https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106457
Bug ID: 106457
Summary: array_at_struct_end_p returns TRUE for a two-dimension
array which is not inside any structure
Product: gcc
Version: 13.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: qinzhao at gcc dot gnu.org
Target Milestone: ---
During my work on updating array_at_struct_end_p with the new
-fstrict-flex-array control, I noticed the following issue in the routine
"array_at_struct_end_p" for the following small testing case:
gcc/testsuite/g++.dg/debug/debug5.C
// { dg-do compile }
// { dg-require-effective-target alloca }
int foo()
{
int a = 1;
int b = 1;
int e[a][b];
e[0][0] = 0;
return e[a-1][b-1];
}
when compiled with -O1 with the latest trunk gcc, when I used the gdb to debug
it as:
(gdb) break array_at_struct_end_p
Breakpoint 1 at 0x1d4cdf8: file ../../latest_gcc/gcc/tree.cc, line 12690.
(gdb) run
Starting program: /home/opc/Work/GCC/build/gcc/cc1plus -quiet -iprefix
/home/opc/Work/GCC/build/gcc/../lib/gcc/aarch64-unknown-linux-gnu/13.0.0/
-isystem /home/opc/Work/GCC/build/gcc/testsuite/g++/../../include -isystem
/home/opc/Work/GCC/build/gcc/testsuite/g++/../../include-fixed -D_GNU_SOURCE
t.C -quiet -dumpbase debug5.C -dumpbase-ext .C -mlittle-endian -mabi=lp64 -O1
-o debug5.s
...
Breakpoint 1, array_at_struct_end_p (ref=0xfffff57a2b88) at
../../latest_gcc/gcc/tree.cc:12690
12690 if (TREE_CODE (ref) == ARRAY_REF
...
(gdb) break 12784
Breakpoint 2 at 0x1d4d50c: file ../../latest_gcc/gcc/tree.cc, line 12784.
(gdb) c
Continuing.
Breakpoint 2, array_at_struct_end_p (ref=0xfffff5771a70) at
../../latest_gcc/gcc/tree.cc:12784
12784 if (TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (atype))) != INTEGER_CST
(gdb) n
12786 || TREE_CODE (TYPE_MIN_VALUE (TYPE_DOMAIN (atype))) !=
INTEGER_CST)
(gdb) n
12784 if (TREE_CODE (TYPE_SIZE_UNIT (TREE_TYPE (atype))) != INTEGER_CST
(gdb) n
12787 return true;
(gdb) n
12803 }
it's obvious that the array reference " e[0][0]" is NOT an array at the end of
a structure.
the utility routine "array_at_struct_end_p" should NOT result true for such
array reference.
We should fix this issue in this routine.
