From 05a1fbfbae7125291ee5842ff7587ead38534874 Mon Sep 17 00:00:00 2001 From: Daniel Lubarov Date: Tue, 19 Jul 2022 15:28:34 -0700 Subject: [PATCH] Stack manipulation macro Uses a variant of Dijkstra's, with a few pruning mechanics, to find a path of instructions between the two stack states. We don't explicitly store the graph though. The Dijkstra implementation is somewhat inspired by the `pathfinding` crate. That crate doesn't quite fit our needs though. If we need to make it faster later, there are a lot of allocations and clones that we could probably eliminate. --- evm/src/cpu/kernel/asm/curve_add.asm | 24 +-- evm/src/cpu/kernel/assembler.rs | 23 ++- evm/src/cpu/kernel/ast.rs | 15 +- evm/src/cpu/kernel/evm_asm.pest | 11 +- evm/src/cpu/kernel/mod.rs | 1 + evm/src/cpu/kernel/parser.rs | 41 ++++- evm/src/cpu/kernel/stack_manipulation.rs | 224 +++++++++++++++++++++++ 7 files changed, 306 insertions(+), 33 deletions(-) create mode 100644 evm/src/cpu/kernel/stack_manipulation.rs diff --git a/evm/src/cpu/kernel/asm/curve_add.asm b/evm/src/cpu/kernel/asm/curve_add.asm index 4ac4e0e4..f6275787 100644 --- a/evm/src/cpu/kernel/asm/curve_add.asm +++ b/evm/src/cpu/kernel/asm/curve_add.asm @@ -111,18 +111,7 @@ ec_add_snd_zero: // stack: x0, y0, x1, y1, retdest // Just return (x1,y1) - SWAP2 - // stack: x1, y0, x0, y1, retdest - POP - // stack: y0, x0, y1, retdest - SWAP2 - // stack: y1, x0, y0, retdest - POP - // stack: x0, y0, retdest - SWAP1 - // stack: y0, x0, retdest - SWAP2 - // stack: retdest, x0, y0 + %stack (x0, y0, x1, y1, retdest) -> (retdest, x0, y0) JUMP // BN254 elliptic curve addition. @@ -170,16 +159,7 @@ ec_add_valid_points_with_lambda: // stack: y2, x2, lambda, x0, y0, x1, y1, retdest // Return x2,y2 - SWAP5 - // stack: x1, x2, lambda, x0, y0, y2, y1, retdest - POP - // stack: x2, lambda, x0, y0, y2, y1, retdest - SWAP5 - // stack: y1, lambda, x0, y0, y2, x2, retdest - %pop4 - // stack: y2, x2, retdest - SWAP2 - // stack: retdest, x2, y2 + %stack (y2, x2, lambda, x0, y0, x1, y1, retdest) -> (retdest, x2, y2) JUMP // BN254 elliptic curve addition. diff --git a/evm/src/cpu/kernel/assembler.rs b/evm/src/cpu/kernel/assembler.rs index 8b7327dc..ad17ae4c 100644 --- a/evm/src/cpu/kernel/assembler.rs +++ b/evm/src/cpu/kernel/assembler.rs @@ -7,6 +7,7 @@ use log::debug; use super::ast::PushTarget; use crate::cpu::kernel::ast::Literal; use crate::cpu::kernel::keccak_util::hash_kernel; +use crate::cpu::kernel::stack_manipulation::expand_stack_manipulation; use crate::cpu::kernel::{ ast::{File, Item}, opcodes::{get_opcode, get_push_opcode}, @@ -63,6 +64,7 @@ pub(crate) fn assemble(files: Vec, constants: HashMap) -> Ke let expanded_file = expand_macros(file.body, ¯os); let expanded_file = expand_repeats(expanded_file); let expanded_file = inline_constants(expanded_file, &constants); + let expanded_file = expand_stack_manipulation(expanded_file); local_labels.push(find_labels(&expanded_file, &mut offset, &mut global_labels)); expanded_files.push(expanded_file); } @@ -187,8 +189,11 @@ fn find_labels( let mut local_labels = HashMap::::new(); for item in body { match item { - Item::MacroDef(_, _, _) | Item::MacroCall(_, _) | Item::Repeat(_, _) => { - panic!("Macros and repeats should have been expanded already") + Item::MacroDef(_, _, _) + | Item::MacroCall(_, _) + | Item::Repeat(_, _) + | Item::StackManipulation(_, _) => { + panic!("Item should have been expanded already: {:?}", item); } Item::GlobalLabelDeclaration(label) => { let old = global_labels.insert(label.clone(), *offset); @@ -215,8 +220,11 @@ fn assemble_file( // Assemble the file. for item in body { match item { - Item::MacroDef(_, _, _) | Item::MacroCall(_, _) | Item::Repeat(_, _) => { - panic!("Macros and repeats should have been expanded already") + Item::MacroDef(_, _, _) + | Item::MacroCall(_, _) + | Item::Repeat(_, _) + | Item::StackManipulation(_, _) => { + panic!("Item should have been expanded already: {:?}", item); } Item::GlobalLabelDeclaration(_) | Item::LocalLabelDeclaration(_) => { // Nothing to do; we processed labels in the prior phase. @@ -427,6 +435,13 @@ mod tests { assert_eq!(kernel.code, vec![add, add, add]); } + #[test] + fn stack_manipulation() { + let kernel = parse_and_assemble(&["%stack (a, b, c) -> (c, b, a)"]); + let swap2 = get_opcode("SWAP2"); + assert_eq!(kernel.code, vec![swap2]); + } + fn parse_and_assemble(files: &[&str]) -> Kernel { parse_and_assemble_with_constants(files, HashMap::new()) } diff --git a/evm/src/cpu/kernel/ast.rs b/evm/src/cpu/kernel/ast.rs index 9bb315ff..92728104 100644 --- a/evm/src/cpu/kernel/ast.rs +++ b/evm/src/cpu/kernel/ast.rs @@ -14,6 +14,11 @@ pub(crate) enum Item { MacroCall(String, Vec), /// Repetition, like `%rep` in NASM. Repeat(Literal, Vec), + /// A directive to manipulate the stack according to a specified pattern. + /// The first list gives names to items on the top of the stack. + /// The second list specifies replacement items. + /// Example: `(a, b, c) -> (c, 5, 0x20, @SOME_CONST, a)`. + StackManipulation(Vec, Vec), /// Declares a global label. GlobalLabelDeclaration(String), /// Declares a label that is local to the current file. @@ -26,6 +31,14 @@ pub(crate) enum Item { Bytes(Vec), } +#[derive(Clone, Debug)] +pub(crate) enum StackReplacement { + NamedItem(String), + Literal(Literal), + MacroVar(String), + Constant(String), +} + /// The target of a `PUSH` operation. #[derive(Clone, Debug)] pub(crate) enum PushTarget { @@ -35,7 +48,7 @@ pub(crate) enum PushTarget { Constant(String), } -#[derive(Clone, Debug)] +#[derive(Clone, Debug, Eq, PartialEq, Hash)] pub(crate) enum Literal { Decimal(String), Hex(String), diff --git a/evm/src/cpu/kernel/evm_asm.pest b/evm/src/cpu/kernel/evm_asm.pest index d5a89d99..78938b64 100644 --- a/evm/src/cpu/kernel/evm_asm.pest +++ b/evm/src/cpu/kernel/evm_asm.pest @@ -15,12 +15,15 @@ literal = { literal_hex | literal_decimal } variable = ${ "$" ~ identifier } constant = ${ "@" ~ identifier } -item = { macro_def | macro_call | repeat | global_label | local_label | bytes_item | push_instruction | nullary_instruction } -macro_def = { ^"%macro" ~ identifier ~ macro_paramlist? ~ item* ~ ^"%endmacro" } -macro_call = ${ "%" ~ !(^"macro" | ^"endmacro" | ^"rep" | ^"endrep") ~ identifier ~ macro_arglist? } +item = { macro_def | macro_call | repeat | stack | global_label | local_label | bytes_item | push_instruction | nullary_instruction } +macro_def = { ^"%macro" ~ identifier ~ paramlist? ~ item* ~ ^"%endmacro" } +macro_call = ${ "%" ~ !(^"macro" | ^"endmacro" | ^"rep" | ^"endrep" | ^"stack") ~ identifier ~ macro_arglist? } repeat = { ^"%rep" ~ literal ~ item* ~ ^"%endrep" } -macro_paramlist = { "(" ~ identifier ~ ("," ~ identifier)* ~ ")" } +paramlist = { "(" ~ identifier ~ ("," ~ identifier)* ~ ")" } macro_arglist = !{ "(" ~ push_target ~ ("," ~ push_target)* ~ ")" } +stack = { ^"%stack" ~ paramlist ~ "->" ~ stack_replacements } +stack_replacements = { "(" ~ stack_replacement ~ ("," ~ stack_replacement)* ~ ")" } +stack_replacement = { literal | identifier | constant } global_label = { ^"GLOBAL " ~ identifier ~ ":" } local_label = { identifier ~ ":" } bytes_item = { ^"BYTES " ~ literal ~ ("," ~ literal)* } diff --git a/evm/src/cpu/kernel/mod.rs b/evm/src/cpu/kernel/mod.rs index 2dd70aa3..1f13a042 100644 --- a/evm/src/cpu/kernel/mod.rs +++ b/evm/src/cpu/kernel/mod.rs @@ -4,6 +4,7 @@ mod ast; pub(crate) mod keccak_util; mod opcodes; mod parser; +mod stack_manipulation; #[cfg(test)] mod interpreter; diff --git a/evm/src/cpu/kernel/parser.rs b/evm/src/cpu/kernel/parser.rs index b8ac3f40..aa84ee05 100644 --- a/evm/src/cpu/kernel/parser.rs +++ b/evm/src/cpu/kernel/parser.rs @@ -1,7 +1,7 @@ use pest::iterators::Pair; use pest::Parser; -use crate::cpu::kernel::ast::{File, Item, Literal, PushTarget}; +use crate::cpu::kernel::ast::{File, Item, Literal, PushTarget, StackReplacement}; /// Parses EVM assembly code. #[derive(pest_derive::Parser)] @@ -24,6 +24,7 @@ fn parse_item(item: Pair) -> Item { Rule::macro_def => parse_macro_def(item), Rule::macro_call => parse_macro_call(item), Rule::repeat => parse_repeat(item), + Rule::stack => parse_stack(item), Rule::global_label => { Item::GlobalLabelDeclaration(item.into_inner().next().unwrap().as_str().into()) } @@ -44,7 +45,7 @@ fn parse_macro_def(item: Pair) -> Item { let name = inner.next().unwrap().as_str().into(); // The parameter list is optional. - let params = if let Some(Rule::macro_paramlist) = inner.peek().map(|pair| pair.as_rule()) { + let params = if let Some(Rule::paramlist) = inner.peek().map(|pair| pair.as_rule()) { let params = inner.next().unwrap().into_inner(); params.map(|param| param.as_str().to_string()).collect() } else { @@ -78,6 +79,42 @@ fn parse_repeat(item: Pair) -> Item { Item::Repeat(count, inner.map(parse_item).collect()) } +fn parse_stack(item: Pair) -> Item { + assert_eq!(item.as_rule(), Rule::stack); + let mut inner = item.into_inner().peekable(); + + let params = inner.next().unwrap(); + assert_eq!(params.as_rule(), Rule::paramlist); + let replacements = inner.next().unwrap(); + assert_eq!(replacements.as_rule(), Rule::stack_replacements); + + let params = params + .into_inner() + .map(|param| param.as_str().to_string()) + .collect(); + let replacements = replacements + .into_inner() + .map(parse_stack_replacement) + .collect(); + Item::StackManipulation(params, replacements) +} + +fn parse_stack_replacement(target: Pair) -> StackReplacement { + assert_eq!(target.as_rule(), Rule::stack_replacement); + let inner = target.into_inner().next().unwrap(); + match inner.as_rule() { + Rule::identifier => StackReplacement::NamedItem(inner.as_str().into()), + Rule::literal => StackReplacement::Literal(parse_literal(inner)), + Rule::variable => { + StackReplacement::MacroVar(inner.into_inner().next().unwrap().as_str().into()) + } + Rule::constant => { + StackReplacement::Constant(inner.into_inner().next().unwrap().as_str().into()) + } + _ => panic!("Unexpected {:?}", inner.as_rule()), + } +} + fn parse_push_target(target: Pair) -> PushTarget { assert_eq!(target.as_rule(), Rule::push_target); let inner = target.into_inner().next().unwrap(); diff --git a/evm/src/cpu/kernel/stack_manipulation.rs b/evm/src/cpu/kernel/stack_manipulation.rs new file mode 100644 index 00000000..b09456ac --- /dev/null +++ b/evm/src/cpu/kernel/stack_manipulation.rs @@ -0,0 +1,224 @@ +use std::cmp::Ordering; +use std::collections::hash_map::Entry::{Occupied, Vacant}; +use std::collections::{BinaryHeap, HashMap}; + +use itertools::Itertools; + +use crate::cpu::columns::NUM_CPU_COLUMNS; +use crate::cpu::kernel::ast::{Item, Literal, PushTarget, StackReplacement}; +use crate::cpu::kernel::stack_manipulation::StackOp::Pop; +use crate::memory; + +pub(crate) fn expand_stack_manipulation(body: Vec) -> Vec { + let mut expanded = vec![]; + for item in body { + if let Item::StackManipulation(names, replacements) = item { + expanded.extend(expand(names, replacements)); + } else { + expanded.push(item); + } + } + expanded +} + +fn expand(names: Vec, replacements: Vec) -> Vec { + let mut src = names.into_iter().map(StackItem::NamedItem).collect_vec(); + + let unique_literals = replacements + .iter() + .filter_map(|item| match item { + StackReplacement::Literal(n) => Some(n.clone()), + _ => None, + }) + .unique() + .collect_vec(); + let all_ops = StackOp::all(unique_literals); + + let mut dst = replacements + .into_iter() + .map(|item| match item { + StackReplacement::NamedItem(name) => StackItem::NamedItem(name), + StackReplacement::Literal(n) => StackItem::Literal(n), + StackReplacement::MacroVar(_) | StackReplacement::Constant(_) => { + panic!("Should have been expanded earlier") + } + }) + .collect_vec(); + + // %stack uses our convention where the top item is written on the left side. + // `shortest_path` expects the opposite, so we reverse src and dst. + src.reverse(); + dst.reverse(); + + let path = shortest_path(src, dst, all_ops); + path.into_iter().map(StackOp::into_item).collect() +} + +/// Finds the lowest-cost sequence of `StackOp`s that transforms `src` to `dst`. +/// Uses a variant of Dijkstra's algorithm. +fn shortest_path(src: Vec, dst: Vec, all_ops: Vec) -> Vec { + // Nodes to visit, starting with the lowest-cost node. + let mut queue = BinaryHeap::new(); + queue.push(Node { + stack: src.clone(), + cost: 0, + }); + + // For each node, stores `(best_cost, Option<(parent, op)>)`. + let mut node_info = HashMap::, (u32, Option<(Vec, StackOp)>)>::new(); + node_info.insert(src.clone(), (0, None)); + + while let Some(node) = queue.pop() { + if node.stack == dst { + // The destination is now the lowest-cost node, so we must have found the best path. + let mut path = vec![]; + let mut stack = &node.stack; + // Rewind back to src, recording a list of operations which will be backwards. + while let Some((parent, op)) = &node_info[stack].1 { + stack = parent; + path.push(op.clone()); + } + assert_eq!(stack, &src); + path.reverse(); + return path; + } + + let (best_cost, _) = node_info[&node.stack]; + if best_cost < node.cost { + // Since we can't efficiently remove nodes from the heap, it can contain duplicates. + // In this case, we've already visited this stack state with a lower cost. + continue; + } + + for op in &all_ops { + let neighbor = match op.apply_to(node.stack.clone()) { + Some(n) => n, + None => continue, + }; + + let cost = node.cost + op.cost(); + let entry = node_info.entry(neighbor.clone()); + if let Occupied(e) = &entry && e.get().0 <= cost { + // We already found a better or equal path. + continue; + } + + let neighbor_info = (cost, Some((node.stack.clone(), op.clone()))); + match entry { + Occupied(mut e) => { + e.insert(neighbor_info); + } + Vacant(e) => { + e.insert(neighbor_info); + } + } + + queue.push(Node { + stack: neighbor, + cost, + }); + } + } + + panic!("No path found from {:?} to {:?}", src, dst) +} + +/// A node in the priority queue used by Dijkstra's algorithm. +#[derive(Eq, PartialEq)] +struct Node { + stack: Vec, + cost: u32, +} + +impl PartialOrd for Node { + fn partial_cmp(&self, other: &Self) -> Option { + Some(self.cmp(other)) + } +} + +impl Ord for Node { + fn cmp(&self, other: &Self) -> Ordering { + // We want a min-heap rather than the default max-heap, so this is the opposite of the + // natural ordering of costs. + other.cost.cmp(&self.cost) + } +} + +/// Like `StackReplacement`, but without constants or macro vars, since those were expanded already. +#[derive(Eq, PartialEq, Hash, Clone, Debug)] +enum StackItem { + NamedItem(String), + Literal(Literal), +} + +#[derive(Clone, Debug)] +enum StackOp { + Push(Literal), + Pop, + Dup(u8), + Swap(u8), +} + +fn get_ops(src: Vec, dst: Vec) -> impl Iterator { + +} + +impl StackOp { + fn all(literals: Vec) -> Vec { + let mut all = literals.into_iter().map(StackOp::Push).collect_vec(); + all.push(Pop); + all.extend((1..=32).map(StackOp::Dup)); + all.extend((1..=32).map(StackOp::Swap)); + all + } + + fn cost(&self) -> u32 { + let (cpu_rows, memory_rows) = match self { + StackOp::Push(n) => { + let bytes = n.to_trimmed_be_bytes().len() as u32; + // This is just a rough estimate; we can update it after implementing PUSH. + (bytes, bytes) + } + Pop => (1, 1), + StackOp::Dup(_) => (1, 2), + StackOp::Swap(_) => (1, 4), + }; + + let cpu_cost = cpu_rows * NUM_CPU_COLUMNS as u32; + let memory_cost = memory_rows * memory::columns::NUM_COLUMNS as u32; + cpu_cost + memory_cost + } + + /// Returns an updated stack after this operation is performed, or `None` if this operation + /// would not be valid on the given stack. + fn apply_to(&self, mut stack: Vec) -> Option> { + let len = stack.len(); + match self { + StackOp::Push(n) => { + stack.push(StackItem::Literal(n.clone())); + } + Pop => { + stack.pop()?; + } + StackOp::Dup(n) => { + let idx = len.checked_sub(*n as usize)?; + stack.push(stack[idx].clone()); + } + StackOp::Swap(n) => { + let from = len.checked_sub(1)?; + let to = len.checked_sub(*n as usize + 1)?; + stack.swap(from, to); + } + } + Some(stack) + } + + fn into_item(self) -> Item { + match self { + StackOp::Push(n) => Item::Push(PushTarget::Literal(n)), + Pop => Item::StandardOp("POP".into()), + StackOp::Dup(n) => Item::StandardOp(format!("DUP{}", n)), + StackOp::Swap(n) => Item::StandardOp(format!("SWAP{}", n)), + } + } +}