On 10/12/21 12:33 PM, Siddhesh Poyarekar wrote:
The warning is falsely triggered for THREAD_SELF in glibc when accessing TCB through the segment register.
Thanks for looking into it! The Glibc warning is being tracked in PR 102630. The root cause behind it is in compute_objsize_r in pointer-query.cc (which is used by -Warray-bounds as well as other warnings). I just posted a patch for it the other day; it's waiting for approval (though as Joseph noted, I need to adjust the test and either make it target-independent or move it under i386). Martin PS Noticing gcc.target/i386/addr-space-2.c makes me wish -Warray-bounds were enabled by default, like other out-of-bounds warnings, and reminds me that it should be able to run even at -O1 (and -O0).
gcc/ChangeLog: * gimple-array-bounds.cc (array_bounds_checker::check_mem_ref): Bail out for non-generic address spaces. gcc/testsuite/ChangeLog: * gcc.target/i386/addr-space-3.c: New test case. Signed-off-by: Siddhesh Poyarekar <siddh...@gotplt.org> --- gcc/gimple-array-bounds.cc | 3 +++ gcc/testsuite/gcc.target/i386/addr-space-3.c | 5 +++++ 2 files changed, 8 insertions(+) create mode 100644 gcc/testsuite/gcc.target/i386/addr-space-3.c diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc index 0517e5ddd8e..36fc1dbe3f8 100644 --- a/gcc/gimple-array-bounds.cc +++ b/gcc/gimple-array-bounds.cc @@ -432,6 +432,9 @@ array_bounds_checker::check_mem_ref (location_t location, tree ref, if (aref.offset_in_range (axssize)) return false;+ if (!ADDR_SPACE_GENERIC_P (TYPE_ADDR_SPACE (axstype)))+ return false; + if (TREE_CODE (aref.ref) == SSA_NAME) { gimple *def = SSA_NAME_DEF_STMT (aref.ref); diff --git a/gcc/testsuite/gcc.target/i386/addr-space-3.c b/gcc/testsuite/gcc.target/i386/addr-space-3.c new file mode 100644 index 00000000000..4bd940e696a --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/addr-space-3.c @@ -0,0 +1,5 @@ +/* Verify that __seg_fs/gs marked variables do not trigger an array bounds + warning. */ +/* { dg-do compile */ +/* { dg-options "-O2 -Warray-bounds" } */ +#include "addr-space-2.c"
