keep noinline for system llvm < 14

Author: erikdesjardins

compiler/rustc_codegen_gcc/src/builder.rs

@@ -1404,7 +1404,7 @@ impl<'a, 'gcc, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'gcc, 'tcx> {
         self.cx
     }
 
-    fn mark_callsite_cold(&mut self, _llret: RValue<'gcc>) {
+    fn apply_attrs_to_cleanup_callsite(&mut self, _llret: RValue<'gcc>) {
         unimplemented!();
     }
 

compiler/rustc_codegen_llvm/src/builder.rs

@@ -1201,8 +1201,15 @@ impl<'a, 'll, 'tcx> BuilderMethods<'a, 'tcx> for Builder<'a, 'll, 'tcx> {
         unsafe { llvm::LLVMBuildZExt(self.llbuilder, val, dest_ty, UNNAMED) }
     }
 
-    fn mark_callsite_cold(&mut self, llret: &'ll Value) {
+    fn apply_attrs_to_cleanup_callsite(&mut self, llret: &'ll Value) {
+        // Cleanup is always the cold path.
         llvm::Attribute::Cold.apply_callsite(llvm::AttributePlace::Function, llret);
+
+        // In LLVM versions with deferred inlining (currently, system LLVM < 14),
+        // inlining drop glue can lead to exponential size blowup, see #41696 and #92110.
+        if !llvm_util::is_rust_llvm() && llvm_util::get_version() < (14, 0, 0) {
+            llvm::Attribute::NoInline.apply_callsite(llvm::AttributePlace::Function, llret);
+        }
     }
 }
 

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1902,6 +1902,8 @@ extern "C" {
     pub fn LLVMRustVersionMinor() -> u32;
     pub fn LLVMRustVersionPatch() -> u32;
 
+    pub fn LLVMRustIsRustLLVM() -> bool;
+
     pub fn LLVMRustAddModuleFlag(M: &Module, name: *const c_char, value: u32);
 
     pub fn LLVMRustMetadataAsValue<'a>(C: &'a Context, MD: &'a Metadata) -> &'a Value;

compiler/rustc_codegen_llvm/src/llvm_util.rs

@@ -217,6 +217,12 @@ pub fn get_version() -> (u32, u32, u32) {
     }
 }
 
+/// Returns `true` if this LLVM is Rust's bundled LLVM (and not system LLVM).
+pub fn is_rust_llvm() -> bool {
+    // Can be called without initializing LLVM
+    unsafe { llvm::LLVMRustIsRustLLVM() }
+}
+
 pub fn print_passes() {
     // Can be called without initializing LLVM
     unsafe {

compiler/rustc_codegen_ssa/src/mir/block.rs

@@ -160,8 +160,7 @@ impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
             let llret = bx.call(fn_ty, fn_ptr, &llargs, self.funclet(fx));
             bx.apply_attrs_callsite(&fn_abi, llret);
             if fx.mir[self.bb].is_cleanup {
-                // Cleanup is always the cold path.
-                bx.mark_callsite_cold(llret);
+                bx.apply_attrs_to_cleanup_callsite(llret);
             }
 
             if let Some((ret_dest, target)) = destination {

compiler/rustc_codegen_ssa/src/traits/builder.rs

@@ -311,5 +311,5 @@ pub trait BuilderMethods<'a, 'tcx>:
     ) -> Self::Value;
     fn zext(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
 
-    fn mark_callsite_cold(&mut self, llret: Self::Value);
+    fn apply_attrs_to_cleanup_callsite(&mut self, llret: Self::Value);
 }

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -716,6 +716,14 @@ extern "C" uint32_t LLVMRustVersionMinor() { return LLVM_VERSION_MINOR; }
 
 extern "C" uint32_t LLVMRustVersionMajor() { return LLVM_VERSION_MAJOR; }
 
+extern "C" bool LLVMRustIsRustLLVM() {
+#ifdef LLVM_RUSTLLVM
+  return true;
+#else
+  return false;
+#endif
+}
+
 extern "C" void LLVMRustAddModuleFlag(LLVMModuleRef M, const char *Name,
                                       uint32_t Value) {
   unwrap(M)->addModuleFlag(Module::Warning, Name, Value);

src/test/codegen/unwind-landingpad-cold.rs

@@ -1,3 +1,4 @@
+// no-system-llvm: needs #92110
 // compile-flags: -Cno-prepopulate-passes
 #![crate_type = "lib"]
 

src/test/codegen/unwind-landingpad-inline.rs

@@ -1,4 +1,4 @@
-// no-system-llvm: needs patch for Rust alloc/dealloc functions
+// no-system-llvm: needs #92110 + patch for Rust alloc/dealloc functions
 // compile-flags: -Copt-level=3
 #![crate_type = "lib"]