[Bug tree-optimization/90594] [9/10/11 regression] Spurious popcount emitted

["hailey.chiu at sifive dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90594

Hsiao-Hui Chiu <hailey.chiu at sifive dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hailey.chiu at sifive dot com

--- Comment #6 from Hsiao-Hui Chiu <hailey.chiu at sifive dot com> ---
Hi, 

I got the same issue that my program is compiled with gcc-10.1 with riscv. Here
is my code,

C source:

void foo()
{
    static long *a;
    static int i;
    static int sum;
    sum = 0;

    for ( i = 1 ; i < n ; i++)
    {
        sum += (*a--);
    }
}

Compiling with riscv-gcc-10.1, with -Os,
riscv-gcc-10.1/riscv64-unknown-elf-gcc -Os -march=rv32imac -mabi=ilp32 -S -o
foo.s foo.c

Asm:

foo:
...skip...
.L6:
    addi    a7,a7,1
    bgt a5,a7,.L7
    li  a4,0
    ble a5,zero,.L9
    li  a4,-4        
    mul a4,a5,a4      
    addi    a4,a4,4   #a = -4*n + 4
.L9:
    add a4,a0,a4
    bgt a5,zero,.L10
    li  a5,1
.L10:
    beq t3,zero,.L5
    sw  a4,%lo(a.1)(a1) 
    sw  a6,%lo(sum.3)(a2)
    sw  a5,%lo(i.2)(a3)
.L5:
    ret
.L7:
    lw  a4,0(t1)
    li  t3,1
    addi    t1,t1,-4    #a--
    add a6,a6,a4
    j   .L6

That .L6 segment is totally redundant. By inspecting the gcc trace, this is
happening at SCCP pass as this reported bug described. But, when I compiled the
bad_popcount function, I didn't see any redundant code emitted. 

According previous comments, I know this is under fixing. I am just wondering
if there is anything updated between last May to now? 

Thanks.