Add BPF rustc option to reduce the optimizations to safer level (backport #17590)

programs/bpf/tests/programs.rs

@@ -1269,19 +1269,19 @@ fn assert_instruction_count() {
     #[cfg(feature = "bpf_rust")]
     {
         programs.extend_from_slice(&[
-            ("solana_bpf_rust_128bit", 584),
-            ("solana_bpf_rust_alloc", 5072),
-            ("solana_bpf_rust_custom_heap", 367),
+            ("solana_bpf_rust_128bit", 572),
+            ("solana_bpf_rust_alloc", 8906),
+            ("solana_bpf_rust_custom_heap", 539),
             ("solana_bpf_rust_dep_crate", 2),
-            ("solana_bpf_rust_external_spend", 336),
-            ("solana_bpf_rust_iter", 279),
-            ("solana_bpf_rust_many_args", 191),
-            ("solana_bpf_rust_mem", 1670),
-            ("solana_bpf_rust_noop", 324),
+            ("solana_bpf_rust_external_spend", 521),
+            ("solana_bpf_rust_iter", 724),
+            ("solana_bpf_rust_many_args", 237),
+            ("solana_bpf_rust_mem", 2297),
+            ("solana_bpf_rust_noop", 495),
             ("solana_bpf_rust_param_passing", 46),
-            ("solana_bpf_rust_rand", 327),
-            ("solana_bpf_rust_sanity", 595),
-            ("solana_bpf_rust_sha", 22417),
+            ("solana_bpf_rust_rand", 498),
+            ("solana_bpf_rust_sanity", 917),
+            ("solana_bpf_rust_sha", 29099),
         ]);
     }
 

sdk/bpf/env.sh

@@ -14,3 +14,5 @@ export CC="$bpf_sdk/dependencies/bpf-tools/llvm/bin/clang"
 export AR="$bpf_sdk/dependencies/bpf-tools/llvm/bin/llvm-ar"
 export OBJDUMP="$bpf_sdk/dependencies/bpf-tools/llvm/bin/llvm-objdump"
 export OBJCOPY="$bpf_sdk/dependencies/bpf-tools/llvm/bin/llvm-objcopy"
+
+export RUSTFLAGS="-C lto=no -C opt-level=2"

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

@@ -377,7 +377,9 @@ fn build_bpf_package(config: &Config, target_directory: &Path, package: &cargo_m
     env::set_var("AR", llvm_bin.join("llvm-ar"));
     env::set_var("OBJDUMP", llvm_bin.join("llvm-objdump"));
     env::set_var("OBJCOPY", llvm_bin.join("llvm-objcopy"));
-
+    let mut rust_flags = String::from("-C lto=no");
+    rust_flags.push_str(" -C opt-level=2");
+    env::set_var("RUSTFLAGS", rust_flags);
     let cargo_build = PathBuf::from("cargo");
     let mut cargo_build_args = vec![
         "+bpf",