From c5e003cfe45c37f8170c12b4037e8dda70dbfb94 Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Wed, 16 Mar 2016 15:37:22 -0400 Subject: [PATCH] re PR c++/70259 (-flifetime-dse=2 bug with empty bases) PR c++/70259 * decl.c (start_preparsed_function): Don't clobber an empty base. From-SVN: r234267 --- gcc/cp/ChangeLog | 5 +++++ gcc/cp/decl.c | 2 ++ gcc/testsuite/g++.dg/opt/flifetime-dse5.C | 13 +++++++++++++ 3 files changed, 20 insertions(+) create mode 100644 gcc/testsuite/g++.dg/opt/flifetime-dse5.C diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog index b1424136a08..ac7387846fe 100644 --- a/gcc/cp/ChangeLog +++ b/gcc/cp/ChangeLog @@ -1,3 +1,8 @@ +2016-03-16 Jason Merrill + + PR c++/70259 + * decl.c (start_preparsed_function): Don't clobber an empty base. + 2016-03-16 Jakub Jelinek PR c++/70147 diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c index 27c3597a570..216d7268c28 100644 --- a/gcc/cp/decl.c +++ b/gcc/cp/decl.c @@ -14121,6 +14121,8 @@ start_preparsed_function (tree decl1, tree attrs, int flags) && (flag_lifetime_dse > 1) && DECL_CONSTRUCTOR_P (decl1) && !DECL_CLONED_FUNCTION_P (decl1) + /* Clobbering an empty base is harmful if it overlays real data. */ + && !is_empty_class (current_class_type) /* We can't clobber safely for an implicitly-defined default constructor because part of the initialization might happen before we enter the constructor, via AGGR_INIT_ZERO_FIRST (c++/68006). */ diff --git a/gcc/testsuite/g++.dg/opt/flifetime-dse5.C b/gcc/testsuite/g++.dg/opt/flifetime-dse5.C new file mode 100644 index 00000000000..2c4902120f0 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/flifetime-dse5.C @@ -0,0 +1,13 @@ +// PR c++/70259 +// { dg-options -O2 } +// { dg-do run } + +struct Empty { }; +struct A { A() : a(true) { } bool a; }; +struct B : Empty { B() : Empty() { } }; +struct C : A, B { C() : A(), B() { } }; +int main() { + C c; + if ( c.a == false ) + __builtin_abort(); +}; -- 2.30.2