| Message ID | 20210615032422.1910808-1-jason@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [RFA] expand: empty class return optimization [PR88529] | expand |
On Tue, Jun 15, 2021 at 5:25 AM Jason Merrill via Gcc-patches <gcc-patches@gcc.gnu.org> wrote: > > The x86_64 psABI says that an empty class isn't passed or returned in memory or > registers, so we shouldn't set %eax in this function. Is this a reasonable > place to implement that? Another possibility would be to remove the hack to > prevent i386.c:function_value_64 from returning NULL in this case and fix the > callers to deal, but that seems like more work. > > The df-scan hunk catches the case where we look at a 0-length reg and build > a range the length of unsigned int, which happened before I changed > assign_parms to match expand_function_end. > > Tested x86_64-pc-linux-gnu. OK for trunk? OK. Thanks, Richard. > PR target/88529 > > gcc/ChangeLog: > > * df-scan.c (df_ref_record): Check that regno < endregno. > * function.c (assign_parms, expand_function_end): Do nothing with a > TYPE_EMPTY_P result. > > gcc/testsuite/ChangeLog: > > * g++.target/i386/empty-class1.C: New test. > --- > gcc/df-scan.c | 2 ++ > gcc/function.c | 16 ++++++++++------ > gcc/testsuite/g++.target/i386/empty-class1.C | 9 +++++++++ > 3 files changed, 21 insertions(+), 6 deletions(-) > create mode 100644 gcc/testsuite/g++.target/i386/empty-class1.C > > diff --git a/gcc/df-scan.c b/gcc/df-scan.c > index 1268536b3f0..e9da64ff3df 100644 > --- a/gcc/df-scan.c > +++ b/gcc/df-scan.c > @@ -2595,6 +2595,8 @@ df_ref_record (enum df_ref_class cl, > ref_flags |= DF_REF_PARTIAL; > ref_flags |= DF_REF_MW_HARDREG; > > + gcc_assert (regno < endregno); > + > hardreg = problem_data->mw_reg_pool->allocate (); > hardreg->type = ref_type; > hardreg->flags = ref_flags; > diff --git a/gcc/function.c b/gcc/function.c > index 67576950983..6abaf3d116f 100644 > --- a/gcc/function.c > +++ b/gcc/function.c > @@ -3821,9 +3821,11 @@ assign_parms (tree fndecl) > tree decl_result = DECL_RESULT (fndecl); > rtx decl_rtl = DECL_RTL (decl_result); > > - if (REG_P (decl_rtl) > - ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER > - : DECL_REGISTER (decl_result)) > + if ((REG_P (decl_rtl) > + ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER > + : DECL_REGISTER (decl_result)) > + /* Unless the psABI says not to. */ > + && !TYPE_EMPTY_P (TREE_TYPE (decl_result))) > { > rtx real_decl_rtl; > > @@ -5410,9 +5412,11 @@ expand_function_end (void) > tree decl_result = DECL_RESULT (current_function_decl); > rtx decl_rtl = DECL_RTL (decl_result); > > - if (REG_P (decl_rtl) > - ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER > - : DECL_REGISTER (decl_result)) > + if ((REG_P (decl_rtl) > + ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER > + : DECL_REGISTER (decl_result)) > + /* Unless the psABI says not to. */ > + && !TYPE_EMPTY_P (TREE_TYPE (decl_result))) > { > rtx real_decl_rtl = crtl->return_rtx; > complex_mode cmode; > diff --git a/gcc/testsuite/g++.target/i386/empty-class1.C b/gcc/testsuite/g++.target/i386/empty-class1.C > new file mode 100644 > index 00000000000..c1992772d26 > --- /dev/null > +++ b/gcc/testsuite/g++.target/i386/empty-class1.C > @@ -0,0 +1,9 @@ > +// PR target/88529 > +// { dg-do compile { target { c++11 && x86_64-*-* } } } > +// { dg-additional-options -fdump-rtl-expand } > +// { dg-final { scan-rtl-dump-not "set" "expand" } } > +// The x86_64 psABI says that f() doesn't put the return value anywhere. > + > +class A{}; > + > +A f() { return {}; } > > base-commit: 08ce1f4c5091b80b680d15c53a17237544a3cca8 > prerequisite-patch-id: 320d08bee3615919d0cf6a9d33bc2247aece51c7 > -- > 2.27.0 >
This introduces an ICE building libgomp for ColdFire, as detected by my glibc bot. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101170
diff --git a/gcc/df-scan.c b/gcc/df-scan.c index 1268536b3f0..e9da64ff3df 100644 --- a/gcc/df-scan.c +++ b/gcc/df-scan.c @@ -2595,6 +2595,8 @@ df_ref_record (enum df_ref_class cl, ref_flags |= DF_REF_PARTIAL; ref_flags |= DF_REF_MW_HARDREG; + gcc_assert (regno < endregno); + hardreg = problem_data->mw_reg_pool->allocate (); hardreg->type = ref_type; hardreg->flags = ref_flags; diff --git a/gcc/function.c b/gcc/function.c index 67576950983..6abaf3d116f 100644 --- a/gcc/function.c +++ b/gcc/function.c @@ -3821,9 +3821,11 @@ assign_parms (tree fndecl) tree decl_result = DECL_RESULT (fndecl); rtx decl_rtl = DECL_RTL (decl_result); - if (REG_P (decl_rtl) - ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER - : DECL_REGISTER (decl_result)) + if ((REG_P (decl_rtl) + ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER + : DECL_REGISTER (decl_result)) + /* Unless the psABI says not to. */ + && !TYPE_EMPTY_P (TREE_TYPE (decl_result))) { rtx real_decl_rtl; @@ -5410,9 +5412,11 @@ expand_function_end (void) tree decl_result = DECL_RESULT (current_function_decl); rtx decl_rtl = DECL_RTL (decl_result); - if (REG_P (decl_rtl) - ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER - : DECL_REGISTER (decl_result)) + if ((REG_P (decl_rtl) + ? REGNO (decl_rtl) >= FIRST_PSEUDO_REGISTER + : DECL_REGISTER (decl_result)) + /* Unless the psABI says not to. */ + && !TYPE_EMPTY_P (TREE_TYPE (decl_result))) { rtx real_decl_rtl = crtl->return_rtx; complex_mode cmode; diff --git a/gcc/testsuite/g++.target/i386/empty-class1.C b/gcc/testsuite/g++.target/i386/empty-class1.C new file mode 100644 index 00000000000..c1992772d26 --- /dev/null +++ b/gcc/testsuite/g++.target/i386/empty-class1.C @@ -0,0 +1,9 @@ +// PR target/88529 +// { dg-do compile { target { c++11 && x86_64-*-* } } } +// { dg-additional-options -fdump-rtl-expand } +// { dg-final { scan-rtl-dump-not "set" "expand" } } +// The x86_64 psABI says that f() doesn't put the return value anywhere. + +class A{}; + +A f() { return {}; }