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8081823: C2 performs unsigned comparison against -1
X <= 0 || x > 0 wrongly folded as (x-1) >u -1 Reviewed-by: kvn, vlivanov
This commit is contained in:
Roland Westrelin
parent
0fb315714c
commit
197ecf9bc1
@ -817,19 +817,78 @@ bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* f
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BoolTest::mask hi_test = this_bool->_test._test;
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BoolTest::mask cond = hi_test;
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// convert:
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//
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// dom_bool = x {<,<=,>,>=} a
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// / \
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// proj = {True,False} / \ otherproj = {False,True}
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// /
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// this_bool = x {<,<=} b
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// / \
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// fail = {True,False} / \ success = {False,True}
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// /
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//
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// (Second test guaranteed canonicalized, first one may not have
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// been canonicalized yet)
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//
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// into:
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//
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// cond = (x - lo) {<u,<=u,>u,>=u} adjusted_lim
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// / \
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// fail / \ success
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// /
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//
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// Figure out which of the two tests sets the upper bound and which
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// sets the lower bound if any.
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Node* adjusted_lim = NULL;
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if (hi_type->_lo > lo_type->_hi && hi_type->_hi == max_jint && lo_type->_lo == min_jint) {
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assert((dom_bool->_test.is_less() && !proj->_con) ||
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(dom_bool->_test.is_greater() && proj->_con), "incorrect test");
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// this test was canonicalized
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assert(this_bool->_test.is_less() && fail->_con, "incorrect test");
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// this_bool = <
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// dom_bool = >= (proj = True) or dom_bool = < (proj = False)
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// x in [a, b[ on the fail (= True) projection, b > a-1 (because of hi_type->_lo > lo_type->_hi test above):
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// lo = a, hi = b, adjusted_lim = b-a, cond = <u
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// dom_bool = > (proj = True) or dom_bool = <= (proj = False)
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// x in ]a, b[ on the fail (= True) projection, b > a:
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// lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <u
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// this_bool = <=
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// dom_bool = >= (proj = True) or dom_bool = < (proj = False)
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// x in [a, b] on the fail (= True) projection, b+1 > a-1:
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// lo = a, hi = b, adjusted_lim = b-a, cond = <=u
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// dom_bool = > (proj = True) or dom_bool = <= (proj = False)
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// x in ]a, b] on the fail (= True) projection b+1 > a:
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// lo = a+1, hi = b, adjusted_lim = b-a, cond = <u
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// lo = a+1, hi = b, adjusted_lim = b-a-1, cond = <=u doesn't work because a = b is possible, then hi-lo = -1
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if (lo_test == BoolTest::gt || lo_test == BoolTest::le) {
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if (hi_test == BoolTest::le) {
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adjusted_lim = igvn->transform(new SubINode(hi, lo));
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cond = BoolTest::lt;
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}
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lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
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}
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} else if (lo_type->_lo > hi_type->_hi && lo_type->_hi == max_jint && hi_type->_lo == min_jint) {
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// this_bool = <
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// dom_bool = < (proj = True) or dom_bool = >= (proj = False)
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// x in [b, a[ on the fail (= False) projection, a > b-1 (because of lo_type->_lo > hi_type->_hi above):
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// lo = b, hi = a, adjusted_lim = a-b, cond = >=u
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// dom_bool = <= (proj = True) or dom_bool = > (proj = False)
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// x in [b, a] on the fail (= False) projection, a+1 > b-1:
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// lo = b, hi = a, adjusted_lim = a-b, cond = >u
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// this_bool = <=
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// dom_bool = < (proj = True) or dom_bool = >= (proj = False)
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// x in ]b, a[ on the fail (= False) projection, a > b:
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// lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >=u
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// dom_bool = <= (proj = True) or dom_bool = > (proj = False)
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// x in ]b, a] on the fail (= False) projection, a+1 > b:
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// lo = b+1, hi = a, adjusted_lim = a-b, cond = >=u
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// lo = b+1, hi = a, adjusted_lim = a-b-1, cond = >u doesn't work because a = b is possible, then hi-lo = -1
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swap(lo, hi);
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swap(lo_type, hi_type);
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swap(lo_test, hi_test);
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@ -842,6 +901,10 @@ bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* f
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cond = (hi_test == BoolTest::le || hi_test == BoolTest::gt) ? BoolTest::gt : BoolTest::ge;
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if (lo_test == BoolTest::le) {
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if (cond == BoolTest::gt) {
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adjusted_lim = igvn->transform(new SubINode(hi, lo));
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cond = BoolTest::ge;
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}
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lo = igvn->transform(new AddINode(lo, igvn->intcon(1)));
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}
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@ -860,7 +923,6 @@ bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* f
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}
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}
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}
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lo = NULL;
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hi = NULL;
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}
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@ -868,12 +930,13 @@ bool IfNode::fold_compares_helper(ProjNode* proj, ProjNode* success, ProjNode* f
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if (lo && hi) {
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// Merge the two compares into a single unsigned compare by building (CmpU (n - lo) (hi - lo))
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Node* adjusted_val = igvn->transform(new SubINode(n, lo));
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Node* adjusted_lim = igvn->transform(new SubINode(hi, lo));
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if (adjusted_lim == NULL) {
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adjusted_lim = igvn->transform(new SubINode(hi, lo));
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}
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Node* newcmp = igvn->transform(new CmpUNode(adjusted_val, adjusted_lim));
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Node* newbool = igvn->transform(new BoolNode(newcmp, cond));
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igvn->is_IterGVN()->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
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igvn->hash_delete(this);
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igvn->replace_input_of(dom_iff, 1, igvn->intcon(proj->_con));
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set_req(1, newbool);
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return true;
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94
hotspot/test/compiler/rangechecks/TestBadFoldCompare.java
Normal file
94
hotspot/test/compiler/rangechecks/TestBadFoldCompare.java
Normal file
@ -0,0 +1,94 @@
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/*
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* Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @bug 8085832
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* @summary x <= 0 || x > 0 wrongly folded as (x-1) >u -1
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* @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement TestBadFoldCompare
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*/
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public class TestBadFoldCompare {
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static boolean test1_taken;
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static void helper1(int i, int a, int b, boolean flag) {
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if (flag) {
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if (i <= a || i > b) {
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test1_taken = true;
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}
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}
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}
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static void test1(int i, boolean flag) {
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helper1(i, 0, 0, flag);
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}
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static boolean test2_taken;
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static void helper2(int i, int a, int b, boolean flag) {
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if (flag) {
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if (i > b || i <= a) {
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test2_taken = true;
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}
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}
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}
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static void test2(int i, boolean flag) {
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helper2(i, 0, 0, flag);
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}
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static public void main(String[] args) {
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boolean success = true;
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for (int i = 0; i < 20000; i++) {
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helper1(5, 0, 10, (i%2)==0);
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helper1(-1, 0, 10, (i%2)==0);
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helper1(15, 0, 10, (i%2)==0);
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test1(0, false);
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}
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test1_taken = false;
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test1(0, true);
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if (!test1_taken) {
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System.out.println("Test1 failed");
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success = false;
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}
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for (int i = 0; i < 20000; i++) {
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helper2(5, 0, 10, (i%2)==0);
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helper2(-1, 0, 10, (i%2)==0);
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helper2(15, 0, 10, (i%2)==0);
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test2(0, false);
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}
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test2_taken = false;
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test2(0, true);
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if (!test2_taken) {
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System.out.println("Test2 failed");
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success = false;
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}
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if (!success) {
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throw new RuntimeException("Some tests failed");
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}
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}
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}
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