* [PATCH] fix off-by-one mistake in -Warray-bounds for major bounds (PR 84079)
@ 2020-07-22 23:35 Martin Sebor
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From: Martin Sebor @ 2020-07-22 23:35 UTC (permalink / raw)
To: gcc-patches
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-Warray-bounds fails to trigger when taking the address of an element
of a multi-dimensional array at an index that's equal to the bound of
one of the higher dimensions of the array. The attached simple patch
corrects this shortcoming. I will commit it tomorrow unless there are
suggestions for changes.
Tested on x86_64-linux.
Martin
[-- Attachment #2: gcc-84079.diff --]
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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):
gcc/testsuite/ChangeLog:
PR tree-optimization/84079
* gcc.dg/Warray-bounds-62.c: New test.
diff --git a/gcc/gimple-array-bounds.cc b/gcc/gimple-array-bounds.cc
index 352d0745178..613bd612139 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 rightmost 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 00000000000..c2421aac1b2
--- /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]'" }
+}
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2020-07-22 23:35 [PATCH] fix off-by-one mistake in -Warray-bounds for major bounds (PR 84079) Martin Sebor
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