Соловьев Алексей. Лабораторная работа 4. MLIR. Вариант 2 #149
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Alexey-Solovev
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m-ly4 and
Kuznetsov-Artyom
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aobolensk
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m-ly4
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| // CHECK-NEXT: %c3 = arith.constant 3 : index | ||
| // CHECK-NEXT: %[[NEG2:.*]] = arith.constant -2 : index | ||
| // CHECK-NEXT: scf.for %{{.*}} = %c0 to %c3 step %[[NEG2]] { | ||
| // CHECK-NEXT: } {trip_count = 0 : index} |
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It is not a safe assumption. Yes, loop is malformed, but it can perform thousands of iterations before it crashes a program. Another weak moment is that there is no formal difference between cases when lb == ub in a loop and when iteration space is malformed. In both cases trip_count == 0.
I'd suggest to set it to -1 or not to set it at all if a loop's iteration space is malformed.
m-ly4
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| // CHECK-NEXT: %c3 = arith.constant 3 : index | ||
| // CHECK-NEXT: %[[NEG2:.*]] = arith.constant -2 : index | ||
| // CHECK-NEXT: scf.for %{{.*}} = %c0 to %c3 step %[[NEG2]] { | ||
| // CHECK-NEXT: } |
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Actually, if the pass suddenly prints trip_count, this check won't detect that. Because it doesn't check that there is no more text in current line after closing brace.
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Added CHECK-NOT for trip_count validation
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Этот MLIR-пасс аннотирует циклы scf.for, у которых статически известны границы и шаг, атрибутом trip_count, содержащим количество итераций цикла. Пасс обходит все операции внутри модуля и для каждого цикла scf.for проверяет, задаются ли нижняя граница, верхняя граница и шаг как константы. Если все три значения заданы явно и шаг не равен нулю, вычисляется количество итераций по формуле (upperBound - lowerBound + step - 1) / step, после чего цикл аннотируется соответствующим атрибутом. Такой подход позволяет упростить последующий анализ и оптимизацию кода, например, при проведении loop unrolling или vectorization.