if-conversion/HOT-COLD partitioning

[Steven Bosscher]

On Tue, Oct 23, 2012 at 10:29 PM, Christophe Lyon
<christophe.lyon@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.

Ciao!
Steven