FreeChainXenon/binutils-gdb
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

testsuite, fortran: Remove self assignment non-statements

Browse source 
There were a couple of places in the testsuite where instructions like

  var = var

were written in the source code of tests.  These were usually dummy
statements meant to generate a line table entry at that line on which
to break later on.

This worked fine for gfortran and ifx, but it seems that, when compiled
with ifort (2021.6.0) these statements do not actually create any
assmbler instructions and especially no line table entries.  Consider
the program

  program test
    Integer var :: var = 1
    var = var
  end program

compiled with gfortran (13.0.0, -O0 -g).  The linetable as emitted by
'objdump --dwarf=decodedline ./a.out' looks like

  test.f90:
  File name   Line number    Starting address    View    Stmt
  test.f90              1            0x401172               x
  test.f90              3            0x401176               x
  test.f90              4            0x401182               x
  test.f90              4            0x401185               x
  test.f90              4            0x401194               x
  test.f90              -            0x4011c0

actually containing line table info for line 3.  Running gdb, breaking
at 3 and checking the assembly we see

   0x0000000000401172 <+0>:     push   %rbp
   0x0000000000401173 <+1>:     mov    %rsp,%rbp
=> 0x0000000000401176 <+4>:     mov    0x2ebc(%rip),%eax   # 0x404038 <var.1>
   0x000000000040117c <+10>:    mov    %eax,0x2eb6(%rip)   # 0x404038 <var.1>
   0x0000000000401182 <+16>:    nop
   0x0000000000401183 <+17>:    pop    %rbp
   0x0000000000401184 <+18>:    ret

so two mov instructions are being issued for this assignment one copying
the value into a register and one writing it back to the same memory.
Ifort (2021.6.0, -O0 -g) on the other hand does not emit anything here
and also has no line table entry:

  test.f90:
  File name   Line number    Starting address    View    Stmt
  test.f90              1            0x4040f8               x
  test.f90              4            0x404109               x
  test.f90              4            0x40410e               x
  test.f90              -            0x404110

As I do not think that this is really a bug (on either side, gfortran/ifx or
ifort), and as I don't think this behavior is covered in the Fortran
standard, I changed these lines to become actual value assignments.

This removes a few FAILs in the testsuite when ran with ifort.

Approved-by: Tom Tromey <tom@tromey.com>
This commit is contained in:
Nils-Christian Kempke 2022-05-20 17:15:44 +02:00 • committed by Ijaz, Abdul B
parent 85832a8c3c
commit 6fe8aea3c0
3 changed files with 8 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
gdb/testsuite/gdb.fortran/library-module-lib.f90
View file

@ -19,7 +19,7 @@ contains
subroutine lib_func
if (var_i .ne. 1) call abort
var_i = 2
var_i = var_i ! i-is-2-in-lib
var_i = 2 ! i-is-2-in-lib
end subroutine lib_func
end module lib

2
gdb/testsuite/gdb.fortran/library-module-main.f90
View file

@ -19,5 +19,5 @@
call lib_func
if (var_i .ne. 2) call abort
if (var_j .ne. 3) call abort
var_i = var_i ! i-is-2-in-main
var_i = 7 ! i-is-2-in-main
end

11
gdb/testsuite/gdb.fortran/module.f90
View file

@ -40,18 +40,19 @@ end module moduse
subroutine sub1
use mod1
if (var_i .ne. 1) call abort
var_i = var_i ! i-is-1
var_i = 1 ! i-is-1
end
subroutine sub2
use mod2
if (var_i .ne. 2) call abort
var_i = var_i ! i-is-2
var_i = 2 ! i-is-2
end
subroutine sub3
USE mod3
var_i = var_i ! i-is-3
use mod3
if (var_i .ne. 3) call abort
var_i = 3 ! i-is-3
END
program module
@ -68,5 +69,5 @@ end module moduse
if (var_i .ne. 14) call abort
if (var_x .ne. 30) call abort
if (var_z .ne. 31) call abort
var_b = var_b ! a-b-c-d
var_b = 11 ! a-b-c-d
end