| Message ID | ZXjjT8Yn80pq7Bky@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] c++: fix ICE with sizeof in a template [PR112869] | expand |
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". > + /* 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. Jason
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))) + /* 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)); +}