From 07bd5544a3ab3a04d1652dbcb5a09d7271a9706a Mon Sep 17 00:00:00 2001 From: Martin Sebor Date: Mon, 27 Jul 2020 13:54:50 -0600 Subject: [PATCH] Diagnose just-past-the-end references for minor array bounds. Resolves: PR tree-optimization/84079 - missing -Warray-bounds taking the address of past-the-end element of a multidimensional array gcc/ChangeLog: PR tree-optimization/84079 * gimple-array-bounds.cc (array_bounds_checker::check_addr_expr): Only allow just-past-the-end references for the most significant array bound. gcc/testsuite/ChangeLog: PR tree-optimization/84079 * gcc.dg/Warray-bounds-62.c: New test. --- gcc/gimple-array-bounds.cc | 11 +- gcc/testsuite/gcc.dg/Warray-bounds-62.c | 130 ++++++++++++++++++++++++ 2 files changed, 139 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/Warray-bounds-62.c diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc index 352d0745178f..c2dd6663c3a2 100644 --- a/gcc/gimple-array-bounds.cc +++ b/gcc/gimple-array-bounds.cc @@ -519,14 +519,21 @@ array_bounds_checker::check_mem_ref (location_t location, tree ref, void array_bounds_checker::check_addr_expr (location_t location, tree t) { + /* For the most significant subscript only, accept taking the address + of the just-past-the-end element. */ + bool ignore_off_by_one = true; + /* Check each ARRAY_REF and MEM_REF in the reference chain. */ do { bool warned = false; if (TREE_CODE (t) == ARRAY_REF) - warned = check_array_ref (location, t, true /*ignore_off_by_one*/); + { + warned = check_array_ref (location, t, ignore_off_by_one); + ignore_off_by_one = false; + } else if (TREE_CODE (t) == MEM_REF) - warned = check_mem_ref (location, t, true /*ignore_off_by_one*/); + warned = check_mem_ref (location, t, ignore_off_by_one); if (warned) TREE_NO_WARNING (t) = true; diff --git a/gcc/testsuite/gcc.dg/Warray-bounds-62.c b/gcc/testsuite/gcc.dg/Warray-bounds-62.c new file mode 100644 index 000000000000..c2421aac1b2c --- /dev/null +++ b/gcc/testsuite/gcc.dg/Warray-bounds-62.c @@ -0,0 +1,130 @@ +/* PR tree-optimization/84079 - missing -Warray-bounds taking the address + of past-the-end element of a multidimensional array + { dg-do compile } + { dg-options "-O2 -Wall -ftrack-macro-expansion=0" } */ + +void sink (int, ...); + +#define T(type, dims, inxs) \ + do { \ + type a dims; \ + sink (__LINE__, &a inxs); \ + } while (0) + + +void test_char_1_1 (int i0, int i1, int i2) +{ +#undef DIMS +#define DIMS [1][1] + + T (char, DIMS, [0]); + T (char, DIMS, [1]); + T (char, DIMS, [2]); // { dg-warning "subscript 2 is above array bounds of 'char\\\[1]\\\[1]'" } + + T (char, DIMS, [0][0]); + T (char, DIMS, [0][1]); + T (char, DIMS, [0][2]); // { dg-warning "subscript 2 is above array bounds of 'char\\\[1]'" } + + T (char, DIMS, [1][0]); // { dg-warning "subscript 1 is above array bounds of 'char\\\[1]\\\[1]'" } + T (char, DIMS, [1][1]); // { dg-warning "subscript 1 is above array bounds of 'char\\\[1]\\\[1]'" } + T (char, DIMS, [1][2]); // { dg-warning "subscript 2 is above array bounds of 'char\\\[1]'" } + + // Exercise ranges. + if (i0 < 0) i0 = 0; + if (i1 < 1) i1 = 1; + if (i2 < 2) i2 = 2; + + T (char, DIMS, [i0]); + T (char, DIMS, [i1]); + T (char, DIMS, [i2]); // { dg-warning "subscript 2 is above array bounds of 'char\\\[1]\\\[1]" } + + T (char, DIMS, [i0][i0]); + T (char, DIMS, [i0][i1]); + T (char, DIMS, [i1][i0]); // { dg-warning "subscript 1 is above array bounds of 'char\\\[1]\\\[1]'" } + T (char, DIMS, [i1][i1]); // { dg-warning "subscript 1 is above array bounds of 'char\\\[1]\\\[1]'" } + T (char, DIMS, [i1][i2]); // { dg-warning "subscript 2 is above array bounds of 'char\\\[1]'" } +} + + +void test_int_3_5 (int i0, int i1, int i2, int i3, int i4, int i5, int i6) +{ +#undef DIMS +#define DIMS [3][5] + + T (int, DIMS, [0]); + T (int, DIMS, [3]); + T (int, DIMS, [4]); // { dg-warning "subscript 4 is above array bounds of 'int\\\[3]\\\[5]'" } + + T (int, DIMS, [0][0]); + T (int, DIMS, [0][5]); + T (int, DIMS, [0][6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + T (int, DIMS, [1][0]); + T (int, DIMS, [1][5]); + T (int, DIMS, [1][6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + T (int, DIMS, [3][0]); // { dg-warning "subscript 3 is above array bounds of 'int\\\[3]\\\[5]'" } + T (int, DIMS, [3][5]); // { dg-warning "subscript 3 is above array bounds of 'int\\\[3]\\\[5]'" } + T (int, DIMS, [3][6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + // Exercise ranges. + if (i0 < 0) i0 = 0; + if (i1 < 1) i1 = 1; + if (i2 < 2) i2 = 2; + if (i3 < 3) i3 = 3; + if (i4 < 4) i4 = 4; + if (i5 < 5) i5 = 5; + if (i6 < 6) i6 = 6; + + T (int, DIMS, [i0]); + T (int, DIMS, [i3]); + T (int, DIMS, [i4]); // { dg-warning "subscript 4 is above array bounds of 'int\\\[3]\\\[5]" } + + T (int, DIMS, [i0][i0]); + T (int, DIMS, [i0][i5]); + T (int, DIMS, [i0][i6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + T (int, DIMS, [i1][i0]); + T (int, DIMS, [i1][i5]); + T (int, DIMS, [i1][i6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + T (int, DIMS, [i3][i0]); // { dg-warning "subscript 3 is above array bounds of 'int\\\[3]\\\[5]'" } + T (int, DIMS, [i3][i5]); // { dg-warning "subscript 3 is above array bounds of 'int\\\[3]\\\[5]'" } + T (int, DIMS, [i3][i6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } +} + + +void test_int_2_3_4_5 (void) +{ +#undef DIMS +#define DIMS [2][3][4][5] + + T (int, DIMS, [0]); + T (int, DIMS, [2]); + T (int, DIMS, [3]); // { dg-warning "subscript 3 is above array bounds of 'int\\\[2]\\\[3]\\\[4]\\\[5]'" } + + T (int, DIMS, [0][0]); + T (int, DIMS, [0][3]); + T (int, DIMS, [0][4]); // { dg-warning "subscript 4 is above array bounds of 'int\\\[3]\\\[4]\\\[5]'" } + T (int, DIMS, [0][9]); // { dg-warning "subscript 9 is above array bounds of 'int\\\[3]\\\[4]\\\[5]'" } + + T (int, DIMS, [0][0][0]); + T (int, DIMS, [0][0][4]); + T (int, DIMS, [0][0][5]); // { dg-warning "subscript 5 is above array bounds of 'int\\\[4]\\\[5]'" } + + T (int, DIMS, [0][0][0][0]); + T (int, DIMS, [0][0][0][5]); + T (int, DIMS, [0][0][0][6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + T (int, DIMS, [0][0][1][0]); + T (int, DIMS, [0][0][1][5]); + T (int, DIMS, [0][0][1][6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + T (int, DIMS, [0][0][3][0]); + T (int, DIMS, [0][0][3][5]); + T (int, DIMS, [0][0][3][6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } + + T (int, DIMS, [0][0][1][0]); + T (int, DIMS, [0][0][1][5]); + T (int, DIMS, [0][0][1][6]); // { dg-warning "subscript 6 is above array bounds of 'int\\\[5]'" } +}