From bda409a02a90ec1c1eaea7940df613eb3db469cf Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Mon, 4 Mar 2019 08:59:17 +0100
Subject: [PATCH] core/vm: optimize push1

---
 core/vm/instructions.go | 15 +++++++++++++++
 core/vm/jump_table.go   |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 5195e716b2..a1188848dc 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -886,6 +886,21 @@ func opSuicide(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memo
 	return nil, nil
 }
 
+// opPush1 is a specialized version of pushN
+func opPush1(pc *uint64, interpreter *EVMInterpreter, contract *Contract, memory *Memory, stack *Stack) ([]byte, error) {
+	var (
+		codeLen = uint64(len(contract.Code))
+		integer = interpreter.intPool.get()
+	)
+	*pc += 1
+	if *pc < codeLen {
+		stack.push(integer.SetUint64(uint64(contract.Code[*pc])))
+	} else {
+		stack.push(integer.SetUint64(0))
+	}
+	return nil, nil
+}
+
 // following functions are used by the instruction jump  table
 
 // make log instruction function
diff --git a/core/vm/jump_table.go b/core/vm/jump_table.go
index dde11dacf1..90d8e64dba 100644
--- a/core/vm/jump_table.go
+++ b/core/vm/jump_table.go
@@ -567,7 +567,7 @@ func newFrontierInstructionSet() [256]operation {
 			valid:       true,
 		},
 		PUSH1: {
-			execute:     makePush(1, 1),
+			execute:     opPush1,
 			constantGas: GasFastestStep,
 			minStack:    minStack(0, 1),
 			maxStack:    maxStack(0, 1),