[SH] Fix for PR 53886

[Oleg Endo]

Hello,

The attached patch is a fix for PR 53886, as suggested in the PR.
I've also replaced another unchecked usage of 'PATTERN (NEXT_INSN
(PREV_INSN (insn)))' in 'find_barrier', just in case.

Tested on rev 189361 with
make -k check RUNTESTFLAGS="--target_board=sh-sim
\{-m2/-ml,-m2/-mb,-m2a/-mb,-m2a-single/-mb,-m4/-ml,-m4/-mb,
-m4-single/-ml,-m4-single/-mb,-m4a-single/-ml,-m4a-single/-mb}"

and no new failures.

Cheers,
Oleg

ChangeLog:

        PR target/53886
        * config/sh/sh.c (sequence_insn_p): New function.
        (find_barrier, sh_insn_length_adjustment): Use it.

Index: gcc/config/sh/sh.c
===================================================================
--- gcc/config/sh/sh.c	(revision 189362)
+++ gcc/config/sh/sh.c	(working copy)
@@ -303,6 +303,7 @@
 static int max_mov_insn_displacement (enum machine_mode, bool);
 static int mov_insn_alignment_mask (enum machine_mode, bool);
 static HOST_WIDE_INT disp_addr_displacement (rtx);
+static bool sequence_insn_p (rtx);
 
 static void sh_init_sync_libfuncs (void) ATTRIBUTE_UNUSED;
 
@@ -4794,7 +4795,7 @@
 	 delay slot scheduler.  */
       if (JUMP_P (from) && !JUMP_TABLE_DATA_P (from) 
 	  && get_attr_type (from) == TYPE_CBRANCH
-	  && GET_CODE (PATTERN (NEXT_INSN (PREV_INSN (from)))) != SEQUENCE)
+	  && ! sequence_insn_p (from))
 	inc += 2;
 
       if (found_si)
@@ -9661,6 +9662,26 @@
 #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)
 {
@@ -9671,7 +9692,7 @@
 	&& 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;
 
@@ -9680,7 +9701,7 @@
   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.  */