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69 lines
1.6 KiB
69 lines
1.6 KiB
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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import java.util.List;
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class Invariant {
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// x is invariant
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void x_is_invariant_ok(int size) {
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int i = 0, x;
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if (size > 10) {
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x = 10;
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} else {
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x = 20;
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}
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while (i < size + x) {
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i++;
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}
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}
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// x shouldn't be invariant since it can have two different values
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// depending on whether the inner conditional is executed or not.
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// Currently, we are getting a quadratic, rather than a linear,
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// because the value of x at the true branch of the if statement is
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// precisely analyzed to [0,4+min(1,size.ub)], rather than [0,5].
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void formal_not_invariant_FP(int size, int x) {
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int i = 0;
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while (i < size + x) {
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if (x > i) {
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x = 0;
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}
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i++;
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}
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}
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// x shouldn't be invariant since it can have two different values
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// depending on whether the inner conditional is executed or not
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// Currently, we are getting T because of a problem in InferBo, see
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// T32798161
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void local_not_invariant_FP(int size) {
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int i = 0;
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int x = 5;
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while (i < size + x) {
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if (x > i) {
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x = 0;
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}
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i++;
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}
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}
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// m will be invariant
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void do_while_invariant(int m, int k) {
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int i = 0;
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do {
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m = k;
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i++;
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} while (i < m);
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}
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// before, we were getting items.size()^2 since all functions were
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// assumed to be impure
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void list_size_invariant(List<?> items) {
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for (int i = 0; i < items.size(); i++) {}
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}
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}
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