| Message ID | ortvq7sasu.fsf@lxoliva.fsfla.org |
|---|---|
| State | New |
| Headers | show |
| Series | [PR86064] split single cross-partition range with nonzero locviews | expand |
On Jun 12, 2018, Alexandre Oliva <oliva@gnu.org> wrote: > We didn't split cross-partition ranges in loclists to output a > whole-function location expression, but with nonzero locviews, we > force loclists, and then we have to split to avoid cross-partition > list entries. Regstrapped on x86_64-linux-gnu and i686-linux-gnu. Ok to install? > From: Alexandre Oliva <aoliva@redhat.com> > for gcc/ChangeLog > PR debug/86064 > * dwarf2out.c (loc_list_has_views): Adjust comments. > (dw_loc_list): Split single cross-partition range with > nonzero locview. > for gcc/testsuite/ChangeLog > PR debug/86064 > * gcc.dg/pr86064.c: New.
On 06/12/2018 08:02 PM, Alexandre Oliva wrote: > > We didn't split cross-partition ranges in loclists to output a > whole-function location expression, but with nonzero locviews, we > force loclists, and then we have to split to avoid cross-partition > list entries. > > From: Alexandre Oliva <aoliva@redhat.com> > for gcc/ChangeLog > > PR debug/86064 > * dwarf2out.c (loc_list_has_views): Adjust comments. > (dw_loc_list): Split single cross-partition range with > nonzero locview. > > for gcc/testsuite/ChangeLog > > PR debug/86064 > * gcc.dg/pr86064.c: New. OK. Jeff
On Jun 22, 2018, Jeff Law <law@redhat.com> wrote: > On 06/12/2018 08:02 PM, Alexandre Oliva wrote: >> >> We didn't split cross-partition ranges in loclists to output a >> whole-function location expression, but with nonzero locviews, we >> force loclists, and then we have to split to avoid cross-partition >> list entries. >> >> From: Alexandre Oliva <aoliva@redhat.com> >> for gcc/ChangeLog >> >> PR debug/86064 >> * dwarf2out.c (loc_list_has_views): Adjust comments. >> (dw_loc_list): Split single cross-partition range with >> nonzero locview. >> >> for gcc/testsuite/ChangeLog >> >> PR debug/86064 >> * gcc.dg/pr86064.c: New. > OK. Thanks. For the gcc 8 branch too? (pending retesting)
On Tue, Jun 26, 2018 at 10:21 AM Alexandre Oliva <oliva@gnu.org> wrote: > > On Jun 22, 2018, Jeff Law <law@redhat.com> wrote: > > > On 06/12/2018 08:02 PM, Alexandre Oliva wrote: > >> > >> We didn't split cross-partition ranges in loclists to output a > >> whole-function location expression, but with nonzero locviews, we > >> force loclists, and then we have to split to avoid cross-partition > >> list entries. > >> > >> From: Alexandre Oliva <aoliva@redhat.com> > >> for gcc/ChangeLog > >> > >> PR debug/86064 > >> * dwarf2out.c (loc_list_has_views): Adjust comments. > >> (dw_loc_list): Split single cross-partition range with > >> nonzero locview. > >> > >> for gcc/testsuite/ChangeLog > >> > >> PR debug/86064 > >> * gcc.dg/pr86064.c: New. > > > OK. > > Thanks. For the gcc 8 branch too? (pending retesting) Yes. Richard. > -- > Alexandre Oliva, freedom fighter https://FSFLA.org/blogs/lxo > Be the change, be Free! FSF Latin America board member > GNU Toolchain Engineer Free Software Evangelist
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c index 620e66986be6..0c5d7e0e0357 100644 --- a/gcc/dwarf2out.c +++ b/gcc/dwarf2out.c @@ -9982,7 +9982,15 @@ new_loc_list (dw_loc_descr_ref expr, const char *begin, var_loc_view vbegin, return retlist; } -/* Return true iff there's any nonzero view number in the loc list. */ +/* Return true iff there's any nonzero view number in the loc list. + + ??? When views are not enabled, we'll often extend a single range + to the entire function, so that we emit a single location + expression rather than a location list. With views, even with a + single range, we'll output a list if start or end have a nonzero + view. If we change this, we may want to stop splitting a single + range in dw_loc_list just because of a nonzero view, even if it + straddles across hot/cold partitions. */ static bool loc_list_has_views (dw_loc_list_ref list) @@ -17090,7 +17098,13 @@ dw_loc_list (var_loc_list *loc_list, tree decl, int want_address) of first partition and second one starting at the beginning of second partition. */ if (node == loc_list->last_before_switch - && (node != loc_list->first || loc_list->first->next) + && (node != loc_list->first || loc_list->first->next + /* If we are to emit a view number, we will emit + a loclist rather than a single location + expression for the entire function (see + loc_list_has_views), so we have to split the + range that straddles across partitions. */ + || !ZERO_VIEW_P (node->view)) && current_function_decl) { endname = cfun->fde->dw_fde_end; diff --git a/gcc/testsuite/gcc.dg/pr86064.c b/gcc/testsuite/gcc.dg/pr86064.c new file mode 100644 index 000000000000..5be820c78f84 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr86064.c @@ -0,0 +1,27 @@ +/* { dg-do compile } */ +/* { dg-options "-g -O2 -fno-var-tracking-assignments -gsplit-dwarf" } */ + +/* This used to fail with location views (implicitly) enabled, because + var-tracking (not at assignments) creates a range for d starting at + the load after the first call, and we did not split the range, + despite its crossing between hot and cold partitions, because it's + a single range, that we normally extend to the entire function. + However, because the range starts at a (presumed) nonzero view, we + end up outputting a loclist instead of a single location entry. + But then, -gsplit-dwarf selects (startx,length) loclist entries, + and the length ends up computing the difference between symbols in + different subsections. */ + +int a; +__attribute__((__cold__)) void b(); + +void e(int *); +int f(); + +void c() { + int d; + e(&d); + a = d; + if (f()) + b(); +}
We didn't split cross-partition ranges in loclists to output a whole-function location expression, but with nonzero locviews, we force loclists, and then we have to split to avoid cross-partition list entries. From: Alexandre Oliva <aoliva@redhat.com> for gcc/ChangeLog PR debug/86064 * dwarf2out.c (loc_list_has_views): Adjust comments. (dw_loc_list): Split single cross-partition range with nonzero locview. for gcc/testsuite/ChangeLog PR debug/86064 * gcc.dg/pr86064.c: New. --- gcc/dwarf2out.c | 18 ++++++++++++++++-- gcc/testsuite/gcc.dg/pr86064.c | 27 +++++++++++++++++++++++++++ 2 files changed, 43 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/pr86064.c