From 83054b0ffee655d7fef4520a6a70d1450d091c64 Mon Sep 17 00:00:00 2001
From: Robin Salen <salenrobin@gmail.com>
Date: Mon, 23 Oct 2023 19:12:54 -0400
Subject: [PATCH 1/2] Handle empty case for memcpy_bytes

---
 evm/src/cpu/kernel/asm/memory/memcpy.asm | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/evm/src/cpu/kernel/asm/memory/memcpy.asm b/evm/src/cpu/kernel/asm/memory/memcpy.asm
index 108b7c6f..e9aea36f 100644
--- a/evm/src/cpu/kernel/asm/memory/memcpy.asm
+++ b/evm/src/cpu/kernel/asm/memory/memcpy.asm
@@ -57,6 +57,17 @@ memcpy_finish:
 // Similar logic to memcpy, but optimized for copying sequences of bytes.
 global memcpy_bytes:
     // stack: DST, SRC, count, retdest
+
+    // Handle empty case
+    DUP7
+    // stack: count, DST, SRC, count, retdest
+    ISZERO
+    // stack: count == 0, DST, SRC, count, retdest
+    %jumpi(memcpy_bytes_empty)
+
+    // stack: DST, SRC, count, retdest
+
+    // Handle small case
     DUP7
     // stack: count, DST, SRC, count, retdest
     %lt_const(0x20)
@@ -119,6 +130,12 @@ memcpy_bytes_finish:
     // stack: retdest
     JUMP
 
+memcpy_bytes_empty:
+    // stack: DST, SRC, count, retdest
+    %pop7
+    // stack: retdest
+    JUMP
+
 %macro memcpy_bytes
     %stack (dst: 3, src: 3, count) -> (dst, src, count, %%after)
     %jump(memcpy_bytes)

From 60811d083f8e3bd34126b955c5ef69b47f12548d Mon Sep 17 00:00:00 2001
From: Robin Salen <salenrobin@gmail.com>
Date: Mon, 23 Oct 2023 19:40:32 -0400
Subject: [PATCH 2/2] Also for memset

---
 evm/src/cpu/kernel/asm/memory/memcpy.asm |  2 +-
 evm/src/cpu/kernel/asm/memory/memset.asm | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/evm/src/cpu/kernel/asm/memory/memcpy.asm b/evm/src/cpu/kernel/asm/memory/memcpy.asm
index e9aea36f..e737dc33 100644
--- a/evm/src/cpu/kernel/asm/memory/memcpy.asm
+++ b/evm/src/cpu/kernel/asm/memory/memcpy.asm
@@ -131,7 +131,7 @@ memcpy_bytes_finish:
     JUMP
 
 memcpy_bytes_empty:
-    // stack: DST, SRC, count, retdest
+    // stack: DST, SRC, 0, retdest
     %pop7
     // stack: retdest
     JUMP
diff --git a/evm/src/cpu/kernel/asm/memory/memset.asm b/evm/src/cpu/kernel/asm/memory/memset.asm
index c0bad482..4c2e363b 100644
--- a/evm/src/cpu/kernel/asm/memory/memset.asm
+++ b/evm/src/cpu/kernel/asm/memory/memset.asm
@@ -2,12 +2,22 @@
 //     DST = (dst_ctx, dst_segment, dst_addr).
 // This tuple definition is used for brevity in the stack comments below.
 global memset:
+    // Handle empty case
+    DUP7
+    // stack: count, DST, count, retdest
+    ISZERO
+    // stack: count == 0, DST, count, retdest
+    %jumpi(memset_bytes_empty)
+
     // stack: DST, count, retdest
+
+    // Handle small case
     DUP4
     // stack: count, DST, count, retdest
     %lt_const(0x20)
     // stack: count < 32, DST, count, retdest
     %jumpi(memset_finish)
+
     // stack: DST, count, retdest
     PUSH 32
     PUSH 0
@@ -43,3 +53,9 @@ memset_finish:
     %pop4
     // stack: retdest
     JUMP
+
+memset_bytes_empty:
+    // stack: DST, 0, retdest
+    %pop4
+    // stack: retdest
+    JUMP