[gcc/devel/lto-offload] vect: Skip epilogue loops for dbgcnt check [PR96451]

[John Ravi]

https://gcc.gnu.org/g:ea858d09571f3f6dcce92d8bfaf077f9d44c6ad6

commit ea858d09571f3f6dcce92d8bfaf077f9d44c6ad6
Author: Kewen Lin <linkw@linux.ibm.com>
Date:   Wed Aug 5 02:50:49 2020 -0500

    vect: Skip epilogue loops for dbgcnt check [PR96451]
    
    As the PR shows, commit r11-2453 exposed one issue that vectorizer
    wants to vectorize the epilogue loop and leaves the if-cvt body there,
    but later dbgcnt check disables it, the left scalar mask_store
    statement causes ICE.
    
    As Richard pointed out in that PR, the dbgcnt is to count original
    scalar loops, so this fix is to make it skip the epilogue loops.
    
    gcc/ChangeLog:
    
            * tree-vectorizer.c (try_vectorize_loop_1): Skip the epilogue loops
            for dbgcnt check.

Diff:
---
 gcc/tree-vectorizer.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index 2a60d37bb87..3c60f30ed8f 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -1066,7 +1066,8 @@ try_vectorize_loop_1 (hash_table<simduid_to_vf> *&simduid_to_vf_htab,
       return ret;
     }
 
-  if (!dbg_cnt (vect_loop))
+  /* Only count the original scalar loops.  */
+  if (!LOOP_VINFO_EPILOGUE_P (loop_vinfo) && !dbg_cnt (vect_loop))
     {
       /* Free existing information if loop is analyzed with some
 	 assumptions.  */