[PATCH] Fix a segfault in reload

[Jakub Jelinek <jakub at redhat dot com>]

Hi!

Attached testcase causes cc1 segfault on i386 (both in RH7 gcc and today's
CVS).
The issue is that calculate_needs_all_insns deletes a noop set insn
(set (reg:DF 272) (reg:DF 272))
(well, turns it into NOTE_INSN_DELETED), but later on caller-save.c's
save_call_clobbered_regs() it calls insert_restore and segfaults because it calls
note_stores on the note.
Below is one attempt to fix this (by removing the deleted insn from
reload_insn_chain - passed i386 bootstrap and regression tests), the other
options I see are checking for NOTEs in caller-save.c and continue instead
of doing anything or kill the optimization in calculate_needs_all_insns
altogether.

2000-10-09  Jakub Jelinek  <jakub@redhat.com>

	* reload1.c (calculate_needs_all_insns): If deleting an instruction,
	remove its insn_chain structure as well.

	* gcc.dg/20001009-1.c: New test.

--- gcc/reload1.c.jj	Thu Sep 28 10:33:03 2000
+++ gcc/reload1.c	Mon Oct  9 13:14:51 2000
@@ -1330,15 +1330,17 @@ calculate_needs_all_insns (global)
      int global;
 {
   struct insn_chain **pprev_reload = &insns_need_reload;
-  struct insn_chain *chain;
+  struct insn_chain *chain, *next = 0;
 
   something_needs_elimination = 0;
 
   reload_insn_firstobj = (char *) obstack_alloc (&reload_obstack, 0);
-  for (chain = reload_insn_chain; chain != 0; chain = chain->next)
+  for (chain = reload_insn_chain; chain != 0; chain = next)
     {
       rtx insn = chain->insn;
 
+      next = chain->next;
+
       /* Clear out the shortcuts.  */
       chain->n_reloads = 0;
       chain->need_elim = 0;
@@ -1394,6 +1396,15 @@ calculate_needs_all_insns (global)
 		  PUT_CODE (insn, NOTE);
 		  NOTE_SOURCE_FILE (insn) = 0;
 		  NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
+		  /* Delete it from the reload chain */
+		  if (chain->prev)
+		    chain->prev->next = next;
+		  else
+		    reload_insn_chain = next;
+		  if (next)
+		    next->prev = chain->prev;
+		  chain->next = unused_insn_chains;
+		  unused_insn_chains = chain;
 		  continue;
 		}
 	    }
--- gcc/testsuite/gcc.dg/20001009-1.c.jj	Mon Oct  9 13:16:02 2000
+++ gcc/testsuite/gcc.dg/20001009-1.c	Mon Oct  9 13:17:22 2000
@@ -0,0 +1,47 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fpic" } */
+
+extern void foo (void *a, double x, double y);
+void
+bar (void *a, double b, double c, double d, double e, double f, double g, double h, double i, double j, double k[6])
+{
+  double l, m, n, o, p;
+  double q, r, s, t, u;
+  double x, y, v, w;
+  double z = 0.5 * j;
+  double aa;
+  l = b - 3 * d;
+  m = 4 * f;
+  n = f - h;
+  q = c + 3 * g - i;
+  r = 2 * (e - 2 * g + i);
+  s = g - i;
+  if (l != 0.0)
+    {
+      aa = 0.0;
+      o = (- m + aa);
+      p = (- m - aa);
+      if (o > 0.0)
+        {
+          x = ((b-h)*o + 3*(d+h)*o + 3*(f-h)*o);
+          y = ((c-i)*o + 3*(e+i)*o + 3*(g-i)*o);
+          foo (a, z, w);
+          foo (a, -z, w);
+        }
+      if (p > 0.0)
+        {
+          x = ((b+3*f-h)*p + 3*(d-2*f+h)*p + 3*p);
+          y = ((c+3*g-i)*p + 3*(e-2*g+i)*p + 3*p);
+          v = x * k[0] + y * k[2];
+          w = x * k[1] + y * k[3];
+          foo (a, z, w);
+          foo (a, - z, w);
+        }
+    }
+  if (q != 0.0)
+    {
+      aa = 0.0;
+      t = (- r + aa) / (2 * q);
+      u = (- r - aa) / (2 * q);
+    }
+}

	Jakub