ge -> cmp and returns 0, 1, -1

evm/src/cpu/kernel/aggregator.rs

@@ -15,7 +15,7 @@ pub(crate) fn combined_kernel() -> Kernel {
         "global jumped_to_1: PANIC",
         include_str!("asm/bignum/add.asm"),
         include_str!("asm/bignum/addmul.asm"),
-        include_str!("asm/bignum/ge.asm"),
+        include_str!("asm/bignum/cmp.asm"),
         include_str!("asm/bignum/iszero.asm"),
         include_str!("asm/bignum/mul.asm"),
         include_str!("asm/bignum/shr.asm"),

evm/src/cpu/kernel/asm/bignum/cmp.asm

@@ -2,8 +2,8 @@
 // All integers must be under a given length bound, and are padded with leading zeroes.
 
 // Compares two bignums of the same given length. Assumes that len > 0.
-// Returns 1 if a > b, 3 if a == b, and 0 if a < b.
-global ge_bignum:
+// Returns 1 if a > b, 0 if a == b, and -1 (that is, 2^256 - 1) if a < b.
+global cmp_bignum:
     // stack: len, a_start_loc, b_start_loc, retdest
     SWAP1
     // stack: a_start_loc, len, b_start_loc, retdest
@@ -59,8 +59,8 @@ equal:
     // stack: i, a_i_loc, b_i_loc, retdest
     %pop3
     // stack: retdest
-    PUSH 3
-    // stack: 3, retdest
+    PUSH 0
+    // stack: 0, retdest
     SWAP1
     JUMP
 greater:
@@ -75,7 +75,7 @@ less:
     // stack: i, a_i_loc, b_i_loc, retdest
     %pop3
     // stack: retdest
-    PUSH 0
-    // stack: 0, retdest
+    PUSH 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+    // stack: -1, retdest
     SWAP1
     JUMP

evm/src/cpu/kernel/tests/bignum.rs

@@ -179,14 +179,14 @@ where
     Ok(())
 }
 
-fn test_ge_bignum<F>(prepare_two_bignums_fn: &F) -> Result<()>
+fn test_cmp_bignum<F>(prepare_two_bignums_fn: &F) -> Result<()>
 where
     F: Fn(usize) -> (BigUint, BigUint, U256, Vec<U256>),
 {
     let (_a, _b, length, memory) = prepare_two_bignums_fn(1000);
 
     let retdest = 0xDEADBEEFu32.into();
-    let ge_bignum = KERNEL.global_labels["ge_bignum"];
+    let cmp_bignum = KERNEL.global_labels["cmp_bignum"];
 
     let a_start_loc = 0.into();
     let b_start_loc = length;
@@ -194,7 +194,7 @@ where
     // Test with a > b.
     let mut initial_stack: Vec<U256> = vec![length, a_start_loc, b_start_loc, retdest];
     initial_stack.reverse();
-    let mut interpreter = Interpreter::new_with_kernel(ge_bignum, initial_stack);
+    let mut interpreter = Interpreter::new_with_kernel(cmp_bignum, initial_stack);
     interpreter.set_kernel_general_memory(memory.clone());
     interpreter.run()?;
     let result = interpreter.stack()[0];
@@ -203,11 +203,21 @@ where
     // Swap a and b, to test the less-than case.
     let mut initial_stack: Vec<U256> = vec![length, b_start_loc, a_start_loc, retdest];
     initial_stack.reverse();
-    let mut interpreter = Interpreter::new_with_kernel(ge_bignum, initial_stack);
+    let mut interpreter = Interpreter::new_with_kernel(cmp_bignum, initial_stack);
+    interpreter.set_kernel_general_memory(memory.clone());
+    interpreter.run()?;
+    let result = interpreter.stack()[0];
+    let minus_one = ((U256::one() << 255) - 1) * 2 + 1;
+    assert_eq!(result, minus_one);
+
+    // Test equal case.
+    let mut initial_stack: Vec<U256> = vec![length, a_start_loc, a_start_loc, retdest];
+    initial_stack.reverse();
+    let mut interpreter = Interpreter::new_with_kernel(cmp_bignum, initial_stack);
     interpreter.set_kernel_general_memory(memory);
     interpreter.run()?;
     let result = interpreter.stack()[0];
-    assert_eq!(result, 0.into());
+    assert_eq!(result, U256::zero());
 
     Ok(())
 }
@@ -350,11 +360,11 @@ fn test_iszero_bignum_all() -> Result<()> {
 }
 
 #[test]
-fn test_ge_bignum_all() -> Result<()> {
-    test_ge_bignum(&prepare_two_bignums_random)?;
-    test_ge_bignum(&prepare_two_bignums_max)?;
-    test_ge_bignum(&prepare_two_bignums_min)?;
-    test_ge_bignum(&prepare_two_bignums_diff)?;
+fn test_cmp_bignum_all() -> Result<()> {
+    test_cmp_bignum(&prepare_two_bignums_random)?;
+    test_cmp_bignum(&prepare_two_bignums_max)?;
+    test_cmp_bignum(&prepare_two_bignums_min)?;
+    test_cmp_bignum(&prepare_two_bignums_diff)?;
 
     Ok(())
 }