Feat/word addressable memory (#509)

* Deal with signed imm values outside of constraints

* SH virtual sequence

* Add memory-ops example

* Fix SH virtual sequence

* SB virtual sequence

* Add LBU, LHU, LB, LH virtual sequences

* Add AssertAlignedMemoryAccessInstruction and LowBitSubtable

* Switch to word-addressable memory in read_write_memory.rs

* Update constraints and remove SWInstruction lookup

* Assert word alignment for LW and SW

* rename load/store instruction lookups

* cargo update

* clippy

Cargo.toml

@@ -48,8 +48,8 @@ members = [
     "examples/muldiv/guest",
     "examples/overflow",
     "examples/overflow/guest",
-
-
+    "examples/memory-ops",
+    "examples/memory-ops/guest",
 ]
 
 [features]

common/src/constants.rs

@@ -3,22 +3,15 @@ const RISCV_REGISTER_COUNT: u64 = 32;
 const VIRTUAL_REGISTER_COUNT: u64 = 32; //  see Section 6.1 of Jolt paper
 pub const REGISTER_COUNT: u64 = RISCV_REGISTER_COUNT + VIRTUAL_REGISTER_COUNT;
 pub const BYTES_PER_INSTRUCTION: usize = 4;
-pub const REG_OPS_PER_INSTRUCTION: usize = 3;
-pub const RAM_OPS_PER_INSTRUCTION: usize = 4;
-pub const MEMORY_OPS_PER_INSTRUCTION: usize = REG_OPS_PER_INSTRUCTION + RAM_OPS_PER_INSTRUCTION;
+/// 3 registers (rd, rs1, rs2) + 1 RAM
+pub const MEMORY_OPS_PER_INSTRUCTION: usize = 4;
 
 pub const RAM_START_ADDRESS: u64 = 0x80000000;
 pub const DEFAULT_MEMORY_SIZE: u64 = 10 * 1024 * 1024;
 pub const DEFAULT_STACK_SIZE: u64 = 4096;
 pub const DEFAULT_MAX_INPUT_SIZE: u64 = 4096;
 pub const DEFAULT_MAX_OUTPUT_SIZE: u64 = 4096;
 
-pub const fn memory_address_to_witness_index(address: u64, ram_witness_offset: u64) -> usize {
-    (address + ram_witness_offset - RAM_START_ADDRESS) as usize
-}
-pub const fn witness_index_to_memory_address(index: usize, ram_witness_offset: u64) -> u64 {
-    index as u64 + RAM_START_ADDRESS - ram_witness_offset
-}
 pub const fn virtual_register_index(index: u64) -> u64 {
     index + VIRTUAL_REGISTER_COUNT
 }

common/src/lib.rs

@@ -1,9 +1,4 @@
-pub fn to_ram_address(index: usize) -> usize {
-    index * constants::BYTES_PER_INSTRUCTION + constants::RAM_START_ADDRESS as usize
-}
-
 pub mod attributes;
 pub mod constants;
-pub mod parallel;
 pub mod rv_trace;
 pub mod serializable;