From 2fa7ebd47c00b5716cb6904648637a65c97b09c7 Mon Sep 17 00:00:00 2001
From: simonm <unknown>
Date: Wed, 24 Sep 1997 16:19:53 +0000
Subject: [PATCH] [project @ 1997-09-24 16:19:53 by simonm] finished today's
changes.
---
docs/rts/rts.verb | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/docs/rts/rts.verb b/docs/rts/rts.verb
index 01e3e34fb10a..97a4fe0602d7 100644
--- a/docs/rts/rts.verb
+++ b/docs/rts/rts.verb
@@ -799,6 +799,36 @@ How do we do this?
\subsection{A GHC thread returns to a Hugs-compiled return address}
+When Hugs pushes return addresses on the stack, they look like this:
+
+@
+ | |
+ |_______________|
+ | | -----> bytecode object
+ |_______________|
+ | | _____
+ |_______________| |___ GHC-friendly return code
+ _____
+ | |
+ | | Info Table
+ |____|
+ . .
+ . . Code
+ . .
+@
+
+If GHC is returning, it will return to the address at the top of the
+stack. The code at this address
+
+\begin{itemize}
+\item saves the thread state in the TSO
+\item returns to the scheduler with a @whatNext@ field of @RunHugs@.
+\end{itemize}
+
+If Hugs is returning to one of these addresses, it can spot the
+special return address at the top and instead jump to the bytecodes
+pointed to by the second word on the stack.
+
\subsection{A Hugs thread enters a GHC-compiled thunk}
When Hugs is called on to enter a non-Hugs closure (these are
--
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