cargo-build-bpf: add --arch option

--arch allows selecting the target SBF version. See
anza-xyz/llvm-project#26.

Author: alessandrod

sdk/cargo-build-bpf/src/main.rs

@@ -31,6 +31,7 @@ struct Config<'a> {
     offline: bool,
     verbose: bool,
     workspace: bool,
+    arch: &'a str,
 }
 
 impl Default for Config<'_> {
@@ -53,6 +54,7 @@ impl Default for Config<'_> {
             offline: false,
             verbose: false,
             workspace: false,
+            arch: "sbf",
         }
     }
 }
@@ -516,11 +518,13 @@ fn build_bpf_package(config: &Config, target_directory: &Path, package: &cargo_m
     env::set_var("OBJDUMP", llvm_bin.join("llvm-objdump"));
     env::set_var("OBJCOPY", llvm_bin.join("llvm-objcopy"));
 
+    let mut rustflags = env::var("RUSTFLAGS").ok().unwrap_or_else(String::new);
+    if config.arch == "sbfv2" {
+        rustflags = format!("{} {}", "-C target_cpu=sbfv2", rustflags);
+        env::set_var("RUSTFLAGS", &rustflags);
+    }
     if config.verbose {
-        println!(
-            "RUSTFLAGS={}",
-            env::var("RUSTFLAGS").ok().as_deref().unwrap_or("")
-        );
+        println!("RUSTFLAGS={}", rustflags);
     };
 
     let cargo_build = PathBuf::from("cargo");
@@ -531,6 +535,9 @@ fn build_bpf_package(config: &Config, target_directory: &Path, package: &cargo_m
         "bpfel-unknown-unknown",
         "--release",
     ];
+    if config.arch == "sbfv2" {
+        cargo_build_args.push("-Zbuild-std=std,panic_abort");
+    }
     if config.no_default_features {
         cargo_build_args.push("--no-default-features");
     }
@@ -793,6 +800,13 @@ fn main() {
                 .alias("all")
                 .help("Build all BPF packages in the workspace"),
         )
+        .arg(
+            Arg::with_name("arch")
+                .long("arch")
+                .possible_values(&["sbf", "sbfv2"])
+                .default_value("sbf")
+                .help("Build for the given SBF version"),
+        )
         .get_matches_from(args);
 
     let bpf_sdk = value_t_or_exit!(matches, "bpf_sdk", PathBuf);
@@ -829,6 +843,7 @@ fn main() {
         offline: matches.is_present("offline"),
         verbose: matches.is_present("verbose"),
         workspace: matches.is_present("workspace"),
+        arch: matches.value_of("arch").unwrap(),
     };
     let manifest_path = value_t!(matches, "manifest_path", PathBuf).ok();
     build_bpf(config, manifest_path);