From 60330938a9b4cd4f334658671a7b5bc54a13c1dc Mon Sep 17 00:00:00 2001
From: flywind <xzsflywind@gmail.com>
Date: Tue, 26 Apr 2022 15:56:17 +0800
Subject: [PATCH] add cache

---
 compiler/ccgexprs.nim |  7 +++++--
 lib/system/arc.nim    | 20 +++++++++++++++++++-
 2 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 1a3e217b2a6c3..307dde65a6d22 100644
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -1615,8 +1615,11 @@ proc genNewFinalize(p: BProc, e: PNode) =
 
 proc genOfHelper(p: BProc; dest: PType; a: Rope; info: TLineInfo): Rope =
   if optTinyRtti in p.config.globalOptions:
-    result = ropecg(p.module, "#isObj($1.m_type, $2)",
-      [a, genTypeInfo2Name(p.module, dest)])
+    let ti = genTypeInfo2Name(p.module, dest)
+    inc p.module.labels
+    let cache = "Nim_OfCheck_CACHE" & p.module.labels.rope
+    p.module.s[cfsVars].addf("static NCSTRING $#[2];$n", [cache])
+    result = ropecg(p.module, "#isObjWithCache($#.m_type, $#, $#)", [a, ti, cache])
   else:
     # unfortunately 'genTypeInfoV1' sets tfObjHasKids as a side effect, so we
     # have to call it here first:
diff --git a/lib/system/arc.nim b/lib/system/arc.nim
index 38415b5311eb0..a1ceeaf5dee38 100644
--- a/lib/system/arc.nim
+++ b/lib/system/arc.nim
@@ -227,8 +227,11 @@ template tearDownForeignThreadGc* =
   ## With `--gc:arc` a nop.
   discard
 
+type ObjCheckCache = array[0..1, cstring]
+
+proc memcmp(str1, str2: cstring, n: csize_t): cint {.importc, header: "<string.h>".}
+
 func endsWith*(s, suffix: cstring): bool {.inline.} =
-  proc memcmp(str1, str2: cstring, n: csize_t): cint {.importc, header: "<string.h>".}
   if s != nil and suffix != nil:
     let
       sLen = s.len
@@ -240,6 +243,21 @@ func endsWith*(s, suffix: cstring): bool {.inline.} =
 proc isObj(obj: PNimTypeV2, subclass: cstring): bool {.compilerRtl, inl.} =
   result = endsWith(obj.name, subclass)
 
+proc isObjSlowPath(objName: cstring, subclass: cstring, cache: var ObjCheckCache): bool {.compilerRtl, inline.} =
+  if endsWith(objName, subclass):
+    cache[1] = objName
+    result = true
+  else:
+    cache[0] = objName
+    result = false
+
+proc isObjWithCache(obj: PNimTypeV2, subclass: cstring, cache: var ObjCheckCache): bool {.compilerRtl.} =
+  let name = obj.name
+  if pointer(cache[0]) == pointer(name): result = false
+  elif pointer(cache[1]) == pointer(name): result = true
+  else:
+    result = isObjSlowPath(name, subclass, cache)
+
 proc chckObj(obj: PNimTypeV2, subclass: cstring) {.compilerRtl.} =
   # checks if obj is of type subclass:
   if not isObj(obj, subclass): sysFatal(ObjectConversionDefect, "invalid object conversion")