Patchwork fix verify_rtl_sharing handling of SEQUENCEs

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Submitter Steven Bosscher
Date April 17, 2013, 10:13 p.m.
Message ID <CABu31nO0Kt9s9yGfGh5L=PJ4cRFG9pphm0-YjtTFVre-xY-GuQ@mail.gmail.com>
Download mbox | patch
Permalink /patch/237375/
State New
Headers show

Comments

Steven Bosscher - April 17, 2013, 10:13 p.m.
On Tue, Apr 16, 2013 at 6:39 PM, Steven Bosscher wrote:
>> My new delay branch scheduler uses TODO_verify_rtl_sharing but it
>> turns out that verify_rtl_sharing doesn't handle SEQUENCEs correctly:
>> Clearing the used-flags is done correctly, but verifying insns in the
>> SEQUENCE fails. The problem is that every insn in the SEQUENCE is
>> marked used via PATTERN(SEQUENCE) and also via PREV_INSN/NEXT_INSN of
>> the insns in the SEQUENCE.
>>
>> Fixed with the attached patch. Bootstrapepd&tested on
>> sparc64-unknown-linux-gnu, and cross-built&tested on mips-elf, both
>> with TODO_verify_rtl_sharing added to the passes in reorg.c.
>> Will commit as obvious.
>
> Andreas Krebbel's patch
> (http://gcc.gnu.org/ml/gcc-patches/2013-04/msg00714.html) makes the
> problem go away for me, so I'm not going to commit this patch after
> all.

Hmm, no it hasn't.

What happens is this:

reset_all_used_flags resets the "used" flags via mark_used_flags,
which doesn't mark or unmark insns:

    case DEBUG_INSN:
    case INSN:
    case JUMP_INSN:
    case CALL_INSN:
    case NOTE:
    case LABEL_REF:
    case BARRIER:
      /* The chain of insns is not being copied.  */
      return;

But verify_rtx_sharing sets the "used" flag on insns if they are
reached via a SEQUENCE. So the first verify_rtl_sharing call with
SEQUENCEs in the insn chain passes, but a second call will fail
because the "used" flags on insns in the SEQUENCE isn't cleared.

So, updated patch attached, will commit after testing on sparc64-linux.

Ciao!
Steven
* emit-rtl.c (reset_insn_used_flags): New function.
	(reset_all_used_flags): Use it.
	(verify_insn_sharing): New function.
	(verify_rtl_sharing): Fix verification for SEQUENCEs.

Patch

Index: emit-rtl.c
===================================================================
--- emit-rtl.c	(revision 198036)
+++ emit-rtl.c	(working copy)
@@ -2596,6 +2596,18 @@  verify_rtx_sharing (rtx orig, rtx insn)
   return;
 }
 
+/* Reset used-flags for INSN.  */
+
+static void
+reset_insn_used_flags (rtx insn)
+{
+  gcc_assert (INSN_P (insn));
+  reset_used_flags (PATTERN (insn));
+  reset_used_flags (REG_NOTES (insn));
+  if (CALL_P (insn))
+    reset_used_flags (CALL_INSN_FUNCTION_USAGE (insn));
+}
+
 /* Go through all the RTL insn bodies and clear all the USED bits.  */
 
 static void
@@ -2606,28 +2618,30 @@  reset_all_used_flags (void)
   for (p = get_insns (); p; p = NEXT_INSN (p))
     if (INSN_P (p))
       {
-	reset_used_flags (PATTERN (p));
-	reset_used_flags (REG_NOTES (p));
-	if (CALL_P (p))
-	  reset_used_flags (CALL_INSN_FUNCTION_USAGE (p));
-	if (GET_CODE (PATTERN (p)) == SEQUENCE)
-	  {
-	    int i;
-	    rtx q, sequence = PATTERN (p);
-
-	    for (i = 0; i < XVECLEN (sequence, 0); i++)
-	      {
-		q = XVECEXP (sequence, 0, i);
-		gcc_assert (INSN_P (q));
-		reset_used_flags (PATTERN (q));
-		reset_used_flags (REG_NOTES (q));
-		if (CALL_P (q))
-		  reset_used_flags (CALL_INSN_FUNCTION_USAGE (q));
-	      }
-	  }
+	rtx pat = PATTERN (p);
+	if (GET_CODE (pat) != SEQUENCE)
+	  reset_insn_used_flags (p);
+	else
+	  {
+	    gcc_assert (REG_NOTES (p) == NULL);
+	    for (int i = 0; i < XVECLEN (pat, 0); i++)
+	      reset_insn_used_flags (XVECEXP (pat, 0, i));
+	  }
       }
 }
 
+/* Verify sharing in INSN.  */
+
+static void
+verify_insn_sharing (rtx insn)
+{
+  gcc_assert (INSN_P (insn));
+  reset_used_flags (PATTERN (insn));
+  reset_used_flags (REG_NOTES (insn));
+  if (CALL_P (insn))
+    reset_used_flags (CALL_INSN_FUNCTION_USAGE (insn));
+}
+
 /* Go through all the RTL insn bodies and check that there is no unexpected
    sharing in between the subexpressions.  */
 
@@ -2643,10 +2657,12 @@  verify_rtl_sharing (void)
   for (p = get_insns (); p; p = NEXT_INSN (p))
     if (INSN_P (p))
       {
-	verify_rtx_sharing (PATTERN (p), p);
-	verify_rtx_sharing (REG_NOTES (p), p);
-	if (CALL_P (p))
-	  verify_rtx_sharing (CALL_INSN_FUNCTION_USAGE (p), p);
+	rtx pat = PATTERN (p);
+	if (GET_CODE (pat) != SEQUENCE)
+	  verify_insn_sharing (p);
+	else
+	  for (i = 0; i < XVECLEN (pat, 0); i++)
+	    verify_insn_sharing (XVECEXP (pat, 0, i));
       }
 
   reset_all_used_flags ();