| Message ID | 558B71A3.3080004@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Thu, Jun 25, 2015 at 5:12 AM, Aldy Hernandez <aldyh@redhat.com> wrote: > The problem here is that we are trying to call dwarf2out_late_global_decl() > on a static variable in a template which has a type of TEMPLATE_TYPE_PARM: > > template <typename T> class A > { > static __thread T a; > }; > > We are calling late_global_decl because we are about to remove the unused > static from the symbol table: > > /* See if the debugger can use anything before the DECL > passes away. Perhaps it can notice a DECL that is now a > constant and can tag the early DIE with an appropriate > attribute. > > Otherwise, this is the last chance the debug_hooks have > at looking at optimized away DECLs, since > late_global_decl will subsequently be called from the > contents of the now pruned symbol table. */ > if (!decl_function_context (node->decl)) > (*debug_hooks->late_global_decl) (node->decl); > > Since gen_type_die_with_usage() cannot handle TEMPLATE_TYPE_PARMs we ICE. > > I think we need to avoid calling late_global_decl on DECL's for which > decl_type_context() is true, similarly to what we do for the call to > early_global_decl in rest_of_decl_compilation: > > && !decl_function_context (decl) > && !current_function_decl > && DECL_SOURCE_LOCATION (decl) != BUILTINS_LOCATION > && !decl_type_context (decl)) > (*debug_hooks->early_global_decl) (decl); > > Presumably the old code did not run into this problem because the > TEMPLATE_TYPE_PARAMs had been lowered by the time dwarf2out_decl was called, > but here we are calling late_global_decl relatively early. I think we need to sort out that instead - by the time we call _early_ global decl it should already be "lowered". Otherwise LTO streaming will run into the decl_type_context it cannot handle. Is the case running into late_global_decl before we called early_global_decl on it btw? Richard. > The attached patch fixes the problem. > > Tested with --enable-languages=all. Ada had other issues, so I skipped it. > > OK for mainline?
> Tested with --enable-languages=all. Ada had other issues, so I skipped it.
What other issues exactly? It's fine at r224930 for example.
On 06/25/2015 06:53 AM, Eric Botcazou wrote: >> Tested with --enable-languages=all. Ada had other issues, so I skipped it. > > What other issues exactly? It's fine at r224930 for example. > There were some defined but not used warnings (??) that caused it to fail, especially since I didn't configure with --disable-werror. I didn't look into it. Aldy
On 06/25/2015 02:48 AM, Richard Biener wrote: > On Thu, Jun 25, 2015 at 5:12 AM, Aldy Hernandez <aldyh@redhat.com> wrote: >> The problem here is that we are trying to call dwarf2out_late_global_decl() >> on a static variable in a template which has a type of TEMPLATE_TYPE_PARM: >> >> template <typename T> class A >> { >> static __thread T a; >> }; >> >> We are calling late_global_decl because we are about to remove the unused >> static from the symbol table: >> >> /* See if the debugger can use anything before the DECL >> passes away. Perhaps it can notice a DECL that is now a >> constant and can tag the early DIE with an appropriate >> attribute. >> >> Otherwise, this is the last chance the debug_hooks have >> at looking at optimized away DECLs, since >> late_global_decl will subsequently be called from the >> contents of the now pruned symbol table. */ >> if (!decl_function_context (node->decl)) >> (*debug_hooks->late_global_decl) (node->decl); >> >> Since gen_type_die_with_usage() cannot handle TEMPLATE_TYPE_PARMs we ICE. >> >> I think we need to avoid calling late_global_decl on DECL's for which >> decl_type_context() is true, similarly to what we do for the call to >> early_global_decl in rest_of_decl_compilation: >> >> && !decl_function_context (decl) >> && !current_function_decl >> && DECL_SOURCE_LOCATION (decl) != BUILTINS_LOCATION >> && !decl_type_context (decl)) >> (*debug_hooks->early_global_decl) (decl); >> >> Presumably the old code did not run into this problem because the >> TEMPLATE_TYPE_PARAMs had been lowered by the time dwarf2out_decl was called, >> but here we are calling late_global_decl relatively early. > > I think we need to sort out that instead - by the time we call _early_ > global decl it > should already be "lowered". Otherwise LTO streaming will run into > the decl_type_context it cannot handle. Is the case running into > late_global_decl > before we called early_global_decl on it btw? Typically in C++ we call early_global_decl via: cp_finish_decl -> make_rtl_for_nonlocal_decl -> rest_of_decl_compilation -> early_global_decl. However, in this case we have not called early_global_decl on the DECL because cp_finish_decl avoids the make_rtl_for_nonlocal_decl path for templates: cp_finish_decl(): ... if (processing_template_decl) { bool type_dependent_p; ... ... return; } Aldy
On 06/24/2015 11:12 PM, Aldy Hernandez wrote: > The problem here is that we are trying to call > dwarf2out_late_global_decl() on a static variable in a template which > has a type of TEMPLATE_TYPE_PARM: > > template <typename T> class A > { > static __thread T a; > }; > > We are calling late_global_decl because we are about to remove the > unused static from the symbol table: The problem here is that 'a' should never have been in the symbol table in the first place, since it's an uninstantiated template. It's there because of honza's change to store the TLS model in the symbol table, so TLS templates end up with varpool entries that, of course, will never be referenced. I guess either we need to avoid putting these templates in the symbol table or we need to mark these fake entries somehow. Jason
> There were some defined but not used warnings (??) that caused it to > fail, especially since I didn't configure with --disable-werror. Weird. I bootstrap the compiler in default mode every day and I haven't had a bootstrap failure for at least a month.
On Thu, Jun 25, 2015 at 6:56 PM, Jason Merrill <jason@redhat.com> wrote: > On 06/24/2015 11:12 PM, Aldy Hernandez wrote: >> >> The problem here is that we are trying to call >> dwarf2out_late_global_decl() on a static variable in a template which >> has a type of TEMPLATE_TYPE_PARM: >> >> template <typename T> class A >> { >> static __thread T a; >> }; >> >> We are calling late_global_decl because we are about to remove the >> unused static from the symbol table: > > > The problem here is that 'a' should never have been in the symbol table in > the first place, since it's an uninstantiated template. It's there because > of honza's change to store the TLS model in the symbol table, so TLS > templates end up with varpool entries that, of course, will never be > referenced. Can we defer TLS model setting to template instantiation? > I guess either we need to avoid putting these templates in the symbol table > or we need to mark these fake entries somehow. > > Jason >
On 06/26/2015 05:37 AM, Richard Biener wrote:
> Can we defer TLS model setting to template instantiation?
We need to represent somehow that __thread (or thread_local) was used in
the declaration, but DECL_THREAD_LOCAL_P was changed to refer to the TLS
model.
Jason
On Fri, Jun 26, 2015 at 11:59 PM, Jason Merrill <jason@redhat.com> wrote: > On 06/26/2015 05:37 AM, Richard Biener wrote: >> >> Can we defer TLS model setting to template instantiation? > > > We need to represent somehow that __thread (or thread_local) was used in the > declaration, but DECL_THREAD_LOCAL_P was changed to refer to the TLS model. Ok, so "easiest" would be to allocate a bit from decl_with_vis for this... Richard. > Jason >
On 06/29/2015 05:07 AM, Richard Biener wrote: > On Fri, Jun 26, 2015 at 11:59 PM, Jason Merrill <jason@redhat.com> wrote: >> On 06/26/2015 05:37 AM, Richard Biener wrote: >>> >>> Can we defer TLS model setting to template instantiation? >> >> We need to represent somehow that __thread (or thread_local) was used in the >> declaration, but DECL_THREAD_LOCAL_P was changed to refer to the TLS model. > > Ok, so "easiest" would be to allocate a bit from decl_with_vis for this... Or I can find a flag in the front end. I guess I'll do that. Jason
diff --git a/gcc/cgraphunit.c b/gcc/cgraphunit.c index 066a155..d2974ad 100644 --- a/gcc/cgraphunit.c +++ b/gcc/cgraphunit.c @@ -1149,7 +1149,8 @@ analyze_functions (bool first_time) at looking at optimized away DECLs, since late_global_decl will subsequently be called from the contents of the now pruned symbol table. */ - if (!decl_function_context (node->decl)) + if (!decl_function_context (node->decl) + && !decl_type_context (node->decl)) (*debug_hooks->late_global_decl) (node->decl); node->remove (); diff --git a/gcc/testsuite/g++.dg/debug/dwarf2/pr66653.C b/gcc/testsuite/g++.dg/debug/dwarf2/pr66653.C new file mode 100644 index 0000000..bcaaf88 --- /dev/null +++ b/gcc/testsuite/g++.dg/debug/dwarf2/pr66653.C @@ -0,0 +1,8 @@ +// PR debug/54508 +// { dg-do compile } +// { dg-options "-g" } + +template <typename T> class A +{ + static __thread T a; +};
The problem here is that we are trying to call dwarf2out_late_global_decl() on a static variable in a template which has a type of TEMPLATE_TYPE_PARM: template <typename T> class A { static __thread T a; }; We are calling late_global_decl because we are about to remove the unused static from the symbol table: /* See if the debugger can use anything before the DECL passes away. Perhaps it can notice a DECL that is now a constant and can tag the early DIE with an appropriate attribute. Otherwise, this is the last chance the debug_hooks have at looking at optimized away DECLs, since late_global_decl will subsequently be called from the contents of the now pruned symbol table. */ if (!decl_function_context (node->decl)) (*debug_hooks->late_global_decl) (node->decl); Since gen_type_die_with_usage() cannot handle TEMPLATE_TYPE_PARMs we ICE. I think we need to avoid calling late_global_decl on DECL's for which decl_type_context() is true, similarly to what we do for the call to early_global_decl in rest_of_decl_compilation: && !decl_function_context (decl) && !current_function_decl && DECL_SOURCE_LOCATION (decl) != BUILTINS_LOCATION && !decl_type_context (decl)) (*debug_hooks->early_global_decl) (decl); Presumably the old code did not run into this problem because the TEMPLATE_TYPE_PARAMs had been lowered by the time dwarf2out_decl was called, but here we are calling late_global_decl relatively early. The attached patch fixes the problem. Tested with --enable-languages=all. Ada had other issues, so I skipped it. OK for mainline? commit 302f9976c53aa09e431bd54f37dbfeaa2c6b2acc Author: Aldy Hernandez <aldyh@redhat.com> Date: Wed Jun 24 20:04:09 2015 -0700 PR debug/66653 * cgraphunit.c (analyze_functions): Do not call debug_hooks->late_global_decl when decl_type_context.