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Fixup environment trait to avoid abstraction leaks #1380

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merged 4 commits into from
Dec 5, 2023
Merged

Fixup environment trait to avoid abstraction leaks #1380

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f3de840
Use debug printing
mrmr1993 Dec 4, 2023
3572a9e
Stop the bleed: no more mul with u32
mrmr1993 Dec 4, 2023
fe9da52
Leak less through the trait
mrmr1993 Dec 4, 2023
d7d4f44
Surprise! We can't `and` either
mrmr1993 Dec 4, 2023
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38 changes: 22 additions & 16 deletions optimism/src/mips/interpreter.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -196,10 +196,8 @@ pub enum ITypeInstruction {
pub trait InterpreterEnv {
type Variable: Clone
+ std::ops::Add<Self::Variable, Output = Self::Variable>
+ std::ops::Mul<u32, Output = Self::Variable>
+ std::ops::Shl<u32, Output = Self::Variable>
+ std::ops::BitAnd<u32, Output = Self::Variable>
+ std::fmt::Display;
+ std::ops::Mul<Self::Variable, Output = Self::Variable>
+ std::fmt::Debug;

fn overwrite_register_checked(&mut self, register_idx: &Self::Variable, value: &Self::Variable);

Expand All @@ -211,8 +209,8 @@ pub trait InterpreterEnv {

fn get_immediate(&self) -> Self::Variable {
// The immediate value is the last 16bits
(self.get_instruction_part(InstructionPart::RD) << 11)
+ (self.get_instruction_part(InstructionPart::Shamt) << 6)
(self.get_instruction_part(InstructionPart::RD) * Self::constant(1 << 11))
+ (self.get_instruction_part(InstructionPart::Shamt) * Self::constant(1 << 6))
+ (self.get_instruction_part(InstructionPart::Funct))
}

Expand Down Expand Up @@ -290,12 +288,12 @@ pub fn interpret_jtype<Env: InterpreterEnv>(env: &mut Env, instr: JTypeInstructi
// > bits (which would always be 00, since addresses are always
// > divisible by 4).
// Source: https://max.cs.kzoo.edu/cs230/Resources/MIPS/MachineXL/InstructionFormats.html
let addr = (env.get_instruction_part(InstructionPart::RS) << 21)
+ (env.get_instruction_part(InstructionPart::RT) << 16)
+ (env.get_instruction_part(InstructionPart::RD) << 11)
+ (env.get_instruction_part(InstructionPart::Shamt) << 6)
let addr = (env.get_instruction_part(InstructionPart::RS) * Env::constant(1 << 21))
+ (env.get_instruction_part(InstructionPart::RT) * Env::constant(1 << 16))
+ (env.get_instruction_part(InstructionPart::RD) * Env::constant(1 << 11))
+ (env.get_instruction_part(InstructionPart::Shamt) * Env::constant(1 << 6))
+ (env.get_instruction_part(InstructionPart::Funct));
env.set_instruction_pointer(addr * 4);
env.set_instruction_pointer(addr * Env::constant(4));
// REMOVEME: when all jtype instructions are implemented.
return;
}
Expand Down Expand Up @@ -326,7 +324,7 @@ pub fn interpret_itype<Env: InterpreterEnv>(env: &mut Env, instr: ITypeInstructi
ITypeInstruction::AddImmediateUnsigned => {
let rs = env.get_instruction_part(InstructionPart::RS);
let rt = env.get_instruction_part(InstructionPart::RT);
debug!("Fetching register: {}", rs);
debug!("Fetching register: {:?}", rs);
let register_rs = env.fetch_register_checked(&rs);
let immediate = env.get_immediate();
let res = register_rs + immediate;
Expand All @@ -344,7 +342,7 @@ pub fn interpret_itype<Env: InterpreterEnv>(env: &mut Env, instr: ITypeInstructi
ITypeInstruction::LoadUpperImmediate => {
// lui $reg, [most significant 16 bits of immediate]
let rt = env.get_instruction_part(InstructionPart::RT);
let immediate_value = env.get_immediate() << 16;
let immediate_value = env.get_immediate() * Env::constant(1 << 16);
env.overwrite_register_checked(&rt, &immediate_value);
env.set_instruction_pointer(env.get_instruction_pointer() + Env::constant(4u32));
// TODO: update next_instruction_pointer
Expand All @@ -358,15 +356,23 @@ pub fn interpret_itype<Env: InterpreterEnv>(env: &mut Env, instr: ITypeInstructi
let addr = env.get_instruction_part(InstructionPart::RS);
let offset = env.get_immediate();
let addr_with_offset = addr.clone() + offset.clone();
debug!("lw {}, {}({})", dest.clone(), offset.clone(), addr.clone());
debug!(
"lw {:?}, {:?}({:?})",
dest.clone(),
offset.clone(),
addr.clone()
);
// We load 4 bytes, i.e. one word.
let v0 = env.fetch_memory(&addr_with_offset);
let v1 = env.fetch_memory(&(addr_with_offset.clone() + Env::constant(1)));
let v2 = env.fetch_memory(&(addr_with_offset.clone() + Env::constant(2)));
let v3 = env.fetch_memory(&(addr_with_offset.clone() + Env::constant(3)));
let value = (v0 << 24) + (v1 << 16) + (v2 << 8) + v3;
let value = (v0 * Env::constant(1 << 24))
+ (v1 * Env::constant(1 << 16))
+ (v2 * Env::constant(1 << 8))
+ v3;
debug!(
"Loaded 32 bits value from {}: {}",
"Loaded 32 bits value from {:?}: {:?}",
addr_with_offset.clone(),
value
);
Expand Down