From e468d3d189918738da5f231bd8725e15390a384d Mon Sep 17 00:00:00 2001
From: Sam Blackshear <shb@fb.com>
Date: Tue, 12 Apr 2016 10:55:16 -0700
Subject: [PATCH] using address equality optimization in all abstract domains

Reviewed By: dkgi

Differential Revision: D3164574

fb-gh-sync-id: 1fab1d2
fbshipit-source-id: 1fab1d2
---
 infer/src/checkers/abstractDomain.ml  | 60 +++++++++++++++++++--------
 infer/src/checkers/copyPropagation.ml | 26 +++++++-----
 2 files changed, 58 insertions(+), 28 deletions(-)

diff --git a/infer/src/checkers/abstractDomain.ml b/infer/src/checkers/abstractDomain.ml
index 2ae3e9d06..5f839831a 100644
--- a/infer/src/checkers/abstractDomain.ml
+++ b/infer/src/checkers/abstractDomain.ml
@@ -30,22 +30,32 @@ module BottomLifted (Domain : S) = struct
 
   let initial = NonBottom Domain.initial
 
-  let (<=) ~lhs ~rhs = match lhs, rhs with
-    | Bottom, _ -> true
-    | _ , Bottom -> false
-    | NonBottom lhs, NonBottom rhs -> Domain.(<=) ~lhs ~rhs
+  let (<=) ~lhs ~rhs =
+    if lhs == rhs
+    then true
+    else
+      match lhs, rhs with
+      | Bottom, _ -> true
+      | _ , Bottom -> false
+      | NonBottom lhs, NonBottom rhs -> Domain.(<=) ~lhs ~rhs
 
   let join astate1 astate2 =
-    match astate1, astate2 with
-    | Bottom, _ -> astate2
-    | _, Bottom -> astate1
-    | NonBottom a1, NonBottom a2 -> NonBottom (Domain.join a1 a2)
+    if astate1 == astate2
+    then astate1
+    else
+      match astate1, astate2 with
+      | Bottom, _ -> astate2
+      | _, Bottom -> astate1
+      | NonBottom a1, NonBottom a2 -> NonBottom (Domain.join a1 a2)
 
   let widen ~prev ~next ~num_iters =
-    match prev, next with
-    | Bottom, _ -> next
-    | _, Bottom -> prev
-    | NonBottom prev, NonBottom next -> NonBottom (Domain.widen ~prev ~next ~num_iters)
+    if prev == next
+    then prev
+    else
+      match prev, next with
+      | Bottom, _ -> next
+      | _, Bottom -> prev
+      | NonBottom prev, NonBottom next -> NonBottom (Domain.widen ~prev ~next ~num_iters)
 
   let pp fmt = function
     | Bottom -> F.fprintf fmt "_|_"
@@ -80,9 +90,12 @@ module Pair (Domain1 : S) (Domain2 : S) = struct
       | _, true -> astate1
       | _ -> Domain1.join (fst astate1) (fst astate2), Domain2.join (snd astate1) (snd astate2)
 
-  let widen ~prev:(astate1_next, astate2_next) ~next:(astate1_prev, astate2_prev) ~num_iters =
-    Domain1.widen ~prev:astate1_next ~next:astate1_prev ~num_iters,
-    Domain2.widen ~prev:astate2_next ~next:astate2_prev ~num_iters
+  let widen ~prev ~next ~num_iters =
+    if prev == next
+    then prev
+    else
+      Domain1.widen ~prev:(fst prev) ~next:(fst next) ~num_iters,
+      Domain2.widen ~prev:(snd prev) ~next:(snd next) ~num_iters
 
   let pp fmt (astate1, astate2) =
     F.fprintf fmt "(%a, %a)" Domain1.pp astate1 Domain2.pp astate2
@@ -95,8 +108,19 @@ module FiniteSet (S : PrettyPrintable.PPSet) = struct
   type astate = t
 
   let initial = empty
+
   let is_bottom _ = false
-  let (<=) ~lhs ~rhs = subset lhs rhs
-  let join = union
-  let widen ~prev ~next ~num_iters:_ = union prev next
+
+  let (<=) ~lhs ~rhs =
+    if lhs == rhs
+    then true
+    else subset lhs rhs
+
+  let join astate1 astate2 =
+    if astate1 == astate2
+    then astate1
+    else union astate1 astate2
+
+  let widen ~prev ~next ~num_iters:_ =
+    join prev next
 end
diff --git a/infer/src/checkers/copyPropagation.ml b/infer/src/checkers/copyPropagation.ml
index 99f925f0e..f615578e8 100644
--- a/infer/src/checkers/copyPropagation.ml
+++ b/infer/src/checkers/copyPropagation.ml
@@ -20,18 +20,24 @@ module Domain = struct
   (* return true if the key-value bindings in [rhs] are a subset of the key-value bindings in
      [lhs] *)
   let (<=) ~lhs ~rhs =
-    Var.Map.for_all
-      (fun k v ->
-         try Var.var_equal v (Var.Map.find k lhs)
-         with Not_found -> false)
-      rhs
+    if lhs == rhs
+    then true
+    else
+      Var.Map.for_all
+        (fun k v ->
+           try Var.var_equal v (Var.Map.find k lhs)
+           with Not_found -> false)
+        rhs
 
   let join astate1 astate2 =
-    let keep_if_same _ v1_opt v2_opt = match v1_opt, v2_opt with
-      | Some v1, Some v2 ->
-          if Var.var_equal v1 v2 then Some v1 else None
-      | _ -> None in
-    Var.Map.merge keep_if_same astate1 astate2
+    if astate1 == astate2
+    then astate1
+    else
+      let keep_if_same _ v1_opt v2_opt = match v1_opt, v2_opt with
+        | Some v1, Some v2 ->
+            if Var.var_equal v1 v2 then Some v1 else None
+        | _ -> None in
+      Var.Map.merge keep_if_same astate1 astate2
 
   let widen ~prev ~next ~num_iters:_=
     join prev next