp_path_ext("no-opt.bc", module_name);
         let out = path_to_c_string(&out);
@@ -628,8 +634,8 @@ pub(crate) unsafe fn optimize(
                         extra_passes.as_ptr(),
                         extra_passes.len() as size_t,
                     );
-                    llvm::LLVMPassManagerBuilderPopulateFunctionPassManager(b, fpm);
-                    llvm::LLVMPassManagerBuilderPopulateModulePassManager(b, mpm);
+                    llvm::LLVMRustPassManagerBuilderPopulateFunctionPassManager(b, fpm);
+                    llvm::LLVMRustPassManagerBuilderPopulateModulePassManager(b, mpm);
                 });
 
                 have_name_anon_globals_pass = have_name_anon_globals_pass || prepare_for_thin_lto;
@@ -1085,7 +1091,7 @@ pub unsafe fn with_llvm_pmb(
     // Create the PassManagerBuilder for LLVM. We configure it with
     // reasonable defaults and prepare it to actually populate the pass
     // manager.
-    let builder = llvm::LLVMPassManagerBuilderCreate();
+    let builder = llvm::LLVMRustPassManagerBuilderCreate();
     let opt_size = config.opt_size.map_or(llvm::CodeGenOptSizeNone, |x| to_llvm_opt_settings(x).1);
     let inline_threshold = config.inline_threshold;
     let pgo_gen_path = get_pgo_gen_path(config);
@@ -1102,14 +1108,9 @@ pub unsafe fn with_llvm_pmb(
         pgo_gen_path.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
         pgo_use_path.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
         pgo_sample_use_path.as_ref().map_or(ptr::null(), |s| s.as_ptr()),
+        opt_size as c_int,
     );
 
-    llvm::LLVMPassManagerBuilderSetSizeLevel(builder, opt_size as u32);
-
-    if opt_size != llvm::CodeGenOptSizeNone {
-        llvm::LLVMPassManagerBuilderSetDisableUnrollLoops(builder, 1);
-    }
-
     llvm::LLVMRustAddBuilderLibraryInfo(builder, llmod, config.no_builtins);
 
     // Here we match what clang does (kinda). For O0 we only inline
@@ -1118,16 +1119,16 @@ pub unsafe fn with_llvm_pmb(
     // thresholds copied from clang.
     match (opt_level, opt_size, inline_threshold) {
         (.., Some(t)) => {
-            llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, t);
+            llvm::LLVMRustPassManagerBuilderUseInlinerWithThreshold(builder, t);
         }
         (llvm::CodeGenOptLevel::Aggressive, ..) => {
-            llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 275);
+            llvm::LLVMRustPassManagerBuilderUseInlinerWithThreshold(builder, 275);
         }
         (_, llvm::CodeGenOptSizeDefault, _) => {
-            llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 75);
+            llvm::LLVMRustPassManagerBuilderUseInlinerWithThreshold(builder, 75);
         }
         (_, llvm::CodeGenOptSizeAggressive, _) => {
-            llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 25);
+            llvm::LLVMRustPassManagerBuilderUseInlinerWithThreshold(builder, 25);
         }
         (llvm::CodeGenOptLevel::None, ..) => {
             llvm::LLVMRustAddAlwaysInlinePass(builder, config.emit_lifetime_markers);
@@ -1136,12 +1137,12 @@ pub unsafe fn with_llvm_pmb(
             llvm::LLVMRustAddAlwaysInlinePass(builder, config.emit_lifetime_markers);
         }
         (llvm::CodeGenOptLevel::Default, ..) => {
-            llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 225);
+            llvm::LLVMRustPassManagerBuilderUseInlinerWithThreshold(builder, 225);
         }
     }
 
     f(builder);
-    llvm::LLVMPassManagerBuilderDispose(builder);
+    llvm::LLVMRustPassManagerBuilderDispose(builder);
 }
 
 // Create a `__imp_<symbol> = &symbol` global for every public static `symbol`.
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index 7f533b0552a..13baaddccd4 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -1825,24 +1825,22 @@ extern "C" {
 
     pub fn LLVMAddAnalysisPasses<'a>(T: &'a TargetMachine, PM: &PassManager<'a>);
 
-    pub fn LLVMPassManagerBuilderCreate() -> &'static mut PassManagerBuilder;
-    pub fn LLVMPassManagerBuilderDispose(PMB: &'static mut PassManagerBuilder);
-    pub fn LLVMPassManagerBuilderSetSizeLevel(PMB: &PassManagerBuilder, Value: Bool);
-    pub fn LLVMPassManagerBuilderSetDisableUnrollLoops(PMB: &PassManagerBuilder, Value: Bool);
-    pub fn LLVMPassManagerBuilderUseInlinerWithThreshold(
+    pub fn LLVMRustPassManagerBuilderCreate() -> &'static mut PassManagerBuilder;
+    pub fn LLVMRustPassManagerBuilderDispose(PMB: &'static mut PassManagerBuilder);
+    pub fn LLVMRustPassManagerBuilderUseInlinerWithThreshold(
         PMB: &PassManagerBuilder,
         threshold: c_uint,
     );
-    pub fn LLVMPassManagerBuilderPopulateModulePassManager(
+    pub fn LLVMRustPassManagerBuilderPopulateModulePassManager(
         PMB: &PassManagerBuilder,
         PM: &PassManager<'_>,
     );
 
-    pub fn LLVMPassManagerBuilderPopulateFunctionPassManager(
+    pub fn LLVMRustPassManagerBuilderPopulateFunctionPassManager(
         PMB: &PassManagerBuilder,
         PM: &PassManager<'_>,
     );
-    pub fn LLVMPassManagerBuilderPopulateLTOPassManager(
+    pub fn LLVMRustPassManagerBuilderPopulateLTOPassManager(
         PMB: &PassManagerBuilder,
         PM: &PassManager<'_>,
         Internalize: Bool,
@@ -2308,6 +2306,7 @@ extern "C" {
         PGOGenPath: *const c_char,
         PGOUsePath: *const c_char,
         PGOSampleUsePath: *const c_char,
+        SizeLevel: c_int,
     );
     pub fn LLVMRustAddLibraryInfo<'a>(
         PM: &PassManager<'a>,
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index c24e369ae72..7b407c94e7b 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -542,6 +542,11 @@ pub(crate) fn should_use_new_llvm_pass_manager(user_opt: &Option<bool>, target_a
     // The new pass manager is enabled by default for LLVM >= 13.
     // This matches Clang, which also enables it since Clang 13.
 
+    // Since LLVM 15, the legacy pass manager is no longer supported.
+    if llvm_util::get_version() >= (15, 0, 0) {
+        return true;
+    }
+
     // There are some perf issues with the new pass manager when targeting
     // s390x with LLVM 13, so enable the new pass manager only with LLVM 14.
     // See https://github.com/rust-lang/rust/issues/89609.