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| author | Martin Sebor <msebor@redhat.com> | 2019-10-28 23:46:09 +0000 |
|---|---|---|
| committer | Martin Sebor <msebor@gcc.gnu.org> | 2019-10-28 17:46:09 -0600 |
| commit | 02c4de7631a177ea44149332aa1294a60ed9adad (patch) | |
| tree | 42ae1d041a7a04aa7f3c1fe8003efd45ff7da865 /gcc/tree-ssa-strlen.c | |
| parent | ad1539d5555a161cf6851de8995641d6dfe792d9 (diff) | |
| download | gcc-02c4de7631a177ea44149332aa1294a60ed9adad.zip gcc-02c4de7631a177ea44149332aa1294a60ed9adad.tar.gz gcc-02c4de7631a177ea44149332aa1294a60ed9adad.tar.bz2 | |
PR tree-optimization/92226 - live nul char store to array eliminated
gcc/testsuite/ChangeLog:
PR tree-optimization/92226
* gcc.dg/strlenopt-88.c: New test.
gcc/ChangeLog:
PR tree-optimization/92226
* tree-ssa-strlen.c (compare_nonzero_chars): Return -1 also when
the offset is in the open range outlined by SI's length.
From-SVN: r277545
Diffstat (limited to 'gcc/tree-ssa-strlen.c')
| -rw-r--r-- | gcc/tree-ssa-strlen.c | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/gcc/tree-ssa-strlen.c b/gcc/tree-ssa-strlen.c index 4381458..476bcf6 100644 --- a/gcc/tree-ssa-strlen.c +++ b/gcc/tree-ssa-strlen.c @@ -193,10 +193,11 @@ static void handle_builtin_stxncpy (built_in_function, gimple_stmt_iterator *); * +1 if SI is known to start with more than OFF nonzero characters. - * 0 if SI is known to start with OFF nonzero characters, - but is not known to start with more. + * 0 if SI is known to start with exactly OFF nonzero characters. - * -1 if SI might not start with OFF nonzero characters. */ + * -1 if SI either does not start with OFF nonzero characters + or the relationship between the number of leading nonzero + characters in SI and OFF is unknown. */ static inline int compare_nonzero_chars (strinfo *si, unsigned HOST_WIDE_INT off) @@ -221,7 +222,7 @@ compare_nonzero_chars (strinfo *si, unsigned HOST_WIDE_INT off, if (TREE_CODE (si->nonzero_chars) == INTEGER_CST) return compare_tree_int (si->nonzero_chars, off); - if (TREE_CODE (si->nonzero_chars) != SSA_NAME) + if (!rvals || TREE_CODE (si->nonzero_chars) != SSA_NAME) return -1; const value_range *vr @@ -232,7 +233,15 @@ compare_nonzero_chars (strinfo *si, unsigned HOST_WIDE_INT off, if (rng != VR_RANGE || !range_int_cst_p (vr)) return -1; - return compare_tree_int (vr->min (), off); + /* If the offset is less than the minimum length or if the bounds + of the length range are equal return the result of the comparison + same as in the constant case. Otherwise return a conservative + result. */ + int cmpmin = compare_tree_int (vr->min (), off); + if (cmpmin > 0 || tree_int_cst_equal (vr->min (), vr->max ())) + return cmpmin; + + return -1; } /* Return true if SI is known to be a zero-length string. */ |