merge GHC HEAD

[ghc-hetmet.git] / includes / stg / MachRegs.h

diff --git a/includes/stg/MachRegs.h b/includes/stg/MachRegs.h
index d607532..6b1d319 100644 (file)
--- a/includes/stg/MachRegs.h
+++ b/includes/stg/MachRegs.h
@@ -1,10 +1,15 @@
 /* -----------------------------------------------------------------------------
  *
- * (c) The GHC Team, 1998-1999
+ * (c) The GHC Team, 1998-2009
  *
  * Registers used in STG code.  Might or might not correspond to
  * actual machine registers.
  *
+ * Do not #include this file directly: #include "Rts.h" instead.
+ *
+ * To understand the structure of the RTS headers, see the wiki:
+ *   http://hackage.haskell.org/trac/ghc/wiki/Commentary/SourceTree/Includes
+ *
  * ---------------------------------------------------------------------------*/
 
 #ifndef MACHREGS_H
@@ -62,6 +67,11 @@
    Caller-saves regs have to be saved around C-calls made from STG
    land, so this file defines CALLER_SAVES_<reg> for each <reg> that
    is designated caller-saves in that machine's C calling convention.
+
+   As it stands, the only registers that are ever marked caller saves
+   are the RX, FX, DX and USER registers; as a result, if you
+   decide to caller save a system register (e.g. SP, HP, etc), note that
+   this code path is completely untested! -- EZY
    -------------------------------------------------------------------------- */
 
 /* -----------------------------------------------------------------------------