[PATCH 7/8] trivial-phi: directly return the unique value

[Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>]

In trivial_phi(), the fact that the phi-node is trivial or not
is returned as an int and, if trivial, the unique value is
returned via the pointer given as first argument.

But these two results can easily be combined in a single one
by returning the unique value if trivial and NULL otherwise.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
 simplify.c | 26 +++++++++-----------------
 1 file changed, 9 insertions(+), 17 deletions(-)

diff --git a/simplify.c b/simplify.c
index 9a2f6c50d..1fa46548a 100644
--- a/simplify.c
+++ b/simplify.c
@@ -175,20 +175,16 @@ static int if_convert_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
+// @pseudo: the candidate resulting pseudo (NULL when starting)
+// @return: the unique result if the phi-node is trivial, NULL 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)
+static pseudo_t trivial_phi(pseudo_t pseudo, struct instruction *insn)
 {
 	pseudo_t phi;
-	struct instruction *last;
-	int same;
 
-	last = NULL;
-	same = 1;
 	FOR_EACH_PTR(insn->phi_list, phi) {
 		struct instruction *def;
 		pseudo_t src;
@@ -201,27 +197,23 @@ static int trivial_phi(pseudo_t *pseudo, struct instruction *insn)
 		src = def->phi_src; // bypass OP_PHISRC & get the real source
 		if (src == VOID)
 			continue;
-		if (!last) {
-			last = def;
+		if (!pseudo) {
+			pseudo = src;
 			continue;
 		}
-		if (last->phi_src == src)
+		if (src == pseudo)
 			continue;
-		return 0;
+		return NULL;
 	} END_FOR_EACH_PTR(phi);
 
-	if (same)
-		*pseudo = last ? last->phi_src : NULL;
-	return same;
+	return pseudo ? pseudo : VOID;
 }
 
 static int clean_up_phi(struct instruction *insn)
 {
 	pseudo_t pseudo;
 
-	if (trivial_phi(&pseudo, insn)) {
-		if (!pseudo)
-			pseudo = VOID;
+	if ((pseudo = trivial_phi(NULL, insn))) {
 		convert_instruction_target(insn, pseudo);
 		kill_instruction(insn);
 		return REPEAT_CSE;
-- 
2.18.0