From 13b958eb45a3569acaa18f9381d28b8f37d42057 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Fri, 9 Apr 2021 06:59:25 +0200
Subject: [PATCH] IC: added basic test case for methods (#17679)

* IC: added basic test case for methods

* IC: better methods test
---
 compiler/ic/cbackend.nim | 35 ++++++++++++++++++++++++++++-------
 compiler/ic/ic.nim       |  2 +-
 tests/ic/mbaseobj.nim    |  7 +++++++
 tests/ic/tmethods.nim    | 28 ++++++++++++++++++++++++++++
 4 files changed, 64 insertions(+), 8 deletions(-)
 create mode 100644 tests/ic/mbaseobj.nim
 create mode 100644 tests/ic/tmethods.nim

diff --git a/compiler/ic/cbackend.nim b/compiler/ic/cbackend.nim
index 9282ac466..2f3910b32 100644
--- a/compiler/ic/cbackend.nim
+++ b/compiler/ic/cbackend.nim
@@ -30,12 +30,16 @@ proc unpackTree(g: ModuleGraph; thisModule: int;
   var decoder = initPackedDecoder(g.config, g.cache)
   result = loadNodes(decoder, g.packed, thisModule, tree, n)
 
-proc generateCodeForModule(g: ModuleGraph; m: var LoadedModule; alive: var AliveSyms) =
+proc setupBackendModule(g: ModuleGraph; m: var LoadedModule) =
   if g.backend == nil:
     g.backend = cgendata.newModuleList(g)
-
+  assert g.backend != nil
   var bmod = cgen.newModule(BModuleList(g.backend), m.module, g.config)
   bmod.idgen = idgenFromLoadedModule(m)
+
+proc generateCodeForModule(g: ModuleGraph; m: var LoadedModule; alive: var AliveSyms) =
+  var bmod = BModuleList(g.backend).modules[m.module.position]
+  assert bmod != nil
   bmod.flags.incl useAliveDataFromDce
   bmod.alive = move alive[m.module.position]
 
@@ -118,6 +122,27 @@ proc generateCode*(g: ModuleGraph) =
     for i in 0..high(g.packed):
       echo i, " is of status ", g.packed[i].status, " ", toFullPath(g.config, FileIndex(i))
 
+  # First pass: Setup all the backend modules for all the modules that have
+  # changed:
+  for i in 0..high(g.packed):
+    # case statement here to enforce exhaustive checks.
+    case g.packed[i].status
+    of undefined:
+      discard "nothing to do"
+    of loading, stored:
+      assert false
+    of storing, outdated:
+      setupBackendModule(g, g.packed[i])
+    of loaded:
+      # Even though this module didn't change, DCE might trigger a change.
+      # Consider this case: Module A uses symbol S from B and B does not use
+      # S itself. A is then edited not to use S either. Thus we have to
+      # recompile B in order to remove S from the final result.
+      if aliveSymsChanged(g.config, g.packed[i].module.position, alive):
+        g.packed[i].loadedButAliveSetChanged = true
+        setupBackendModule(g, g.packed[i])
+
+  # Second pass: Code generation.
   for i in 0..high(g.packed):
     # case statement here to enforce exhaustive checks.
     case g.packed[i].status
@@ -130,11 +155,7 @@ proc generateCode*(g: ModuleGraph) =
       closeRodFile(g, g.packed[i].module)
       storeAliveSyms(g.config, g.packed[i].module.position, alive)
     of loaded:
-      # Even though this module didn't change, DCE might trigger a change.
-      # Consider this case: Module A uses symbol S from B and B does not use
-      # S itself. A is then edited not to use S either. Thus we have to
-      # recompile B in order to remove S from the final result.
-      if aliveSymsChanged(g.config, g.packed[i].module.position, alive):
+      if g.packed[i].loadedButAliveSetChanged:
         generateCodeForModule(g, g.packed[i], alive)
       else:
         addFileToLink(g.config, g.packed[i].module)
diff --git a/compiler/ic/ic.nim b/compiler/ic/ic.nim
index b5fed7d4e..46bb63e07 100644
--- a/compiler/ic/ic.nim
+++ b/compiler/ic/ic.nim
@@ -666,7 +666,7 @@ type
 
   LoadedModule* = object
     status*: ModuleStatus
-    symsInit, typesInit: bool
+    symsInit, typesInit, loadedButAliveSetChanged*: bool
     fromDisk*: PackedModule
     syms: seq[PSym] # indexed by itemId
     types: seq[PType]
diff --git a/tests/ic/mbaseobj.nim b/tests/ic/mbaseobj.nim
new file mode 100644
index 000000000..0f4e4a90d
--- /dev/null
+++ b/tests/ic/mbaseobj.nim
@@ -0,0 +1,7 @@
+
+type
+  Base* = ref object of RootObj
+    s*: string
+
+method m*(b: Base) {.base.} =
+  echo "Base ", b.s
diff --git a/tests/ic/tmethods.nim b/tests/ic/tmethods.nim
new file mode 100644
index 000000000..251f26889
--- /dev/null
+++ b/tests/ic/tmethods.nim
@@ -0,0 +1,28 @@
+discard """
+  output: '''Base abc'''
+"""
+
+import mbaseobj
+
+var c = Base(s: "abc")
+m c
+
+#!EDIT!#
+
+discard """
+  output: '''Base abc
+Inherited abc'''
+"""
+
+import mbaseobj
+
+type
+  Inherited = ref object of Base
+
+method m(i: Inherited) =
+  procCall m(Base i)
+  echo "Inherited ", i.s
+
+var c = Inherited(s: "abc")
+m c
+