Rollup merge of #108722 - petrhosek:fuchsia-riscv, r=petrochenkov

Support for Fuchsia RISC-V target

Fuchsia is in the process of implementing the RISC-V support. This change implements the minimal Rust compiler support. The support for building runtime libraries will be implemented in follow up changes once Fuchsia SDK has the RISC-V support.

compiler/rustc_target/src/spec/mod.rs

@@ -1115,6 +1115,7 @@ supported_targets! {
     // FIXME(#106649): Remove aarch64-fuchsia in favor of aarch64-unknown-fuchsia
     ("aarch64-fuchsia", aarch64_fuchsia),
     ("aarch64-unknown-fuchsia", aarch64_unknown_fuchsia),
+    ("riscv64gc-unknown-fuchsia", riscv64gc_unknown_fuchsia),
     // FIXME(#106649): Remove x86_64-fuchsia in favor of x86_64-unknown-fuchsia
     ("x86_64-fuchsia", x86_64_fuchsia),
     ("x86_64-unknown-fuchsia", x86_64_unknown_fuchsia),

compiler/rustc_target/src/spec/riscv64gc_unknown_fuchsia.rs

@@ -0,0 +1,19 @@
+use crate::spec::{CodeModel, SanitizerSet, Target, TargetOptions};
+
+pub fn target() -> Target {
+    Target {
+        llvm_target: "riscv64gc-unknown-fuchsia".into(),
+        pointer_width: 64,
+        data_layout: "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128".into(),
+        arch: "riscv64".into(),
+        options: TargetOptions {
+            code_model: Some(CodeModel::Medium),
+            cpu: "generic-rv64".into(),
+            features: "+m,+a,+f,+d,+c".into(),
+            llvm_abiname: "lp64d".into(),
+            max_atomic_width: Some(64),
+            supported_sanitizers: SanitizerSet::SHADOWCALLSTACK,
+            ..super::fuchsia_base::opts()
+        },
+    }
+}