Merge pull request #2905 from o1-labs/dw/mul-overflow

o1vm/riscv32im: test overflow for MUL

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

@@ -0,0 +1,18 @@
+.section .text
+.globl _start
+
+_start:
+    li t0, 10000000         # Large number
+    li t1, 10000000         # Another large number
+    mul t2, t0, t1          # Test large multiplication (Expected overflow)
+
+    # 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

@@ -416,3 +416,19 @@ fn test_remu_by_zero() {
         witness.step();
     }
 }
+
+#[test]
+fn test_mul_overflow() {
+    let curr_dir = std::env::current_dir().unwrap();
+    let path = curr_dir.join(std::path::PathBuf::from(
+        "resources/programs/riscv32im/bin/mul_overflow",
+    ));
+    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[T2], 276447232);
+}