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From: "Joost.VandeVondele at mat dot ethz.ch" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/63311] New: [4.9/5 Regression] -O1 optimization introduces valgrind warning Date: Fri, 19 Sep 2014 15:03:00 -0000 [thread overview] Message-ID: <bug-63311-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63311 Bug ID: 63311 Summary: [4.9/5 Regression] -O1 optimization introduces valgrind warning Product: gcc Version: 5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: Joost.VandeVondele at mat dot ethz.ch The following testcase yields a valgrind error when compiled with -O1 but not at -O0. 4.8 is fine 4.9/trunk is not. > gfortran -O1 -g bug.f90 && valgrind ./a.out ==57092== Conditional jump or move depends on uninitialised value(s) ==57092== at 0x4006F5: __m1_MOD_test (bug.f90:20) ==57092== by 0x4007BB: main (bug.f90:36) ==57092== ERROR SUMMARY: 4 errors from 1 contexts (suppressed: 6 from 6) > cat bug.f90 MODULE M1 IMPLICIT NONE CONTAINS INTEGER FUNCTION foo() INTEGER, VOLATILE :: v=42 foo=v END FUNCTION SUBROUTINE test(n,flag) INTEGER :: n,i,j,k,l,tt LOGICAL :: flag REAL(KIND=8) :: v,t IF (flag) THEN t=42 tt=foo() ENDIF v=0 DO i=1,n v=0 IF (flag) THEN IF (tt==i) v=MAX(v,t) ENDIF DO j=1,n DO k=1,n v=MAX(v,sin(REAL(j*k))) ENDDO ENDDO ENDDO END SUBROUTINE END MODULE M1 USE M1 INTEGER :: n LOGICAL :: flag n=4 flag=.FALSE. CALL test(n,flag) END what seems to happen is that '(tt==i)' is evaluated before IF (flag) is evaluated, also in the case where 'flag==.FALSE.', while 'tt' is only initialized in the .TRUE. case. I actually think generated code might nevertheless be correct, but it makes valgrind less useful on -O1 code.
next reply other threads:[~2014-09-19 15:03 UTC|newest] Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-09-19 15:03 Joost.VandeVondele at mat dot ethz.ch [this message] 2014-09-22 10:24 ` [Bug middle-end/63311] " rguenth at gcc dot gnu.org 2014-09-22 10:24 ` rguenth at gcc dot gnu.org 2014-09-22 10:34 ` dominiq at lps dot ens.fr 2014-10-09 9:45 ` jakub at gcc dot gnu.org 2014-10-30 10:42 ` jakub at gcc dot gnu.org 2014-10-31 9:30 ` Joost.VandeVondele at mat dot ethz.ch 2014-10-31 9:34 ` Joost.VandeVondele at mat dot ethz.ch 2014-11-24 13:27 ` rguenth at gcc dot gnu.org 2014-11-24 13:54 ` Joost.VandeVondele at mat dot ethz.ch 2015-06-26 20:12 ` [Bug middle-end/63311] [4.9/5/6 " jakub at gcc dot gnu.org 2015-06-26 20:36 ` jakub at gcc dot gnu.org 2021-05-14 9:47 ` [Bug middle-end/63311] [9/10/11/12 " jakub at gcc dot gnu.org 2021-06-01 8:06 ` rguenth at gcc dot gnu.org 2022-02-15 12:09 ` mark at gcc dot gnu.org 2022-02-16 22:49 ` dmalcolm at gcc dot gnu.org 2022-02-17 2:41 ` cvs-commit at gcc dot gnu.org 2022-05-27 9:35 ` [Bug middle-end/63311] [10/11/12/13 " rguenth at gcc dot gnu.org 2022-06-28 10:31 ` jakub at gcc dot gnu.org 2023-07-07 10:30 ` [Bug middle-end/63311] [11/12/13/14 " rguenth at gcc dot gnu.org 2023-09-03 3:39 ` [Bug middle-end/63311] [11/12 " pinskia at gcc dot gnu.org
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