On 12/9/2021 3:16 PM, Alexandre Oliva via Gcc-patches wrote:
The testcase confuses the code that detects min and max len for the
memset, so max_len ends up less than min_len. That shouldn't be
possible, but the testcase requires us to handle this case.
The store-by-mult-pieces algorithm actually relies on min and max
lengths, so if we find them to be inconsistent, the best we can do is
punting.
Regstrapped on x86_64-linux-gnu. Ok to install?
for gcc/ChangeLog
PR middle-end/100843
* builtins.c (try_store_by_multiple_pieces): Fail if min_len
is greater than max_len.
for gcc/testsuite/ChangeLog
PR middle-end/100843
* gcc.dg/pr100843.c: New.
The patch is clearly safe. My question is should we have caught this
earlier in the call chain? If so, I'd prefer to fix it there and leave
the gcc_unreachable in place to catch other bogus cases that may get
into try_store_by_multiple_pieces.
Jeff
