On Wed, Jan 25, 2012 at 6:36 AM, Andrew Pinski <pins...@gmail.com> wrote: > Hi, > value_replacement in PHIOPT currently works only when there is one > PHI (which is non virtual). > http://gcc.gnu.org/ml/gcc-patches/2012-01/msg01195.html improves the > situation but we can improve it even more as replacing a PHI argument > with a SSA_NAME is almost always a benefit. > > This patch improves the situation even more for value replacement > (though it does not fix all the cases I wanted to fix but that would > require much more rewrite of phiopt that I was willing to take on > right now, see the bug report for the two testcases where we miss > still). We improve the situation by just going through all the PHIs > and seeing if we want to do value replacement and only remove the > middle basic block if it is empty or we used the only assignment in > the PHI (for if(p)a=&p->a;else a= 0; case). > > OK for 4.8? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
Ok. Thanks, Richard. > Note I have two improvements when both this and > http://gcc.gnu.org/ml/gcc-patches/2012-01/msg01195.html are applied; > remove the xfail and instead of gimple_seq_singleton_p use the new > single_non_singleton_phi_for_edges (I will test that patch after both > are applied). Currently these patches are independent and I want to > keep it that way. > > Thanks, > Andrew Pinski > > ChangeLog: > * tree-ssa-phiopt.c: Include tree-pretty-print.h for print_generic_expr. > (tree_ssa_phiopt_worker): Go through all the PHIs for > value_replacement instead of just the singleton one. > (value_replacement): Change return type to int. Return 0 instead of false. > Allow the middle basic block to contain more than just the defining statement. > Handle non empty middle basic blocks. > * Makefile.in (tree-ssa-phiopt.o): Add tree-pretty-print.h > > testsuite/ChangeLog: > * gcc.dg/tree-ssa/phi-opt-8.c: New testcase. > * gcc.dg/tree-ssa/phi-opt-9.c: New testcase.
