On 06/12/2018 03:11 PM, Jeff Law wrote:
On 06/05/2018 03:43 PM, Martin Sebor wrote:
The attached patch adds basic support for handling strnlen
as a built-in function. It touches the strlen pass where
it folds constant results of the function, and builtins.c
to add simple support for expanding strnlen calls with known
results. It also changes calls.c to detect excessive bounds
to the function and unsafe calls with arguments declared
attribute nonstring.
A side-effect of the strlen change I should call out is that
strlen() calls to all zero-length arrays that aren't considered
flexible array members (i.e., internal members or non-members)
are folded into zero. No warning is issued for such invalid
uses of zero-length arrays but based on the responses to my
question Re: aliasing between internal zero-length-arrays and
other members(*) it sounds like one would be appropriate.
I will see about adding one in a separate patch.
Martin
[*] https://gcc.gnu.org/ml/gcc/2018-06/msg00046.html
gcc-81384.diff
PR tree-optimization/81384 - built-in form of strnlen missing
gcc/ChangeLog:
PR tree-optimization/81384
* builtin-types.def (BT_FN_SIZE_CONST_STRING_SIZE): New.
* builtins.c (expand_builtin_strnlen): New function.
(expand_builtin): Call it.
(fold_builtin_n): Avoid setting TREE_NO_WARNING.
* builtins.def (BUILT_IN_STRNLEN): New.
* calls.c (maybe_warn_nonstring_arg): Handle BUILT_IN_STRNLEN.
Warn for bounds in excess of maximum object size.
* tree-ssa-strlen.c (maybe_set_strlen_range): Return tree representing
single-value ranges. Handle strnlen.
(handle_builtin_strlen): Handle strnlen.
(strlen_check_and_optimize_stmt): Same.
gcc/testsuite/ChangeLog:
PR tree-optimization/81384
* gcc.c-torture/execute/builtins/lib/strnlen.c: New test.
* gcc.c-torture/execute/builtins/strnlen-lib.c: New test.
* gcc.c-torture/execute/builtins/strnlen.c: New test.
* gcc.dg/attr-nonstring-2.c: New test.
* gcc.dg/attr-nonstring-3.c: New test.
* gcc.dg/attr-nonstring-4.c: New test.
* gcc.dg/strlenopt-44.c: New test.
* gcc.dg/strlenopt.h (strnlen): Declare.
diff --git a/gcc/builtin-types.def b/gcc/builtin-types.def
index 5365bef..1f15350 100644
--- a/gcc/builtin-types.def
+++ b/gcc/builtin-types.def
@@ -322,6 +322,8 @@ DEF_FUNCTION_TYPE_2 (BT_FN_STRING_CONST_STRING_INT,
BT_STRING, BT_CONST_STRING, BT_INT)
DEF_FUNCTION_TYPE_2 (BT_FN_STRING_CONST_STRING_SIZE,
BT_STRING, BT_CONST_STRING, BT_SIZE)
+DEF_FUNCTION_TYPE_2 (BT_FN_SIZE_CONST_STRING_SIZE,
+ BT_SIZE, BT_CONST_STRING, BT_SIZE)
DEF_FUNCTION_TYPE_2 (BT_FN_INT_CONST_STRING_FILEPTR,
BT_INT, BT_CONST_STRING, BT_FILEPTR)
DEF_FUNCTION_TYPE_2 (BT_FN_INT_INT_FILEPTR,
I believe Jakub already suggested these change and you ack'd that.
You have some hunks which will need updating now that the CHKP/MPX bits
are gone.
So OK after the cleanups noted above and a fresh bootstrap & regression
test cycle.
Done. I also added documentation for the built-in, reran GCC
and Glibc tests with no regressions, and committed 261705.
Martin
