Avoid passing addrspacecast to lifetime intrinsics

Since LLVM 22 the alloca must be passed directly. Do this by
stripping the addrspacecast if it exists.

Author: nikic

compiler/rustc_codegen_llvm/src/builder.rs

@@ -1773,6 +1773,9 @@ impl<'a, 'll, 'tcx> Builder<'a, 'll, 'tcx> {
         }
 
         if crate::llvm_util::get_version() >= (22, 0, 0) {
+            // LLVM 22 requires the lifetime intrinsic to act directly on the alloca,
+            // there can't be an addrspacecast in between.
+            let ptr = unsafe { llvm::LLVMRustStripPointerCasts(ptr) };
             self.call_intrinsic(intrinsic, &[self.val_ty(ptr)], &[ptr]);
         } else {
             self.call_intrinsic(intrinsic, &[self.val_ty(ptr)], &[self.cx.const_u64(size), ptr]);

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1959,6 +1959,7 @@ unsafe extern "C" {
         Metadata: &'a Metadata,
     );
     pub(crate) fn LLVMRustIsNonGVFunctionPointerTy(Val: &Value) -> bool;
+    pub(crate) fn LLVMRustStripPointerCasts<'a>(Val: &'a Value) -> &'a Value;
 
     // Operations on scalar constants
     pub(crate) fn LLVMRustConstIntGetZExtValue(ConstantVal: &ConstantInt, Value: &mut u64) -> bool;

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1745,6 +1745,10 @@ extern "C" bool LLVMRustIsNonGVFunctionPointerTy(LLVMValueRef V) {
   return false;
 }
 
+extern "C" LLVMValueRef LLVMRustStripPointerCasts(LLVMValueRef V) {
+  return wrap(unwrap(V)->stripPointerCasts());
+}
+
 extern "C" bool LLVMRustLLVMHasZlibCompression() {
   return llvm::compression::zlib::isAvailable();
 }

tests/codegen-llvm/amdgpu-addrspacecast.rs

@@ -3,14 +3,23 @@
 //@ compile-flags: --crate-type=rlib --target=amdgcn-amd-amdhsa -Ctarget-cpu=gfx900
 //@ needs-llvm-components: amdgpu
 //@ add-minicore
+//@ revisions: LLVM21 LLVM22
+//@ [LLVM21] max-llvm-major-version: 21
+//@ [LLVM22] min-llvm-version: 22
 #![feature(no_core)]
 #![no_core]
 
 extern crate minicore;
 
+// Make sure that on LLVM 22, the alloca is passed directly to the lifetime intrinsics,
+// not the addrspacecast.
+
 // CHECK-LABEL: @ref_of_local
 // CHECK: [[alloca:%[0-9]]] = alloca
 // CHECK: %i = addrspacecast ptr addrspace(5) [[alloca]] to ptr
+// LLVM22: call void @llvm.lifetime.start.p5(ptr addrspace(5) [[alloca]])
+// CHECK: call void %f(ptr{{.*}}%i)
+// LLVM22: call void @llvm.lifetime.end.p5(ptr addrspace(5) [[alloca]])
 #[no_mangle]
 pub fn ref_of_local(f: fn(&i32)) {
     let i = 0;