From 4e8ea57821d8deaccd9ffb47ff7a4a7f505880c5 Mon Sep 17 00:00:00 2001
From: dos-reis <gdr@axiomatics.org>
Date: Wed, 9 Jun 2010 11:48:18 +0000
Subject: 	* interp/g-opt.boot (removeNeedlessThrow): Tidy.

---
 src/interp/g-opt.boot | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

(limited to 'src/interp')

diff --git a/src/interp/g-opt.boot b/src/interp/g-opt.boot
index ad2cff91..3557f554 100644
--- a/src/interp/g-opt.boot
+++ b/src/interp/g-opt.boot
@@ -145,13 +145,17 @@ changeThrowToGo(s,g) ==
 
 ++ Change any `(THROW tag (%return expr))' in x to just
 ++ `(%return expr) since a return-operator transfer control
-++ out of the function body anyway.
+++ out of the function body anyway.  Similarly, transform
+++ reudant `(THROW tag (THROW tag expr))' to `(THROW tag expr)'.
 removeNeedlessThrow x ==
   isAtomicForm x => x
   x is ['THROW,.,y] and y is ['%return,:.] =>
     removeNeedlessThrow third y
     x.op := y.op
     x.args := y.args
+  x is ['THROW,g,y] and y is ['THROW,=g,z] =>
+    removeNeedlessThrow z
+    second(x.args) := z
   for x' in x repeat
     removeNeedlessThrow x'
 
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