On Thu, Nov 24, 2011 at 05:28:00PM +0100, Michael Matz wrote: > As the default defs are already automatically handled by all our ssa > infrastructure (including warning and propagation machinery) I think it > would be best to generate such one instead of a clobber for the RHS.
So like this? 2011-11-24 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/51246 * tree-predcom.c (replace_ref_with): Handle also clobber on the rhs. * gcc.c-torture/compile/pr51246.c: New test. --- gcc/tree-predcom.c.jj 2011-09-26 14:07:06.000000000 +0200 +++ gcc/tree-predcom.c 2011-11-24 17:39:08.196727939 +0100 @@ -1306,8 +1306,20 @@ replace_ref_with (gimple stmt, tree new_ val = gimple_assign_lhs (stmt); if (TREE_CODE (val) != SSA_NAME) { - gcc_assert (gimple_assign_copy_p (stmt)); val = gimple_assign_rhs1 (stmt); + gcc_assert (gimple_assign_single_p (stmt)); + if (TREE_CLOBBER_P (val)) + { + val = gimple_default_def (cfun, SSA_NAME_VAR (new_tree)); + if (val == NULL_TREE) + { + val = make_ssa_name (SSA_NAME_VAR (new_tree), + gimple_build_nop ()); + set_default_def (SSA_NAME_VAR (new_tree), val); + } + } + else + gcc_assert (gimple_assign_copy_p (stmt)); } } else --- gcc/testsuite/gcc.c-torture/compile/pr51246.c.jj 2011-11-24 09:15:10.322906812 +0100 +++ gcc/testsuite/gcc.c-torture/compile/pr51246.c 2011-11-24 09:14:52.000000000 +0100 @@ -0,0 +1,14 @@ +/* PR tree-optimization/51246 */ + +int a, *b; + +void +test (void) +{ + while (1) + { + int c; + a = c; + b = &c; + } +} Jakub