| Message ID | 20210619194544.3360999-1-ppalka@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | c++: REF_PARENTHESIZED_P wrapper inhibiting NRVO [PR67302] | expand |
On 6/19/21 3:45 PM, Patrick Palka wrote: > Here, in C++14 or later, we remember the parentheses around 'a' in the > return statement by using a REF_PARENTHESIZED_P wrapper, which ends up > inhibiting NRVO because we don't look through this wrapper before > checking the conditions for NRVO. This patch fixes this by calling > maybe_undo_parenthesized_ref sooner in check_return_expr. > > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for > trunk? OK. > PR c++/67302 > > gcc/cp/ChangeLog: > > * typeck.c (check_return_expr): Call maybe_undo_parenthesized_ref > sooner, before the NRVO handling. > > gcc/testsuite/ChangeLog: > > * g++.dg/opt/nrv21.C: New test. > --- > gcc/cp/typeck.c | 9 ++++----- > gcc/testsuite/g++.dg/opt/nrv21.C | 14 ++++++++++++++ > 2 files changed, 18 insertions(+), 5 deletions(-) > create mode 100644 gcc/testsuite/g++.dg/opt/nrv21.C > > diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c > index dbb2370510c..aa014c3812a 100644 > --- a/gcc/cp/typeck.c > +++ b/gcc/cp/typeck.c > @@ -10306,7 +10306,10 @@ check_return_expr (tree retval, bool *no_warning) > > See finish_function and finalize_nrv for the rest of this optimization. */ > if (retval) > - STRIP_ANY_LOCATION_WRAPPER (retval); > + { > + retval = maybe_undo_parenthesized_ref (retval); > + STRIP_ANY_LOCATION_WRAPPER (retval); > + } > > bool named_return_value_okay_p = can_do_nrvo_p (retval, functype); > if (fn_returns_value_p && flag_elide_constructors) > @@ -10340,10 +10343,6 @@ check_return_expr (tree retval, bool *no_warning) > if (VOID_TYPE_P (functype)) > return error_mark_node; > > - /* If we had an id-expression obfuscated by force_paren_expr, we need > - to undo it so we can try to treat it as an rvalue below. */ > - retval = maybe_undo_parenthesized_ref (retval); > - > if (processing_template_decl) > retval = build_non_dependent_expr (retval); > > diff --git a/gcc/testsuite/g++.dg/opt/nrv21.C b/gcc/testsuite/g++.dg/opt/nrv21.C > new file mode 100644 > index 00000000000..31bff79afc1 > --- /dev/null > +++ b/gcc/testsuite/g++.dg/opt/nrv21.C > @@ -0,0 +1,14 @@ > +// PR c++/67302 > +// { dg-additional-options -fdump-tree-gimple } > +// { dg-final { scan-tree-dump-not "<retval> = a" "gimple" } } > + > +struct A > +{ > + int ar[42]; > + A(); > +}; > + > +A f() { > + A a; > + return (a); > +} >
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c index dbb2370510c..aa014c3812a 100644 --- a/gcc/cp/typeck.c +++ b/gcc/cp/typeck.c @@ -10306,7 +10306,10 @@ check_return_expr (tree retval, bool *no_warning) See finish_function and finalize_nrv for the rest of this optimization. */ if (retval) - STRIP_ANY_LOCATION_WRAPPER (retval); + { + retval = maybe_undo_parenthesized_ref (retval); + STRIP_ANY_LOCATION_WRAPPER (retval); + } bool named_return_value_okay_p = can_do_nrvo_p (retval, functype); if (fn_returns_value_p && flag_elide_constructors) @@ -10340,10 +10343,6 @@ check_return_expr (tree retval, bool *no_warning) if (VOID_TYPE_P (functype)) return error_mark_node; - /* If we had an id-expression obfuscated by force_paren_expr, we need - to undo it so we can try to treat it as an rvalue below. */ - retval = maybe_undo_parenthesized_ref (retval); - if (processing_template_decl) retval = build_non_dependent_expr (retval); diff --git a/gcc/testsuite/g++.dg/opt/nrv21.C b/gcc/testsuite/g++.dg/opt/nrv21.C new file mode 100644 index 00000000000..31bff79afc1 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/nrv21.C @@ -0,0 +1,14 @@ +// PR c++/67302 +// { dg-additional-options -fdump-tree-gimple } +// { dg-final { scan-tree-dump-not "<retval> = a" "gimple" } } + +struct A +{ + int ar[42]; + A(); +}; + +A f() { + A a; + return (a); +}