4 files changed, 22 insertions, 18 deletions
diff --git a/compiler/rustc_codegen_llvm/src/back/lto.rs b/compiler/rustc_codegen_llvm/src/back/lto.rs
index 8655aeec13d..db297425b03 100644
--- a/compiler/rustc_codegen_llvm/src/back/lto.rs
+++ b/compiler/rustc_codegen_llvm/src/back/lto.rs
@@ -25,6 +25,7 @@ use std::ffi::{CStr, CString};
 use std::fs::File;
 use std::io;
 use std::iter;
+use std::mem::ManuallyDrop;
 use std::path::Path;
 use std::slice;
 use std::sync::Arc;
@@ -734,7 +735,7 @@ pub unsafe fn optimize_thin_module(
     let llcx = llvm::LLVMRustContextCreate(cgcx.fewer_names);
     let llmod_raw = parse_module(llcx, module_name, thin_module.data(), &diag_handler)? as *const _;
     let mut module = ModuleCodegen {
-        module_llvm: ModuleLlvm { llmod_raw, llcx, tm },
+        module_llvm: ModuleLlvm { llmod_raw, llcx, tm: ManuallyDrop::new(tm) },
         name: thin_module.name().to_string(),
         kind: ModuleKind::Regular,
     };
diff --git a/compiler/rustc_codegen_llvm/src/back/write.rs b/compiler/rustc_codegen_llvm/src/back/write.rs
index 3a8b8e1ad11..1a567c0fce8 100644
--- a/compiler/rustc_codegen_llvm/src/back/write.rs
+++ b/compiler/rustc_codegen_llvm/src/back/write.rs
@@ -571,7 +571,6 @@ pub(crate) unsafe fn llvm_optimize(
         unroll_loops,
         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()),
@@ -686,7 +685,6 @@ pub(crate) unsafe fn codegen(
         unsafe fn with_codegen<'ll, F, R>(
             tm: &'ll llvm::TargetMachine,
             llmod: &'ll llvm::Module,
-            no_builtins: bool,
             f: F,
         ) -> R
         where
@@ -694,7 +692,7 @@ pub(crate) unsafe fn codegen(
         {
             let cpm = llvm::LLVMCreatePassManager();
             llvm::LLVMAddAnalysisPasses(tm, cpm);
-            llvm::LLVMRustAddLibraryInfo(cpm, llmod, no_builtins);
+            llvm::LLVMRustAddLibraryInfo(cpm, llmod);
             f(cpm)
         }
 
@@ -797,7 +795,7 @@ pub(crate) unsafe fn codegen(
             } else {
                 llmod
             };
-            with_codegen(tm, llmod, config.no_builtins, |cpm| {
+            with_codegen(tm, llmod, |cpm| {
                 write_output_file(
                     diag_handler,
                     tm,
@@ -832,7 +830,7 @@ pub(crate) unsafe fn codegen(
                     (_, SplitDwarfKind::Split) => Some(dwo_out.as_path()),
                 };
 
-                with_codegen(tm, llmod, config.no_builtins, |cpm| {
+                with_codegen(tm, llmod, |cpm| {
                     write_output_file(
                         diag_handler,
                         tm,
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index f8a0423e9b1..915cf31de08 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -52,6 +52,7 @@ use rustc_span::symbol::Symbol;
 use std::any::Any;
 use std::ffi::CStr;
 use std::io::Write;
+use std::mem::ManuallyDrop;
 
 mod back {
     pub mod archive;
@@ -407,8 +408,9 @@ pub struct ModuleLlvm {
     llcx: &'static mut llvm::Context,
     llmod_raw: *const llvm::Module,
 
-    // independent from llcx and llmod_raw, resources get disposed by drop impl
-    tm: OwnedTargetMachine,
+    // This field is `ManuallyDrop` because it is important that the `TargetMachine`
+    // is disposed prior to the `Context` being disposed otherwise UAFs can occur.
+    tm: ManuallyDrop<OwnedTargetMachine>,
 }
 
 unsafe impl Send for ModuleLlvm {}
@@ -419,7 +421,11 @@ impl ModuleLlvm {
         unsafe {
             let llcx = llvm::LLVMRustContextCreate(tcx.sess.fewer_names());
             let llmod_raw = context::create_module(tcx, llcx, mod_name) as *const _;
-            ModuleLlvm { llmod_raw, llcx, tm: create_target_machine(tcx, mod_name) }
+            ModuleLlvm {
+                llmod_raw,
+                llcx,
+                tm: ManuallyDrop::new(create_target_machine(tcx, mod_name)),
+            }
         }
     }
 
@@ -427,7 +433,11 @@ impl ModuleLlvm {
         unsafe {
             let llcx = llvm::LLVMRustContextCreate(tcx.sess.fewer_names());
             let llmod_raw = context::create_module(tcx, llcx, mod_name) as *const _;
-            ModuleLlvm { llmod_raw, llcx, tm: create_informational_target_machine(tcx.sess) }
+            ModuleLlvm {
+                llmod_raw,
+                llcx,
+                tm: ManuallyDrop::new(create_informational_target_machine(tcx.sess)),
+            }
         }
     }
 
@@ -448,7 +458,7 @@ impl ModuleLlvm {
                 }
             };
 
-            Ok(ModuleLlvm { llmod_raw, llcx, tm })
+            Ok(ModuleLlvm { llmod_raw, llcx, tm: ManuallyDrop::new(tm) })
         }
     }
 
@@ -460,6 +470,7 @@ impl ModuleLlvm {
 impl Drop for ModuleLlvm {
     fn drop(&mut self) {
         unsafe {
+            ManuallyDrop::drop(&mut self.tm);
             llvm::LLVMContextDispose(&mut *(self.llcx as *mut _));
         }
     }
diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
index d701b20e953..6c3ccc9cf0d 100644
--- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs
@@ -2163,13 +2163,8 @@ extern "C" {
         ArgsCstrBuff: *const c_char,
         ArgsCstrBuffLen: usize,
     ) -> *mut TargetMachine;
-
     pub fn LLVMRustDisposeTargetMachine(T: *mut TargetMachine);
-    pub fn LLVMRustAddLibraryInfo<'a>(
-        PM: &PassManager<'a>,
-        M: &'a Module,
-        DisableSimplifyLibCalls: bool,
-    );
+    pub fn LLVMRustAddLibraryInfo<'a>(PM: &PassManager<'a>, M: &'a Module);
     pub fn LLVMRustWriteOutputFile<'a>(
         T: &'a TargetMachine,
         PM: &PassManager<'a>,
@@ -2191,7 +2186,6 @@ extern "C" {
         UnrollLoops: bool,
         SLPVectorize: bool,
         LoopVectorize: bool,
-        DisableSimplifyLibCalls: bool,
         EmitLifetimeMarkers: bool,
         SanitizerOptions: Option<&SanitizerOptions>,
         PGOGenPath: *const c_char,