This is a better patch to fix PR 117096 (phiopt vs clobbers). The only time we remove clobbers of local variables is during remove_unused_locals. Since DSE might remove all of the stores to a local variable, it makes sense to also try to remove unused local variables afterwards. This shows up more in C++ code with encapsulation.
This was previously mentioned to be done: https://gcc.gnu.org/pipermail/gcc-patches/2021-April/567744.html In the end it was chosen "Or we might want to place explicit schedules of remove_unused_locals in the pass pipeline." (in stdargs, https://gcc.gnu.org/pipermail/gcc-patches/2021-April/568807.html) but that is too late for early phiopt. This patch does the "maybe we should unconditionally do so" option instead. Bootstrapped and tested on x86_64-linux-gnu. gcc/ChangeLog: PR tree-optimization/117096 * tree-ssa-dse.cc (pass_data_dse): Add TODO_remove_unused_locals to todo_flags_finish. Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com> --- gcc/tree-ssa-dse.cc | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gcc/tree-ssa-dse.cc b/gcc/tree-ssa-dse.cc index 63bf4491cf6..42a133b8631 100644 --- a/gcc/tree-ssa-dse.cc +++ b/gcc/tree-ssa-dse.cc @@ -1654,7 +1654,7 @@ const pass_data pass_data_dse = 0, /* properties_provided */ 0, /* properties_destroyed */ 0, /* todo_flags_start */ - 0, /* todo_flags_finish */ + TODO_remove_unused_locals, /* todo_flags_finish */ }; class pass_dse : public gimple_opt_pass -- 2.43.0
