start adding amdgpu intrinsics

[ZuseZ4]

Just storing some wip here. We should also add a proper abstraction over amd+nvptx(+intel/etc)., so we can write vendor agnostic code.

cc @Sa4dUs @kevinsala

[rust-log-analyzer]

The job aarch64-gnu-llvm-20-2 failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

fmt: checked 6587 files
tidy check
tidy [rustdoc_json (src)]: `rustdoc-json-types` modified, checking format version
tidy: Skipping binary file check, read-only filesystem
tidy [alphabetical (compiler)]: /checkout/compiler/rustc_span/src/symbol.rs:2150: line not in alphabetical order
tidy [alphabetical (compiler)]: /checkout/compiler/rustc_span/src/symbol.rs:2151: line not in alphabetical order
tidy [alphabetical (compiler)]: /checkout/compiler/rustc_hir_analysis/src/check/intrinsic.rs:203: line not in alphabetical order
tidy [alphabetical (compiler)]: /checkout/compiler/rustc_hir_analysis/src/check/intrinsic.rs:204: line not in alphabetical order
tidy [alphabetical (compiler)]: FAIL
tidy: The following check failed: alphabetical (compiler)
Bootstrap failed while executing `--stage 2 test --skip tests --skip coverage-map --skip coverage-run --skip library --skip tidyselftest`
Command `/checkout/obj/build/aarch64-unknown-linux-gnu/stage1-tools-bin/rust-tidy /checkout /checkout/obj/build/aarch64-unknown-linux-gnu/stage0/bin/cargo /checkout/obj/build 4 yarn` failed with exit code 1
Created at: src/bootstrap/src/core/build_steps/tool.rs:1612:23
Executed at: src/bootstrap/src/core/build_steps/test.rs:1317:29

Command has failed. Rerun with -v to see more details.
Build completed unsuccessfully in 0:00:48
  local time: Wed Dec  3 19:42:19 UTC 2025
  network time: Wed, 03 Dec 2025 19:42:20 GMT
##[error]Process completed with exit code 1.
##[group]Run echo "disk usage:"