From d21a8e3bc6325a94da178050181a4bcb7e017dfa Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 24 Apr 2017 07:34:51 +0000 Subject: [PATCH] re PR c++/2972 (-Wuninitialized could warn about uninitialized member variable usage in constructors) 2017-04-24 Richard Biener PR c++/2972 * tree-ssa-uninit.c (warn_uninitialized_vars): Handle some pointer-based references. * g++.dg/warn/Wuninitialized-10.C: New testcase. From-SVN: r247090 --- gcc/ChangeLog | 6 +++++ gcc/testsuite/ChangeLog | 5 ++++ gcc/testsuite/g++.dg/warn/Wuninitialized-10.C | 14 +++++++++++ gcc/tree-ssa-uninit.c | 25 ++++++++++++++----- 4 files changed, 44 insertions(+), 6 deletions(-) create mode 100644 gcc/testsuite/g++.dg/warn/Wuninitialized-10.C diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 2f3a3985415..a9c9a3698e6 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,9 @@ +2017-04-24 Richard Biener + + PR c++/2972 + * tree-ssa-uninit.c (warn_uninitialized_vars): Handle some + pointer-based references. + 2017-04-24 Richard Biener PR bootstrap/79814 diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index e87a01adf3c..148901463f4 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2017-04-24 Richard Biener + + PR c++/2972 + * g++.dg/warn/Wuninitialized-10.C: New testcase. + 2017-04-23 Jerry DeLisle PR fortran/80484 diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-10.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-10.C new file mode 100644 index 00000000000..1fd8b1d3069 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-10.C @@ -0,0 +1,14 @@ +// { dg-do compile } +// { dg-options "-Wuninitialized" } + +struct A +{ + int f,g; + + A() + { + f = g; // { dg-warning "g. is used uninitialized" } + } +}; + +A a; diff --git a/gcc/tree-ssa-uninit.c b/gcc/tree-ssa-uninit.c index e019ecc9d29..60731b2737d 100644 --- a/gcc/tree-ssa-uninit.c +++ b/gcc/tree-ssa-uninit.c @@ -279,20 +279,22 @@ warn_uninitialized_vars (bool warn_possibly_uninitialized) ao_ref ref; ao_ref_init (&ref, rhs); - /* Do not warn if it can be initialized outside this function. */ + /* Do not warn if the base was marked so or this is a + hard register var. */ tree base = ao_ref_base (&ref); - if (!VAR_P (base) - || DECL_HARD_REGISTER (base) - || is_global_var (base) + if ((VAR_P (base) + && DECL_HARD_REGISTER (base)) || TREE_NO_WARNING (base)) continue; /* Do not warn if the access is fully outside of the variable. */ - if (ref.size != -1 + if (DECL_P (base) + && ref.size != -1 && ref.max_size == ref.size && (ref.offset + ref.size <= 0 || (ref.offset >= 0 + && DECL_SIZE (base) && TREE_CODE (DECL_SIZE (base)) == INTEGER_CST && compare_tree_int (DECL_SIZE (base), ref.offset) <= 0))) @@ -305,11 +307,12 @@ warn_uninitialized_vars (bool warn_possibly_uninitialized) && oracle_cnt > vdef_cnt * 2) limit = 32; check_defs_data data; + bool fentry_reached = false; data.found_may_defs = false; use = gimple_vuse (stmt); int res = walk_aliased_vdefs (&ref, use, check_defs, &data, NULL, - NULL, limit); + &fentry_reached, limit); if (res == -1) { oracle_cnt += limit; @@ -318,6 +321,16 @@ warn_uninitialized_vars (bool warn_possibly_uninitialized) oracle_cnt += res; if (data.found_may_defs) continue; + /* Do not warn if it can be initialized outside this function. + If we did not reach function entry then we found killing + clobbers on all paths to entry. */ + if (fentry_reached + /* ??? We'd like to use ref_may_alias_global_p but that + excludes global readonly memory and thus we get bougs + warnings from p = cond ? "a" : "b" for example. */ + && (!VAR_P (base) + || is_global_var (base))) + continue; /* We didn't find any may-defs so on all paths either reached function entry or a killing clobber. */ -- 2.30.2