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From: "scherrer.sv at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110992] New: [14 Regression] Dead Code
 Elimination Regression at -O3 since r14-1654-g7ceed7e3e29
Date: Fri, 11 Aug 2023 13:24:08 +0000
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X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 14.0
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110992

            Bug ID: 110992
           Summary: [14 Regression] Dead Code Elimination Regression at
                    -O3 since r14-1654-g7ceed7e3e29
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: scherrer.sv at gmail dot com
  Target Milestone: ---

static unsigned b;
static short c =3D 4;
void foo(void);
static short(a)(short d, short g) { return d * g; }
void e();
static char f() {
  b =3D 0;
  return 0;
}
int main() {
  int h =3D b;
  if ((short)(a(c && e, 65535) & h)) {
    foo();
    h || f();
  }
}

gcc-bcda361daae (trunk) -O3 cannot eliminate the call to foo but
gcc-releases/gcc-13.1.0 -O3 can.
-----------------------------------------------------------------------
gcc-bcda361daaec8623c91d0dff3ea8e576373b5f50 -O3 case.c -S -o case.s
--------- OUTPUT ---------
main:
.LFB2:
        .cfi_startproc
        cmpw    $0, b(%rip)
        jne     .L8
        xorl    %eax, %eax
        ret
.L8:
        pushq   %rax
        .cfi_def_cfa_offset 16
        call    foo
        xorl    %eax, %eax
        popq    %rdx
        .cfi_def_cfa_offset 8
        ret
---------- END OUTPUT ---------

-----------------------------------------------------------------------
gcc-2b98cc24d6af0432a74f6dad1c722ce21c1f7458 -O3 case.c -S -o case.s
--------- OUTPUT ---------
main:
.LFB2:
        .cfi_startproc
        xorl    %eax, %eax
        ret
---------- END OUTPUT ---------

-----------------------------------------------------------------------
Bisects to r14-1654-g7ceed7e3e29=