On Thu, Aug 27, 2020 at 3:38 AM Hu Jiangping <hujiangp...@cn.fujitsu.com> wrote:
>
> This patch add -fno-tree-fre to dg-options in gcc.dg/guality/sra-1.c,
> to make the following testcases passed.
>
> FAIL: gcc.dg/guality/sra-1.c -Og -DPREVENT_OPTIMIZATION line 43 a.i == 4
> FAIL: gcc.dg/guality/sra-1.c -Og -DPREVENT_OPTIMIZATION line 43 a.j == 14
> FAIL: gcc.dg/guality/sra-1.c -O2 -flto -fuse-linker-plugin
> -fno-fat-lto-objects -DPREVENT_OPTIMIZATION line 21 a.j == 14
> FAIL: gcc.dg/guality/sra-1.c -O2 -flto -fuse-linker-plugin
> -fno-fat-lto-objects -DPREVENT_OPTIMIZATION line 32 a[1] == 14
> FAIL: gcc.dg/guality/sra-1.c -O2 -flto -fuse-linker-plugin
> -fno-fat-lto-objects -DPREVENT_OPTIMIZATION line 43 a.j == 14
>
> The detail error logs like this:
> > Spawning: gdb -nx -nw -quiet -batch -x sra-1.gdb ./sra-1.exe
> > spawn gdb -nx -nw -quiet -batch -x sra-1.gdb ./sra-1.exe
> > Breakpoint 1 at 0x40074c: file
> > /home/build_gcc/gcc-a64fx-1-a/gcc/testsuite/gcc.dg/guality/sra-1.c, line 43.
> >
> > Breakpoint 1, f3 (k=k@entry=7) at
> > /home/build_gcc/gcc-a64fx-1-a/gcc/testsuite/gcc.dg/guality/sra-1.c:43
> > 43 bar (a.j); /* { dg-final { gdb-test . "a.j" "14" } } */
> > $1 = <optimized out>
> > $2 = 4
> > <optimized out> != 4
>
> Tested on aarch64.
Huh well - I guess it should be XFAILed instead? But then we see
XPASSes. Disabling
FRE doesn't look correct - we _do_ want the test to succeed here. Did
you analyze
why it fails?
It looks like we assign 'a' a register at RTL expansion time for -Og
but do not perform any
fancy tracking of components of it then. On GIMPLE we assume it's eventually
memory and thus wouldn't bother with any debug stmts.
So it's a genuine FAIL for -Og at least. That said, the logic is simple - both
a.i and a.j need to be available for a.i + a.j to be evaluated. For
some reasons
we fail to record where their value resides. For -Og they are in
%rbp, resp. %rbx.
But obviously some elaborate DWARF is necessary to convey that info.
Richard.
> Regards!
> hujp
>
> ---
> gcc/testsuite/gcc.dg/guality/sra-1.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gcc/testsuite/gcc.dg/guality/sra-1.c
> b/gcc/testsuite/gcc.dg/guality/sra-1.c
> index 8ad57cf3f8e..94ea29dd727 100644
> --- a/gcc/testsuite/gcc.dg/guality/sra-1.c
> +++ b/gcc/testsuite/gcc.dg/guality/sra-1.c
> @@ -1,6 +1,6 @@
> /* PR debug/43983 */
> /* { dg-do run } */
> -/* { dg-options "-g -fno-ipa-icf" } */
> +/* { dg-options "-g -fno-tree-fre -fno-ipa-icf" } */
>
> struct A { int i; int j; };
> struct B { int : 4; int i : 12; int j : 12; int : 4; };
> --
> 2.17.1
>
>
>
