allow vuses in ifcombine blocks

Disallowing vuses in blocks for ifcombine is too strict, and it
prevents usefully moving fold_truth_andor into ifcombine.  That
tree-level folder has long ifcombined loads, absent other relevant
side effects.

for  gcc/ChangeLog

	* tree-ssa-ifcombine.c (bb_no_side_effects_p): Allow vuses,
	but not vdefs.

diff --git a/gcc/tree-ssa-ifcombine.cc b/gcc/tree-ssa-ifcombine.cc
index 39702929fc01174d7bde4994f63299bc145c7bfb..57b7e4b62f291c98b67f4c7d03ce52fe6eb9b204 100644 (file)
--- a/gcc/tree-ssa-ifcombine.cc
+++ b/gcc/tree-ssa-ifcombine.cc
@@ -130,7 +130,7 @@ bb_no_side_effects_p (basic_block bb)
       enum tree_code rhs_code;
       if (gimple_has_side_effects (stmt)
          || gimple_could_trap_p (stmt)
-         || gimple_vuse (stmt)
+         || gimple_vdef (stmt)
          /* We need to rewrite stmts with undefined overflow to use
             unsigned arithmetic but cannot do so for signed division.  */
          || ((ass = dyn_cast <gassign *> (stmt))