Turn 64-bit integer division and modulus by constants into multiply-high

This trick was already implemented for 32-bit integer division and modulus.  Here we extend it to the 64-bit case.

For 32-bit target processors, the runtime library must implement 64-bit multiply-high (signed and unsigned).  Tentative implementations are provided for IA32 and PowerPC, but need testing.

1 files changed, 12 insertions, 0 deletions

diff --git a/common/Values.v b/common/Values.v
index 88506bab..cfabb7a5 100644
--- a/common/Values.v
+++ b/common/Values.v
@@ -622,6 +622,18 @@ Definition mull' (v1 v2: val): val :=
   | _, _ => Vundef
   end.
 
+Definition mullhs (v1 v2: val): val :=
+  match v1, v2 with
+  | Vlong n1, Vlong n2 => Vlong(Int64.mulhs n1 n2)
+  | _, _ => Vundef
+  end.
+
+Definition mullhu (v1 v2: val): val :=
+  match v1, v2 with
+  | Vlong n1, Vlong n2 => Vlong(Int64.mulhu n1 n2)
+  | _, _ => Vundef
+  end.
+
 Definition divls (v1 v2: val): option val :=
   match v1, v2 with
   | Vlong n1, Vlong n2 =>