From: wolfgang.thaller@gmx.net <unknown>
Date: Mon, 20 Nov 2006 17:25:16 +0000 (+0000)
Subject: i386-darwin: disable use of code stubs for dynamic linking
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=5cfeedcc9f3ad65283d98063f0b228edca9990b2;p=ghc-hetmet.git

i386-darwin: disable use of code stubs for dynamic linking

We can't use lazy binding for tail-calls accross shared libraries, because dyld
will crash due to incorrect stack layout. We can't get the stack alignment right for
both cross-library tailcalls and foreign calls, so we have to bypass the stub code altogether
and load the address to branch to from the non-lazy pointer table.
---

diff --git a/compiler/nativeGen/PositionIndependentCode.hs b/compiler/nativeGen/PositionIndependentCode.hs
index 0daccb6..ffd6577 100644
--- a/compiler/nativeGen/PositionIndependentCode.hs
+++ b/compiler/nativeGen/PositionIndependentCode.hs
@@ -175,6 +175,11 @@ howToAccessLabel _ lbl | labelDynamic lbl = AccessViaSymbolPtr
 -- It is always possible to access something indirectly,
 -- even when it's not necessary.
 
+#if powerpc_TARGET_ARCH || powerpc64_TARGET_ARCH
+    -- on i386 and probably also on x86_64, dyld code stubs don't
+    -- work for tailcalls because the stack alignment is only right
+    -- for regular calls.
+
 howToAccessLabel True lbl
       -- jumps to a dynamic library go via a symbol stub
     | labelDynamic lbl = AccessViaStub
@@ -186,7 +191,8 @@ howToAccessLabel True lbl
       -- we'd need to pass the current Module all the way in to
       -- this function.
     | opt_PIC && externallyVisibleCLabel lbl = AccessViaStub
-howToAccessLabel False lbl
+#endif
+howToAccessLabel _ lbl
       -- data access to a dynamic library goes via a symbol pointer
     | labelDynamic lbl = AccessViaSymbolPtr
       -- cross-module PIC references: same as above