Offload device1

[ZuseZ4]

r? @oli-obk

Here I'll continue the device side code generation, and park the second commit for now.
I first want to land the mvp in the other PR.

[bors]

☔ The latest upstream changes (presumably #143026) made this pull request unmergeable. Please resolve the merge conflicts.

[ZuseZ4]

We'll still need #143684 to properly recognize our GPU hardware and run the binary on end-user hardware, but here I'll only add codegen tests, so it should work fine for CI.

[ZuseZ4]

related (also wip) rustc-dev-guide update: rust-lang/rustc-dev-guide#2524

[rust-log-analyzer]

The job tidy failed! Check out the build log: (web) (plain enhanced) (plain)

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##[endgroup]
[TIMING:end] tool::ToolBuild { build_compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu, tool: "tidy", path: "src/tools/tidy", mode: ToolBootstrap, source_type: InTree, extra_features: [], allow_features: "", cargo_args: [], artifact_kind: Binary } -- 11.675
[TIMING:end] tool::Tidy { compiler: Compiler { stage: 0, host: x86_64-unknown-linux-gnu, forced_compiler: false }, target: x86_64-unknown-linux-gnu } -- 0.000
fmt check
Diff in /checkout/compiler/rustc_codegen_llvm/src/builder/gpu_offload.rs:225:
     // A non-mutable reference or pointer will be 1, an array that's not read, but fully overwritten
     // will be 2. For now, everything is 3, until we have our frontend set up.
     // 1+2+32: 1 (MapTo), 2 (MapFrom), 32 (Add extra input ptr once, idk, figure out later)
-    let o_types =
-        add_priv_unnamed_arr(&cx, &format!(".offload_maptypes.{num}"), &vec![1+2+32; num_ptr_types]);
+    let o_types = add_priv_unnamed_arr(
+        &cx,
+        &format!(".offload_maptypes.{num}"),
+        &vec![1 + 2 + 32; num_ptr_types],
+    );
     // Next: For each function, generate these three entries. A weak constant,
     // the llvm.rodata entry name, and  the llvm_offload_entries value
 
fmt: checked 6312 files
Build completed unsuccessfully in 0:00:49
  local time: Mon Aug 18 22:54:10 UTC 2025
  network time: Mon, 18 Aug 2025 22:54:10 GMT