Optimize integer divisions by positive constants, turning them into

multiply-high and shifts.


git-svn-id: https://yquem.inria.fr/compcert/svn/compcert/trunk@2300 fca1b0fc-160b-0410-b1d3-a4f43f01ea2e

1 files changed, 8 insertions, 0 deletions

diff --git a/ia32/Asmgen.v b/ia32/Asmgen.v
index 4543ac9..0410057 100644
--- a/ia32/Asmgen.v
+++ b/ia32/Asmgen.v
@@ -311,6 +311,14 @@ Definition transl_op
   | Omulimm n, a1 :: nil =>
       assertion (mreg_eq a1 res);
       do r <- ireg_of res; OK (Pimul_ri r n :: k)
+  | Omulhs, a1 :: a2 :: nil =>
+      assertion (mreg_eq a1 AX);
+      assertion (mreg_eq res DX);
+      do r2 <- ireg_of a2; OK (Pimul_r r2 :: k)
+  | Omulhu, a1 :: a2 :: nil =>
+      assertion (mreg_eq a1 AX);
+      assertion (mreg_eq res DX);
+      do r2 <- ireg_of a2; OK (Pmul_r r2 :: k)
   | Odiv, a1 :: a2 :: nil =>
       assertion (mreg_eq a1 AX);
       assertion (mreg_eq a2 CX);