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| author | Jakub Jelinek <jakub@redhat.com> | 2021-02-23 09:49:48 +0100 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-02-23 09:49:48 +0100 |
| commit | 37b64a3547b91677189c6cbf4c08d7c80770a93a (patch) | |
| tree | f0cba1525653beae219f2f3379164de524cbaf6c | |
| parent | efa64fcce12074dd542670feb02eaee53e810a30 (diff) | |
| download | gcc-37b64a3547b91677189c6cbf4c08d7c80770a93a.tar.gz | |
fold-const: Fix ICE in fold_read_from_constant_string on invalid code [PR99204]
fold_read_from_constant_string and expand_expr_real_1 have code to optimize
constant reads from string (tree vs. rtl).
If the STRING_CST array type has zero low bound, index is fold converted to
sizetype and so the compare_tree_int works fine, but if it has some other
low bound, it calls size_diffop_loc and that function from 2 sizetype
operands creates a ssizetype difference. expand_expr_real_1 then uses
tree_fits_uhwi_p + compare_tree_int and so works fine, but fold-const.c
only checked if index is INTEGER_CST and calls compare_tree_int, which means
for negative index it will succeed and result in UB in the compiler.
2021-02-23 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/99204
* fold-const.c (fold_read_from_constant_string): Check that
tree_fits_uhwi_p (index) rather than just that index is INTEGER_CST.
* gfortran.dg/pr99204.f90: New test.
| -rw-r--r-- | gcc/fold-const.c | 2 | ||||
| -rw-r--r-- | gcc/testsuite/gfortran.dg/pr99204.f90 | 10 |
2 files changed, 11 insertions, 1 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index c35f987ab89..afc3b7f8772 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -15433,7 +15433,7 @@ fold_read_from_constant_string (tree exp) if (string && TYPE_MODE (TREE_TYPE (exp)) == TYPE_MODE (TREE_TYPE (TREE_TYPE (string))) && TREE_CODE (string) == STRING_CST - && TREE_CODE (index) == INTEGER_CST + && tree_fits_uhwi_p (index) && compare_tree_int (index, TREE_STRING_LENGTH (string)) < 0 && is_int_mode (TYPE_MODE (TREE_TYPE (TREE_TYPE (string))), &char_mode) diff --git a/gcc/testsuite/gfortran.dg/pr99204.f90 b/gcc/testsuite/gfortran.dg/pr99204.f90 new file mode 100644 index 00000000000..9b6f27fa3d2 --- /dev/null +++ b/gcc/testsuite/gfortran.dg/pr99204.f90 @@ -0,0 +1,10 @@ +! PR tree-optimization/99204 +! { dg-do compile } +! { dg-options "-O2 -w" } + +program pr99204 + character :: c + integer :: i = -12345678 + c = 'abc'(i:i) + print *, c +end |