[PATCH]: Fix hang while compiling cpu2k6/perlbench at -O2

["Daniel Berlin" <dberlin at dberlin dot org>]

On 1/29/07, Grigory Zagorodnev <grigory_zagorodnev@linux.intel.com> wrote:
> Grigory Zagorodnev wrote:
> > GCC 4.3 compiler revision 121206 goes into infinitive loop while
> > compiling cpu2k6/perlbench source file regcomp.c at -O2 optimization
> > level on x86_64-redhat-linux.
>
> This regression is caused by "Rewrite of portions of points-to solver"
> patch http://gcc.gnu.org/ml/gcc-patches/2007-01/msg01541.html
> revision 120931 http://gcc.gnu.org/viewcvs?view=rev&revision=120931

Patch attached and committed after bootstrap and regtest on i686-darwin.

2007-01-29  Daniel Berlin  <dberlin@dberlin.org>

	* tree-ssa-structalias.c (do_complex_constraint): Mark correct
	variable as changed.


> - Grigory
Index: testsuite/gcc.c-torture/compile/20070129.c
===================================================================
--- testsuite/gcc.c-torture/compile/20070129.c	(revision 0)
+++ testsuite/gcc.c-torture/compile/20070129.c	(revision 0)
@@ -0,0 +1,94 @@
+/* This testcase would cause a hang in PTA solving due to a complex copy
+   constraint and marking the wrong variable as changed.  */
+
+typedef struct RExC_state_t
+{
+ char *end;
+ char *parse;
+} RExC_state_t;
+
+struct regnode_string
+{
+ unsigned char str_len;
+ char string[1];
+};
+
+static void *regatom (RExC_state_t * pRExC_state, int *flagp);
+
+static void *
+regpiece (RExC_state_t * pRExC_state, int *flagp)
+{
+ return regatom (0, 0);
+}
+
+static void *
+regbranch (RExC_state_t * pRExC_state, int *flagp, int first)
+{
+ return regpiece (0, 0);
+}
+
+static void *
+reg (RExC_state_t * pRExC_state, int paren, int *flagp)
+{
+ return regbranch (0, 0, 1);
+}
+
+void *
+Perl_pregcomp (char *exp, char *xend, void *pm)
+{
+ return reg (0, 0, 0);
+}
+
+static void *
+regatom (RExC_state_t * pRExC_state, int *flagp)
+{
+ register void *ret = 0;
+ int flags;
+
+tryagain:
+ switch (*(pRExC_state->parse))
+   {
+   case '(':
+     ret = reg (pRExC_state, 1, &flags);
+     if (flags & 0x8)
+       {
+         goto tryagain;
+       }
+     break;
+   default:
+ {
+       register unsigned long len;
+       register unsigned ender;
+       register char *p;
+       char *oldp, *s;
+       unsigned long numlen;
+       unsigned long foldlen;
+       unsigned char tmpbuf[6 + 1], *foldbuf;
+
+     defchar:
+       s = (((struct regnode_string *) ret)->string);
+       for (len = 0, p = (pRExC_state->parse) - 1;
+            len < 127 && p < (pRExC_state->end); len++)
+         {
+           if (((*p) == '*' || (*p) == '+' || (*p) == '?'
+                || ((*p) == '{' && regcurly (p))))
+             {
+               unsigned long unilen;
+               for (foldbuf = tmpbuf; foldlen; foldlen -= numlen)
+                 {
+                   reguni (pRExC_state, ender, s, &unilen);
+                   s += unilen;
+                 }
+               break;
+             }
+           unsigned long unilen;
+
+           reguni (pRExC_state, ender, s, &unilen);
+           s += unilen;
+         }
+
+     };
+     break;
+   }
+ return (ret);
+}
Index: tree-ssa-structalias.c
===================================================================
--- tree-ssa-structalias.c	(revision 121279)
+++ tree-ssa-structalias.c	(working copy)
@@ -1538,9 +1538,9 @@ do_complex_constraint (constraint_graph_
       if (flag)
 	{
 	  get_varinfo (t)->solution = tmp;
-	  if (!TEST_BIT (changed, c->lhs.var))
+	  if (!TEST_BIT (changed, t))
 	    {
-	      SET_BIT (changed, c->lhs.var);
+	      SET_BIT (changed, t);
 	      changed_count++;
 	    }
 	}
@@ -2065,6 +2065,7 @@ solve_graph (constraint_graph_t graph)
 	      bitmap solution;
 	      VEC(constraint_t,heap) *complex = graph->complex[i];
 	      bool solution_empty;
+
 	      RESET_BIT (changed, i);
 	      changed_count--;