Tracking Issue for amdgcn target

This issue tracks the implementation of the amdgpu target.

• MCP: https://github.com/rust-lang/compiler-team/issues/823

Old, closed tracking issue: #51575

Current work-in-progress branch: https://github.com/Flakebi/rust/tree/amdgpu

Examples and support libraries: https://github.com/Flakebi/amdgpu-rs

Implementation

• Add amdgpu target: #134740
• Disable f128 in compiler-builtins: https://github.com/rust-lang/compiler-builtins/pull/737
• Cast allocas to default address space: #135025
• Cast global vars to default address space: #135026
• Add triple to cc crate (once target is in nightly) (not necessary anymore)
• Add test compiling core and alloc
• Add gpu-kernel calling convention: #135047
• Require no_mangle or export_name for gpu-kernel functions: #149991
• Export <kernel>.kd kernel descriptor symbol: #135909
• Require explicit -C target-cpu=: #135030
• Fix linker-plugin-lto only doing thin lto: #136840
• Fix requiring lto automatically: #149624
• Remove range-metadata amdgpu workaround: #135027
• Add tests for the gpu-kernel calling convention lowering to amdgpu_kernel and the global variable addrspacecasts: #146148
• Support shared memory (dynamic): #135516 #146181
• Support shared memory (static): #135516
• Inline assembly: #149793
• Allow vector types: #149994
• Get kernel dispatch packet pointer: #150607
• Tracking Issue for amdgpu arch intrinsics: #149988

Bugs

• Debug compilation fails due to a bug in LLVM’s AMDGPUResourceUsageAnalysis. This is fixed in llvm main, so will be fixed with the update to LLVM 20
• rustc may incorrectly copy convergent operations: #137086 #149637 #153995
• Taking structs as arguments to gpu-kernel functions does not work correctly and should be forbidden: #149991
• Need -Clink-arg=--no-gc-sections when using linker-plugin-lto: https://github.com/llvm/llvm-project/issues/119479
• MergeFunctions LLVM pass can generate invalid calls to kernels. Fixed in llvm main, so will be fixed with the next LLVM update: #57356 https://github.com/llvm/llvm-project/pull/174254

Start with the unchecked implementation items, especially static shared memory support and the amdgpu arch intrinsics tracking issue, then follow the referenced issues and current work-in-progress branch. Done means the remaining checklist items are implemented and the corresponding compiler tests and amdgpu target behavior pass.