//===----------------------------------------------------------------------===//
+
+An alternative to the store/store/load approach for illegal insert element
+lowering would be:
+
+1. store element to any ol' slot
+2. lvx the slot
+3. lvsl 0; splat index; vcmpeq to generate a select mask
+4. lvsl slot + x; vperm to rotate result into correct slot
+5. vsel result together.
insertions.
See comments in LowerINSERT_VECTOR_ELT_SSE4.
+
+//===---------------------------------------------------------------------===//
+
+On a random note, SSE2 should declare insert/extract of 2 x f64 as legal, not
+Custom. All combinations of insert/extract reg-reg, reg-mem, and mem-reg are
+legal, it'll just take a few extra patterns written in the .td file.
+
+Note: this is not a code quality issue; the custom lowered code happens to be
+right, but we shouldn't have to custom lower anything. This is probably related
+to <2 x i64> ops being so bad.
+