[codegen] Use descriptive benchmark target fn name.

benches/ref_from_bytes.rs

@@ -2,6 +2,6 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8]) -> Option<&format::LocoPacket> {
+fn bench_ref_from_bytes(source: &[u8]) -> Option<&format::LocoPacket> {
     zerocopy::FromBytes::ref_from_bytes(source).ok()
 }

benches/ref_from_bytes.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_ref_from_bytes:
 	mov rdx, rsi
 	cmp rsi, 4
 	setb al

benches/ref_from_bytes_with_elems.rs

@@ -2,6 +2,6 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8], count: usize) -> Option<&format::LocoPacket> {
+fn bench_ref_from_bytes_with_elems(source: &[u8], count: usize) -> Option<&format::LocoPacket> {
     zerocopy::FromBytes::ref_from_bytes_with_elems(source, count).ok()
 }

benches/ref_from_bytes_with_elems.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_ref_from_bytes_with_elems:
 	movabs rax, 9223372036854775805
 	cmp rdx, rax
 	seta cl

benches/ref_from_prefix.rs

@@ -2,7 +2,7 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8]) -> Option<&format::LocoPacket> {
+fn bench_ref_from_prefix(source: &[u8]) -> Option<&format::LocoPacket> {
     match zerocopy::FromBytes::ref_from_prefix(source) {
         Ok((packet, _rest)) => Some(packet),
         _ => None,

benches/ref_from_prefix.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_ref_from_prefix:
 	xor edx, edx
 	mov eax, 0
 	test dil, 1

benches/ref_from_prefix_with_elems.rs

@@ -2,7 +2,7 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8], count: usize) -> Option<&format::LocoPacket> {
+fn bench_ref_from_prefix_with_elems(source: &[u8], count: usize) -> Option<&format::LocoPacket> {
     match zerocopy::FromBytes::ref_from_prefix_with_elems(source, count) {
         Ok((packet, _rest)) => Some(packet),
         _ => None,

benches/ref_from_prefix_with_elems.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_ref_from_prefix_with_elems:
 	movabs rax, 9223372036854775805
 	cmp rdx, rax
 	ja .LBB5_1

benches/ref_from_suffix.rs

@@ -2,7 +2,7 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8]) -> Option<&format::LocoPacket> {
+fn bench_ref_from_suffix(source: &[u8]) -> Option<&format::LocoPacket> {
     match zerocopy::FromBytes::ref_from_suffix(source) {
         Ok((_rest, packet)) => Some(packet),
         _ => None,

benches/ref_from_suffix.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_ref_from_suffix:
 	mov rdx, rsi
 	lea ecx, [rsi + rdi]
 	mov eax, edx

benches/ref_from_suffix_with_elems.rs

@@ -2,7 +2,7 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8], count: usize) -> Option<&format::LocoPacket> {
+fn bench_ref_from_suffix_with_elems(source: &[u8], count: usize) -> Option<&format::LocoPacket> {
     match zerocopy::FromBytes::ref_from_suffix_with_elems(source, count) {
         Ok((_rest, packet)) => Some(packet),
         _ => None,

benches/ref_from_suffix_with_elems.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_ref_from_suffix_with_elems:
 	movabs rax, 9223372036854775805
 	cmp rdx, rax
 	ja .LBB5_1

benches/transmute_ref.rs

@@ -11,6 +11,6 @@ struct MinimalViableSource {
 }
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &MinimalViableSource) -> &format::LocoPacket {
+fn bench_transmute_ref(source: &MinimalViableSource) -> &format::LocoPacket {
     zerocopy::transmute_ref!(source)
 }

benches/transmute_ref.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_transmute_ref:
 	mov rdx, rsi
 	mov rax, rdi
 	ret

benches/try_ref_from_bytes.rs

@@ -2,6 +2,6 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8]) -> Option<&format::CocoPacket> {
+fn bench_try_ref_from_bytes(source: &[u8]) -> Option<&format::CocoPacket> {
     zerocopy::TryFromBytes::try_ref_from_bytes(source).ok()
 }

benches/try_ref_from_bytes.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_try_ref_from_bytes:
 	mov rdx, rsi
 	mov rax, rdi
 	cmp rsi, 4

benches/try_ref_from_bytes_with_elems.rs

@@ -2,6 +2,6 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8], count: usize) -> Option<&format::CocoPacket> {
+fn bench_try_ref_from_bytes_with_elems(source: &[u8], count: usize) -> Option<&format::CocoPacket> {
     zerocopy::TryFromBytes::try_ref_from_bytes_with_elems(source, count).ok()
 }

benches/try_ref_from_bytes_with_elems.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_try_ref_from_bytes_with_elems:
 	movabs rax, 9223372036854775805
 	cmp rdx, rax
 	seta cl

benches/try_ref_from_prefix.rs

@@ -2,7 +2,7 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8]) -> Option<&format::CocoPacket> {
+fn bench_try_ref_from_prefix(source: &[u8]) -> Option<&format::CocoPacket> {
     match zerocopy::TryFromBytes::try_ref_from_prefix(source) {
         Ok((packet, _rest)) => Some(packet),
         _ => None,

benches/try_ref_from_prefix.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_try_ref_from_prefix:
 	xor edx, edx
 	mov eax, 0
 	test dil, 1

benches/try_ref_from_prefix_with_elems.rs

@@ -2,7 +2,10 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8], count: usize) -> Option<&format::CocoPacket> {
+fn bench_try_ref_from_prefix_with_elems(
+    source: &[u8],
+    count: usize,
+) -> Option<&format::CocoPacket> {
     match zerocopy::TryFromBytes::try_ref_from_prefix_with_elems(source, count) {
         Ok((packet, _rest)) => Some(packet),
         _ => None,

benches/try_ref_from_prefix_with_elems.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_try_ref_from_prefix_with_elems:
 	movabs rax, 9223372036854775805
 	cmp rdx, rax
 	ja .LBB5_1

benches/try_ref_from_suffix.rs

@@ -2,7 +2,7 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8]) -> Option<&format::CocoPacket> {
+fn bench_try_ref_from_suffix(source: &[u8]) -> Option<&format::CocoPacket> {
     match zerocopy::TryFromBytes::try_ref_from_suffix(source) {
         Ok((_rest, packet)) => Some(packet),
         _ => None,

benches/try_ref_from_suffix.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_try_ref_from_suffix:
 	lea eax, [rsi + rdi]
 	cmp rsi, 4
 	setb cl

benches/try_ref_from_suffix_with_elems.rs

@@ -2,7 +2,10 @@
 mod format;
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &[u8], count: usize) -> Option<&format::CocoPacket> {
+fn bench_try_ref_from_suffix_with_elems(
+    source: &[u8],
+    count: usize,
+) -> Option<&format::CocoPacket> {
     match zerocopy::TryFromBytes::try_ref_from_suffix_with_elems(source, count) {
         Ok((_rest, packet)) => Some(packet),
         _ => None,

benches/try_ref_from_suffix_with_elems.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_try_ref_from_suffix_with_elems:
 	movabs rax, 9223372036854775805
 	cmp rdx, rax
 	ja .LBB5_1

benches/try_transmute_ref.rs

@@ -11,6 +11,6 @@ struct MinimalViableSource {
 }
 
 #[unsafe(no_mangle)]
-fn codegen_test(source: &MinimalViableSource) -> Option<&format::CocoPacket> {
+fn bench_try_transmute_ref(source: &MinimalViableSource) -> Option<&format::CocoPacket> {
     zerocopy::try_transmute_ref!(source).ok()
 }

benches/try_transmute_ref.x86-64

@@ -1,4 +1,4 @@
-codegen_test:
+bench_try_transmute_ref:
 	mov rdx, rsi
 	xor eax, eax
 	cmp word ptr [rdi], -16192

tests/codegen.rs

@@ -51,18 +51,23 @@ fn run_codegen_test(bench_name: &str, target_cpu: &str, bless: bool) {
                 target_cpu,
                 "--simplify",
                 directive.arg(),
-                "codegen_test",
+                &format!("bench_{bench_name}"),
             ])
             .output()
             .expect("failed to execute process")
     };
 
     let test_directive = |directive: Directive| {
+        println!("{bench_name}");
         let output = cargo_asm(&directive);
         let actual_result = output.stdout;
 
         if !(output.status.success()) {
-            panic!("{}", String::from_utf8_lossy(&output.stderr));
+            panic!(
+                "{}\n{}",
+                String::from_utf8_lossy(&actual_result),
+                String::from_utf8_lossy(&output.stderr)
+            );
         }
 
         let expected_file_path = {