Improve code generation for 64-bit signed integer division

Implement the 'shift right extended' trick, both in the generic implementation (backend/SplitLong) and in the IA32 port.

Note that now SelectDiv depends on SelectLong, and that some work was moved from SelectLong to SelectDiv.

1 files changed, 3 insertions, 0 deletions

diff --git a/ia32/Machregs.v b/ia32/Machregs.v
index 34d88328..a9383d18 100644
--- a/ia32/Machregs.v
+++ b/ia32/Machregs.v
@@ -137,6 +137,7 @@ Definition destroyed_by_op (op: operation): list mreg :=
   | Odivlu => AX :: DX :: nil
   | Omodl => AX :: DX :: nil
   | Omodlu => AX :: DX :: nil
+  | Oshrxlimm _ => DX :: nil
   | Ocmp _ => AX :: CX :: nil
   | _ => nil
   end.
@@ -217,6 +218,7 @@ Definition mregs_for_operation (op: operation): list (option mreg) * option mreg
   | Oshll => (None :: Some CX :: nil, None)
   | Oshrl => (None :: Some CX :: nil, None)
   | Oshrlu => (None :: Some CX :: nil, None)
+  | Oshrxlimm _ => (Some AX :: nil, Some AX)
   | _ => (nil, None)
   end.
 
@@ -313,6 +315,7 @@ Definition two_address_op (op: operation) : bool :=
   | Oshllimm _ => true
   | Oshrl => true
   | Oshrlimm _ => true
+  | Oshrxlimm _ => false
   | Oshrlu => true
   | Oshrluimm _ => true
   | Ororlimm _ => true