01-fyi-fix-tc.patch

[Akim Demaille]

Index: ChangeLog
from  Akim Demaille  <address@hidden>
        
        Bison dumps core on bash.y.
        Reported by Pascal Bart.
        
        * src/warshall.c (bitmatrix_print): New.
        (TC): Use it.
        When performing a transitive closure R(i, j) && R(j, k) => R(i, k),
        j must be the outer loop.
        * tests/regression.at (Broken Closure): New.
        
Index: src/warshall.c
--- src/warshall.c Mon, 03 Dec 2001 20:11:46 +0100 akim
+++ src/warshall.c Sat, 08 Dec 2001 13:00:41 +0100 akim
@@ -20,6 +20,7 @@
 
 
 #include "system.h"
+#include "getargs.h"
 #include "warshall.h"
 
 /*-------------------------------------------------------------.
@@ -27,6 +28,51 @@
 | transive closure of what was given.                          |
 `-------------------------------------------------------------*/
 
+static void
+bitmatrix_print (const char *title, unsigned *matrix, size_t size)
+{
+  size_t i, j;
+  size_t rowsize = WORDSIZE (size) * sizeof (unsigned);
+#define ROW(Num) ((unsigned *) ((char *) matrix + ((Num) * rowsize)))
+
+  /* Title. */
+  fprintf (stderr, "%s BEGIN\n", title);
+
+  /* Column numbers. */
+  fputs ("   ", stderr);
+  for (i = 0; i < size; ++i)
+    putc (i / 10 ? '0' + i / 10 : ' ', stderr);
+  putc ('\n', stderr);
+  fputs ("   ", stderr);
+  for (i = 0; i < size; ++i)
+    fprintf (stderr, "%d", i % 10);
+  putc ('\n', stderr);
+
+  /* Bar. */
+  fputs ("  +", stderr);
+  for (i = 0; i < size; ++i)
+    putc ('-', stderr);
+  fputs ("+\n", stderr);
+
+  /* Contents. */
+  for (i = 0; i < size; ++i)
+    {
+      fprintf (stderr, "%2d|", i);
+      for (j = 0; j < size; ++j)
+       fputs (BITISSET (ROW (i), j) ? "1" : " ", stderr);
+      fputs ("|\n", stderr);
+    }
+
+  /* Bar. */
+  fputs ("  +", stderr);
+  for (i = 0; i < size; ++i)
+    putc ('-', stderr);
+  fputs ("+\n", stderr);
+
+  /* End title. */
+  fprintf (stderr, "%s END\n\n", title);
+}
+
 #define R(Num) (unsigned *) ((char *) R + ((Num) * rowsize))
 
 static void
@@ -35,12 +81,21 @@
   int rowsize = WORDSIZE (n) * sizeof (unsigned);
   int i, j, k;
 
+  if (trace_flag)
+    bitmatrix_print ("TC: Input", R, n);
+
+  /* R (J, I) && R (I, K) => R (J, K).
+     I *must* be the outter loop. */
+
   for (i = 0; i < n; ++i)
     for (j = 0; j < n; ++j)
-      if (BITISSET (R (i), j))
-       for (k = 0; k < rowsize; ++k)
+      if (BITISSET (R (j), i))
+       for (k = 0; k < n; ++k)
          if (BITISSET (R (i), k))
            SETBIT (R (j), k);
+
+  if (trace_flag)
+    bitmatrix_print ("TC: Output", R, n);
 }
 
 
Index: tests/regression.at
--- tests/regression.at Thu, 29 Nov 2001 23:08:07 +0100 akim
+++ tests/regression.at Sat, 08 Dec 2001 13:03:47 +0100 akim
@@ -611,3 +611,78 @@ dummy:
 
 AT_TEST_CPP_GUARD_H([input/input])
 AT_TEST_CPP_GUARD_H([9foo])
+
+
+## ---------------- ##
+## Broken Closure.  ##
+## ---------------- ##
+
+# TC was once broken during a massive `simplification' of the code.
+# It resulted in bison dumping core on the following grammar (the
+# computation of FIRSTS uses TC).  It managed to produce a pretty
+# exotic closure:
+#
+# TC: Input
+#
+#    01234567
+#   +--------+
+#  0| 1      |
+#  1|  1     |
+#  2|   1    |
+#  3|    1   |
+#  4|     1  |
+#  5|      1 |
+#  6|       1|
+#  7|        |
+#   +--------+
+#
+# TC: Output
+#
+#    01234567
+#   +--------+
+#  0| 1      |
+#  1| 111    |
+#  2| 111    |
+#  3| 1111   |
+#  4| 111 1  |
+#  5| 111  1 |
+#  6| 111   1|
+#  7| 111    |
+#   +--------+
+#
+# instead of that below.
+
+AT_SETUP([Broken Closure])
+
+AT_DATA([input.y],
+[[%%
+a: b
+b: c
+c: d
+d: e
+e: f
+f: g
+g: h
+h: 'h'
+]])
+
+AT_CHECK([bison --trace input.y 2>&1 |
+          sed -n '/^TC: Output BEGIN/,/^TC: Output END/p'],
+         [0],
+[[TC: Output BEGIN
+           @&t@
+   01234567
+  +--------+
+ 0| 1111111|
+ 1|  111111|
+ 2|   11111|
+ 3|    1111|
+ 4|     111|
+ 5|      11|
+ 6|       1|
+ 7|        |
+  +--------+
+TC: Output END
+]])
+
+AT_CLEANUP