From 6a97ea0ba74b51c06adb1ba6b3334f971ad02d3b Mon Sep 17 00:00:00 2001
From: Anton Lisanin <lisanin.anton@gmail.com>
Date: Wed, 9 Jun 2021 08:44:02 +0300
Subject: [PATCH 1/2] Optimize U256 conversions

---
 core/src/eval/misc.rs       |  2 +-
 core/src/primitive_types.rs | 22 ++++++++++++++++++++++
 core/src/stack.rs           |  4 ++--
 runtime/src/eval/macros.rs  |  8 +++-----
 4 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/core/src/eval/misc.rs b/core/src/eval/misc.rs
index 102b1fb71..c23faaae3 100644
--- a/core/src/eval/misc.rs
+++ b/core/src/eval/misc.rs
@@ -153,7 +153,7 @@ pub fn msize(state: &mut Machine) -> Control {
 
 pub fn push(state: &mut Machine, n: usize, position: usize) -> Control {
 	let end = min(position + 1 + n, state.code.len());
-	let val = U256::from(&state.code[(position + 1)..end]);
+	let val = U256::from_big_endian_fast(&state.code[(position + 1)..end]);
 
 	push_u256!(state, val);
 	trace_op!("Push [@{}]: {}", state.stack.len() - 1, val);
diff --git a/core/src/primitive_types.rs b/core/src/primitive_types.rs
index ba09c85a6..8d4376e82 100644
--- a/core/src/primitive_types.rs
+++ b/core/src/primitive_types.rs
@@ -171,4 +171,26 @@ impl<'de> serde::Deserialize<'de> for U256 {
 
 		deserializer.deserialize_bytes(Visitor)
 	}
+}
+
+
+impl U256 {
+	pub fn into_big_endian_fast(self, buffer: &mut [u8]) {
+		let data: [u8; 32] = unsafe { core::mem::transmute(self) };
+		
+		let buffer = &mut buffer[0..32];
+		buffer.copy_from_slice(&data[..]);
+		buffer.reverse();
+	}
+
+	pub fn from_big_endian_fast(buffer: &[u8]) -> U256 {
+		assert!(32 >= buffer.len());
+
+		let mut data = [0u8; 32];
+
+		data[32 - buffer.len()..32].copy_from_slice(buffer);
+		data.reverse();
+
+		unsafe { core::mem::transmute(data) }
+	}
 }
\ No newline at end of file
diff --git a/core/src/stack.rs b/core/src/stack.rs
index 8fa1c1f28..e129872f9 100644
--- a/core/src/stack.rs
+++ b/core/src/stack.rs
@@ -83,7 +83,7 @@ impl Stack {
 		self.data.pop()
 			.map(|d| {
 				let mut value = H256::default();
-				d.to_big_endian(&mut value[..]);
+				d.into_big_endian_fast(&mut value[..]);
 				value
 			})
 			.ok_or(ExitError::StackUnderflow)
@@ -95,7 +95,7 @@ impl Stack {
 		if self.data.len() + 1 > self.limit {
 			return Err(ExitError::StackOverflow)
 		}
-		self.data.push(U256::from_big_endian(&value[..]));
+		self.data.push(U256::from_big_endian_fast(&value[..]));
 		Ok(())
 	}
 
diff --git a/runtime/src/eval/macros.rs b/runtime/src/eval/macros.rs
index fa2caab08..ca8538497 100644
--- a/runtime/src/eval/macros.rs
+++ b/runtime/src/eval/macros.rs
@@ -21,8 +21,8 @@ macro_rules! pop {
 macro_rules! pop_u256 {
 	( $machine:expr, $( $x:ident ),* ) => (
 		$(
-			let $x = match $machine.machine.stack_mut().pop() {
-				Ok(value) => U256::from_big_endian(&value[..]),
+			let $x = match $machine.machine.stack_mut().pop_u256() {
+				Ok(value) => value,
 				Err(e) => return Control::Exit(e.into()),
 			};
 		)*
@@ -43,9 +43,7 @@ macro_rules! push {
 macro_rules! push_u256 {
 	( $machine:expr, $( $x:expr ),* ) => (
 		$(
-			let mut value = H256::default();
-			$x.to_big_endian(&mut value[..]);
-			match $machine.machine.stack_mut().push(value) {
+			match $machine.machine.stack_mut().push_u256($x) {
 				Ok(()) => (),
 				Err(e) => return Control::Exit(e.into()),
 			}

From b1c4832ac00885723e554089947e1f7d17929b3b Mon Sep 17 00:00:00 2001
From: Anton Lisanin <lisanin.anton@gmail.com>
Date: Wed, 9 Jun 2021 08:44:28 +0300
Subject: [PATCH 2/2] Optimize calldataload

---
 core/src/eval/misc.rs | 14 ++++----------
 1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/core/src/eval/misc.rs b/core/src/eval/misc.rs
index c23faaae3..6eccff754 100644
--- a/core/src/eval/misc.rs
+++ b/core/src/eval/misc.rs
@@ -28,17 +28,11 @@ pub fn calldataload(state: &mut Machine) -> Control {
 	pop_u256!(state, index);
 	trace_op!("CallDataLoad: {}", index);
 
+	let index = as_usize_or_fail!(index);
+	let len = if index > state.data.len() { 0 } else { min(32, state.data.len() - index) };
+
 	let mut load = [0u8; 32];
-	for i in 0..32 {
-		if let Some(p) = index.checked_add(U256::from(i)) {
-			if p <= U256::from(usize::max_value()) {
-				let p = p.as_usize();
-				if p < state.data.len() {
-					load[i] = state.data[p];
-				}
-			}
-		}
-	}
+	load[0..len].copy_from_slice(&state.data[index..index + len]);
 
 	push!(state, H256::from(load));
 	Control::Continue(1)