| Message ID | ZXttN88kOtvRVn4t@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v4] c++: fix ICE with sizeof in a template [PR112869] | expand |
On 12/14/23 16:01, Marek Polacek wrote: > On Wed, Dec 13, 2023 at 03:28:38PM -0500, Jason Merrill wrote: >> On 12/12/23 17:48, Marek Polacek wrote: >>> On Fri, Dec 08, 2023 at 11:09:15PM -0500, Jason Merrill wrote: >>>> On 12/8/23 16:15, Marek Polacek wrote: >>>>> On Fri, Dec 08, 2023 at 12:09:18PM -0500, Jason Merrill wrote: >>>>>> On 12/5/23 15:31, Marek Polacek wrote: >>>>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? >>>>>>> >>>>>>> -- >8 -- >>>>>>> This test shows that we cannot clear *walk_subtrees in >>>>>>> cp_fold_immediate_r when we're in_immediate_context, because that, >>>>>>> as the comment says, affects cp_fold_r as well. Here we had an >>>>>>> expression with >>>>>>> >>>>>>> min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr >>>>>>> (int) <<< error >>> >>>) >>>>>>> >>>>>>> as its sub-expression, and we never evaluated that into >>>>>>> >>>>>>> min ((long int) bytecount, 4) >>>>>>> >>>>>>> so the SIZEOF_EXPR leaked into the middle end. >>>>>>> >>>>>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that >>>>>>> one should be OK.) >>>>>>> >>>>>>> PR c++/112869 >>>>>>> >>>>>>> gcc/cp/ChangeLog: >>>>>>> >>>>>>> * cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees >>>>>>> for unevaluated operands. >>>>>> >>>>>> I agree that we want this change for in_immediate_context (), but I don't >>>>>> see why we want it for TYPE_P or unevaluated_p (code) or >>>>>> cp_unevaluated_operand? >>>>> >>>>> No particular reason, just paranoia. How's this? >>>>> >>>>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? >>>>> >>>>> -- >8 -- >>>>> This test shows that we cannot clear *walk_subtrees in >>>>> cp_fold_immediate_r when we're in_immediate_context, because that, >>>>> as the comment says, affects cp_fold_r as well. Here we had an >>>>> expression with >>>>> >>>>> min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr >>>>> (int) <<< error >>> >>>) >>>>> >>>>> as its sub-expression, and we never evaluated that into >>>>> >>>>> min ((long int) bytecount, 4) >>>>> >>>>> so the SIZEOF_EXPR leaked into the middle end. >>>>> >>>>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that >>>>> one should be OK.) >>>>> >>>>> PR c++/112869 >>>>> >>>>> gcc/cp/ChangeLog: >>>>> >>>>> * cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees >>>>> for in_immediate_context. >>>>> >>>>> gcc/testsuite/ChangeLog: >>>>> >>>>> * g++.dg/template/sizeof18.C: New test. >>>>> --- >>>>> gcc/cp/cp-gimplify.cc | 6 +++++- >>>>> gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++ >>>>> 2 files changed, 13 insertions(+), 1 deletion(-) >>>>> create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C >>>>> >>>>> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc >>>>> index 5abb91bbdd3..6af7c787372 100644 >>>>> --- a/gcc/cp/cp-gimplify.cc >>>>> +++ b/gcc/cp/cp-gimplify.cc >>>>> @@ -1179,11 +1179,15 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_) >>>>> /* No need to look into types or unevaluated operands. >>>>> NB: This affects cp_fold_r as well. */ >>>>> - if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ()) >>>>> + if (TYPE_P (stmt) || unevaluated_p (code)) >>>>> { >>>>> *walk_subtrees = 0; >>>>> return NULL_TREE; >>>>> } >>>>> + else if (in_immediate_context ()) >>>>> + /* Don't clear *walk_subtrees here: we still need to walk the subtrees >>>>> + of SIZEOF_EXPR and similar. */ >>>>> + return NULL_TREE; >>>>> tree decl = NULL_TREE; >>>>> bool call_p = false; >>>>> diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C >>>>> new file mode 100644 >>>>> index 00000000000..afba9946258 >>>>> --- /dev/null >>>>> +++ b/gcc/testsuite/g++.dg/template/sizeof18.C >>>>> @@ -0,0 +1,8 @@ >>>>> +// PR c++/112869 >>>>> +// { dg-do compile } >>>>> + >>>>> +void min(long, long); >>>>> +template <class T> void Binaryread(int &, T, unsigned long); >>>>> +template <> void Binaryread(int &, float, unsigned long bytecount) { >>>>> + min(bytecount, sizeof(int)); >>>>> +} >>>> >>>> Hmm, actually, why does the above make a difference for this testcase? >>>> >>>> ... >>>> >>>> It seems that in_immediate_context always returns true in cp_fold_function >>>> because current_binding_level->kind == sk_template_parms. That seems like a >>>> problem. Maybe for cp_fold_immediate_r we only want to check >>>> cp_unevaluated_operand or DECL_IMMEDIATE_CONTEXT (current_function_decl)? >>> >>> Yeah, I suppose that could become an issue. How about this, then? >>> >>> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? >>> -- >8 -- >>> This test shows that we cannot clear *walk_subtrees in >>> cp_fold_immediate_r when we're in_immediate_context, because that, >>> as the comment says, affects cp_fold_r as well. Here we had an >>> expression with >>> >>> min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr >>> (int) <<< error >>> >>>) >>> >>> as its sub-expression, and we never evaluated that into >>> >>> min ((long int) bytecount, 4) >>> >>> so the SIZEOF_EXPR leaked into the middle end. >>> >>> (There's still one *walk_subtrees = 0; in cp_fold_immediate_r, but that >>> one should be OK.) >>> >>> PR c++/112869 >>> >>> gcc/cp/ChangeLog: >>> >>> * cp-gimplify.cc (cp_fold_immediate_r): Don't clear *walk_subtrees >>> in an unevaluated operand or immediate function. >>> >>> gcc/testsuite/ChangeLog: >>> >>> * g++.dg/template/sizeof18.C: New test. >>> --- >>> gcc/cp/cp-gimplify.cc | 8 +++++++- >>> gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++ >>> 2 files changed, 15 insertions(+), 1 deletion(-) >>> create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C >>> >>> diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc >>> index c307e1b62db..413ebafbd1a 100644 >>> --- a/gcc/cp/cp-gimplify.cc >>> +++ b/gcc/cp/cp-gimplify.cc >>> @@ -1179,11 +1179,17 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_) >>> /* No need to look into types or unevaluated operands. >>> NB: This affects cp_fold_r as well. */ >>> - if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ()) >>> + if (TYPE_P (stmt) || unevaluated_p (code)) >>> { >>> *walk_subtrees = 0; >>> return NULL_TREE; >>> } >>> + else if (cp_unevaluated_operand >>> + || (current_function_decl >>> + && DECL_IMMEDIATE_FUNCTION_P (current_function_decl))) >> >> It should still be fine to clear *walk_subtrees in these cases; the problem >> I was talking about above was that in_immediate_context was returning true >> for all functions, not just consteval functions. >> >> I think the fix is not adding an else, but rather replacing the >> in_immediate_context call with "unevaluated or consteval cfun". > > Aha, sorry, I misunderstood what you meant. > >>> + /* Don't clear *walk_subtrees here: we still need to walk the subtrees >>> + of SIZEOF_EXPR and similar. */ >> >> We shouldn't need to walk subtrees of SIZEOF_EXPR or other unevaluated >> operands, they'll all get cp_folded away. The bug was that we weren't >> calling cp_fold on the SIZEOF_EXPR itself. > > Yes. I suppose the comment should have read "because of SIZEOF_EXPR". > > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? OK, thanks. > -- >8 -- > This test shows that we cannot clear *walk_subtrees in > cp_fold_immediate_r when we're in_immediate_context, because that > checks even e.g. sk_template_parms, and, as the comment says, affects > cp_fold_r as well. Here we had an expression with > > min ((long int) VIEW_CONVERT_EXPR<long unsigned int>(bytecount), (long int) <<< Unknown tree: sizeof_expr > (int) <<< error >>> >>>) > > as its sub-expression, and we never evaluated that into > > min ((long int) bytecount, 4) > > so the SIZEOF_EXPR leaked into the middle end. We need to make sure > we are calling cp_fold on the SIZEOF_EXPR. > > PR c++/112869 > > gcc/cp/ChangeLog: > > * cp-gimplify.cc (cp_fold_immediate_r): Check cp_unevaluated_operand > and DECL_IMMEDIATE_FUNCTION_P rather than in_immediate_context. > > gcc/testsuite/ChangeLog: > > * g++.dg/template/sizeof18.C: New test. > --- > gcc/cp/cp-gimplify.cc | 8 +++++++- > gcc/testsuite/g++.dg/template/sizeof18.C | 8 ++++++++ > 2 files changed, 15 insertions(+), 1 deletion(-) > create mode 100644 gcc/testsuite/g++.dg/template/sizeof18.C > > diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc > index c307e1b62db..64049f4154e 100644 > --- a/gcc/cp/cp-gimplify.cc > +++ b/gcc/cp/cp-gimplify.cc > @@ -1179,7 +1179,13 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_) > > /* No need to look into types or unevaluated operands. > NB: This affects cp_fold_r as well. */ > - if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ()) > + if (TYPE_P (stmt) > + || unevaluated_p (code) > + /* We do not use in_immediate_context here because it checks > + more than is desirable, e.g., sk_template_parms. */ > + || cp_unevaluated_operand > + || (current_function_decl > + && DECL_IMMEDIATE_FUNCTION_P (current_function_decl))) > { > *walk_subtrees = 0; > return NULL_TREE; > diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C > new file mode 100644 > index 00000000000..afba9946258 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/template/sizeof18.C > @@ -0,0 +1,8 @@ > +// PR c++/112869 > +// { dg-do compile } > + > +void min(long, long); > +template <class T> void Binaryread(int &, T, unsigned long); > +template <> void Binaryread(int &, float, unsigned long bytecount) { > + min(bytecount, sizeof(int)); > +} > > base-commit: 83088b331cde0843d65d316e554873ef6d7b6bca
diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc index c307e1b62db..64049f4154e 100644 --- a/gcc/cp/cp-gimplify.cc +++ b/gcc/cp/cp-gimplify.cc @@ -1179,7 +1179,13 @@ cp_fold_immediate_r (tree *stmt_p, int *walk_subtrees, void *data_) /* No need to look into types or unevaluated operands. NB: This affects cp_fold_r as well. */ - if (TYPE_P (stmt) || unevaluated_p (code) || in_immediate_context ()) + if (TYPE_P (stmt) + || unevaluated_p (code) + /* We do not use in_immediate_context here because it checks + more than is desirable, e.g., sk_template_parms. */ + || cp_unevaluated_operand + || (current_function_decl + && DECL_IMMEDIATE_FUNCTION_P (current_function_decl))) { *walk_subtrees = 0; return NULL_TREE; diff --git a/gcc/testsuite/g++.dg/template/sizeof18.C b/gcc/testsuite/g++.dg/template/sizeof18.C new file mode 100644 index 00000000000..afba9946258 --- /dev/null +++ b/gcc/testsuite/g++.dg/template/sizeof18.C @@ -0,0 +1,8 @@ +// PR c++/112869 +// { dg-do compile } + +void min(long, long); +template <class T> void Binaryread(int &, T, unsigned long); +template <> void Binaryread(int &, float, unsigned long bytecount) { + min(bytecount, sizeof(int)); +}