Use conditional dependencies in riscv-rt depending on base extension

riscv-rt/Cargo.toml

@@ -25,7 +25,7 @@ riscv-target-parser = { path = "../riscv-target-parser", version = "0.1.0" }
 [dependencies]
 riscv = { path = "../riscv", version = "0.12.0" }
 riscv-pac = { path = "../riscv-pac", version = "0.2.0" }
-riscv-rt-macros = { path = "macros", version = "0.2.2" }
+riscv-rt-macros = { path = "macros", version = "0.3.0" }
 
 [dev-dependencies]
 panic-halt = "1.0.0"

riscv-rt/build.rs

@@ -29,12 +29,20 @@ fn main() {
 
     if let Ok(target) = RiscvTarget::build(&target, &cargo_flags) {
         let width = target.width();
-        if matches!(width, riscv_target_parser::Width::W128) {
-            panic!("Unsupported RISC-V target: {width}");
-        }
-        if target.base_extension().is_none() {
-            panic!("Unsupported RISC-V target: no base extension");
-        }
+        let base_extension = match width {
+            riscv_target_parser::Width::W32 => match target.base_extension() {
+                Some(riscv_target_parser::Extension::I) => "RV32I",
+                Some(riscv_target_parser::Extension::E) => "RV32E",
+                other => panic!("Unsupported RISC-V target: {:?}-{:?}", width, other),
+            },
+            riscv_target_parser::Width::W64 => match target.base_extension() {
+                Some(riscv_target_parser::Extension::I) => "RV64I",
+                Some(riscv_target_parser::Extension::E) => "RV64E",
+                other => panic!("Unsupported RISC-V target: {:?}-{:?}", width, other),
+            },
+            _ => panic!("Unsupported RISC-V target width: {:?}", width),
+        };
+        println!("cargo:rustc-env=RUSTC_CFG_RISCV32I={base_extension}");
         for flag in target.rustc_flags() {
             // Required until target_feature risc-v is stable and in-use
             println!("cargo:rustc-check-cfg=cfg({flag})");

riscv-rt/macros/Cargo.toml

@@ -10,7 +10,7 @@ keywords = ["riscv", "runtime", "startup"]
 license = "MIT OR Apache-2.0"
 name = "riscv-rt-macros"
 repository = "https://github.com/rust-embedded/riscv"
-version = "0.2.2"
+version = "0.3.0"
 edition = "2021"
 
 [lib]
@@ -25,3 +25,7 @@ syn = { version = "2.0", features = ["extra-traits", "full"] }
 s-mode = []
 v-trap = []
 u-boot = []
+riscv32i = []
+riscv32e = []
+riscv64i = []
+riscv64e = []

riscv-rt/macros/build.rs

@@ -0,0 +1,20 @@
+fn main() {
+    match option_env!("RISCV_BASE_EXTENSION") {
+        Some("RV32I") => {
+            println!("cargo:rustc-cfg=feature=\"riscv32\"");
+        }
+        Some("RV32E") => {
+            println!("cargo:rustc-cfg=feature=\"riscv32e\"");
+        }
+        Some("RV64I") | None => {
+            // RV64I is the default base extension for docs
+            println!("cargo:rustc-cfg=feature=\"riscv64\"");
+        }
+        Some("RV64E") => {
+            println!("cargo:rustc-cfg=feature=\"riscv64e\"");
+        }
+        Some(other) => {
+            panic!("Unsupported RISC-V base extension: {other}");
+        }
+    }
+}