[Bug other/80492] [5/6/7 Regression] Wrong code when unrolling a loop with inline asm and local regs

[gjl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80492

Georg-Johann Lay <gjl at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Target|avr                         |avr,x86,x86_64
            Summary|[5/6 Regression] Wrong code |[5/6/7 Regression] Wrong
                   |when unrolling a loop with  |code when unrolling a loop
                   |inline asm and local regs   |with inline asm and local
                   |                            |regs

--- Comment #4 from Georg-Johann Lay <gjl at gcc dot gnu.org> ---
Also occurs for x68 and x86_64:

static __inline__ __attribute__((__always_inline__))
void syscall_7 (int val)
{
    register int reg __asm ("4") = val;
    __asm __volatile__ ("/* Some Code %0 */" :: "r" (reg));
}

void do_syscalls (void)
{
    for (int s = 0; s < 2; s++)
    {
        syscall_7 (0);
        syscall_7 (1);
    }
}

$ gcc -S -O2 -dp -v ...

Configured with: ../../gcc.gnu.org/gcc-7-branch/configure
--prefix=/local/gnu/install/gcc-7-host --enable-languages=c,c++
--enable-checking=release --disable-bootstrap
Thread model: posix
gcc version 7.0.1 20170424 (prerelease) (GCC) 
GNU C11 (GCC) version 7.0.1 20170424 (prerelease) (x86_64-pc-linux-gnu)
        compiled by GNU C version 5.4.0 20160609, GMP version 6.1.0, MPFR
version 3.1.4, MPC version 1.0.3, isl version isl-0.16.1-GMP

Generated asm:

do_syscalls:
.LFB1:
        .cfi_startproc
        xorl    %esi, %esi      # 20    *movdi_xor      [length = 2]
#APP
# 5 "sys.c" 1
        /* Some Code %esi */
# 0 "" 2
#NO_APP
        movl    $1, %esi        # 7     *movsi_internal/1       [length = 5]
#APP
# 5 "sys.c" 1
        /* Some Code %esi */
# 0 "" 2
# 5 "sys.c" 1
        /* Some Code %esi */
# 0 "" 2
# 5 "sys.c" 1
        /* Some Code %esi */
# 0 "" 2
#NO_APP
        ret     # 16    simple_return_internal  [length = 1]


The 2 last inline asms are missing the set of ESI.