This will allow us, at a later step, to recursivaely test
the operands.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
simplify.c | 25 ++++++++++++++++++++++---
1 file changed, 22 insertions(+), 3 deletions(-)
diff --git a/simplify.c b/simplify.c
index f6471a4ef..b9f13f655 100644
--- a/simplify.c
+++ b/simplify.c
@@ -172,7 +172,16 @@ static int if_convert_phi(struct instruction *insn)
return REPEAT_CSE;
}
-static int clean_up_phi(struct instruction *insn)
+///
+// detect trivial phi-nodes
+// @insn: the phi-node
+// @pseudo: a pointer to the resulting pseudo
+// @return: 1 if the phi-node is trivial, 0 otherwise
+//
+// A phi-node is trivial if it has a single possible result:
+// # all operands are the same
+// Since the result is unique, these phi-nodes can be removed.
+static int trivial_phi(pseudo_t *pseudo, struct instruction *insn)
{
pseudo_t phi;
struct instruction *last;
@@ -196,8 +205,18 @@ static int clean_up_phi(struct instruction *insn)
same = 0;
} END_FOR_EACH_PTR(phi);
- if (same) {
- pseudo_t pseudo = last ? last->phi_src : VOID;
+ if (same)
+ *pseudo = last ? last->phi_src : NULL;
+ return same;
+}
+
+static int clean_up_phi(struct instruction *insn)
+{
+ pseudo_t pseudo;
+
+ if (trivial_phi(&pseudo, insn)) {
+ if (!pseudo)
+ pseudo = VOID;
convert_instruction_target(insn, pseudo);
kill_instruction(insn);
return REPEAT_CSE;
--
2.18.0
