[Bug tree-optimization/92938] New: constprop function is assigned to a different section than the original function

[jcmvbkbc at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92938

            Bug ID: 92938
           Summary: constprop function is assigned to a different section
                    than the original function
           Product: gcc
           Version: 9.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jcmvbkbc at gcc dot gnu.org
  Target Milestone: ---

Created attachment 47496
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=47496&action=edit
test_bitmap.i

A bug is reported on the linux kernel mailing list:
https://lore.kernel.org/lkml/20191213211901.GL32742@smile.fi.intel.com/T/#t

In linux kernel there must be no references from .text* sections to data or
functions in .init* sections.

In the attached source there's no such reference:
__init test_replace calls regular bitmap_replace passing it a pointer to
__initconst exp2_to_exp3_mask variable.

But during optimization process such reference appears. When I look into
test_bitmap.i.085t.fixup_cfg3 I see the following:

__attribute__((no_instrument_function, unused, gnu_inline))
bitmap_replace.constprop (long unsigned int * dst, const long unsigned int *
old, const long unsigned int * new)
{ 
  ...
  __bitmap_replace (dst_11(D), old_3(D), new_6(D), &exp2_to_exp3_mask, 64);
  ...
}

__attribute__((cold, section (".init.text")))
test_replace ()
{
  ...
  bitmap_replace.constprop (&bmap, &exp2[0], &exp2[1]);
  ...
}

It looks like the function bitmap_replace.constprop should belong to the same
section as the function test_replace.

Compiler command line:

cc1 -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -std=gnu89
-ffreestanding -mlongcalls -mtext-section-literals -mforce-no-pic
-mno-serialize-volatile -fno-delete-null-pointer-checks -O2
-fstack-protector-strong -fno-omit-frame-pointer -fno-optimize-sibling-calls
-fno-var-tracking-assignments -g -femit-struct-debug-baseonly -fno-var-tracking
-fno-inline-functions-called-once -fno-strict-overflow -fno-merge-all-constants
-fmerge-constants -fno-stack-check -fconserve-stack test_bitmap.i