| Message ID | ZXOHWR4pNh5gNs2C@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] c++: fix ICE with sizeof in a template [PR112869] | expand |
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)? Jason
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)); +}