[PATCH] Rerun df_analyze if delete_trivially_dead_insns deleted something during IRA (PR debug/47881)

Jakub Jelinek jakub@redhat.com
Tue Mar 8 15:33:00 GMT 2011


Hi!

If delete_trivially_dead_insns deletes some insn, DF state might be
out of date, and, what's worse, if there are pseudos set multiple times
referenced in debug_insns, where the debug_insn references were ok
before the deletions, but the deletions shortened lifetime of such a pseudo
in certain location, nothing resets the debug insns afterwards and we end up
with -fcompare-debug failures because the lifetime of the pseudos is
different between -g0 and -g.

Fixed by rerunning df_analyze () if delete_trivially_dead_insns removed
anything, bootstrapped/regtested on x86_64-linux and i686-linux.
Ok for trunk?

2011-03-07  Jakub Jelinek  <jakub@redhat.com>

	PR debug/47881
	* ira.c (ira): Call df_analyze again if delete_trivially_dead_insns
	removed anything.

	* gcc.dg/pr47881.c: New test.

--- gcc/ira.c.jj	2011-02-21 15:37:42.000000000 +0100
+++ gcc/ira.c	2011-03-07 12:33:59.000000000 +0100
@@ -3232,7 +3232,8 @@ ira (FILE *f)
     check_allocation ();
 #endif
 
-  delete_trivially_dead_insns (get_insns (), max_reg_num ());
+  if (delete_trivially_dead_insns (get_insns (), max_reg_num ()))
+    df_analyze ();
 
   init_reg_equiv_memory_loc ();
 
--- gcc/testsuite/gcc.dg/pr47881.c.jj	2011-03-08 14:12:04.000000000 +0100
+++ gcc/testsuite/gcc.dg/pr47881.c	2011-03-08 14:11:46.000000000 +0100
@@ -0,0 +1,24 @@
+/* PR debug/47881 */
+/* { dg-do compile } */
+/* { dg-options "-O -fcompare-debug -fno-dce -funroll-loops -fno-web" } */
+
+extern int data[];
+
+int
+foo (int *t, int *f, int n)
+{
+  int i = 0, a, b, c, d;
+  while (data[*f] && n)
+    n--;
+  for (; i < n; i += 4)
+    {
+      a = data[*(f++) & 0x7f];
+      c = data[*(f++) & 0x7f];
+      c = data[*(f++) & 0x7f];
+      d = data[*(f++) & 0x7f];
+      if ((a & 0x80) || (b & 0x80) || (c & 0x80) || (d & 0x80))
+	return 1;
+      *(t++) = 16;
+    }
+  return 0;
+}

	Jakub



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