Reduces LUT needed by mul extension

bench/tests/op/rem.s

@@ -1,27 +1,60 @@
-# expected: dead0, ffffffffffffffff, 0, 0, 18, 0, -57
     .text
 _start:
-    li x1, 0x0293
-    li x2, 0xdead0
-    li x3, 0x0
-    li x4, 0x1
-    li x5, (-1)
-    li x6, 0xdead0
-    li x7, (-2355)
-    li x8, (-324)
-    li x9, 0x8000000000000000
+    li x2,  0xdead0        # 912080
+    li x3,  0x1234         # 4660
+    li x4,  1              # 1
+    li x5, -123456         # -123456
+    li x6,  0xdead0        # duplicate of x2
+    li x7, -765432         # -765432
+    li x8,  123456         # 123456
+    li x9, -234567         # -234567
+    li x10, 0x7fffffffffffffff  # max positive 64b
+    li x11, 0x8000000000000000  # min negative 64b
 
-    # Remainder by 0
-    rem x31, x2, x3
-    rem x31, x5, x3
-
-    # Basic remainders
+    # 1. REM : a % 1
     rem x31, x2, x4
+    # expected: 0000000000000000
+
+    # 2. REM : a % a
     rem x31, x2, x6
-    rem x31, x6, x1
+    # expected: 0000000000000000
 
-    # Overflow
-    rem x31, x9, x5
+    # 3. REM : negative % positive
+    rem x31, x5, x8
+    # expected: 0000000000000000
 
-    # Signed / signed
+    # 4. REM : negative % positive
     rem x31, x7, x8
+    # expected: 00000000000181c8
+
+    # 5. REM : positive % negative
+    rem x31, x8, x7
+    # expected: -9cbb8
+
+    # 6. REM : negative % negative
+    rem x31, x7, x9
+    # expected: -f123
+
+    # 7. REM : max % 2
+    li x12, 2
+    rem x31, x10, x12
+    # expected: 0000000000000001
+
+    # 8. REM : min % -1
+    li x12, -1
+    rem x31, x11, x12
+    # expected: 0000000000000000
+
+    # 9. REM : min % 1
+    rem x31, x11, x4
+    # expected: 0000000000000000
+
+    # 10. REM : 0 % any
+    rem x31, x3, x2
+    # expected: 0000000000001234
+
+    # 11. REM : any % 0
+    rem x31, x2, x0
+    # expected: 00000000000dead0
+    rem x31, x7, x0
+    # expected: -badf8