[Bug c/93278] huge almost empty array takes huge time to compile and produces huge object file

[doug at cs dot dartmouth.edu]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93278

--- Comment #6 from doug mcilroy <doug at cs dot dartmouth.edu> ---
The waste of time and space happens in the assembler, but the assembler only
does what it is told to do. There must be a way for gcc to tell it to put array
a in a partially filled ELF section.

$ cat junk.c
char a[10000000] = "x";
int main(){ return 0; }

$ bin/gcc --version
bin/gcc (GCC) 7.4.0
Copyright (C) 2017 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


$ time /bin/gcc junk.c

real    0m3.864s
user    0m2.919s
sys     0m0.326s

$ ls -l a.exe
-rwxr-xr-x 1 DOUG DOUG 10158440 Jan 17 14:43 a.exe