hrkrshnn

Encoding stack too deep

{
    let a := calldataload(0) // x1
    let b := calldataload(2) // x2
    mstore(100, 200)  // x3
    mstore(a, b)  // x4
}  

hrkrshnn

"""
An approach for
https://github.com/ethereum/solidity/pull/11493/files#r651807831
"""
# stack is modelled by an array of characters
stackAfter = ['a', 'x', 'b', 'e', 'x', 'b', 'd', 'a', 'z', 'c']

# operation
# (a, b, c, d) -> (x, y, z)

hrkrshnn

ethereum/solidity#10286

Click for a table of gas differences

reative = (ir_optimized - legacy_optimized) / legacy_optimized * 100

File name	IR-optimized	Legacy-Optimized	relative (%)
abiEncoderV1/abi_decode_v2_storage.sol	193182	193405	-0.115302
abiEncoderV1/abi_encode_calldata_slice.sol	1034560	873928	18.3805

hrkrshnn

diff -u /tmp/oldyul.txt /tmp/newyul.txt
--- /tmp/oldyul.txt	2021-06-23 15:41:31.859708208 +0200
+++ /tmp/newyul.txt	2021-06-23 15:41:06.418758767 +0200
@@ -28,11 +28,11 @@
                     {
                         if callvalue() { revert(_1, _1) }
                         if slt(add(calldatasize(), not(3)), _1) { revert(_1, _1) }
-                        let expr_mpos := allocate_memory_1132()
+                        let expr_mpos := allocate_memory_1140()
                         mstore(expr_mpos, 0x2a)

hrkrshnn

#include <iostream>
#include <vector>
#include <set>

/// `_sigma` denotes a vector of size say `n`.
/// Corresponds to a permutation of {0, 1, 2, ..., n - 1}
/// The value `_sigma[i]` means `i` is mapped to `_sigma[i]`.
///
/// A cycle is a set {a_1, a_2, ..., a_N} such that
/// a_1 -> a_2; a_2 -> a_3, ..., a_{N-1} -> a_N; a_N -> a_1

hrkrshnn

Optimized IR:
/*******************************************************
 ,*                       WARNING                       *
 ,*  Solidity to Yul compilation is still EXPERIMENTAL  *
 ,*       It can result in LOSS OF FUNDS or worse       *
 ,*                !USE AT YOUR OWN RISK!               *
 ,*******************************************************/

object "C_26" {
    code {

hrkrshnn

{
    let x := 64
    // can be removed
    mstore(x, 128)
    if iszero(lt(calldatasize(), 4))
    {
        let _1 := 0
        if eq(0x8868a931, shr(224, calldataload(_1)))
        {
            if callvalue() { revert(_1, _1) }

hrkrshnn

"""A script to collect gas statistics and print it.

Dependencies: Parsec (https://pypi.org/project/parsec/) and Tabulate
https://pypi.org/project/tabulate/

  pip install parsec tabulate

Run from root project dir.

  python3 scripts/gas_stats.py

hrkrshnn

diff -u /tmp/old.txt /tmp/new.txt
--- /tmp/old.txt	2021-03-26 11:50:28.707345655 +0100
+++ /tmp/new.txt	2021-03-26 11:50:03.290450403 +0100
@@ -3,7 +3,7 @@
 
 ======= <stdin>:Test =======
 EVM assembly:
-    /* "<stdin>":0:210  contract Test {... */
+    /* "<stdin>":0:233  contract Test {... */
   mstore(0x40, 0x80)

hrkrshnn

diff -u /tmp/jumpold.txt /tmp/jumpnew.txt
--- /tmp/jumpold.txt	2021-03-24 13:23:56.931683183 +0100
+++ /tmp/jumpnew.txt	2021-03-24 13:23:41.046763769 +0100
@@ -97,16 +97,18 @@
       iszero
       tag_11
       jumpi
-        /* "<stdin>":128:133  leave */
-      jump(tag_10)
+        /* "<stdin>":119:144  { if x { leave } y := 8 } */