[Bug c/65219] New: GCC wrongly deletes a function which is not completely inlined.

[Bug c/65219] New: GCC wrongly deletes a function which is not completely inlined.

[bmei at broadcom dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65219

            Bug ID: 65219
           Summary: GCC wrongly deletes a function which is not completely
                    inlined.
           Product: gcc
           Version: 5.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bmei at broadcom dot com

Compile the following code with gcc 5.0 (
Target: x86_64-unknown-linux-gnu gcc version 5.0.0 20150226 (experimental)
[trunk revision 143368] (GCC))

~/scratch/install-x86/bin/gcc tst.c -O2 -S

#include <stdio.h>
inline int foo()
{
  printf ("HEREEEEEEEEEEEEE\n");
  printf ("HEREEEEEEEEEEEEE\n");
  printf ("HEREEEEEEEEEEEEE\n");
  printf ("HEREEEEEEEEEEEEE\n");
  return 0;
}


int bar1 ()
{
  return foo();
}


__attribute__((optimize("-funsafe-loop-optimizations")))
int bar2 ()
{
 return foo();
}

Resulting assemble code:

    .file    "tst.c"
    .section    .rodata.str1.1,"aMS",@progbits,1
.LC0:
    .string    "HEREEEEEEEEEEEEE"
    .section    .text.unlikely,"ax",@progbits
.LCOLDB1:
    .text
.LHOTB1:
    .p2align 4,,15
    .globl    bar1
    .type    bar1, @function
bar1:
.LFB12:
    .cfi_startproc
    subq    $8, %rsp
    .cfi_def_cfa_offset 16
    movl    $.LC0, %edi
    call    puts
    movl    $.LC0, %edi
    call    puts
    movl    $.LC0, %edi
    call    puts
    movl    $.LC0, %edi
    call    puts
    xorl    %eax, %eax
    addq    $8, %rsp
    .cfi_def_cfa_offset 8
    ret
    .cfi_endproc
.LFE12:
    .size    bar1, .-bar1
    .section    .text.unlikely
.LCOLDE1:
    .text
.LHOTE1:
    .section    .text.unlikely
.LCOLDB2:
    .text
.LHOTB2:
    .p2align 4,,-1
    .globl    bar2
    .type    bar2, @function
bar2:
.LFB13:
    .cfi_startproc
    xorl    %eax, %eax
    jmp    foo
    .cfi_endproc
.LFE13:
    .size    bar2, .-bar2
    .section    .text.unlikely
.LCOLDE2:
    .text
.LHOTE2:
    .ident    "GCC: (GNU) 5.0.0 20150226 (experimental) [trunk revision
143368]"
    .section    .note.GNU-stack,"",@progbits


The function body of foo is gone, but there is still a call to foo left in
bar2. I did some initial investigation. The bar1 function inline foo in einline
pass. But the bar2 cannot inline it because it has a function-specific optimize
attribute. For some reason the body of foo is just removed anyway.

[Bug c/65219] GCC wrongly deletes a function which is not completely inlined.

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65219

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |INVALID

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
This is how c99 (now the default) behaves.  You are expected to have an
out-of-line copy somewhere.