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gh-131798: Optimize _ITER_CHECK_RANGE and _ITER_CHECK_LIST#144583

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Sacul0457 wants to merge 3 commits intopython:mainfrom
Sacul0457:Optimize_ITER_CHECKs
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gh-131798: Optimize _ITER_CHECK_RANGE and _ITER_CHECK_LIST#144583
Sacul0457 wants to merge 3 commits intopython:mainfrom
Sacul0457:Optimize_ITER_CHECKs

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@Sacul0457 Sacul0457 commented Feb 8, 2026 •
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Adds _ITER_CHECK_RANGE and _ITER_CHECK_LIST to the optimizer.

Regarding testing, as far as I know, we can't accurately test for this optimization, similar to #134803.
But if I am mistaken, please let me know :)

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Sacul0457 commented Feb 18, 2026 •
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Regarding testing, as far as I know, we can't accurately test for this optimization, similar to #134803.
But if I am mistaken, please let me know :)Regarding testing, as far as I know, we can't accurately test for this optimization, similar to #134803.

Oops, we in fact can test for _ITER_CHECK_LIST as _BUILD_LIST sets the symbolic type to a PyList_Type.

But for _ITER_CHECK_RANGE, we need to iterate the range twice but the trace produced seems to show 2/3 iterations

Testcase:

def testfunc(n):
    x = 0
    for _ in range(n):
        r = range(1, 2)
        for num in r: # guarded
            x += num
        for num in r: # unguarded
            x += num
    return x
Trace Produced: 

   1 ADD_TO_TRACE: _START_EXECUTOR (0, target=42, operand0=0x259268c8764, operand1=0)
   2 ADD_TO_TRACE: _MAKE_WARM (0, target=0, operand0=0, operand1=0)
00000259268C8640 42: JUMP_BACKWARD(13) 0
   3 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=42, operand0=0, operand1=0)
   4 ADD_TO_TRACE: _SET_IP (0, target=42, operand0=0x259268c8764, operand1=0)
   5 ADD_TO_TRACE: _CHECK_PERIODIC (0, target=42, operand0=0, operand1=0)
Trace continuing
Unsupported: dynamic jump taken FOR_ITER_RANGE
Trace done
   5 ADD_TO_TRACE: _EXIT_TRACE (0, target=31, operand0=0, operand1=0)
Tracing TestUopsOptimization.test_iter_check_range.<locals>.testfunc (...) at byte offset 28 at chain depth 0
   1 ADD_TO_TRACE: _START_EXECUTOR (0, target=46, operand0=0x259268c876c, operand1=0)
   2 ADD_TO_TRACE: _MAKE_WARM (0, target=0, operand0=0, operand1=0)
00000259268C8640 46: JUMP_BACKWARD(34) 0
   3 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=46, operand0=0, operand1=0)
   4 ADD_TO_TRACE: _SET_IP (0, target=46, operand0=0x259268c876c, operand1=0)
   5 ADD_TO_TRACE: _CHECK_PERIODIC (0, target=46, operand0=0, operand1=0x1)
Trace continuing
00000259268C8640 14: FOR_ITER_RANGE(32) 0
   6 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=14, operand0=0, operand1=0)
   7 ADD_TO_TRACE: _SET_IP (0, target=14, operand0=0x259268c872c, operand1=0)
   8 ADD_TO_TRACE: _ITER_CHECK_RANGE (32, target=14, operand0=0, operand1=0)
   9 ADD_TO_TRACE: _GUARD_NOT_EXHAUSTED_RANGE (32, target=49, operand0=0, operand1=0)
  10 ADD_TO_TRACE: _ITER_NEXT_RANGE (32, target=14, operand0=0, operand1=0)
Trace continuing
00000259268C8640 16: STORE_FAST(2) 0
  11 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=16, operand0=0, operand1=0)
  12 ADD_TO_TRACE: _SET_IP (0, target=16, operand0=0x259268c8730, operand1=0)
  13 ADD_TO_TRACE: _SWAP_FAST (2, target=16, operand0=0, operand1=0)
  14 ADD_TO_TRACE: _POP_TOP (2, target=16, operand0=0, operand1=0)
Trace continuing
00000259268C8640 17: LOAD_GLOBAL_BUILTIN(1) 0
  15 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=17, operand0=0, operand1=0)
  16 ADD_TO_TRACE: _SET_IP (0, target=17, operand0=0x259268c8732, operand1=0)
  17 ADD_TO_TRACE: _GUARD_GLOBALS_VERSION (1, target=17, operand0=0xa9, operand1=0)
  18 ADD_TO_TRACE: _LOAD_GLOBAL_BUILTINS (1, target=17, operand0=0x2e, operand1=0)
  19 ADD_TO_TRACE: _PUSH_NULL_CONDITIONAL (1, target=17, operand0=0, operand1=0)
Trace continuing
00000259268C8640 22: LOAD_SMALL_INT(1) 0
  20 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=22, operand0=0, operand1=0)
  21 ADD_TO_TRACE: _SET_IP (0, target=22, operand0=0x259268c873c, operand1=0)
  22 ADD_TO_TRACE: _LOAD_SMALL_INT (1, target=22, operand0=0, operand1=0)
Trace continuing
00000259268C8640 23: LOAD_SMALL_INT(2) 0
  23 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=23, operand0=0, operand1=0)
  24 ADD_TO_TRACE: _SET_IP (0, target=23, operand0=0x259268c873e, operand1=0)
  25 ADD_TO_TRACE: _LOAD_SMALL_INT (2, target=23, operand0=0, operand1=0)
Trace continuing
00000259268C8640 24: CALL_BUILTIN_CLASS(2) 0
  26 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=24, operand0=0, operand1=0)
  27 ADD_TO_TRACE: _SET_IP (0, target=24, operand0=0x259268c8740, operand1=0)
  28 ADD_TO_TRACE: _RECORD_CALLABLE (2, target=24, operand0=0x7fff265dd6b0, operand1=0)
  29 ADD_TO_TRACE: _CALL_BUILTIN_CLASS (2, target=24, operand0=0, operand1=0)
  30 ADD_TO_TRACE: _TIER2_RESUME_CHECK (2, target=28, operand0=0, operand1=0)
Trace continuing
00000259268C8640 28: STORE_FAST(3) 0
  31 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=28, operand0=0, operand1=0)
  32 ADD_TO_TRACE: _SET_IP (0, target=28, operand0=0x259268c8748, operand1=0)
  33 ADD_TO_TRACE: _SWAP_FAST (3, target=28, operand0=0, operand1=0)
  34 ADD_TO_TRACE: _POP_TOP (3, target=28, operand0=0, operand1=0)
Trace continuing
00000259268C8640 29: LOAD_FAST(3) 0
  35 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=29, operand0=0, operand1=0)
  36 ADD_TO_TRACE: _SET_IP (0, target=29, operand0=0x259268c874a, operand1=0)
  37 ADD_TO_TRACE: _LOAD_FAST (3, target=29, operand0=0, operand1=0)
Trace continuing
00000259268C8640 30: GET_ITER(0) 0
  38 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=30, operand0=0, operand1=0)
  39 ADD_TO_TRACE: _SET_IP (0, target=30, operand0=0x259268c874c, operand1=0)
  40 ADD_TO_TRACE: _GET_ITER (0, target=30, operand0=0, operand1=0)
Trace continuing
00000259268C8640 31: FOR_ITER_RANGE(11) 0
  41 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=31, operand0=0, operand1=0)
  42 ADD_TO_TRACE: _SET_IP (0, target=31, operand0=0x259268c874e, operand1=0)
  43 ADD_TO_TRACE: _ITER_CHECK_RANGE (11, target=31, operand0=0, operand1=0)
  44 ADD_TO_TRACE: _GUARD_NOT_EXHAUSTED_RANGE (11, target=45, operand0=0, operand1=0)
  45 ADD_TO_TRACE: _ITER_NEXT_RANGE (11, target=31, operand0=0, operand1=0)
Trace continuing
00000259268C8640 33: STORE_FAST(4) 0
  46 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=33, operand0=0, operand1=0)
  47 ADD_TO_TRACE: _SET_IP (0, target=33, operand0=0x259268c8752, operand1=0)
  48 ADD_TO_TRACE: _SWAP_FAST (4, target=33, operand0=0, operand1=0)
  49 ADD_TO_TRACE: _POP_TOP (4, target=33, operand0=0, operand1=0)
Trace continuing
00000259268C8640 34: LOAD_FAST_BORROW_LOAD_FAST_BORROW(20) 0
  50 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=34, operand0=0, operand1=0)
  51 ADD_TO_TRACE: _SET_IP (0, target=34, operand0=0x259268c8754, operand1=0)
  52 ADD_TO_TRACE: _LOAD_FAST_BORROW (1, target=34, operand0=0, operand1=0)
  53 ADD_TO_TRACE: _LOAD_FAST_BORROW (4, target=34, operand0=0, operand1=0)
Trace continuing
00000259268C8640 35: BINARY_OP_ADD_INT(13) 0
  54 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=35, operand0=0, operand1=0)
  55 ADD_TO_TRACE: _SET_IP (0, target=35, operand0=0x259268c8756, operand1=0)
  56 ADD_TO_TRACE: _GUARD_TOS_INT (13, target=35, operand0=0, operand1=0)
  57 ADD_TO_TRACE: _GUARD_NOS_INT (13, target=35, operand0=0, operand1=0)
  58 ADD_TO_TRACE: _BINARY_OP_ADD_INT (13, target=35, operand0=0, operand1=0)
  59 ADD_TO_TRACE: _POP_TOP_INT (13, target=35, operand0=0, operand1=0)
  60 ADD_TO_TRACE: _POP_TOP_INT (13, target=35, operand0=0, operand1=0)
Trace continuing
00000259268C8640 41: STORE_FAST(1) 0
  61 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=41, operand0=0, operand1=0)
  62 ADD_TO_TRACE: _SET_IP (0, target=41, operand0=0x259268c8762, operand1=0)
  63 ADD_TO_TRACE: _SWAP_FAST (1, target=41, operand0=0, operand1=0)
  64 ADD_TO_TRACE: _POP_TOP (1, target=41, operand0=0, operand1=0)
Trace continuing
00000259268C8640 42: JUMP_BACKWARD(13) 0
  65 ADD_TO_TRACE: _CHECK_VALIDITY (0, target=42, operand0=0, operand1=0)
  66 ADD_TO_TRACE: _SET_IP (0, target=42, operand0=0x259268c8764, operand1=0)
  67 ADD_TO_TRACE: _CHECK_PERIODIC (0, target=42, operand0=0, operand1=0)
  68 ADD_TO_TRACE: _EXIT_TRACE (0, target=42, operand0=0, operand1=0)
JUMP_BACKWARD not to top ends trace 00000259268C874E 00000259268C872C 00000259268C876C
Trace done
  69 ADD_TO_TRACE: _EXIT_TRACE (0, target=42, operand0=0, operand1=0)
Optimized trace (length 72):
   0 OPTIMIZED: _START_EXECUTOR_r00 (0, jump_target=52, operand0=0x259265a7570, operand1=0)
   1 OPTIMIZED: _MAKE_WARM_r00 (0, target=0, operand0=0, operand1=0)
   2 OPTIMIZED: _SET_IP_r00 (0, target=46, operand0=0x259268c876c, operand1=0)
   3 OPTIMIZED: _CHECK_PERIODIC_r00 (0, jump_target=0, operand0=0, operand1=0x1, error_target=53)
   4 OPTIMIZED: _CHECK_VALIDITY_r00 (0, jump_target=54, operand0=0, operand1=0)
   5 OPTIMIZED: _ITER_CHECK_RANGE_r02 (32, jump_target=55, operand0=0, operand1=0)
   6 OPTIMIZED: _GUARD_NOT_EXHAUSTED_RANGE_r22 (32, jump_target=56, operand0=0, operand1=0)
   7 OPTIMIZED: _ITER_NEXT_RANGE_r23 (32, jump_target=0, operand0=0, operand1=0, error_target=57)
   8 OPTIMIZED: _SET_IP_r33 (0, target=16, operand0=0x259268c8730, operand1=0)
   9 OPTIMIZED: _SWAP_FAST_2_r33 (2, target=16, operand0=0, operand1=0)
  10 OPTIMIZED: _SPILL_OR_RELOAD_r31 (0, target=0, operand0=0, operand1=0)
  11 OPTIMIZED: _POP_TOP_r10 (2, target=16, operand0=0, operand1=0)
  12 OPTIMIZED: _CHECK_VALIDITY_r00 (0, jump_target=58, operand0=0, operand1=0)
  13 OPTIMIZED: _GUARD_GLOBALS_VERSION_r00 (1, jump_target=58, operand0=0xa9, operand1=0)
  14 OPTIMIZED: _LOAD_CONST_INLINE_BORROW_r01 (1, target=17, operand0=0x7fff265dd6b0, operand1=0x46)
  15 OPTIMIZED: _PUSH_NULL_r12 (0, target=17, operand0=0, operand1=0)
  16 OPTIMIZED: _LOAD_CONST_INLINE_BORROW_r23 (0, target=22, operand0=0x7fff266ca3e0, operand1=0)
  17 OPTIMIZED: _SPILL_OR_RELOAD_r32 (0, target=0, operand0=0x7fff265dd6b0, operand1=0x46)
  18 OPTIMIZED: _LOAD_CONST_INLINE_BORROW_r23 (0, target=23, operand0=0x7fff266ca400, operand1=0)
  19 OPTIMIZED: _SET_IP_r33 (0, target=24, operand0=0x259268c8740, operand1=0)
  20 OPTIMIZED: _SPILL_OR_RELOAD_r30 (0, target=0, operand0=0x259268c873c, operand1=0)
  21 OPTIMIZED: _CALL_BUILTIN_CLASS_r01 (2, jump_target=59, operand0=0, operand1=0, error_target=60)
  22 OPTIMIZED: _TIER2_RESUME_CHECK_r11 (2, jump_target=61, operand0=0, operand1=0)
  23 OPTIMIZED: _CHECK_VALIDITY_r11 (0, jump_target=62, operand0=0, operand1=0)
  24 OPTIMIZED: _SET_IP_r11 (0, target=28, operand0=0x259268c8748, operand1=0)
  25 OPTIMIZED: _SWAP_FAST_3_r11 (3, target=28, operand0=0, operand1=0)
  26 OPTIMIZED: _POP_TOP_r10 (3, target=28, operand0=0, operand1=0)
  27 OPTIMIZED: _CHECK_VALIDITY_r00 (0, jump_target=63, operand0=0, operand1=0)
  28 OPTIMIZED: _LOAD_FAST_3_r01 (3, target=29, operand0=0, operand1=0)
  29 OPTIMIZED: _SET_IP_r11 (0, target=30, operand0=0x259268c874c, operand1=0)
  30 OPTIMIZED: _GET_ITER_r12 (0, jump_target=0, operand0=0, operand1=0, error_target=64)
  31 OPTIMIZED: _CHECK_VALIDITY_r22 (0, jump_target=65, operand0=0, operand1=0)
  32 OPTIMIZED: _ITER_CHECK_RANGE_r22 (11, jump_target=66, operand0=0, operand1=0)
  33 OPTIMIZED: _GUARD_NOT_EXHAUSTED_RANGE_r22 (11, jump_target=67, operand0=0, operand1=0)
  34 OPTIMIZED: _ITER_NEXT_RANGE_r23 (11, jump_target=0, operand0=0, operand1=0, error_target=68)
  35 OPTIMIZED: _SET_IP_r33 (0, target=33, operand0=0x259268c8752, operand1=0)
  36 OPTIMIZED: _SWAP_FAST_4_r33 (4, target=33, operand0=0, operand1=0)
  37 OPTIMIZED: _SPILL_OR_RELOAD_r31 (0, target=0, operand0=0, operand1=0)
  38 OPTIMIZED: _POP_TOP_r10 (4, target=33, operand0=0, operand1=0)
  39 OPTIMIZED: _CHECK_VALIDITY_r00 (0, jump_target=69, operand0=0, operand1=0)
  40 OPTIMIZED: _LOAD_FAST_BORROW_1_r01 (1, target=34, operand0=0, operand1=0)
  41 OPTIMIZED: _LOAD_FAST_BORROW_4_r12 (4, target=34, operand0=0, operand1=0)
  42 OPTIMIZED: _GUARD_TOS_OVERFLOWED_r22 (0, jump_target=70, operand0=0, operand1=0)
  43 OPTIMIZED: _GUARD_NOS_INT_r22 (13, jump_target=70, operand0=0, operand1=0)
  44 OPTIMIZED: _BINARY_OP_ADD_INT_r23 (13, jump_target=70, operand0=0, operand1=0)
  45 OPTIMIZED: _POP_TOP_NOP_r32 (0, target=35, operand0=0, operand1=0)
  46 OPTIMIZED: _POP_TOP_NOP_r21 (0, target=35, operand0=0, operand1=0)
  47 OPTIMIZED: _SWAP_FAST_1_r11 (1, target=41, operand0=0, operand1=0)
  48 OPTIMIZED: _POP_TOP_INT_r10 (0, target=41, operand0=0, operand1=0)
  49 OPTIMIZED: _SET_IP_r00 (0, target=42, operand0=0x259268c8764, operand1=0)
  50 OPTIMIZED: _CHECK_PERIODIC_r00 (0, jump_target=0, operand0=0, operand1=0, error_target=71)
  51 OPTIMIZED: _EXIT_TRACE_r00 (0, target=42, operand0=0x259265a75f0, operand1=0x1)
  52 OPTIMIZED: _DEOPT_r00 (0, target=46, operand0=0, operand1=0)
  53 OPTIMIZED: _ERROR_POP_N_r00 (0, target=0, operand0=0x2e, operand1=0)
  54 OPTIMIZED: _DEOPT_r00 (0, target=14, operand0=0, operand1=0)
  55 OPTIMIZED: _EXIT_TRACE_r00 (0, target=14, operand0=0x259265a7600, operand1=0)
  56 OPTIMIZED: _EXIT_TRACE_r20 (0, target=49, operand0=0x259265a7610, operand1=0x1)
  57 OPTIMIZED: _ERROR_POP_N_r00 (0, target=0, operand0=0xe, operand1=0)
  58 OPTIMIZED: _DEOPT_r00 (0, target=17, operand0=0, operand1=0)
  59 OPTIMIZED: _DEOPT_r00 (0, target=24, operand0=0, operand1=0)
  60 OPTIMIZED: _ERROR_POP_N_r00 (0, target=0, operand0=0x18, operand1=0)
  61 OPTIMIZED: _HANDLE_PENDING_AND_DEOPT_r10 (0, target=28, operand0=0, operand1=0)
  62 OPTIMIZED: _DEOPT_r10 (0, target=28, operand0=0, operand1=0)
  63 OPTIMIZED: _DEOPT_r00 (0, target=29, operand0=0, operand1=0)
  64 OPTIMIZED: _ERROR_POP_N_r00 (0, target=0, operand0=0x1e, operand1=0)
  65 OPTIMIZED: _DEOPT_r20 (0, target=31, operand0=0, operand1=0)
  66 OPTIMIZED: _EXIT_TRACE_r20 (0, target=31, operand0=0x259265a7620, operand1=0)
  67 OPTIMIZED: _EXIT_TRACE_r20 (0, target=45, operand0=0x259265a7630, operand1=0x1)
  68 OPTIMIZED: _ERROR_POP_N_r00 (0, target=0, operand0=0x1f, operand1=0)
  69 OPTIMIZED: _DEOPT_r00 (0, target=34, operand0=0, operand1=0)
  70 OPTIMIZED: _EXIT_TRACE_r20 (0, target=35, operand0=0x259265a7640, operand1=0)
  71 OPTIMIZED: _ERROR_POP_N_r00 (0, target=0, operand0=0x2a, operand1=0)

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