Merge pull request #2894 from o1-labs/dw/test-addi-negative-values

o1vm/riscv32im: add tests for addi with negative values

o1vm/resources/programs/riscv32im/src/addi_negative.S

@@ -0,0 +1,22 @@
+.section .text
+.globl _start
+
+_start:
+    li t0, 100            # t0 = 100
+
+    # Subtract 50 using addi (addi with negative immediate)
+    addi t1, t0, -50      # t1 = t0 + (-50) (Expected: t1 = 50)
+
+    # Subtract 100 using addi (addi with negative immediate)
+    addi t2, t1, -100     # t2 = t1 + (-100) (Expected: t2 = -50)
+
+    # Custom exit syscall
+    li a0, 0
+    li a1, 0
+    li a2, 0
+    li a3, 0
+    li a4, 0
+    li a5, 0
+    li a6, 0
+    li a7, 42
+    ecall

o1vm/tests/test_riscv_elf.rs

@@ -178,3 +178,21 @@ fn test_add_overflow() {
     assert_eq!(witness.registers[T3], 0b11111111111111111111111111111111);
     assert_eq!(witness.registers[T4], 0b00000000000000000000000000000000);
 }
+
+#[test]
+fn test_addi_negative() {
+    let curr_dir = std::env::current_dir().unwrap();
+    let path = curr_dir.join(std::path::PathBuf::from(
+        "resources/programs/riscv32im/bin/addi_negative",
+    ));
+    let state = o1vm::elf_loader::parse_riscv32(&path).unwrap();
+    let mut witness = Env::<Fp>::create(PAGE_SIZE.try_into().unwrap(), state);
+
+    while !witness.halt {
+        witness.step();
+    }
+
+    assert_eq!(witness.registers[T0], 100);
+    assert_eq!(witness.registers[T1], 50);
+    assert_eq!(witness.registers[T2], (-50_i32) as u32);
+}