[PATCH] fix GIMPLE parser for loops

[Richard Biener]

We do not tolerate "growing" a vector to a lower size.

Bootstrap on x86_64-unknown-linux-gnu running, will commit
as obvious.

2021-01-07  Richard Biener  <rguenther@suse.de>

gcc/c/
	* gimple-parser.c (c_parser_gimple_compound_statement): Only
	reallocate loop array if it is too small.
---
 gcc/c/gimple-parser.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/gcc/c/gimple-parser.c b/gcc/c/gimple-parser.c
index e64c6e5ebd5..724d8394b4f 100644
--- a/gcc/c/gimple-parser.c
+++ b/gcc/c/gimple-parser.c
@@ -616,8 +616,9 @@ c_parser_gimple_compound_statement (gimple_parser &parser, gimple_seq *seq)
 		      class loop *loop = alloc_loop ();
 		      loop->num = is_loop_header_of;
 		      loop->header = bb;
-		      vec_safe_grow_cleared (loops_for_fn (cfun)->larray,
-					     is_loop_header_of + 1, true);
+		      if (number_of_loops (cfun) <= is_loop_header_of)
+			vec_safe_grow_cleared (loops_for_fn (cfun)->larray,
+					       is_loop_header_of + 1, true);
 		      (*loops_for_fn (cfun)->larray)[is_loop_header_of] = loop;
 		      flow_loop_tree_node_add (loops_for_fn (cfun)->tree_root,
 					       loop);
-- 
2.26.2