Fix more ICEs in -fsave-optimization-record (PR tree-optimization/89235)

PR tree-optimization/89235 reports an ICE inside -fsave-optimization-record
whilst reporting the inlining chain of of the location_t in the
vect_location global.

This is very similar to PR tree-optimization/86637, fixed in r266821.

The issue is that the inlining chains are read from the location_t's
ad-hoc data, referencing GC-managed tree blocks, but the former are
not GC roots; it's simply assumed that old locations referencing dead
blocks never get used again.

The fix is to reset the "vect_location" global in more places.  Given
that is a somewhat subtle detail, the patch adds a sentinel class to
reset vect_location at the end of a scope.  Doing it as a class
simplifies the task of ensuring that the global is reset on every
exit path from a function, and also gives a good place to signpost
the above subtlety (in the documentation for the class).

The patch also adds test cases for both of the PRs mentioned above.

gcc/testsuite/ChangeLog:
	PR tree-optimization/86637
	PR tree-optimization/89235
	* gcc.c-torture/compile/pr86637-1.c: New test.
	* gcc.c-torture/compile/pr86637-2.c: New test.
	* gcc.c-torture/compile/pr86637-3.c: New test.
	* gcc.c-torture/compile/pr89235.c: New test.

gcc/ChangeLog:
	PR tree-optimization/86637
	PR tree-optimization/89235
	* tree-vect-loop.c (optimize_mask_stores): Add an
	auto_purge_vect_location sentinel to ensure that vect_location is
	purged on exit.
	* tree-vectorizer.c
	(auto_purge_vect_location::~auto_purge_vect_location): New dtor.
	(try_vectorize_loop_1): Add an auto_purge_vect_location sentinel
	to ensure that vect_location is purged on exit.
	(pass_slp_vectorize::execute): Likewise, replacing the manual
	reset.
	* tree-vectorizer.h (class auto_purge_vect_location): New class.

From-SVN: r268659

1 files changed, 11 insertions, 2 deletions

diff --git a/gcc/tree-vectorizer.c b/gcc/tree-vectorizer.c
index fa5b22e..d271049 100644
--- a/gcc/tree-vectorizer.c
+++ b/gcc/tree-vectorizer.c
@@ -86,6 +86,15 @@ along with GCC; see the file COPYING3.  If not see
 /* Loop or bb location, with hotness information.  */
 dump_user_location_t vect_location;
 
+/* auto_purge_vect_location's dtor: reset the vect_location
+   global, to avoid stale location_t values that could reference
+   GC-ed blocks.  */
+
+auto_purge_vect_location::~auto_purge_vect_location ()
+{
+  vect_location = dump_user_location_t ();
+}
+
 /* Dump a cost entry according to args to F.  */
 
 void
@@ -860,6 +869,7 @@ try_vectorize_loop_1 (hash_table<simduid_to_vf> *&simduid_to_vf_htab,
 {
   unsigned ret = 0;
   vec_info_shared shared;
+  auto_purge_vect_location sentinel;
   vect_location = find_loop_location (loop);
   if (LOCATION_LOCUS (vect_location.get_location_t ()) != UNKNOWN_LOCATION
       && dump_enabled_p ())
@@ -1269,6 +1279,7 @@ public:
 unsigned int
 pass_slp_vectorize::execute (function *fun)
 {
+  auto_purge_vect_location sentinel;
   basic_block bb;
 
   bool in_loop_pipeline = scev_initialized_p ();
@@ -1303,8 +1314,6 @@ pass_slp_vectorize::execute (function *fun)
       loop_optimizer_finalize ();
     }
 
-  vect_location = dump_user_location_t ();
-
   return 0;
 }