https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103584
Bug ID: 103584
Summary: Points-to information is not conservatively correct
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rsandifo at gcc dot gnu.org
CC: hubicka at gcc dot gnu.org, rguenth at gcc dot gnu.org
Target Milestone: ---
Created attachment 51934
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=51934&action=edit
Patch to demonstrate the behaviour
Applying the attached patch shows that points-to information
cannot be used independently of check_fnspec. E.g. for
gcc.c-torture/execute/20000703-1.c, the patch trips the
new assert for:
(gdb) call debug (def_stmt)
__builtin_memset (p_3(D), 0, 28);
(gdb) call debug (ref.base)
*p_3(D)
The check:
else if ((TREE_CODE (base) == MEM_REF
|| TREE_CODE (base) == TARGET_MEM_REF)
&& TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
{
struct ptr_info_def *pi = SSA_NAME_PTR_INFO (TREE_OPERAND (base, 0));
if (pi
&& !pt_solutions_intersect (gimple_call_clobber_set (call), &pi->pt))
{
passes. If the asserts in the patch are disabled (by setting
ASSERTS to 0) then we instead get:
FAIL: gcc.c-torture/execute/memcpy-1.c -O2 execution test
FAIL: gcc.c-torture/execute/memcpy-1.c -O2 -flto -fno-use-linker-plugin
-flto-partition=none execution test
FAIL: gcc.c-torture/execute/memcpy-1.c -O2 -flto -fuse-linker-plugin
-fno-fat-lto-objects execution test
FAIL: gcc.c-torture/execute/memcpy-1.c -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions execution test
FAIL: gcc.c-torture/execute/memcpy-1.c -O3 -g execution test
FAIL: gcc.c-torture/execute/memcpy-1.c -Os execution test
FAIL: gcc.c-torture/execute/memset-3.c -O3 -fomit-frame-pointer
-funroll-loops -fpeel-loops -ftracer -finline-functions execution test
FAIL: gcc.c-torture/execute/memset-3.c -O3 -g execution test
See https://gcc.gnu.org/pipermail/gcc-patches/2021-December/586201.html
for more details.
