On February 14, 2019 12:10:54 AM GMT+01:00, Jakub Jelinek <ja...@redhat.com>
wrote:
>Hi!
>
>The ubsan pass makes early uninit warning harder (and often doesn't
>warn),
>because e.g. for enum/bool loads we add instrumentation and the reads
>from
>the fields isn't easily visible to the uninit pass, we have
> _7 = &a.a;
> _8 = MEM[(_Bool *)_7];
>instead etc. As the early uninit warning pass shouldn't change the IL
>(except for nowarning flags), I think it should be ok to swap the
>passes,
>first warn and only then do ubsan instrumentation.
>
>Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk (or
>just for GCC10)?
OK for trunk.
Richard.
>2019-02-13 Jakub Jelinek <ja...@redhat.com>
>
> PR middle-end/89284
> * passes.def: Swap pass_ubsan and pass_early_warn_uninitialized.
>
> * gcc.dg/ubsan/pr89284.c: New test.
>
>--- gcc/passes.def.jj 2019-01-01 12:37:18.041960447 +0100
>+++ gcc/passes.def 2019-02-13 14:45:20.205700845 +0100
>@@ -56,8 +56,8 @@ along with GCC; see the file COPYING3.
> NEXT_PASS (pass_fixup_cfg);
> NEXT_PASS (pass_build_ssa);
> NEXT_PASS (pass_warn_nonnull_compare);
>- NEXT_PASS (pass_ubsan);
> NEXT_PASS (pass_early_warn_uninitialized);
>+ NEXT_PASS (pass_ubsan);
> NEXT_PASS (pass_nothrow);
> NEXT_PASS (pass_rebuild_cgraph_edges);
> POP_INSERT_PASSES ()
>--- gcc/testsuite/gcc.dg/ubsan/pr89284.c.jj 2019-02-13
>15:01:25.666165920 +0100
>+++ gcc/testsuite/gcc.dg/ubsan/pr89284.c 2019-02-13 15:01:09.987414305
>+0100
>@@ -0,0 +1,23 @@
>+/* PR middle-end/89284 */
>+/* { dg-do compile } */
>+/* { dg-options "-fsanitize=undefined -O0 -Wuninitialized" } */
>+
>+struct A { _Bool a; int i; };
>+
>+int
>+foo (void)
>+{
>+ struct A a;
>+ if (a.i) /* { dg-warning "'a.i' is used uninitialized in this
>function" } */
>+ return 1;
>+ return 0;
>+}
>+
>+int
>+bar (void)
>+{
>+ struct A a;
>+ if (a.a) /* { dg-warning "'a.a' is used uninitialized in this
>function" } */
>+ return 1;
>+ return 0;
>+}
>
> Jakub
