add details for csky-unknown-linux-gnuabiv2 and add docs

8 files changed, 145 insertions, 56 deletions

diff --git a/compiler/rustc_codegen_llvm/src/asm.rs b/compiler/rustc_codegen_llvm/src/asm.rs
index 4d7db96cc82..ca9fd76a997 100644
--- a/compiler/rustc_codegen_llvm/src/asm.rs
+++ b/compiler/rustc_codegen_llvm/src/asm.rs
@@ -261,7 +261,7 @@ impl<'ll, 'tcx> AsmBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
                 InlineAsmArch::M68k => {
                     constraints.push("~{ccr}".to_string());
                 }
-                InlineAsmArch::CSKY => {} // https://github.com/llvm/llvm-project/blob/8b76aea8d8b1b71f6220bc2845abc749f18a19b7/clang/lib/Basic/Targets/CSKY.h getClobers()
+                InlineAsmArch::CSKY => {}
             }
         }
         if !options.contains(InlineAsmOptions::NOMEM) {
diff --git a/compiler/rustc_codegen_ssa/src/target_features.rs b/compiler/rustc_codegen_ssa/src/target_features.rs
index f1571dd2219..baf6b19d3f9 100644
--- a/compiler/rustc_codegen_ssa/src/target_features.rs
+++ b/compiler/rustc_codegen_ssa/src/target_features.rs
@@ -297,14 +297,50 @@ const WASM_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
 const BPF_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[("alu32", Some(sym::bpf_target_feature))];
 
 const CSKY_ALLOWED_FEATURES: &[(&str, Option<Symbol>)] = &[
-    ("hard-float", Some(sym::csky_target_feature)),
-    ("hard-float-abi", Some(sym::csky_target_feature)),
-    ("fpuv2_sf", Some(sym::csky_target_feature)),
+    // tidy-alphabetical-start
+    ("10e60", Some(sym::csky_target_feature)),
+    ("2e3", Some(sym::csky_target_feature)),
+    ("3e3r1", Some(sym::csky_target_feature)),
+    ("3e3r2", Some(sym::csky_target_feature)),
+    ("3e3r3", Some(sym::csky_target_feature)),
+    ("3e7", Some(sym::csky_target_feature)),
+    ("7e10", Some(sym::csky_target_feature)),
+    ("cache", Some(sym::csky_target_feature)),
+    ("doloop", Some(sym::csky_target_feature)),
+    ("dsp1e2", Some(sym::csky_target_feature)),
+    ("dspe60", Some(sym::csky_target_feature)),
+    ("e1", Some(sym::csky_target_feature)),
+    ("e2", Some(sym::csky_target_feature)),
+    ("edsp", Some(sym::csky_target_feature)),
+    ("elrw", Some(sym::csky_target_feature)),
+    ("float1e2", Some(sym::csky_target_feature)),
+    ("float1e3", Some(sym::csky_target_feature)),
+    ("float3e4", Some(sym::csky_target_feature)),
+    ("float7e60", Some(sym::csky_target_feature)),
+    ("floate1", Some(sym::csky_target_feature)),
+    ("hard-tp", Some(sym::csky_target_feature)),
+    ("high-registers", Some(sym::csky_target_feature)),
+    ("hwdiv", Some(sym::csky_target_feature)),
+    ("mp", Some(sym::csky_target_feature)),
+    ("mp1e2", Some(sym::csky_target_feature)),
+    ("nvic", Some(sym::csky_target_feature)),
+    ("trust", Some(sym::csky_target_feature)),
+    ("vdsp2e60f", Some(sym::csky_target_feature)),
+    ("vdspv1", Some(sym::csky_target_feature)),
+    ("vdspv2", Some(sym::csky_target_feature)),
+    // tidy-alphabetical-end
+    //fpu
+    // tidy-alphabetical-start
+    ("fdivdu", Some(sym::csky_target_feature)),
     ("fpuv2_df", Some(sym::csky_target_feature)),
-    ("fpuv3_sf", Some(sym::csky_target_feature)),
+    ("fpuv2_sf", Some(sym::csky_target_feature)),
     ("fpuv3_df", Some(sym::csky_target_feature)),
-    ("vdspv2", Some(sym::csky_target_feature)),
-    ("dspv2", Some(sym::csky_target_feature)),
+    ("fpuv3_hf", Some(sym::csky_target_feature)),
+    ("fpuv3_hi", Some(sym::csky_target_feature)),
+    ("fpuv3_sf", Some(sym::csky_target_feature)),
+    ("hard-float", Some(sym::csky_target_feature)),
+    ("hard-float-abi", Some(sym::csky_target_feature)),
+    // tidy-alphabetical-end
 ];
 /// When rustdoc is running, provide a list of all known features so that all their respective
 /// primitives may be documented.
diff --git a/compiler/rustc_target/src/asm/csky.rs b/compiler/rustc_target/src/asm/csky.rs
index 13bb846c731..6f0e7f79949 100644
--- a/compiler/rustc_target/src/asm/csky.rs
+++ b/compiler/rustc_target/src/asm/csky.rs
@@ -36,8 +36,8 @@ impl CSKYInlineAsmRegClass {
         _arch: InlineAsmArch,
     ) -> &'static [(InlineAsmType, Option<Symbol>)] {
         match self {
-            Self::reg => types! { _: I8, I16, I32, I64, F32, F64; },
-            Self::freg => types! { _: F32, F64; },
+            Self::reg => types! { _: I8, I16, I32; },
+            Self::freg => types! { _: F32; },
         }
     }
 }
@@ -52,31 +52,21 @@ def_regs! {
         r4: reg = ["r4","l0"],
         r5: reg = ["r5","l1"],
         r6: reg = ["r6","l2"],
-        // r7: reg = ["r7","l3"],
-        // r8: reg = ["r8","l4"],
-        // r9: reg = ["r9","l5"],
-        // r10: reg = ["r10","l6"],
-        // r11: reg = ["r11","l7"],
-        // r12: reg = ["r12","t0"],
-        // r13: reg = ["r13","t1"],
-        // r14: reg = ["r14","sp"],
-        // r15: reg = ["r15","lr"],
-        // r16: reg = ["r16","l8"],
-        // r17: reg = ["r17","l9"],
-        // r18: reg = ["r18","t2"],
-        // r19: reg = ["r19","t3"],
-        // r20: reg = ["r20","t4"],
-        // r21: reg = ["r21","t5"],
-        // r22: reg = ["r22","t6"],
-        // r23: reg = ["r23","t7", "fp"],
-        // r24: reg = ["r24","t8", "sop"],
-        // r25: reg = ["r25","tp", "bsp"],
-        // r26: reg = ["r26"],
-        // r27: reg = ["r27"],
-        // r28: reg = ["r28","gb", "rgb", "rdb"],
-        // r29: reg = ["r29","tb", "rtb"],
-        // r30: reg = ["r30","svbr"],
-        // r31: reg = ["r31","tls"],
+        r9: reg = ["r9","l5"],// feature e2
+        r10: reg = ["r10","l6"],// feature e2
+        r11: reg = ["r11","l7"],// feature e2
+        r12: reg = ["r12","t0"],// feature e2
+        r13: reg = ["r13","t1"],// feature e2
+        r16: reg = ["r16","l8"],// feature high-register
+        r17: reg = ["r17","l9"],// feature high-register
+        r18: reg = ["r18","t2"],// feature high-register
+        r19: reg = ["r19","t3"],// feature high-register
+        r20: reg = ["r20","t4"],// feature high-register
+        r21: reg = ["r21","t5"],// feature high-register
+        r22: reg = ["r22","t6"],// feature high-register
+        r23: reg = ["r23","t7", "fp"],// feature high-register
+        r24: reg = ["r24","t8", "sop"],// feature high-register
+        r25: reg = ["r25","t9","tp", "bsp"],// feature high-register
         f0: freg = ["fr0","vr0"],
         f1: freg = ["fr1","vr1"],
         f2: freg = ["fr2","vr2"],
@@ -121,10 +111,6 @@ def_regs! {
             "reserver for tls",
         #error = ["r28", "gb", "rgb", "rdb"] =>
             "the global pointer cannot be used as an operand for inline asm",
-        #error = ["r9","l5", "r10","l6", "r11","l7", "r12","t0", "r13","t1"] =>
-            "reserved (no E2)",
-        #error = ["r16","l8", "r17","l9", "r18","t2", "r19","t3", "r20","t4", "r21","t5", "r22","t6", "r23","t7", "fp", "r24","t8", "sop", "r25","tp", "bsp"] =>
-            "reserved (no HighRegisters)",
         #error = ["r26","r27","r29","tb", "rtb", "r30","svbr"] =>
             "reserved by the ABI",
     }
diff --git a/compiler/rustc_target/src/spec/csky_unknown_linux_gnuabiv2.rs b/compiler/rustc_target/src/spec/csky_unknown_linux_gnuabiv2.rs
index 3bc075f6920..7d03dd26f5d 100644
--- a/compiler/rustc_target/src/spec/csky_unknown_linux_gnuabiv2.rs
+++ b/compiler/rustc_target/src/spec/csky_unknown_linux_gnuabiv2.rs
@@ -1,7 +1,6 @@
-use crate::spec::{Target, TargetOptions};
+use crate::spec::{Cc, LinkerFlavor, Lld, Target, TargetOptions};
 
 // This target is for glibc Linux on Csky
-// hardfloat.
 
 pub fn target() -> Target {
     Target {
@@ -12,10 +11,9 @@ pub fn target() -> Target {
         arch: "csky".into(),
         options: TargetOptions {
             abi: "abiv2".into(),
-            //+hard-float, +hard-float-abi, +fpuv2_sf, +fpuv2_df, +fpuv3_sf, +fpuv3_df,  +vdspv2, +dspv2, +vdspv1, +3e3r1
-            features: "".into(),
+            features: "+2e3,+3e7,+7e10,+cache,+dsp1e2,+dspe60,+e1,+e2,+edsp,+elrw,+hard-tp,+high-registers,+hwdiv,+mp,+mp1e2,+nvic,+trust".into(),
+            late_link_args_static: TargetOptions::link_args(LinkerFlavor::Gnu(Cc::Yes, Lld::No), &["-l:libatomic.a"]),
             max_atomic_width: Some(32),
-            // mcount: "\u{1}__gnu_mcount_nc".into(),
             ..super::linux_gnu_base::opts()
         },
     }
diff --git a/src/bootstrap/llvm.rs b/src/bootstrap/llvm.rs
index 7acf657f630..da7ff626cb2 100644
--- a/src/bootstrap/llvm.rs
+++ b/src/bootstrap/llvm.rs
@@ -390,6 +390,22 @@ impl Step for Llvm {
             ldflags.shared.push(" -latomic");
         }
 
+        if target.starts_with("csky")
+            && !target.contains("freebsd")
+            && !target.contains("openbsd")
+            && !target.contains("netbsd")
+        {
+            // CSKY GCC erroneously requires linking against
+            // `libatomic` when using 1-byte and 2-byte C++
+            // atomics but the LLVM build system check cannot
+            // detect this. Therefore it is set manually here.
+            // Some BSD uses Clang as its system compiler and
+            // provides no libatomic in its base system so does
+            // not want this.
+            ldflags.exe.push(" -latomic");
+            ldflags.shared.push(" -latomic");
+        }
+
         if target.contains("msvc") {
             cfg.define("LLVM_USE_CRT_DEBUG", "MT");
             cfg.define("LLVM_USE_CRT_RELEASE", "MT");
diff --git a/src/doc/rustc/src/platform-support.md b/src/doc/rustc/src/platform-support.md
index a78b5314fcc..371ee378d1a 100644
--- a/src/doc/rustc/src/platform-support.md
+++ b/src/doc/rustc/src/platform-support.md
@@ -259,7 +259,7 @@ target | std | host | notes
 `avr-unknown-gnu-atmega328` | * |  | AVR. Requires `-Z build-std=core`
 `bpfeb-unknown-none` | * |  | BPF (big endian)
 `bpfel-unknown-none` | * |  | BPF (little endian)
-`csky-unknown-linux-gnuabiv2` | ? |  | C-SKY iv2 Linux
+`csky-unknown-linux-gnuabiv2` | ✓ |  | C-SKY abiv2 Linux(little endian)
 `hexagon-unknown-linux-musl` | ? |  |
 `i386-apple-ios` | ✓ |  | 32-bit x86 iOS
 [`i586-pc-nto-qnx700`](platform-support/nto-qnx.md) | * |  | 32-bit x86 QNX Neutrino 7.0 RTOS |
diff --git a/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md b/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md
index 240d58596cf..e73598be0d9 100644
--- a/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md
+++ b/src/doc/rustc/src/platform-support/csky-unknown-linux-gnuabiv2.md
@@ -5,6 +5,8 @@
 This target supports [C-SKY](https://github.com/c-sky) CPUs with `abi` v2 and `glibc`.
 
 https://c-sky.github.io/
+https://gitlab.com/c-sky/
+
 ## Target maintainers
 
 * [@Dirreke](https://github.com/Dirreke)
@@ -14,20 +16,55 @@ https://c-sky.github.io/
 
 ## Building the target
 
-add `csky-unknown-linux-gnuabiv2` to the `target` list in `config.toml` and `./x build`.
+### Get a C toolchain
+
+Compiling rust for this target has been tested on `x86_64` linux hosts.  Other host types have not been tested, but may work, if you can find a suitable cross compilation toolchain for them.
+
+If you don't already have a suitable toolchain, you can download from [here](https://occ-oss-prod.oss-cn-hangzhou.aliyuncs.com/resource/1356021/1619528643136/csky-linux-gnuabiv2-tools-x86_64-glibc-linux-4.9.56-20210423.tar.gz), and unpack it into a directory.
+
+### Configure rust
+
+The target can be built by enabling it for a `rustc` build, by placing the following in `config.toml`:
+
+```toml
+[build]
+target = ["x86_64-unknown-linux-gnu", "csky-unknown-linux-gnuabiv2"]
+stage = 2
 
-## Building Rust programs
+[target.csky-unknown-linux-gnuabiv2]
+# ADJUST THIS PATH TO POINT AT YOUR TOOLCHAIN
+cc = "${TOOLCHAIN_PATH}/bin/csky-linux-gnuabiv2-gcc"
 
-Rust programs can be built for that target:
+### Build
 
-```text
-cargo +stage2 --target csky-unknown-linux-gnuabiv2 your-code.rs
+```sh
+# in rust dir
+./x.py build --stage 2
 ```
 
-## Testing
+## Building and Running Rust programs
 
-Currently there is no support to run the rustc test suite for this target.
+To test cross-compiled binaries on a `x86_64` system, you can use the `qemu-cskyv2`. This avoids having a full emulated ARM system by doing dynamic binary translation and dynamic system call translation.  It lets you run CSKY programs directly on your `x86_64` kernel.  It's very convenient!
 
-## Cross-compilation toolchains and C code
+To use:
+
+* Install `qemu-cskyv2` (If you don't already have a qemu, you can download from [here](https://occ-oss-prod.oss-cn-hangzhou.aliyuncs.com/resource//1689324918932/xuantie-qemu-x86_64-Ubuntu-18.04-20230714-0202.tar.gz"), and unpack it into a directory.)
+* Link your built toolchain via:
+  * `rustup toolchain link stage2 ${RUST}/build/x86_64-unknown-linux-gnu/stage2`
+* Create a test program
+
+```sh
+cargo new hello_world
+cd hello_world
+```
+
+* Build and run
+
+```sh
+CARGO_TARGET_CSKY_UNKNOWN_LINUX_GNUABIV2_RUNNER=${QEMU_PATH}/bin/qemu-cskyv2 -L ${TOOLCHAIN_PATH}/csky-linux-gnuabiv2/libc \
+CARGO_TARGET_CSKY_UNKNOWN_LINUX_GNUABIV2_LINKER=${TOOLCHAIN_PATH}/bin/csky-linux-gnuabiv2-gcc \
+RUSTFLAGS="-C target-features=+crt-static" \
+cargo +stage2 run --target csky-unknown-linux-gnuabiv2
+```
 
-This target can be cross-compiled from `x86_64` on either Linux systems with [`csky-linux-gunabiv2-tools-x86_64-glibc-linux`](https://github.com/c-sky/toolchain-build).
+Attention: The dynamic-linked program may nor be run by `qemu-cskyv2` but can be run on the target.
diff --git a/src/doc/unstable-book/src/language-features/asm-experimental-arch.md b/src/doc/unstable-book/src/language-features/asm-experimental-arch.md
index d52287051c6..968c9bb4ebb 100644
--- a/src/doc/unstable-book/src/language-features/asm-experimental-arch.md
+++ b/src/doc/unstable-book/src/language-features/asm-experimental-arch.md
@@ -82,8 +82,8 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | MSP430       | `reg`                           | None           | `i8`, `i16`                             |
 | M68k         | `reg`, `reg_addr`               | None           | `i16`, `i32`                            |
 | M68k         | `reg_data`                      | None           | `i8`, `i16`, `i32`                      |
-| CSKY         | `reg`                           | None           | `i8`, `i16`, `i32`, `i64`               |
-| CSKY         | `freg`                          | None           | `f32`, `f64`                            |
+| CSKY         | `reg`                           | None           | `i8`, `i16`, `i32`                      |
+| CSKY         | `freg`                          | None           | `f32`,                                  |
 | s390x        | `reg`                           | None           | `i8`, `i16`, `i32`, `i64`               |
 | s390x        | `freg`                          | None           | `f32`, `f64`                            |
 
@@ -107,9 +107,16 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | M68k         | `a5`          | `bp`      |
 | M68k         | `a6`          | `fp`      |
 | M68k         | `a7`          | `sp`, `usp`, `ssp`, `isp` |
+| CSKY         | `r[0-3]`      | `a[0-3]`  |
+| CSKY         | `r[4-11]`     | `l[0-7]`  |
+| CSKY         | `r[12-13]`    | `t[0-1]`  |
 | CSKY         | `r14`         | `sp`      |
 | CSKY         | `r15`         | `lr`      |
-| CSKY         | `r28`         | `gb`, `rgb`, `rdb` |
+| CSKY         | `r[16-17]`    | `l[8-9]`  |
+| CSKY         | `r[18-25]`    | `t[2-9]`  |
+| CSKY         | `r28`         | `rgb`     |
+| CSKY         | `r29`         | `rtb`     |
+| CSKY         | `r30`         | `svbr`    |
 | CSKY         | `r31`         | `tls`     |
 
 > **Notes**:
@@ -132,6 +139,13 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | AVR          | `r0`, `r1`, `r1r0`                      | Due to an issue in LLVM, the `r0` and `r1` registers cannot be used as inputs or outputs.  If modified, they must be restored to their original values before the end of the block. |
 |MSP430        | `r0`, `r2`, `r3`                        | These are the program counter, status register, and constant generator respectively. Neither the status register nor constant generator can be written to.                          |
 | M68k         | `a4`, `a5`                              | Used internally by LLVM for the base pointer and global base pointer. |
+| CSKY         | `r7`, `r28`                             | Used internally by LLVM for the base pointer and global base pointer. |
+| CSKY         | `r8`                                    | Used internally by LLVM for the frame pointer. |
+| CSKY         | `r14`                                   | Used internally by LLVM for the stack pointer. |
+| CSKY         | `r15`                                   | This is the link register. |
+| CSKY         | `r[26-30]`                              | Reserved by its ABI.       |
+| CSKY         | `r31`                                   | This is the TLS register.  |
+
 
 ## Template modifiers
 
@@ -148,6 +162,8 @@ This feature tracks `asm!` and `global_asm!` support for the following architect
 | PowerPC      | `freg`         | None     | `0`            | None          |
 | s390x        | `reg`          | None     | `%r0`          | None          |
 | s390x        | `freg`         | None     | `%f0`          | None          |
+| CSKY         | `reg`          | None     | `r0`           | None          |
+| CSKY         | `freg`         | None     | `f0`           | None          |
 
 # Flags covered by `preserves_flags`