On 24 October 2012 00:42, Steven Bosscher <stevenb....@gmail.com> wrote: > On Tue, Oct 23, 2012 at 10:29 PM, Christophe Lyon > <christophe.l...@linaro.org> wrote: >> Well, both of these functions appear to check that the 2 blocks to >> merge belong to the same partition, so it should be OK. > > In your first email, you said if-convert was merging two blocks from > different partitions. can_merge_block_p() would rejected merging the > two blocks, so merge_blocks shouldn't be called on them. > > IIRC cfghooks.c:merge_blocks() used to have a > gcc_assert(can_merge_blocks(a,b)) but it's not there now. But if > can_merge_blocks() returns false, merge_blocks should fail. Your bug > is that merge_blocks is being called at all on those blocks from > different partitions. > > >> But not all calls to merge_blocks are guarded by if >> (can_merge_block_p()), this is probably where the problem is? > > Not sure. Depends on what blocks get merged. It may be that > if-conversion shouldn't even be attempting whatever transformation > it's attempting. Not enough information. >
What happens is that merge_if_block() is called with test_bb, then_bb and else_bb in the cold section, while join_bb is in the hot one. merge_if_block calls merge_blocks unconditionally several times (in my case, the wrong one is merge_blocks (combo_bb, join_bb)). Christophe.
