[project @ 2002-04-25 18:48:02 by panne]

Ooops, I mixed up PowerPC and SPARC ABIs: On SPARC the stack is always
double-word aligned (quad-word on PowerPC), so the "fully correct"
solution is very probably really correct. => Fixed the comment.  :-}

diff --git a/ghc/rts/Adjustor.c b/ghc/rts/Adjustor.c
index b6887ad..72cc3b6 100644 (file)
--- a/ghc/rts/Adjustor.c
+++ b/ghc/rts/Adjustor.c
@@ -193,9 +193,13 @@ createAdjustor(int cconv, StgStablePtr hptr, StgFunPtr wptr)
     machinery should then work in all cases.  (Or would it?  Perhaps
     it would trash parts of the caller's frame.  Dunno).  
 
     machinery should then work in all cases.  (Or would it?  Perhaps
     it would trash parts of the caller's frame.  Dunno).  
 

-    SUP, 25 Apr 02: Alas, the "fully correct" solution above is only
-    half correct: "%sp has to be 16-byte aligned at all time", the
-    almighty ABI spec says...
+    SUP, 25 Apr 02: We are quite lucky to push a multiple of 8 bytes in
+    front of the existing arguments, because %sp must stay double-word
+    aligned at all times, see: http://www.sparc.org/standards/psABI3rd.pdf
+    Although we extend the *caller's* stack frame, this shouldn't cause
+    any problems for a C-like caller: alloca is implemented similarly, and
+    local variables should be accessed via %fp, not %sp. In a nutshell:
+    This should work. (Famous last words! :-)

   */
     if ((adjustor = stgMallocBytes(4*(8+1), "createAdjustor")) != NULL) {
        unsigned long *const adj_code = (unsigned long *)adjustor;
   */
     if ((adjustor = stgMallocBytes(4*(8+1), "createAdjustor")) != NULL) {
        unsigned long *const adj_code = (unsigned long *)adjustor;