[Bug target/81490] x86: Handling of symbol ranges for __seg_fs/__seg_gs

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81490

--- Comment #18 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to H.J. Lu from comment #17)
> Created attachment 41920 [details]
> A binutils patch
> 

With this patch:

diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 587dbe61e8b..953c153a834 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -19429,8 +19429,10 @@ ix86_print_operand_address_as (FILE *file, rtx addr,
       fputs (string, file);
     }

-  /* Use one byte shorter RIP relative addressing for 64bit mode.  */
-  if (TARGET_64BIT && !base && !index && !no_rip)
+  /* Use one byte shorter RIP relative addressing for
+     symbols in the generic address space.  */
+  if (TARGET_64BIT && !base && !index
+      && ADDR_SPACE_GENERIC_P (as) && !no_rip)
     {
       rtx symbol = disp;

@@ -19465,6 +19467,8 @@ ix86_print_operand_address_as (FILE *file, rtx addr,
        output_pic_addr_const (file, disp, 0);
       else
        output_addr_const (file, disp);
+      if (!ADDR_SPACE_GENERIC_P (as))
+       fputs ("@GPREL", file);
     }
   else
     {


I got

[hjl@gnu-6 gprel-1]$ cat xx.c
extern int __seg_gs foo;

int
xxx (void)
{
  return foo;
}
[hjl@gnu-6 gprel-1]$ /export/build/gnu/gcc-x32/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc-x32/build-x86_64-linux/gcc/ -B./ -fPIE -O2 xx.c -S
[hjl@gnu-6 gprel-1]$ cat xx.s
        .file   "xx.c"
        .text
        .p2align 4,,15
        .globl  xxx
        .type   xxx, @function
xxx:
.LFB0:
        .cfi_startproc
        movl    %gs:foo@GPREL, %eax
        ret
        .cfi_endproc
.LFE0:
        .size   xxx, .-xxx
        .ident  "GCC: (GNU) 8.0.0 20170801 (experimental)"
        .section        .note.GNU-stack,"",@progbits
[hjl@gnu-6 gprel-1]$ ./as -o xx.o xx.s
[hjl@gnu-6 gprel-1]$ ./objdump -dwr xx.o

xx.o:     file format elf64-x86-64


Disassembly of section .text:

0000000000000000 <xxx>:
   0:   65 8b 04 25 00 00 00 00         mov    %gs:0x0,%eax     4:
R_X86_64_GPREL       foo
   8:   c3                      retq   
[hjl@gnu-6 gprel-1]$