gate offload behind -Zunstable-options

Author: ZuseZ4

compiler/rustc_codegen_llvm/src/back/lto.rs

@@ -672,7 +672,7 @@ pub(crate) fn run_pass_manager(
         write::llvm_optimize(cgcx, dcx, module, None, config, opt_level, opt_stage, stage)?;
     }
 
-    if cfg!(llvm_enzyme) && enable_gpu && !thin {
+    if enable_gpu && !thin {
         let cx =
             SimpleCx::new(module.module_llvm.llmod(), &module.module_llvm.llcx, cgcx.pointer_size);
         crate::builder::gpu_offload::handle_gpu_code(cgcx, &cx);

compiler/rustc_interface/src/tests.rs

@@ -13,10 +13,10 @@ use rustc_session::config::{
     CoverageOptions, DebugInfo, DumpMonoStatsFormat, ErrorOutputType, ExternEntry, ExternLocation,
     Externs, FmtDebug, FunctionReturn, InliningThreshold, Input, InstrumentCoverage,
     InstrumentXRay, LinkSelfContained, LinkerPluginLto, LocationDetail, LtoCli, MirIncludeSpans,
-    NextSolverConfig, OomStrategy, Options, OutFileName, OutputType, OutputTypes, PAuthKey, PacRet,
-    Passes, PatchableFunctionEntry, Polonius, ProcMacroExecutionStrategy, Strip, SwitchWithOptPath,
-    SymbolManglingVersion, WasiExecModel, build_configuration, build_session_options,
-    rustc_optgroups,
+    NextSolverConfig, Offload, OomStrategy, Options, OutFileName, OutputType, OutputTypes,
+    PAuthKey, PacRet, Passes, PatchableFunctionEntry, Polonius, ProcMacroExecutionStrategy, Strip,
+    SwitchWithOptPath, SymbolManglingVersion, WasiExecModel, build_configuration,
+    build_session_options, rustc_optgroups,
 };
 use rustc_session::lint::Level;
 use rustc_session::search_paths::SearchPath;
@@ -833,6 +833,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(no_profiler_runtime, true);
     tracked!(no_trait_vptr, true);
     tracked!(no_unique_section_names, true);
+    tracked!(offload, vec![Offload::Enable]);
     tracked!(on_broken_pipe, OnBrokenPipe::Kill);
     tracked!(oom, OomStrategy::Panic);
     tracked!(osx_rpath_install_name, true);

compiler/rustc_session/src/config.rs

@@ -2654,6 +2654,15 @@ pub fn build_session_options(early_dcx: &mut EarlyDiagCtxt, matches: &getopts::M
         )
     }
 
+    if !nightly_options::is_unstable_enabled(matches)
+        && unstable_opts.offload.contains(&Offload::Enable)
+    {
+        early_dcx.early_fatal(
+            "`-Zoffload=Enable` also requires `-Zunstable-options` \
+                and a nightly compiler",
+        )
+    }
+
     // For testing purposes, until we have more feedback about these options: ensure `-Z
     // unstable-options` is required when using the unstable `-C link-self-contained` and `-C
     // linker-flavor` options.

tests/codegen/gpu_offload/gpu_host.rs

@@ -1,4 +1,4 @@
-//@ compile-flags: -Zoffload=Enable -C opt-level=3  -Clto=fat
+//@ compile-flags: -Zoffload=Enable -Zunstable-options -C opt-level=3  -Clto=fat
 //@ no-prefer-dynamic
 //@ needs-enzyme