Consistently use LLVM lifetime markers during codegen

src/librustc_codegen_llvm/back/write.rs

@@ -394,6 +394,7 @@ pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(
         config.vectorize_slp,
         config.vectorize_loop,
         config.no_builtins,
+        config.emit_lifetime_markers,
         sanitizer_options.as_ref(),
         pgo_gen_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
         pgo_use_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
@@ -934,10 +935,10 @@ pub unsafe fn with_llvm_pmb(
             llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 25);
         }
         (llvm::CodeGenOptLevel::None, ..) => {
-            llvm::LLVMRustAddAlwaysInlinePass(builder, false);
+            llvm::LLVMRustAddAlwaysInlinePass(builder, config.emit_lifetime_markers);
         }
         (llvm::CodeGenOptLevel::Less, ..) => {
-            llvm::LLVMRustAddAlwaysInlinePass(builder, true);
+            llvm::LLVMRustAddAlwaysInlinePass(builder, config.emit_lifetime_markers);
         }
         (llvm::CodeGenOptLevel::Default, ..) => {
             llvm::LLVMPassManagerBuilderUseInlinerWithThreshold(builder, 225);

src/librustc_codegen_llvm/builder.rs

@@ -18,7 +18,6 @@ use rustc_data_structures::small_c_str::SmallCStr;
 use rustc_hir::def_id::DefId;
 use rustc_middle::ty::layout::TyAndLayout;
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_session::config::{self, Sanitizer};
 use rustc_target::abi::{self, Align, Size};
 use rustc_target::spec::{HasTargetSpec, Target};
 use std::borrow::Cow;
@@ -1243,14 +1242,7 @@ impl Builder<'a, 'll, 'tcx> {
             return;
         }
 
-        let opts = &self.cx.sess().opts;
-        let emit = match opts.debugging_opts.sanitizer {
-            // Some sanitizer use lifetime intrinsics. When they are in use,
-            // emit lifetime intrinsics regardless of optimization level.
-            Some(Sanitizer::Address | Sanitizer::Memory) => true,
-            _ => opts.optimize != config::OptLevel::No,
-        };
-        if !emit {
+        if !self.cx().sess().emit_lifetime_markers() {
             return;
         }
 

src/librustc_codegen_llvm/llvm/ffi.rs

@@ -2000,6 +2000,7 @@ extern "C" {
         SLPVectorize: bool,
         LoopVectorize: bool,
         DisableSimplifyLibCalls: bool,
+        EmitLifetimeMarkers: bool,
         SanitizerOptions: Option<&SanitizerOptions>,
         PGOGenPath: *const c_char,
         PGOUsePath: *const c_char,

src/librustc_codegen_ssa/back/write.rs

@@ -110,6 +110,7 @@ pub struct ModuleConfig {
     pub merge_functions: bool,
     pub inline_threshold: Option<usize>,
     pub new_llvm_pass_manager: bool,
+    pub emit_lifetime_markers: bool,
 }
 
 impl ModuleConfig {
@@ -244,6 +245,7 @@ impl ModuleConfig {
 
             inline_threshold: sess.opts.cg.inline_threshold,
             new_llvm_pass_manager: sess.opts.debugging_opts.new_llvm_pass_manager,
+            emit_lifetime_markers: sess.emit_lifetime_markers(),
         }
     }
 

src/librustc_session/session.rs

@@ -936,6 +936,16 @@ impl Session {
         // then try to skip it where possible.
         dbg_opts.plt.unwrap_or(needs_plt || !full_relro)
     }
+
+    /// Checks if LLVM lifetime markers should be emitted.
+    pub fn emit_lifetime_markers(&self) -> bool {
+        match self.opts.debugging_opts.sanitizer {
+            // AddressSanitizer uses lifetimes to detect use after scope bugs.
+            // MemorySanitizer uses lifetimes to detect use of uninitialized stack variables.
+            Some(Sanitizer::Address | Sanitizer::Memory) => true,
+            _ => self.opts.optimize != config::OptLevel::No,
+        }
+    }
 }
 
 pub fn build_session(

src/rustllvm/PassWrapper.cpp

@@ -717,7 +717,7 @@ LLVMRustOptimizeWithNewPassManager(
     LLVMRustOptStage OptStage,
     bool NoPrepopulatePasses, bool VerifyIR, bool UseThinLTOBuffers,
     bool MergeFunctions, bool UnrollLoops, bool SLPVectorize, bool LoopVectorize,
-    bool DisableSimplifyLibCalls,
+    bool DisableSimplifyLibCalls, bool EmitLifetimeMarkers,
     LLVMRustSanitizerOptions *SanitizerOptions,
     const char *PGOGenPath, const char *PGOUsePath,
     void* LlvmSelfProfiler,
@@ -853,7 +853,7 @@ LLVMRustOptimizeWithNewPassManager(
         MPM.addPass(createModuleToFunctionPassAdaptor(std::move(FPM)));
       }
 
-      MPM.addPass(AlwaysInlinerPass(/*InsertLifetimeIntrinsics=*/false));
+      MPM.addPass(AlwaysInlinerPass(EmitLifetimeMarkers));
 
 #if LLVM_VERSION_GE(10, 0)
       if (PGOOpt) {

src/test/ui/sanitize/issue-72154-lifetime-markers.rs

@@ -0,0 +1,31 @@
+// Regression test for issue 72154, where the use of AddressSanitizer enabled
+// emission of lifetime markers during codegen, while at the same time asking
+// always inliner pass not to insert them.  This eventually lead to a
+// miscompilation which was subsequently detected by AddressSanitizer as UB.
+//
+// needs-sanitizer-support
+// only-x86_64
+//
+// compile-flags: -Copt-level=0 -Zsanitizer=address
+// run-pass
+
+pub struct Wrap {
+    pub t: [usize; 1]
+}
+
+impl Wrap {
+    #[inline(always)]
+    pub fn new(t: [usize; 1]) -> Self {
+        Wrap { t }
+    }
+}
+
+#[inline(always)]
+pub fn assume_init() -> [usize; 1] {
+    [1234]
+}
+
+fn main() {
+    let x: [usize; 1] = assume_init();
+    Wrap::new(x);
+}