[Bug target/19746] printf() optimisation ignores longcall attribute

["msebor at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19746

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2005-05-09 01:18:53         |2016-1-27
                 CC|                            |msebor at gcc dot gnu.org
      Known to fail|                            |5.3.0, 6.0

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
The behavior is still present on trunk and currently supported versions.  The
test case below shows the difference between the expected call sequence (in
bar_long) and the actual call sequence (in foo, which matches that in
bar_short).

That said, I don't think this is a target-specific problem.  The same issue
exists in other back ends, and is likely caused by some early folding not
taking into account differences in attributes or the presence of user-defined
declarations (as suggested by the patch in comment #2).

It seems that this bug should be reclassified as middle-end?

$ cat t.c && /build/sysroot/powerpc-eabispe/bin/powerpc-eabispe-gcc -O2 -S -o
/dev/stdout t.c
int printf (const char*, ...) __attribute__ ((__longcall__)); 
int puts (const char*) __attribute__ ((__longcall__));

void foo (void) { printf (" \n"); }

int puts_long (const char*) __attribute__ ((__longcall__));
int puts_short (const char*) __attribute__ ((__shortcall__));

void bar_long (void) { puts_long (" "); }
void bar_short (void) { puts_short (" "); }


        .file   "t.c"
        .section        ".text"
        .align 2
        .globl foo
        .type   foo, @function
foo:
        lis 3,.LC0@ha
        la 3,.LC0@l(3)
        b puts
        .size   foo, .-foo
        .align 2
        .globl bar_long
        .type   bar_long, @function
bar_long:
        stwu 1,-8(1)
        lis 9,puts_long@ha
        mflr 0
        la 9,puts_long@l(9)
        lis 3,.LC0@ha
        stw 0,12(1)
        la 3,.LC0@l(3)
        mtctr 9
        bctrl
        lwz 0,12(1)
        addi 1,1,8
        mtlr 0
        blr
        .size   bar_long, .-bar_long
        .align 2
        .globl bar_short
        .type   bar_short, @function
bar_short:
        lis 3,.LC0@ha
        la 3,.LC0@l(3)
        b puts_short
        .size   bar_short, .-bar_short
        .section        .rodata.str1.4,"aMS",@progbits,1
        .align 2
.LC0:
        .string " "
        .ident  "GCC: (GNU) 6.0.0 20160121 (experimental)"