From 2fe211c5e0d3444184a3c275bff94cf659a11995 Mon Sep 17 00:00:00 2001
From: Dmitri Makarov <dmakarov@users.noreply.github.com>
Date: Wed, 9 Jun 2021 22:04:17 -0700
Subject: [PATCH] Remove O2 option for compiling BPF programs (#17865)

rustc default compiler optimization level is O3. This change removes
the option that overrides the default optimization level, because it
is safe to do so.  The code generation is incorrect in some cases
because of link-time optimizations, which remain disabled for
compiling BPF programs.  In addition, this commit updates the expected
instruction counts for assert_instruction_count test.
---
 programs/bpf/tests/programs.rs  | 28 ++++++++++++++--------------
 sdk/bpf/env.sh                  |  2 +-
 sdk/cargo-build-bpf/src/main.rs |  4 +---
 3 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/programs/bpf/tests/programs.rs b/programs/bpf/tests/programs.rs
index 2feb5c3cf4..376e816400 100644
--- a/programs/bpf/tests/programs.rs
+++ b/programs/bpf/tests/programs.rs
@@ -1277,11 +1277,11 @@ fn assert_instruction_count() {
             ("alloc", 1137),
             ("bpf_to_bpf", 13),
             ("multiple_static", 8),
-            ("noop", 42),
-            ("noop++", 42),
+            ("noop", 5),
+            ("noop++", 5),
             ("relative_call", 10),
-            ("sanity", 174),
-            ("sanity++", 174),
+            ("sanity", 169),
+            ("sanity++", 168),
             ("sha", 1040),
             ("struct_pass", 8),
             ("struct_ret", 22),
@@ -1291,19 +1291,19 @@ fn assert_instruction_count() {
     {
         programs.extend_from_slice(&[
             ("solana_bpf_rust_128bit", 584),
-            ("solana_bpf_rust_alloc", 8906),
-            ("solana_bpf_rust_custom_heap", 539),
+            ("solana_bpf_rust_alloc", 7082),
+            ("solana_bpf_rust_custom_heap", 522),
             ("solana_bpf_rust_dep_crate", 2),
-            ("solana_bpf_rust_external_spend", 521),
+            ("solana_bpf_rust_external_spend", 504),
             ("solana_bpf_rust_iter", 724),
-            ("solana_bpf_rust_many_args", 237),
-            ("solana_bpf_rust_mem", 3166),
-            ("solana_bpf_rust_membuiltins", 4069),
-            ("solana_bpf_rust_noop", 495),
+            ("solana_bpf_rust_many_args", 233),
+            ("solana_bpf_rust_mem", 3096),
+            ("solana_bpf_rust_membuiltins", 4065),
+            ("solana_bpf_rust_noop", 478),
             ("solana_bpf_rust_param_passing", 46),
-            ("solana_bpf_rust_rand", 498),
-            ("solana_bpf_rust_sanity", 917),
-            ("solana_bpf_rust_sha", 32384),
+            ("solana_bpf_rust_rand", 481),
+            ("solana_bpf_rust_sanity", 873),
+            ("solana_bpf_rust_sha", 32295),
         ]);
     }
 
diff --git a/sdk/bpf/env.sh b/sdk/bpf/env.sh
index 8c15625871..8dfb02464d 100644
--- a/sdk/bpf/env.sh
+++ b/sdk/bpf/env.sh
@@ -15,4 +15,4 @@ 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"
+export RUSTFLAGS="-C lto=no"
diff --git a/sdk/cargo-build-bpf/src/main.rs b/sdk/cargo-build-bpf/src/main.rs
index 4772fd25d4..14ec3ff223 100644
--- a/sdk/cargo-build-bpf/src/main.rs
+++ b/sdk/cargo-build-bpf/src/main.rs
@@ -383,9 +383,7 @@ 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);
+    env::set_var("RUSTFLAGS", "-C lto=no");
     let cargo_build = PathBuf::from("cargo");
     let mut cargo_build_args = vec![
         "+bpf",