Added custom risc32-imac for esp-espidf target

compiler/rustc_target/src/spec/mod.rs

@@ -1284,6 +1284,7 @@ supported_targets! {
     ("riscv32im-unknown-none-elf", riscv32im_unknown_none_elf),
     ("riscv32imc-unknown-none-elf", riscv32imc_unknown_none_elf),
     ("riscv32imc-esp-espidf", riscv32imc_esp_espidf),
+    ("riscv32imac-esp-espidf", riscv32imac_esp_espidf),
     ("riscv32imac-unknown-none-elf", riscv32imac_unknown_none_elf),
     ("riscv32imac-unknown-xous-elf", riscv32imac_unknown_xous_elf),
     ("riscv32gc-unknown-linux-gnu", riscv32gc_unknown_linux_gnu),

compiler/rustc_target/src/spec/riscv32imac_esp_espidf.rs

@@ -0,0 +1,31 @@
+use crate::spec::{cvs, PanicStrategy, RelocModel, Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        data_layout: "e-m:e-p:32:32-i64:64-n32-S128".into(),
+        llvm_target: "riscv32".into(),
+        pointer_width: 32,
+        arch: "riscv32".into(),
+
+        options: TargetOptions {
+            families: cvs!["unix"],
+            os: "espidf".into(),
+            env: "newlib".into(),
+            vendor: "espressif".into(),
+            linker: Some("riscv32-esp-elf-gcc".into()),
+            cpu: "generic-rv32".into(),
+
+            // As RiscV32IMAC architecture does natively support atomics,
+            // automatically enable the support for the Rust STD library.
+            max_atomic_width: Some(64),
+            atomic_cas: true,
+
+            features: "+m,+a,+c".into(),
+            panic_strategy: PanicStrategy::Abort,
+            relocation_model: RelocModel::Static,
+            emit_debug_gdb_scripts: false,
+            eh_frame_header: false,
+            ..Default::default()
+        },
+    }
+}

src/doc/rustc/src/platform-support.md

@@ -298,6 +298,7 @@ target | std | host | notes
 `riscv32im-unknown-none-elf` | * |  | Bare RISC-V (RV32IM ISA)
 [`riscv32imac-unknown-xous-elf`](platform-support/riscv32imac-unknown-xous-elf.md) | ? |  | RISC-V Xous (RV32IMAC ISA)
 [`riscv32imc-esp-espidf`](platform-support/esp-idf.md) | ✓ |  | RISC-V ESP-IDF
+[`riscv32imac-esp-espidf`](platform-support/esp-idf.md) | ✓ |  | RISC-V ESP-IDF
 `riscv64gc-unknown-freebsd` |   |   | RISC-V FreeBSD
 `riscv64gc-unknown-fuchsia` |   |   | RISC-V Fuchsia
 `riscv64gc-unknown-linux-musl` |   |   | RISC-V Linux (kernel 4.20, musl 1.2.0)

src/doc/rustc/src/platform-support/esp-idf.md

@@ -13,11 +13,12 @@ Targets for the [ESP-IDF](https://github.com/espressif/esp-idf) development fram
 
 The target names follow this format: `$ARCH-esp-espidf`, where `$ARCH` specifies the target processor architecture. The following targets are currently defined:
 
-|          Target name           | Target CPU(s)         |
+|          Target name           | Target CPU(s)         | Minimum ESP-IDF version |
-|--------------------------------|-----------------------|
+|--------------------------------|-----------------------|-------------------------|
-| `riscv32imc-esp-espidf`        |  [ESP32-C3](https://www.espressif.com/en/products/socs/esp32-c3)             |
+| `riscv32imc-esp-espidf`        |  [ESP32-C3](https://www.espressif.com/en/products/socs/esp32-c3)             | `v4.3`                |
+| `riscv32imac-esp-espidf`       |  [ESP32-C6](https://www.espressif.com/en/products/socs/esp32-c6)             | `v5.1`                |
 
-The minimum supported ESP-IDF version is `v4.3`, though it is recommended to use the latest stable release if possible.
+It is recommended to use the latest ESP-IDF stable release if possible.
 
 ## Building the target