[Bug target/53886] Seg fault in sh_insn_length_adjustment

[olegendo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53886

--- Comment #4 from Oleg Endo <olegendo at gcc dot gnu.org> 2012-07-08 12:19:09 UTC ---
(In reply to comment #3)
> Created attachment 27763 [details]
> preprocessed src
> 
> Sorry, I had tried to attach it during the bug creation but I didn't notice it
> didn't take.

Thanks.  I could reproduce the problem here.  It seems to happen for
-Os and-m{2a|4*}.

The reason is the subexpression

  PATTERN (NEXT_INSN (PREV_INSN (insn)))

can return nullptr in some cases like this.

The patch below fixes this particular crash, but I'm not sure whether it is
the right thing to do in this case.


Index: gcc/config/sh/sh.c
===================================================================
--- gcc/config/sh/sh.c    (revision 189339)
+++ gcc/config/sh/sh.c    (working copy)
@@ -9652,6 +9652,26 @@
 #define IS_ASM_LOGICAL_LINE_SEPARATOR(C, STR) ((C) == ';')
 #endif

+static bool
+sequence_insn_p (rtx insn)
+{
+  rtx prev,next,pat;
+
+  prev = PREV_INSN (insn);
+  if (prev == NULL)
+    return false;
+
+  next = NEXT_INSN (prev);
+  if (next == NULL)
+    return false;
+
+  pat = PATTERN (next);
+  if (pat == NULL)
+    return false;
+
+  return GET_CODE (pat) == SEQUENCE;
+}
+
 int
 sh_insn_length_adjustment (rtx insn)
 {
@@ -9662,7 +9682,7 @@
     && GET_CODE (PATTERN (insn)) != CLOBBER)
        || CALL_P (insn)
        || (JUMP_P (insn) && !JUMP_TABLE_DATA_P (insn)))
-      && GET_CODE (PATTERN (NEXT_INSN (PREV_INSN (insn)))) != SEQUENCE
+      && ! sequence_insn_p (insn)
       && get_attr_needs_delay_slot (insn) == NEEDS_DELAY_SLOT_YES)
     return 2;

@@ -9671,7 +9691,7 @@
   if (sh_cpu_attr == CPU_SH2E
       && JUMP_P (insn) && !JUMP_TABLE_DATA_P (insn)
       && get_attr_type (insn) == TYPE_CBRANCH
-      && GET_CODE (PATTERN (NEXT_INSN (PREV_INSN (insn)))) != SEQUENCE)
+      && ! sequence_insn_p (insn))
     return 2;

   /* sh-dsp parallel processing insn take four bytes instead of two.  */