The following teaches simple_dce_from_worklist to remove the LHS
from calls like DCE does.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
* tree-ssa-dce.cc (simple_dce_from_worklist): For calls
with side-effects remove their LHS.
---
gcc/tree-ssa-dce.cc | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/gcc/tree-ssa-dce.cc b/gcc/tree-ssa-dce.cc
index 160c28cb807..53bbd7584fd 100644
--- a/gcc/tree-ssa-dce.cc
+++ b/gcc/tree-ssa-dce.cc
@@ -2399,7 +2399,15 @@ simple_dce_from_worklist (bitmap worklist, bitmap
need_eh_cleanup)
gimple *t = SSA_NAME_DEF_STMT (def);
if (gimple_has_side_effects (t))
- continue;
+ {
+ if (gcall *call = dyn_cast <gcall *> (t))
+ {
+ gimple_call_set_lhs (call, NULL_TREE);
+ update_stmt (call);
+ release_ssa_name (def);
+ }
+ continue;
+ }
/* The defining statement needs to be defining only this name.
ASM is the only statement that can define more than one
--
2.51.0
