aarch64 inline asm / -fPIC problem

[Joe Buehler via Gcc-help <gcc-help@xxxxxxxxxxx>]

My (compiler test) program:

    int
    main()
    {
        __asm__ volatile(".8byte %0\n\t" : : "i" ("message %s\n"));
        return 0;
    }

This compiles fine with gcc 4.3.3 MIPS using:

gcc -S -fPIC temp.c

It fails with gcc 7.3.0 aarch64.  Output is:

    temp.c: In function  main :
    temp.c:4:2: warning: asm operand 0 probably doesn t match constraints
      __asm__ volatile(".8byte %0\n\t" : : "i" ("message %s\n"));
      ^~~~~~~
    temp.c:4:2: error: impossible constraint in  asm

Removing the -fPIC it will compile fine.

The relevant section of the MIPS generated code looks like this:

        .rdata
        .align    2
    $LC0:
        .ascii    "message %s\012\000"
        .text
        .align    2
        .globl    main
        .ent    main
        .type    main, @function
    main:
        .set    nomips16
        .frame    $fp,8,$31        # vars= 0, regs= 1/0, args= 0, gp= 0
        .mask    0x40000000,-4
        .fmask    0x00000000,0
        addiu    $sp,$sp,-8
        sw    $fp,4($sp)
        move    $fp,$sp
    #APP
     # 4 "temp.c" 1
        .8byte $LC0

I am unable to code something similar manually using inline asm because
the string is a format string containing % characters, which inline asm
will of course try to interpret. (Does gcc provide anything to escape %
chars in a literal string?)

Any suggestions? 

Joe Buehler