Merge pull request #72 from aya-rs/llvm-new-pm

Use new pass manager

Cargo.toml

@@ -17,21 +17,21 @@ edition = "2021"
 
 [dependencies]
 # cli deps
-clap = { version = "4.3", features = ["derive"] }
+clap = { version = "4.3.0", features = ["derive"] }
 simplelog = { version = "0.12.1" }
 
 # lib deps
 ar = { version = "0.9.0" }
-aya-rustc-llvm-proxy = { version = "0.6.0", optional = true }
-libc = { version = "0.2" }
-llvm-sys = { version = "160" }
-log = { version = "0.4" }
-thiserror = { version = "1.0" }
+aya-rustc-llvm-proxy = { version = "0.7.0", optional = true }
+libc = { version = "0.2.0" }
+llvm-sys = { version = "160.0.0" }
+log = { version = "0.4.0" }
+thiserror = { version = "1.0.0" }
 
 [dev-dependencies]
-compiletest_rs = { version = "0.5", path = "third-party/compiletest-rs" }
+compiletest_rs = { version = "0.5.0", path = "third-party/compiletest-rs" }
 rustc-build-sysroot = { version = "0.4.2" }
-which = { version = "4.2" }
+which = { version = "4.2.0" }
 
 [[bin]]
 name = "bpf-linker"

src/bin/bpf-linker.rs

@@ -141,7 +141,7 @@ struct CommandLine {
     export: Vec<String>,
 
     /// Whether to treat LLVM errors as fatal.
-    #[clap(long, action = clap::ArgAction::Set, default_value_t = false)]
+    #[clap(long, action = clap::ArgAction::Set, default_value_t = true)]
     fatal_errors: bool,
 
     // The options below are for wasm-ld compatibility

src/linker.rs

@@ -516,8 +516,24 @@ impl Linker {
 
 impl llvm::LLVMDiagnosticHandler for Linker {
     fn handle_diagnostic(&mut self, severity: llvm_sys::LLVMDiagnosticSeverity, message: &str) {
+        // TODO(https://reviews.llvm.org/D155894): Remove this when LLVM no longer emits these
+        // errors.
+        //
+        // See https://github.com/rust-lang/compiler-builtins/blob/a61823f/src/mem/mod.rs#L22-L68.
+        const MATCHERS: &[&str] = &[
+            "A call to built-in function 'memcpy' is not supported.\n",
+            "A call to built-in function 'memmove' is not supported.\n",
+            "A call to built-in function 'memset' is not supported.\n",
+            "A call to built-in function 'memcmp' is not supported.\n",
+            "A call to built-in function 'bcmp' is not supported.\n",
+            "A call to built-in function 'strlen' is not supported.\n",
+        ];
+
         match severity {
             llvm_sys::LLVMDiagnosticSeverity::LLVMDSError => {
+                if MATCHERS.iter().any(|matcher| message.ends_with(matcher)) {
+                    return;
+                }
                 self.has_errors = true;
 
                 error!("llvm: {}", message)

src/llvm/mod.rs

@@ -18,8 +18,7 @@ use llvm_sys::prelude::*;
 use llvm_sys::support::LLVMParseCommandLineOptions;
 use llvm_sys::target::*;
 use llvm_sys::target_machine::*;
-use llvm_sys::transforms::ipo::*;
-use llvm_sys::transforms::pass_manager_builder::*;
+use llvm_sys::transforms::pass_builder::*;
 use llvm_sys::LLVMAttributeFunctionIndex;
 use llvm_sys::{LLVMLinkage, LLVMVisibility};
 use log::*;
@@ -176,65 +175,48 @@ pub unsafe fn optimize(
         LLVMSetModuleInlineAsm2(module, ptr::null_mut(), 0);
     }
 
-    let mpm = LLVMCreatePassManager();
-    let fpm = LLVMCreateFunctionPassManagerForModule(module);
-
-    LLVMAddAnalysisPasses(tm, mpm);
-    LLVMAddAnalysisPasses(tm, fpm);
-
-    // even with -O0 and without LTO we still want to avoid linking in unused code from core etc
-    LLVMAddGlobalDCEPass(mpm);
-
-    let pmb = LLVMPassManagerBuilderCreate();
-
-    use OptLevel::*;
-    let (inline_threshold, opt) = match opt_level {
-        No | SizeMin => (0, 1), // Pretty much nothing compiles with -O0 s∫o make it an alias for -O1
-        Less => (25, 1),
-        Default => (225, 2),
-        Aggressive => (275, 3),
-        Size => (25, 0),
-    };
-    LLVMPassManagerBuilderSetOptLevel(pmb, opt);
-    LLVMPassManagerBuilderSetSizeLevel(
-        pmb,
-        match opt_level {
-            Size => 1,
-            SizeMin => 2,
-            _ => 0,
-        },
-    );
-    LLVMPassManagerBuilderUseInlinerWithThreshold(pmb, inline_threshold);
-
-    // populate the pass managers
-    LLVMPassManagerBuilderPopulateFunctionPassManager(pmb, fpm);
-    LLVMPassManagerBuilderPopulateModulePassManager(pmb, mpm);
-
     for sym in module.globals_iter() {
         internalize(sym, symbol_name(sym), export_symbols);
     }
     for sym in module.global_aliases_iter() {
         internalize(sym, symbol_name(sym), export_symbols);
     }
 
-    debug!("running function passes");
-    LLVMInitializeFunctionPassManager(fpm);
     for function in module.functions_iter() {
         let name = symbol_name(function);
         if !name.starts_with("llvm.") {
             if ignore_inline_never {
                 remove_attribute(function, "noinline");
             }
             internalize(function, name, export_symbols);
-            if LLVMIsDeclaration(function) == 0 {
-                LLVMRunFunctionPassManager(fpm, function);
-            }
         }
     }
-    LLVMFinalizeFunctionPassManager(fpm);
 
-    debug!("running module passes");
-    LLVMRunPassManager(mpm, module);
+    let options = LLVMCreatePassBuilderOptions();
+
+    let passes = [
+        // NB: "default<_>" must be the first pass in the list, otherwise it will be ignored.
+        match opt_level {
+            // Pretty much nothing compiles with -O0 so make it an alias for -O1.
+            OptLevel::No | OptLevel::Less => "default<O1>",
+            OptLevel::Default => "default<O2>",
+            OptLevel::Aggressive => "default<O3>",
+            OptLevel::Size => "default<Os>",
+            OptLevel::SizeMin => "default<Oz>",
+        },
+        // NB: This seems to be included in most default pipelines, but not obviously all of them.
+        // See
+        // https://github.com/llvm/llvm-project/blob/bbe2887f/llvm/lib/Passes/PassBuilderPipelines.cpp#L2011-L2012
+        // for a case which includes DCE only conditionally. Better safe than sorry; include it always.
+        "dce",
+    ];
+
+    let passes = passes.join(",");
+    debug!("running passes: {passes}");
+    let passes = CString::new(passes).unwrap();
+    LLVMRunPasses(module, passes.as_ptr(), tm, options);
+
+    LLVMDisposePassBuilderOptions(options);
 
     // Some debug info generated by rustc seems to trigger a segfault in the
     // BTF code in llvm, so strip it until that is fixed

tests/assembly/auxiliary/dep.rs

@@ -5,4 +5,4 @@
 #[no_mangle]
 fn some_dep() -> u8 {
     42
-}
+}

tests/assembly/auxiliary/loop-panic-handler.rs

@@ -6,4 +6,3 @@
 fn panic_impl(_: &core::panic::PanicInfo) -> ! {
     loop {}
 }
-

tests/assembly/elf-sections.rs

@@ -22,4 +22,4 @@ static mut COUNTER: u32 = 0;
 
 // CHECK: .section "uprobe/connect","ax"
 // CHECK: .section "uprobe/dep","ax"
-// CHECK: .section "maps/counter","aw"
+// CHECK: .section "maps/counter","aw"

tests/assembly/re-export-symbols.rs

@@ -15,4 +15,4 @@ fn connect() {
 }
 
 // CHECK: .globl connect
-// CHECK: .globl some_dep
+// CHECK: .globl some_dep