k: A memory operand whose address is formed by a base register and
(optionally scaled) index register.
m: A memory operand whose address is formed by a base register and
offset that is suitable for use in instructions with the same
addressing mode as st.w and ld.w.
ZB: An address that is held in a general-purpose register. The offset
is zero.
ZC: A memory operand whose address is formed by a base register and
offset that is suitable for use in instructions with the same
addressing mode as ll.w and sc.w.
Differential Revision: https://reviews.llvm.org/D134638
This patch adds support for constraints `f`, `l`, `I`, `K` according
to [1]. The remain constraints (`k`, `m`, `ZB`, `ZC`) will be added
later as they are a little more complex than the others.
f: A floating-point register (if available).
l: A signed 16-bit constant.
I: A signed 12-bit constant (for arithmetic instructions).
K: An unsigned 12-bit constant (for logic instructions).
For now, no need to support register alias (e.g. `$a0`) in llvm as
clang will correctly decode the usage of register name aliases into
their official names. And AFAIK, the not yet upstreamed `rustc` for
LoongArch will always use official register names (e.g. `$r4`).
[1] https://gcc.gnu.org/onlinedocs/gccint/Machine-Constraints.html
Differential Revision: https://reviews.llvm.org/D134157
With the initial support added, clang can compile `helloworld` C
to executable file for loongarch64. For example:
```
$ cat hello.c
int main() {
printf("Hello, world!\n");
return 0;
}
$ clang --target=loongarch64-unknown-linux-gnu --gcc-toolchain=xxx --sysroot=xxx hello.c
```
The output a.out can run within qemu or native machine. For example:
```
$ file ./a.out
./a.out: ELF 64-bit LSB pie executable, LoongArch, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-loongarch-lp64d.so.1, for GNU/Linux 5.19.0, with debug_info, not stripped
$ ./a.out
Hello, world!
```
Currently gcc toolchain and sysroot can be found here:
https://github.com/loongson/build-tools/releases/download/2022.08.11/loongarch64-clfs-5.1-cross-tools-gcc-glibc.tar.xz
Reference: https://github.com/loongson/LoongArch-Documentation
The last commit hash (main branch) is:
99016636af64d02dee05e39974d4c1e55875c45b
Note loongarch32 is not fully tested because there is no reference
gcc toolchain yet.
Differential Revision: https://reviews.llvm.org/D130255
Fangrui Song