From 38525a206c5eb6bbd093496dca322c1b49b35bd3 Mon Sep 17 00:00:00 2001
From: Robin Salen <salenrobin@gmail.com>
Date: Fri, 10 Nov 2023 11:39:17 -0500
Subject: [PATCH 1/3] Use table for JUMPDEST

---
 .../cpu/kernel/asm/core/jumpdest_analysis.asm | 56 ++++++++++++++-----
 1 file changed, 43 insertions(+), 13 deletions(-)

diff --git a/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm b/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
index a9d8adf2ff..f6c862e676 100644
--- a/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
+++ b/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
@@ -23,7 +23,8 @@ loop:
     %jumpi(encountered_jumpdest)
 
     // stack: opcode, i, ctx, code_len, retdest
-    %code_bytes_to_skip
+    %add_const(code_bytes_to_skip)
+    %mload_kernel_code
     // stack: bytes_to_skip, i, ctx, code_len, retdest
     ADD
     %jump(continue)
@@ -50,15 +51,44 @@ return:
 //
 // Note that the range of PUSH opcodes is [0x60, 0x80). I.e. PUSH1 is 0x60
 // and PUSH32 is 0x7f.
-%macro code_bytes_to_skip
-    // stack: opcode
-    %sub_const(0x60)
-    // stack: opcode - 0x60
-    DUP1 %lt_const(0x20)
-    // stack: is_push_opcode, opcode - 0x60
-    SWAP1
-    %increment // n = opcode - 0x60 + 1
-    // stack: n, is_push_opcode
-    MUL
-    // stack: bytes_to_skip
-%endmacro
+code_bytes_to_skip:
+    %rep 96
+        BYTES 0 // 0x00-0x5f
+    %endrep
+
+    BYTES 1
+    BYTES 2
+    BYTES 3
+    BYTES 4
+    BYTES 5
+    BYTES 6
+    BYTES 7
+    BYTES 8
+    BYTES 9
+    BYTES 10
+    BYTES 11
+    BYTES 12
+    BYTES 13
+    BYTES 14
+    BYTES 15
+    BYTES 16
+    BYTES 17
+    BYTES 18
+    BYTES 19
+    BYTES 20
+    BYTES 21
+    BYTES 22
+    BYTES 23
+    BYTES 24
+    BYTES 25
+    BYTES 26
+    BYTES 27
+    BYTES 28
+    BYTES 29
+    BYTES 30
+    BYTES 31
+    BYTES 32
+
+    %rep 128
+        BYTES 0 // 0x80-0xff
+    %endrep

From 21b5a481df8d41cf0209c0b2fa0bb1e39325b336 Mon Sep 17 00:00:00 2001
From: Hamy Ratoanina <hamy.ratoanina@toposware.com>
Date: Fri, 10 Nov 2023 11:56:41 -0500
Subject: [PATCH 2/3] Refactor jumpdest loop

---
 .../cpu/kernel/asm/core/jumpdest_analysis.asm | 31 +++++++++----------
 1 file changed, 14 insertions(+), 17 deletions(-)

diff --git a/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm b/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
index f6c862e676..68a381b724 100644
--- a/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
+++ b/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
@@ -18,27 +18,24 @@ loop:
     MLOAD_GENERAL
     // stack: opcode, i, ctx, code_len, retdest
 
-    DUP1 %eq_const(0x5b)
-    // stack: opcode == JUMPDEST, opcode, i, ctx, code_len, retdest
-    %jumpi(encountered_jumpdest)
+    DUP1 
+    // Slightly more efficient than `%eq_const(0x5b) ISZERO`
+    PUSH 0x5b
+    SUB
+    // stack: opcode != JUMPDEST, opcode, i, ctx, code_len, retdest
+    %jumpi(continue)
 
+    // stack: JUMPDEST, i, ctx, code_len, retdest
+    %stack (JUMPDEST, i, ctx) -> (ctx, @SEGMENT_JUMPDEST_BITS, i, 1, JUMPDEST, i, ctx)
+    MSTORE_GENERAL
+
+continue:
     // stack: opcode, i, ctx, code_len, retdest
     %add_const(code_bytes_to_skip)
     %mload_kernel_code
     // stack: bytes_to_skip, i, ctx, code_len, retdest
     ADD
-    %jump(continue)
-
-encountered_jumpdest:
-    // stack: opcode, i, ctx, code_len, retdest
-    POP
-    // stack: i, ctx, code_len, retdest
-    %stack (i, ctx) -> (ctx, @SEGMENT_JUMPDEST_BITS, i, 1, i, ctx)
-    MSTORE_GENERAL
-
-continue:
     // stack: i, ctx, code_len, retdest
-    %increment
     %jump(loop)
 
 return:
@@ -53,10 +50,9 @@ return:
 // and PUSH32 is 0x7f.
 code_bytes_to_skip:
     %rep 96
-        BYTES 0 // 0x00-0x5f
+        BYTES 1 // 0x00-0x5f
     %endrep
 
-    BYTES 1
     BYTES 2
     BYTES 3
     BYTES 4
@@ -88,7 +84,8 @@ code_bytes_to_skip:
     BYTES 30
     BYTES 31
     BYTES 32
+    BYTES 33
 
     %rep 128
-        BYTES 0 // 0x80-0xff
+        BYTES 1 // 0x80-0xff
     %endrep

From 3c9c9b4d99308f353b7fe08562b952f0800438c6 Mon Sep 17 00:00:00 2001
From: Hamy Ratoanina <hamy.ratoanina@toposware.com>
Date: Fri, 10 Nov 2023 12:31:31 -0500
Subject: [PATCH 3/3] Update comment

---
 evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm b/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
index 68a381b724..a99168058e 100644
--- a/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
+++ b/evm/src/cpu/kernel/asm/core/jumpdest_analysis.asm
@@ -43,8 +43,8 @@ return:
     %pop3
     JUMP
 
-// Determines how many bytes to skip, if any, based on the opcode we read.
-// If we read a PUSH<n> opcode, we skip over n bytes, otherwise we skip 0.
+// Determines how many bytes away is the next opcode, based on the opcode we read.
+// If we read a PUSH<n> opcode, next opcode is in n + 1 bytes, otherwise it's the next one.
 //
 // Note that the range of PUSH opcodes is [0x60, 0x80). I.e. PUSH1 is 0x60
 // and PUSH32 is 0x7f.