[RFC RESEND 1/2] scripts: generate_rust_target: enable building on RISC-V

[Conor Dooley <conor.dooley@xxxxxxxxxxxxx>]

From: Miguel Ojeda <ojeda@xxxxxxxxxx>

Add the required bits from rust-for-linux to enable generating a RISC-V
target for rust.

Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
---
 scripts/generate_rust_target.rs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/scripts/generate_rust_target.rs b/scripts/generate_rust_target.rs
index 3c6cbe2b278d..72428fc66502 100644
--- a/scripts/generate_rust_target.rs
+++ b/scripts/generate_rust_target.rs
@@ -161,6 +161,25 @@ fn main() {
         ts.push("features", features);
         ts.push("llvm-target", "x86_64-linux-gnu");
         ts.push("target-pointer-width", "64");
+    } else if cfg.has("RISCV") {
+        if cfg.has("64BIT") {
+            ts.push("arch", "riscv64");
+            ts.push("data-layout", "e-m:e-p:64:64-i64:64-i128:128-n64-S128");
+            ts.push("llvm-target", "riscv64-linux-gnu");
+            ts.push("target-pointer-width", "64");
+        } else {
+            ts.push("arch", "riscv32");
+            ts.push("data-layout", "e-m:e-p:32:32-i64:64-n32-S128");
+            ts.push("llvm-target", "riscv32-linux-gnu");
+            ts.push("target-pointer-width", "32");
+        }
+        ts.push("code-model", "medium");
+        ts.push("disable-redzone", true);
+        let mut features = "+m,+a".to_string();
+        if cfg.has("RISCV_ISA_C") {
+            features += ",+c";
+        }
+        ts.push("features", features);
     } else {
         panic!("Unsupported architecture");
     }
-- 
2.39.2