| Message ID | 45e2a6ee-6c67-a26d-c3dc-8d989e8c7134@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | avoid dereferencing a null pointer (PR 100250) | expand |
On 4/26/2021 5:30 PM, Martin Sebor via Gcc-patches wrote: > The VLA bounds that are included by the C front end to attribute > access added to functions with VLA parameters to help detect > redeclaratations of function with "mismatched" VLA bounds are > cleared by the free_lang_data pass before the IL reaches the middle > end. The clearing was done to fix pr97172 on the basis that > the bounds aren't used by the middle end to trigger any warnings. > While that's true, it turns out that the bounds are sometimes used > when formatting informational notes. I forgot about that when > implementing the final revision of the patch for pr97172 and > removing the assumptions that the bounds are nonnull. > > The attached patch removes the (hopefully last) assumption that > the bounds are nonnull. I reviewed the code and didn't find any > others. > > Bootstrapped & tested on x86_64-linux. > > Martin > > gcc-100250.diff > > PR middle-end/100250 - ICE related to -Wmaybe-uninitialized > > gcc/ChangeLog: > > PR middle-end/100250 > * attribs.c (attr_access::array_as_string): Avoid dereferencing > a pointer when it's null. > > gcc/testsuite/ChangeLog: > > PR middle-end/100250 > * gcc.dg/uninit-pr100250.c: New test. OK jeff
PR middle-end/100250 - ICE related to -Wmaybe-uninitialized gcc/ChangeLog: PR middle-end/100250 * attribs.c (attr_access::array_as_string): Avoid dereferencing a pointer when it's null. gcc/testsuite/ChangeLog: PR middle-end/100250 * gcc.dg/uninit-pr100250.c: New test. diff --git a/gcc/attribs.c b/gcc/attribs.c index 3ffa1b6bc81..ebc0783c439 100644 --- a/gcc/attribs.c +++ b/gcc/attribs.c @@ -2388,7 +2388,8 @@ attr_access::array_as_string (tree type) const const char *p = end; for ( ; p != str && *p-- != ']'; ); if (*p == '$') - index_type = build_index_type (TREE_VALUE (size)); + /* SIZE may have been cleared. Use it with care. */ + index_type = build_index_type (size ? TREE_VALUE (size) : size); } else if (minsize) index_type = build_index_type (size_int (minsize - 1)); diff --git a/gcc/testsuite/gcc.dg/uninit-pr100250.c b/gcc/testsuite/gcc.dg/uninit-pr100250.c new file mode 100644 index 00000000000..8e7a787ddac --- /dev/null +++ b/gcc/testsuite/gcc.dg/uninit-pr100250.c @@ -0,0 +1,29 @@ +/* PR middle-end/100250 - ICE related to -Wmaybe-uninitialized + { dg-do compile } + { dg-options "-O2 -Wall" } */ + +extern void f (int D, const int[D], const int[D]); + +void g (int D, const int a[D], const int b[D], const int c[D], const int d[D]) +{ + int c2[D]; + + for (int i = 0; i < D; i++) { + + if (a[i] >= D) __builtin_abort (); + if (b[i] != d[a[i]]) __builtin_abort (); + + c2[a[i]] = c[i]; + } + + f (D, d, c2); +} + +void h (int D, const int d[D]) +{ + int a[D]; + int b[D]; + int c[D]; + + g (D, a, b, c, d); // { dg-warning "-Wmaybe-uninitialized" } +}