On Wed, Oct 19, 2011 at 10:23 AM, Tom de Vries <tom_devr...@mentor.com> wrote: > Richard, > > For the example from the PR, -ftree-tail-merge discovers that blocks 6 and 7 > are > equal, removes block 7 and redirects the outgoing edge of it's predecessor > block > 11 to block 6. > > Block 6 contains a phi, which after redirecting the edge from block 11 looks > like this: > ... > .MEM_54 = PHI <.MEM_27(18), .MEM_26(17), (11)> > ... > > Since update_vops is false, TODO_update_ssa_only_virtuals will be run > and -ftree-tail-merge doesn't update the phi. > > However during cleanup_tree_cfg (which is done before updating the ssa), > phi_alternatives_equal is called which asserts that the phi arguments are > defined. > > The patch fixes the ICE by setting the empty phi argument to .MEM. > > bootstrapped and reg-tested on x86_64. > > Ok for trunk?
Ok. Thanks, Richard. > Thanks, > - Tom > > 2011-10-19 Tom de Vries <t...@codesourcery.com> > > PR 50769/tree-optimization > * tree-ssa-tail-merge.c (replace_block_by): Calculate phi_vuse2 > unconditionally. Handle case that phi_vuse2 is not an SSA_NAME. Add > dummy argument .MEM to phi when increasing number of arguments of phi > by > redirecting edges to the block with phi. >
