[Bug tree-optimization/109008] New: [13 Regression ]Maybe wrong code in scipy package since r13-3926-gd4c2f1d376da6f

[marxin at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109008

            Bug ID: 109008
           Summary: [13 Regression ]Maybe wrong code in scipy package
                    since r13-3926-gd4c2f1d376da6f
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: aldyh at gcc dot gnu.org, jakub at gcc dot gnu.org
  Target Milestone: ---

Created attachment 54578
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54578&action=edit
test-case

Since the revision, the scipy package fails in tests due to:
https://github.com/scipy/scipy/blob/main/scipy/integrate/odepack/vode.f#L3500-L3515

$ cat /tmp/x.f
      DOUBLE PRECISION FUNCTION D1MACH (IDUM)
      INTEGER IDUM
C-----------------------------------------------------------------------
C This routine computes the unit roundoff of the machine.
C This is defined as the smallest positive machine number
C u such that  1.0 + u .ne. 1.0
C
C Subroutines/functions called by D1MACH.. None
C-----------------------------------------------------------------------
      DOUBLE PRECISION U, COMP
      U = 1.0D0
 10   U = U*0.5D0
      COMP = 1.0D0 + U
      IF (COMP .NE. 1.0D0) GO TO 10
      D1MACH = U*2.0D0
      RETURN

      END FUNCTION D1MACH

$ gcc /tmp/x.f -c -O2 -fdump-tree-optimized=/dev/stdout
;; Function d1mach (d1mach_, funcdef_no=0, decl_uid=4259, cgraph_uid=1,
symbol_order=0)

__attribute__((fn spec (". w ")))
real(kind=8) d1mach (integer(kind=4) & restrict idum)
{
  <bb 2> [local count: 20293720]:
  return 0.0;

}

Before the revision we did:


;; Function d1mach (d1mach_, funcdef_no=0, decl_uid=4259, cgraph_uid=1,
symbol_order=0)

Removing basic block 5
__attribute__((fn spec (". w ")))
real(kind=8) d1mach (integer(kind=4) & restrict idum)
{
  real(kind=8) u;
  real(kind=8) _1;
  character(kind=4) ivtmp_7;
  character(kind=4) ivtmp_8;

  <bb 2> [local count: 20293720]:

  <bb 3> [local count: 1073741824]:
  # u_2 = PHI <1.0e+0(2), u_4(3)>
  # ivtmp_7 = PHI <53(2), ivtmp_8(3)>
  u_4 = u_2 * 5.0e-1;
  ivtmp_8 = ivtmp_7 + 4294967295;
  if (ivtmp_8 != 0)
    goto <bb 3>; [98.11%]
  else
    goto <bb 4>; [1.89%]

  <bb 4> [local count: 20293720]:
  _1 = u_4 * 2.0e+0;
  return _1;

}