range-cache: Fix ranger ICE if number of bbs increases [PR116899]

Ranger cache during initialization reserves number of basic block slots
in the m_workback vector (in an inefficient way by doing create (0)
and safe_grow_cleared (n) and truncate (0) rather than say create (n)
or reserve (n) after create).  The problem is that some passes split bbs and/or
create new basic blocks and so when one is unlucky, the quick_push into that
vector can ICE.

The following patch replaces those 4 quick_push calls with safe_push.

I've also gathered some statistics from compiling 63 gcc sources (picked those
that dependent on gimple-range-cache.h just because I had to rebuild them once
for the instrumentation), and that showed that in 81% of cases nothing has
been pushed into the vector at all (and note, not everything was small, there
were even cases with 10000+ basic blocks), another 18.5% of cases had just 1-4
elements in the vector at most, 0.08% had 5-8 and 19 out of 305386 cases
had at most 9-11 elements, nothing more.  So, IMHO reserving number of basic
block in the vector is a waste of compile time memory and with the safe_push
calls, the patch just initializes the vector to vNULL.

2024-10-01  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/116899
	* gimple-range-cache.cc (ranger_cache::ranger_cache): Set m_workback
	to vNULL instead of creating it, growing and then truncating.
	(ranger_cache::fill_block_cache): Use safe_push rather than quick_push
	on m_workback.
	(ranger_cache::range_from_dom): Likewise.

	* gcc.dg/bitint-111.c: New test.

2 files changed, 21 insertions, 7 deletions

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index c0b8916..035076b 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -997,9 +997,7 @@ update_list::pop ()
 
 ranger_cache::ranger_cache (int not_executable_flag, bool use_imm_uses)
 {
-  m_workback.create (0);
-  m_workback.safe_grow_cleared (last_basic_block_for_fn (cfun));
-  m_workback.truncate (0);
+  m_workback = vNULL;
   m_temporal = new temporal_cache;
 
   // If DOM info is available, spawn an oracle as well.
@@ -1560,7 +1558,7 @@ ranger_cache::fill_block_cache (tree name, basic_block bb, basic_block def_bb)
   // Visit each block back to the DEF.  Initialize each one to UNDEFINED.
   // m_visited at the end will contain all the blocks that we needed to set
   // the range_on_entry cache for.
-  m_workback.quick_push (bb);
+  m_workback.safe_push (bb);
   undefined.set_undefined ();
   m_on_entry.set_bb_range (name, bb, undefined);
   gcc_checking_assert (m_update->empty_p ());
@@ -1634,7 +1632,7 @@ ranger_cache::fill_block_cache (tree name, basic_block bb, basic_block def_bb)
 	  // the list.
 	  gcc_checking_assert (!m_on_entry.bb_range_p (name, pred));
 	  m_on_entry.set_bb_range (name, pred, undefined);
-	  m_workback.quick_push (pred);
+	  m_workback.safe_push (pred);
 	}
     }
 
@@ -1729,7 +1727,7 @@ ranger_cache::range_from_dom (vrange &r, tree name, basic_block start_bb,
 
       // This block has an outgoing range.
       if (gori ().has_edge_range_p (name, bb))
-	m_workback.quick_push (prev_bb);
+	m_workback.safe_push (prev_bb);
       else
 	{
 	  // Normally join blocks don't carry any new range information on
@@ -1753,7 +1751,7 @@ ranger_cache::range_from_dom (vrange &r, tree name, basic_block start_bb,
 		    break;
 		  }
 	      if (all_dom)
-		m_workback.quick_push (prev_bb);
+		m_workback.safe_push (prev_bb);
 	    }
 	}
 
diff --git a/gcc/testsuite/gcc.dg/bitint-111.c b/gcc/testsuite/gcc.dg/bitint-111.c
new file mode 100644
index 0000000..3cc2368
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/bitint-111.c
@@ -0,0 +1,16 @@
+/* PR middle-end/116899 */
+/* { dg-do compile { target bitint575 } } */
+/* { dg-options "-O2" } */
+
+float f;
+_BitInt(255) b;
+
+void
+foo (signed char c)
+{
+  for (;;)
+    {
+      c %= (unsigned _BitInt(512)) 0;	/* { dg-warning "division by zero" } */
+      f /= b >= c;
+    }
+}