More efficient padding (#11656) (#11823)

(cherry picked from commit f1ba238) Co-authored-by: Jack May <[email protected]>
solana-labs · Aug 25, 2020 · 08bece7 · 08bece7
1 parent f162c6d
commit 08bece7
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Showing 4 changed files with 10 additions and 11 deletions.
diff --git a/programs/bpf_loader/src/serialization.rs b/programs/bpf_loader/src/serialization.rs
@@ -147,9 +147,10 @@ pub fn serialize_parameters_aligned(
             v.write_u64::<LittleEndian>(keyed_account.data_len()? as u64)
                 .unwrap();
             v.write_all(&keyed_account.try_account_ref()?.data).unwrap();
-            for _ in 0..16 - (v.len() % 16) {
-                v.write_u8(0).unwrap(); // 128 bit aligned again
-            }
+            v.resize(
+                v.len() + (v.len() as *const u8).align_offset(align_of::<u128>()),
+                0,
+            );
             v.write_u64::<LittleEndian>(keyed_account.rent_epoch()? as u64)
                 .unwrap();
         }
@@ -188,7 +189,7 @@ pub fn deserialize_parameters_aligned(
                 .data
                 .clone_from_slice(&buffer[start..end]);
             start += keyed_account.data_len()?; // data
-            start += 16 - (start % 16); // padding
+            start += (start as *const u8).align_offset(align_of::<u128>());
             start += mem::size_of::<u64>(); // rent_epoch
         } else {
             start += 7; // padding

diff --git a/programs/bpf_loader/test_elfs/noop_aligned.so b/programs/bpf_loader/test_elfs/noop_aligned.so
diff --git a/sdk/bpf/c/inc/solana_sdk.h b/sdk/bpf/c/inc/solana_sdk.h
@@ -297,7 +297,7 @@ static bool sol_deserialize(
         uint64_t data_len = *(uint64_t *) input;
         input += sizeof(uint64_t);
         input += data_len;
-        input += 16 - (data_len % 16); // padding
+        input = (uint8_t*)(((uint64_t)input + 8 - 1) & ~(8 - 1)); // padding
         input += sizeof(uint64_t);
       }
       continue;
@@ -334,8 +334,7 @@ static bool sol_deserialize(
       input += sizeof(uint64_t);
       params->ka[i].data = (uint8_t *) input;
       input += params->ka[i].data_len;
-
-      input += 16 - (params->ka[i].data_len % 16); // padding
+      input = (uint8_t*)(((uint64_t)input + 8 - 1) & ~(8 - 1)); // padding
 
       // rent epoch
       params->ka[i].rent_epoch = *(uint64_t *) input;

diff --git a/sdk/src/entrypoint.rs b/sdk/src/entrypoint.rs
@@ -5,7 +5,7 @@ use crate::{account_info::AccountInfo, program_error::ProgramError, pubkey::Pubk
 use alloc::vec::Vec;
 use std::{
     cell::RefCell,
-    mem::size_of,
+    mem::{align_of, size_of},
     rc::Rc,
     // Hide Result from bindgen gets confused about generics in non-generic type declarations
     result::Result as ResultGeneric,
@@ -80,7 +80,7 @@ pub unsafe fn deserialize<'a>(input: *mut u8) -> (&'a Pubkey, Vec<AccountInfo<'a
             let executable = *(input.add(offset) as *const u8) != 0;
             offset += size_of::<u8>();
 
-            offset += 4; // padding
+            offset += size_of::<u32>(); // padding to u64
 
             let key: &Pubkey = &*(input.add(offset) as *const Pubkey);
             offset += size_of::<Pubkey>();
@@ -100,8 +100,7 @@ pub unsafe fn deserialize<'a>(input: *mut u8) -> (&'a Pubkey, Vec<AccountInfo<'a
                 from_raw_parts_mut(input.add(offset), data_len)
             }));
             offset += data_len;
-
-            offset += 16 - (offset % 16); // padding
+            offset += (offset as *const u8).align_offset(align_of::<u128>()); // padding
 
             #[allow(clippy::cast_ptr_alignment)]
             let rent_epoch = *(input.add(offset) as *const u64);