In Rust bare-metal targets, there is no environment component in triple name. This patch ignores warnings that look like:
```
warning: triple-implied ABI conflicts with provided target-abi ‘lp64s', using target-abi
```
Reviewed By: SixWeining, xen0n
Differential Revision: https://reviews.llvm.org/D152778
According to the [[ https://loongson.github.io/LoongArch-Documentation/LoongArch-toolchain-conventions-EN.html | LoongArch Toolchain Conventions ]]
it is possible to specify the ABI modifier (the "D" part of "LP64D")
via the environment field in the target triple. This is needed for
proper support for Debian-style multiarch tuples as well, so add triple
awareness to `LoongArchSubtarget` via addition of
`LoongArchABI::computeTargetABI`. Let the explicit `--target-abi`
argument intuitively take precedence over the triple-implied ABI.
Reviewed By: SixWeining
Differential Revision: https://reviews.llvm.org/D142685
This patch introduces basic tablegen infra such as
LoongArch{InstrFormats,InstrInfo,RegisterInfo,CallingConv,}.td.
For now, only add instruction definitions for LoongArch basic integer
operations.
Our initial target is a working MC layer rather than codegen,
so appropriate SelectionDAG patterns will come later.
Differential revision: https://reviews.llvm.org/D115861
