Add a codegen option to allow loading LLVM pass plugins

Author: eskarn

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -470,6 +470,8 @@ pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(
 
     let extra_passes = config.passes.join(",");
 
+    let pass_plugins = config.pass_plugins.join(" ");
+
     // FIXME: NewPM doesn't provide a facility to pass custom InlineParams.
     // We would have to add upstream support for this first, before we can support
     // config.inline_threshold and our more aggressive default thresholds.
@@ -499,6 +501,8 @@ pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(
         selfprofile_after_pass_callback,
         extra_passes.as_ptr().cast(),
         extra_passes.len(),
+        pass_plugins.as_ptr().cast(),
+        pass_plugins.len(),
     );
     result.into_result().map_err(|()| llvm_err(diag_handler, "failed to run LLVM passes"))
 }

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -2304,6 +2304,8 @@ extern "C" {
         end_callback: SelfProfileAfterPassCallback,
         ExtraPasses: *const c_char,
         ExtraPassesLen: size_t,
+        PassPlugins: *const c_char,
+        PassPluginsLen: size_t,
     ) -> LLVMRustResult;
     pub fn LLVMRustPrintModule(
         M: &'a Module,

compiler/rustc_codegen_ssa/src/back/write.rs

@@ -74,6 +74,8 @@ pub enum BitcodeSection {
 pub struct ModuleConfig {
     /// Names of additional optimization passes to run.
     pub passes: Vec<String>,
+    /// Paths of LLVM pass plugins to load.
+    pub pass_plugins: Vec<String>,
     /// Some(level) to optimize at a certain level, or None to run
     /// absolutely no optimizations (used for the metadata module).
     pub opt_level: Option<config::OptLevel>,
@@ -170,6 +172,8 @@ impl ModuleConfig {
         ModuleConfig {
             passes: if_regular!(sess.opts.cg.passes.clone(), vec![]),
 
+            pass_plugins: if_regular!(sess.opts.cg.pass_plugins.clone(), vec![]),
+
             opt_level: opt_level_and_size,
             opt_size: opt_level_and_size,
 

compiler/rustc_interface/src/tests.rs

@@ -587,6 +587,7 @@ fn test_codegen_options_tracking_hash() {
     tracked!(overflow_checks, Some(true));
     tracked!(panic, Some(PanicStrategy::Abort));
     tracked!(passes, vec![String::from("1"), String::from("2")]);
+    tracked!(pass_plugins, vec![String::from("1"), String::from("2")]);
     tracked!(prefer_dynamic, true);
     tracked!(profile_generate, SwitchWithOptPath::Enabled(None));
     tracked!(profile_use, Some(PathBuf::from("abc")));

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -17,6 +17,7 @@
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Object/IRObjectFile.h"
 #include "llvm/Passes/PassBuilder.h"
+#include "llvm/Passes/PassPlugin.h"
 #include "llvm/Passes/StandardInstrumentations.h"
 #include "llvm/Support/CBindingWrapping.h"
 #include "llvm/Support/FileSystem.h"
@@ -753,7 +754,8 @@ LLVMRustOptimizeWithNewPassManager(
     void* LlvmSelfProfiler,
     LLVMRustSelfProfileBeforePassCallback BeforePassCallback,
     LLVMRustSelfProfileAfterPassCallback AfterPassCallback,
-    const char *ExtraPasses, size_t ExtraPassesLen) {
+    const char *ExtraPasses, size_t ExtraPassesLen,
+    const char *PassPlugins, size_t PassPluginsLen) {
   Module *TheModule = unwrap(ModuleRef);
   TargetMachine *TM = unwrap(TMRef);
   OptimizationLevel OptLevel = fromRust(OptLevelRust);
@@ -924,6 +926,20 @@ LLVMRustOptimizeWithNewPassManager(
     }
   }
 
+  if (PassPluginsLen) {
+    auto PluginsStr = StringRef(PassPlugins, PassPluginsLen);
+    SmallVector<StringRef> Plugins;
+    PluginsStr.split(Plugins, ' ', -1, false);
+    for (auto PluginPath: Plugins) {
+      auto Plugin = PassPlugin::Load(PluginPath.str());
+      if (!Plugin) {
+        LLVMRustSetLastError(("Failed to load pass plugin" + PluginPath.str()).c_str());
+        continue;
+      }
+      Plugin->registerPassBuilderCallbacks(PB);
+    }
+  }
+
 #if LLVM_VERSION_GE(13, 0)
   ModulePassManager MPM;
 #else

compiler/rustc_session/src/options.rs

@@ -1033,6 +1033,8 @@ options! {
         "panic strategy to compile crate with"),
     passes: Vec<String> = (Vec::new(), parse_list, [TRACKED],
         "a list of extra LLVM passes to run (space separated)"),
+    pass_plugins: Vec<String> = (Vec::new(), parse_list, [TRACKED],
+        "a list of LLVM pass plugins to load (space separated)"),
     prefer_dynamic: bool = (false, parse_bool, [TRACKED],
         "prefer dynamic linking to static linking (default: no)"),
     profile_generate: SwitchWithOptPath = (SwitchWithOptPath::Disabled,