Explicitly construct phi set during def propagation

Previously the phi set was first computed during def propagation
and then computed again (per-block) during actual phi placement.
This commit changes this to store the phi set computed during
def propagation.

This makes SSA construction slightly faster (5%), but the main
purpose here is to pave the way for the next commit.

This also fixes a potential issue with the handling of irreducible
loops -- they generated additional phis, but these were not
accounted for in def propagation. (Though I'm not sure if we can
even have any irreducible loops right now.)

1 files changed, 12 insertions, 0 deletions

diff --git a/Zend/zend_bitset.h b/Zend/zend_bitset.h
index fb19b54329..e1a95466b8 100644
--- a/Zend/zend_bitset.h
+++ b/Zend/zend_bitset.h
@@ -137,6 +137,18 @@ static inline void zend_bitset_union_with_difference(zend_bitset set1, zend_bits
 	}
 }
 
+static inline zend_bool zend_bitset_subset(zend_bitset set1, zend_bitset set2, uint32_t len)
+{
+	uint32_t i;
+
+	for (i = 0; i < len; i++) {
+		if (set1[i] & ~set2[i]) {
+			return 0;
+		}
+	}
+	return 1;
+}
+
 static inline int zend_bitset_first(zend_bitset set, uint32_t len)
 {
 	uint32_t i;