Optimize MLOAD memory fast path

vm/bytecode.go

@@ -66,16 +66,11 @@ func (b *Bytecode) ResetWithHash(code []byte, hash types.B256) {
 	// If same hash as previous call on this pooled bytecode, skip analysis
 	if b.hash != nil && *b.hash == hash && b.originalLen == originalLen {
 		needed := originalLen + bytecodeEndPadding
-		if cap(b.code) >= needed {
-			b.code = b.code[:needed]
-		} else {
-			b.code = make([]byte, needed)
-		}
-		copy(b.code, code)
-		clear(b.code[originalLen:needed])
+		b.code = b.code[:needed]
 		b.pc = 0
 		b.running = true
-		// jumpTable + jumpTableReady still valid from previous Reset
+		// code bytes, padding, jumpTable, and jumpTableReady are still valid
+		// from the previous Reset for this hash.
 		return
 	}
 

vm/gen/main.go

@@ -747,6 +747,7 @@ func (e *emitter) emitHeader() {
 	e.p("// Code generated by gen/main.go; DO NOT EDIT.\n\n")
 	e.p("package vm\n\n")
 	e.p("import (\n")
+	e.p("\t\"encoding/binary\"\n")
 	e.p("\t\"github.com/Giulio2002/gevm/opcode\"\n")
 	e.p("\t\"github.com/Giulio2002/gevm/spec\"\n")
 	e.p("\t\"github.com/holiman/uint256\"\n")
@@ -757,6 +758,7 @@ func (e *emitter) emitHeader() {
 	e.p("\t_ = uint256.Int{}\n")
 	e.p("\t_ = spec.GasVerylow\n")
 	e.p("\t_ = opcode.STOP\n")
+	e.p("\t_ = binary.BigEndian\n")
 	e.p(")\n\n")
 }
 

vm/inst_memory.go

@@ -2,6 +2,8 @@
 package vm
 
 import (
+	"encoding/binary"
+
 	"github.com/Giulio2002/gevm/spec"
 )
 
@@ -20,13 +22,20 @@ func opMload(interp *Interpreter) {
 	top := &s.data[s.top-1]
 	if top[1]|top[2]|top[3] == 0 {
 		offset := int(top[0])
-		if offset >= 0 && offset+32 <= interp.Memory.Len() {
-			*top = interp.Memory.GetU256(offset)
-		} else {
-			if interp.ResizeMemory(offset, 32) {
-				*top = interp.Memory.GetU256(offset)
+		mem := interp.Memory
+		if offset < 0 || offset+32 > len(*mem.buffer)-mem.checkpoint {
+			if !interp.ResizeMemory(offset, 32) {
+				return
 			}
 		}
+		p := mem.checkpoint + offset
+		b := (*mem.buffer)[p : p+32 : p+32]
+		*top = [4]uint64{
+			binary.BigEndian.Uint64(b[24:]),
+			binary.BigEndian.Uint64(b[16:]),
+			binary.BigEndian.Uint64(b[8:]),
+			binary.BigEndian.Uint64(b[0:]),
+		}
 	} else {
 		interp.Halt(InstructionResultInvalidOperandOOG)
 	}