On Fri, 13 Nov 2020, Jakub Jelinek wrote:
> Hi!
>
> Apparently older GDB versions didn't handle this test right and so while
> it has been properly printing 42 on line 14 (e.g. on x86_64), it issued
> a weird error on line 17 (and because it didn't print any value, guality
> testsuite wasn't marking it as FAIL).
> That has been apparently fixed in GDB 10, where it now (on x86_64) prints
> properly.
> Unfortunately that revealed that the test can suffer from instruction
> scheduling, where e.g. on i686 (but various other arches) the very first
> insn of the function (or whatever b 14 is on) happens to be load of the
> S::i variable from memory and that insn has the inner lexical scope, so
> GDB 10 prints there 24 instead of 42. The following insn is then
> the first store to l and there the automatic i is in scope and prints as 42
> and then the second store to l where the inner lexical scope is current
> and prints 24 again.
> The test wasn't meant about insn scheduling but about whether we emit the
> DIEs properly, so this hack attempts to prevent the undesirable scheduling.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
> 2020-11-13 Jakub Jelinek <ja...@redhat.com>
>
> * g++.dg/guality/redeclaration1.C (p): New variable.
> (S::f): Increment what p points to before storing S::i into l. Adjust
> gdb-test line numbers.
> (main): Initialize p to address of an automatic variable.
>
> --- gcc/testsuite/g++.dg/guality/redeclaration1.C.jj 2020-01-12
> 11:54:37.182401807 +0100
> +++ gcc/testsuite/g++.dg/guality/redeclaration1.C 2020-11-13
> 13:40:40.684122957 +0100
> @@ -3,6 +3,7 @@
> // { dg-skip-if "" { *-*-* } { "-flto" } { "" } }
>
> volatile int l;
> +int *volatile p;
>
> namespace S
> {
> @@ -11,10 +12,11 @@ namespace S
> f()
> {
> int i = 42;
> - l = i; // { dg-final { gdb-test 14 "i" "42" } }
> + l = i; // { dg-final { gdb-test 15 "i" "42" } }
> {
> extern int i;
> - l = i; // { dg-final { gdb-test 17 "i" "24" } }
> + p[0]++;
> + l = i; // { dg-final { gdb-test 19 "i" "24" } }
> }
> }
> }
> @@ -22,6 +24,8 @@ namespace S
> int
> main (void)
> {
> + int x = 0;
> + p = &x;
> S::f ();
> return 0;
> }
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imend
