[Bug tree-optimization/110903] New: [14 Regression] Dead Code Elimination Regression since r14-1597-g64d90d06d2d

["theodort at inf dot ethz.ch" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110903

            Bug ID: 110903
           Summary: [14 Regression] Dead Code Elimination Regression since
                    r14-1597-g64d90d06d2d
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: theodort at inf dot ethz.ch
  Target Milestone: ---

https://godbolt.org/z/7of4jjM3K

Given the following code:

void foo(void);
static char b, c;
static short e, f;
static int g = 41317;
static int(a)(int h, int i) { return h + i; }
static int(d)(int h, int i) { return i ? h : 0; }
int main() {
    {
        char j;
        short k;
        for (; g >= 10; g = (short)g) {
            int l = 1, m = 0;
            j = 8 * k;
            k = j <= 0;
            f = c + 3;
            for (; c < 2; c = f) {
                char n = 4073709551615;
                if (!(((m) >= 0) && ((m) <= 0))) {
                    __builtin_unreachable();
                }
                if (g)
                    ;
                else {
                    if ((m = k, (b = a(d(l, k), e) && n) || l) < k) foo();
                    e = l = 0;
                }
            }
        }
    }
}

gcc-trunk -O3 does not eliminate the call to foo:

main:
        movl    g(%rip), %edi
        cmpl    $9, %edi
        jle     .L25
        pushq   %rbp
        movl    %edi, %ecx
        movl    $1, %ebp
        movl    $1, %esi
        pushq   %rbx
        movl    $1, %ebx
        subq    $8, %rsp
        movzbl  c(%rip), %edx
        movsbw  %dl, %ax
        addl    $3, %eax
        movw    %ax, f(%rip)
        cmpb    $1, %dl
        jg      .L12
        .p2align 4,,10
        .p2align 3
.L6:
        testl   %edi, %edi
        je      .L7
        movb    %al, c(%rip)
        movsbw  %al, %dx
        cmpb    $1, %al
        jle     .L6
.L9:
        movswl  %di, %ecx
        movl    %ecx, g(%rip)
        cmpl    $9, %ecx
        jle     .L17
        addl    $3, %edx
        movw    %dx, f(%rip)
.L12:
        movswl  %cx, %eax
        cmpw    $9, %cx
        jle     .L29
.L4:
        jmp     .L4
        .p2align 4,,10
        .p2align 3
.L7:
        movswl  e(%rip), %ecx
        movl    %ebx, %edx
        andl    %esi, %edx
        addl    %ecx, %edx
        orl     %esi, %edx
        jne     .L10
        testb   %bpl, %bpl
        jne     .L30
.L10:
        xorl    %edx, %edx
        movb    %al, c(%rip)
        movw    %dx, e(%rip)
        movsbw  %al, %dx
        cmpb    $1, %al
        jg      .L9
        xorl    %esi, %esi
        jmp     .L6
        .p2align 4,,10
        .p2align 3
.L30:
        call    foo
        movzwl  f(%rip), %eax
        movl    g(%rip), %edi
        jmp     .L10
.L29:
        movl    %eax, g(%rip)
.L17:
        addq    $8, %rsp
        xorl    %eax, %eax
        popq    %rbx
        popq    %rbp
        ret
.L25:
        xorl    %eax, %eax
        ret

gcc-13.2.0 -O3 eliminates the call to foo:

main:
        movl    g(%rip), %esi
        movl    %esi, %ecx
        cmpl    $9, %esi
        jle     .L14
        movzbl  c(%rip), %eax
        movsbw  %al, %dx
        addl    $3, %edx
        movw    %dx, f(%rip)
        cmpb    $1, %al
        jg      .L12
        xorl    %eax, %eax
        testb   %al, %al
        movl    %edx, %eax
        je      .L6
        cmpb    $1, %dl
        jg      .L22
.L7:
        jmp     .L7
        .p2align 4,,10
        .p2align 3
.L22:
        movb    %dl, c(%rip)
.L8:
        movswl  %si, %ecx
        movl    %ecx, g(%rip)
        cmpl    $9, %ecx
        jle     .L14
        addl    $3, %eax
        cbtw
        movw    %ax, f(%rip)
.L12:
        movswl  %cx, %eax
        cmpw    $9, %cx
        jle     .L23
.L4:
        jmp     .L4
        .p2align 4,,10
        .p2align 3
.L6:
        movb    %dl, c(%rip)
        cmpw    $1, %dx
        jg      .L8
        .p2align 4,,10
        .p2align 3
.L9:
        movl    g(%rip), %eax
        testl   %eax, %eax
        jne     .L9
        movw    $0, e(%rip)
        movb    %dl, c(%rip)
.L23:
        movl    %eax, g(%rip)
.L14:
        xorl    %eax, %eax
        ret

Bisects to r14-1597-g64d90d06d2d