Changes between Version 6 and Version 7 of ExplicitCallStack/StackTraceExperience

Timestamp:

02/02/07 08:46:04 (6 years ago)

Author:

guest

Comment:

--

ExplicitCallStack/StackTraceExperience

@@ -8 +8 @@
   * Andy Gill's HpcT tracer
   * The ghci debugger extended with a simple stack passing transformation. We will try both a full transformation and some kind of partial transformation (where only part of the code is transformed).
+
+== Test cases ==
 
 The test suite is a selection of programs from the nofig-buggy suite provided by the group at Technical University of Valencia. It is a modified version of the usual nofib benchmark suite. The suite can be obtained like so:
@@ -19 +21 @@
   * anna: Julien's strictness analyzer. It has been modified to divide by zero.
   * whatever
+
+=== Anna ===
+
+We test the program on the `big.cor` input file, which causes a divide by zero error.
+
+This is a rather simple bug:
+{{{
+utRandomInts s1 s2
+   = let seed1_ok = 1 <= s1 && s1 <= 2147483562
+         seed2_ok = 1 <= s2 && s2 <= 2147483398
+
+         rands :: Int -> Int -> [Int]
+         rands s1 s2
+            = let k    = s1 `div` 53668
+                  s1'  = 40014 * (s1 - k * 53668) - k * 12211
+                  s1'' = if s1' < 0 then s1' + 2147483563 else s1'
+                -- BUG: The following line contains a bug
+                  k'   = s2 `div` (s1' - s1')
+                -- CORRECT -- k'   = s2 `div` 52774
+}}}
+The actual bug is in k', and it is local to that definition (it does not depen on values which flow into k').
+
+Nonetheless, utRandomInts seems to be called in a deep context.
 
 == Test results ==
@@ -47 +72 @@
 Commands to see stack trace:
 {{{
+   ./Main < big.cor
    hat-stack Main | less
 }}}