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From: Eric Botcazou <ebotcazou@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-3287] Fix bogus -Wstringop-overflow warning Date: Thu, 13 Oct 2022 23:02:32 +0000 (GMT) [thread overview] Message-ID: <20221013230232.147E33858C55@sourceware.org> (raw) https://gcc.gnu.org/g:c26d335fffc689051ee5826455c9d54d1fcf1816 commit r13-3287-gc26d335fffc689051ee5826455c9d54d1fcf1816 Author: Eric Botcazou <ebotcazou@adacore.com> Date: Fri Oct 14 00:55:40 2022 +0200 Fix bogus -Wstringop-overflow warning If you compile the testcase with -O2 -fno-inline -Wall, you get: In function 'process_array3': cc1: warning: 'process_array4' accessing 4 bytes in a region of size 3 [- Wstringop-overflow=] cc1: note: referencing argument 1 of type 'char[4]' t.c:6:6: note: in a call to function 'process_array4' 6 | void process_array4 (char a[4], int n) | ^~~~~~~~~~~~~~ cc1: warning: 'process_array4' accessing 4 bytes in a region of size 3 [- Wstringop-overflow=] cc1: note: referencing argument 1 of type 'char[4]' t.c:6:6: note: in a call to function 'process_array4' That's because the ICF IPA pass has identified the two functions and turned process_array3 into a wrapper of process_array4. gcc/ * gimple-ssa-warn-access.cc (pass_waccess::check_call): Return early for calls made from thunks. gcc/testsuite/ * gcc.dg/Wstringop-overflow-89.c: New test. Diff: --- gcc/gimple-ssa-warn-access.cc | 8 ++++++-- gcc/testsuite/gcc.dg/Wstringop-overflow-89.c | 16 ++++++++++++++++ 2 files changed, 22 insertions(+), 2 deletions(-) diff --git a/gcc/gimple-ssa-warn-access.cc b/gcc/gimple-ssa-warn-access.cc index 04aa849a4b1..59a70530600 100644 --- a/gcc/gimple-ssa-warn-access.cc +++ b/gcc/gimple-ssa-warn-access.cc @@ -4291,14 +4291,18 @@ pass_waccess::check_pointer_uses (gimple *stmt, tree ptr, void pass_waccess::check_call (gcall *stmt) { - if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)) - check_builtin (stmt); + /* Skip special calls generated by the compiler. */ + if (gimple_call_from_thunk_p (stmt)) + return; /* .ASAN_MARK doesn't access any vars, only modifies shadow memory. */ if (gimple_call_internal_p (stmt) && gimple_call_internal_fn (stmt) == IFN_ASAN_MARK) return; + if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)) + check_builtin (stmt); + if (!m_early_checks_p) if (tree callee = gimple_call_fndecl (stmt)) { diff --git a/gcc/testsuite/gcc.dg/Wstringop-overflow-89.c b/gcc/testsuite/gcc.dg/Wstringop-overflow-89.c new file mode 100644 index 00000000000..ba25a9386a7 --- /dev/null +++ b/gcc/testsuite/gcc.dg/Wstringop-overflow-89.c @@ -0,0 +1,16 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fno-inline -Wall" } */ + +extern void process (char); + +void process_array4 (char a[4], int n) +{ + for (int i = 0; i < n; i++) + process (a[i]); +} + +void process_array3 (char a[3], int n) +{ + for (int i = 0; i < n; i++) + process (a[i]); +}
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