From d59b9a21689d82d424b7be0d699ccbf3ba538d31 Mon Sep 17 00:00:00 2001
From: Reimer Behrends <behrends@gmail.com>
Date: Thu, 14 Aug 2014 03:09:39 +0200
Subject: Fix stack bottom initialization for non-main modules.

Because PreMain() was now called before the new stack bottom
initialization, it still relied on the old version of initStackBottom(),
which may not handle the top few words of the stack correctly. This
patch also sets the stack bottom in PreMain() using the new approach.
---
 compiler/cgen.nim | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/compiler/cgen.nim b/compiler/cgen.nim
index 112a2af34..2d3831a15 100644
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -949,12 +949,23 @@ proc genFilenames(m: BModule): PRope =
 
 proc genMainProc(m: BModule) =
   const 
+    # The use of a volatile function pointer to call Pre/NimMainInner
+    # prevents inlining of the NimMainInner function and dependent
+    # functions, which might otherwise merge their stack frames.
     PreMainBody =
-      "\tsystemDatInit();$N" &
+      "void PreMainInner() {$N" &
       "\tsystemInit();$N" &
       "$1" &
       "$2" &
-      "$3"
+      "$3" &
+      "}$N$N" &
+      "void PreMain() {$N" &
+      "\tvoid (*volatile inner)();$N" &
+      "\tsystemDatInit();$N" &
+      "\tinner = PreMainInner;$N" &
+      "$4" &
+      "\t(*inner)();$N" &
+      "}$N$N"
 
     MainProcs =
       "\tNimMain();$N"
@@ -962,9 +973,6 @@ proc genMainProc(m: BModule) =
     MainProcsWithResult =
       MainProcs & "\treturn nim_program_result;$N"
 
-    # The use of a volatile function pointer to call NimMainInner
-    # prevents inlining of the NimMainInner function and dependent
-    # functions, which might otherwise merge their stack frames.
     NimMainBody =
       "N_CDECL(void, NimMainInner)(void) {$N" &
         "$1" &
@@ -1047,8 +1055,8 @@ proc genMainProc(m: BModule) =
       platform.targetOS == osStandalone: "".toRope
     else: ropecg(m, "\t#initStackBottomWith((void *)&inner);$N")
   inc(m.labels)
-  appcg(m, m.s[cfsProcs], "void PreMain() {$N" & PreMainBody & "}$N$N", [
-    mainDatInit, gBreakpoints, otherModsInit])
+  appcg(m, m.s[cfsProcs], PreMainBody, [
+    mainDatInit, gBreakpoints, otherModsInit, initStackBottomCall])
 
   appcg(m, m.s[cfsProcs], nimMain, [mainModInit, initStackBottomCall, toRope(m.labels)])
   if optNoMain notin gGlobalOptions:
-- 
cgit 1.4.1-2-gfad0