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From: "slyfox at inbox dot ru" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/96015] New: [regression] gcc-10.1.0 miscompiles Python on hppa Date: Wed, 01 Jul 2020 07:29:50 +0000 [thread overview] Message-ID: <bug-96015-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96015 Bug ID: 96015 Summary: [regression] gcc-10.1.0 miscompiles Python on hppa Product: gcc Version: 10.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: target Assignee: unassigned at gcc dot gnu.org Reporter: slyfox at inbox dot ru CC: dave.anglin at bell dot net, law at redhat dot com Target Milestone: --- Target: hppa2.0-unknown-linux-gnu Originally reported as https://bugs.gentoo.org/729570 where gcc-10.1.0 miscompiles Python into generating invalid bytecode. I shrunk Python's code into single file that illustrates the problem: // $ cat bug_test.c /* The test is extracted from Python-3.9.0 miscompilation on hppa2.0: https://bugs.gentoo.org/729570 Original bug happens as an invalid bytecode generation due to bad results from 'long_richcompare(0xFFFFffff, 1, EQ)' calls. Failure example: $ hppa2.0-unknown-linux-gnu-gcc -lm -Wsign-compare -Wall -O1 bug_test.c -o good-bug $ hppa2.0-unknown-linux-gnu-gcc -lm -Wsign-compare -Wall -O2 bug_test.c -o bad-bug $ ./good-bug long_richcompare(2, 1, EQ) = FALSE (expect FALSE) $ ./bad-bug long_richcompare(2, 1, EQ) = TRUE (expect FALSE) */ // We use '__attribute__((noipa));' aggressively to simulate // unavailable function definitions from outside translation units. static int cmp(int *lhs, int *rhs) { int sign = *lhs - *rhs; // semantically this should be 'return 0;' but this condition is not // supposed to trigger on our input data. if (sign == 0) return 1; return sign; } static int yes(void) __attribute__((noipa)); static int yes(void) { return 1; } static int long_richcompare(int *self, int *other, int op) __attribute__((noipa)); static int long_richcompare(int *self, int *other, int op) { int result; if (!yes() || !yes()) return 0; if (self == other) result = 0; else result = cmp(self, other); // has to force jump table switch (op) { // only 0 case is used on actual data case 0: return (result == 0); case 1: return 0; case 3: return 0; case 5: if (result == 0) return 1; else return 0; default: __builtin_unreachable(); } } #include <stdio.h> int main() { int l = 2; int r = 1; int res = long_richcompare(&l, &r, 0); printf("long_richcompare(2, 1, EQ) = %s (expect FALSE)\n", res ? "TRUE" : "FALSE"); }
next reply other threads:[~2020-07-01 7:29 UTC|newest] Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-01 7:29 slyfox at inbox dot ru [this message] 2020-07-01 7:30 ` [Bug target/96015] " slyfox at inbox dot ru 2020-07-01 7:32 ` slyfox at inbox dot ru 2020-07-01 7:38 ` slyfox at inbox dot ru 2020-07-01 8:03 ` [Bug target/96015] [10/11 Regression] " rguenth at gcc dot gnu.org 2020-07-01 8:11 ` marxin at gcc dot gnu.org 2020-07-01 9:14 ` slyfox at inbox dot ru 2020-07-01 9:15 ` slyfox at inbox dot ru 2020-07-01 13:11 ` marxin at gcc dot gnu.org 2020-07-01 13:12 ` marxin at gcc dot gnu.org 2020-07-01 15:39 ` slyfox at inbox dot ru 2020-07-01 15:40 ` slyfox at inbox dot ru 2020-07-01 15:46 ` slyfox at inbox dot ru 2020-07-01 16:35 ` law at redhat dot com 2020-07-01 17:33 ` law at redhat dot com 2020-07-01 17:57 ` slyfox at inbox dot ru 2020-07-01 19:15 ` slyfox at inbox dot ru 2020-07-02 6:58 ` slyfox at inbox dot ru 2020-07-02 7:58 ` marxin at gcc dot gnu.org 2020-07-02 9:34 ` ebotcazou at gcc dot gnu.org 2020-07-02 17:15 ` slyfox at inbox dot ru 2020-07-02 17:15 ` slyfox at inbox dot ru 2020-07-02 17:16 ` slyfox at inbox dot ru 2020-07-02 20:21 ` slyfox at inbox dot ru 2020-07-02 20:50 ` slyfox at inbox dot ru 2020-07-02 21:35 ` slyfox at inbox dot ru 2020-07-02 22:36 ` slyfox at inbox dot ru 2020-07-02 23:16 ` [Bug rtl-optimization/96015] " ebotcazou at gcc dot gnu.org 2020-07-03 7:19 ` slyfox at inbox dot ru 2020-07-03 7:45 ` marxin at gcc dot gnu.org 2020-07-03 8:23 ` ebotcazou at gcc dot gnu.org 2020-07-03 9:23 ` ebotcazou at gcc dot gnu.org 2020-07-03 17:24 ` slyfox at inbox dot ru 2020-07-03 19:29 ` ebotcazou at gcc dot gnu.org 2020-07-06 20:31 ` law at redhat dot com 2020-07-07 8:09 ` ebotcazou at gcc dot gnu.org 2020-07-08 17:01 ` law at redhat dot com 2020-07-23 6:51 ` rguenth at gcc dot gnu.org 2021-01-14 9:04 ` rguenth at gcc dot gnu.org 2021-01-14 16:33 ` law at redhat dot com 2021-01-14 19:14 ` mikpelinux at gmail dot com 2021-01-15 16:54 ` ebotcazou at gcc dot gnu.org 2021-02-09 18:56 ` cvs-commit at gcc dot gnu.org 2021-02-09 18:59 ` cvs-commit at gcc dot gnu.org 2021-02-09 19:01 ` ebotcazou at gcc dot gnu.org 2021-02-09 20:21 ` dave.anglin at bell dot net
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