When merging BBs, it's possible that the top BB feeds one or
several phi-nodes in the bottom BB. Since phi-nodes only make
sense for values incoming from the parent BBs, these phi-nodes
can and should be removed when merging the BBs.
So, when merging BBs, remove these related phi-nodes.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
flow.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/flow.c b/flow.c
index e9c8f6b7355e..23886f9d84fa 100644
--- a/flow.c
+++ b/flow.c
@@ -760,6 +760,26 @@ static void adjust_phisrc(struct basic_block *top, struct instruction *insn)
} END_FOR_EACH_PTR(phi);
}
+static void adjust_phi(struct basic_block *top, struct instruction *insn)
+{
+ pseudo_t phi;
+
+ FOR_EACH_PTR(insn->phi_list, phi) {
+ struct instruction *def;
+
+ if (phi == VOID)
+ continue;
+
+ def = phi->def;
+ if (def->bb != top)
+ continue;
+
+ convert_instruction_target(insn, def->src);
+ kill_instruction(def);
+ kill_instruction(insn);
+ } END_FOR_EACH_PTR(phi);
+}
+
///
// merge two BBs
// @top: the first BB to be merged
@@ -786,6 +806,9 @@ static int merge_bb(struct basic_block *top, struct basic_block *bot)
continue;
assert(insn->bb == bot);
switch (insn->opcode) {
+ case OP_PHI:
+ adjust_phi(top, insn);
+ continue;
case OP_PHISOURCE:
adjust_phisrc(top, insn);
break;
--
2.29.2
