[gcc r12-7128] Register non-null side effects properly.

[gcc r12-7128] Register non-null side effects properly.

[Andrew Macleod]

https://gcc.gnu.org/g:c6bb1db76b3ac127aff7dacf391fc1798a94bb7d

commit r12-7128-gc6bb1db76b3ac127aff7dacf391fc1798a94bb7d
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Mon Feb 7 15:52:16 2022 -0500

    Register non-null side effects properly.
    
    This patch adjusts uses of nonnull to accurately reflect "somewhere in block".
    It also adds the ability to register statement side effects within a block
    for ranger which will apply for the rest of the block.
    
            PR tree-optimization/104288
            gcc/
            * gimple-range-cache.cc (non_null_ref::set_nonnull): New.
            (non_null_ref::adjust_range): Move to header.
            (ranger_cache::range_of_def): Don't check non-null.
            (ranger_cache::entry_range): Don't check non-null.
            (ranger_cache::range_on_edge): Check for nonnull on normal edges.
            (ranger_cache::update_to_nonnull): New.
            (non_null_loadstore): New.
            (ranger_cache::block_apply_nonnull): New.
            * gimple-range-cache.h (class non_null_ref): Update prototypes.
            (non_null_ref::adjust_range): Move to here and inline.
            (class ranger_cache): Update prototypes.
            * gimple-range-path.cc (path_range_query::range_defined_in_block): Do
            not search dominators.
            (path_range_query::adjust_for_non_null_uses): Ditto.
            * gimple-range.cc (gimple_ranger::range_of_expr): Check on-entry for
            def overrides.  Do not check nonnull.
            (gimple_ranger::range_on_entry): Check dominators for nonnull.
            (gimple_ranger::range_on_edge): Check for nonnull on normal edges..
            (gimple_ranger::register_side_effects): New.
            * gimple-range.h (gimple_ranger::register_side_effects): New.
            * tree-vrp.cc (rvrp_folder::fold_stmt): Call register_side_effects.
    
            gcc/testsuite/
            * gcc.dg/pr104288.c: New.

Diff:
---
 gcc/gimple-range-cache.cc       | 135 ++++++++++++++++++++++++++++++----------
 gcc/gimple-range-cache.h        |  31 +++++++++
 gcc/gimple-range-path.cc        |   4 +-
 gcc/gimple-range.cc             |  27 +++++++-
 gcc/gimple-range.h              |   1 +
 gcc/testsuite/gcc.dg/pr104288.c |  23 +++++++
 gcc/tree-vrp.cc                 |   8 ++-
 7 files changed, 187 insertions(+), 42 deletions(-)

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index 16c881b13e1..613135266a4 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -29,6 +29,10 @@ along with GCC; see the file COPYING3.  If not see
 #include "gimple-pretty-print.h"
 #include "gimple-range.h"
 #include "tree-cfg.h"
+#include "target.h"
+#include "attribs.h"
+#include "gimple-iterator.h"
+#include "gimple-walk.h"
 
 #define DEBUG_RANGE_CACHE (dump_file					\
 			   && (param_ranger_debug & RANGER_DEBUG_CACHE))
@@ -50,6 +54,21 @@ non_null_ref::~non_null_ref ()
   m_nn.release ();
 }
 
+// This routine will update NAME in BB to be nonnull if it is not already.
+// return TRUE if the update happens.
+
+bool
+non_null_ref::set_nonnull (basic_block bb, tree name)
+{
+  gcc_checking_assert (gimple_range_ssa_p (name)
+		       && POINTER_TYPE_P (TREE_TYPE (name)));
+  // Only process when its not already set.
+  if (non_null_deref_p  (name, bb, false))
+    return false;
+  bitmap_set_bit (m_nn[SSA_NAME_VERSION (name)], bb->index);
+  return true;
+}
+
 // Return true if NAME has a non-null dereference in block bb.  If this is the
 // first query for NAME, calculate the summary first.
 // If SEARCH_DOM is true, the search the dominator tree as well.
@@ -87,35 +106,6 @@ non_null_ref::non_null_deref_p (tree name, basic_block bb, bool search_dom)
   return false;
 }
 
-// If NAME has a non-null dereference in block BB, adjust R with the
-// non-zero information from non_null_deref_p, and return TRUE.  If
-// SEARCH_DOM is true, non_null_deref_p should search the dominator tree.
-
-bool
-non_null_ref::adjust_range (irange &r, tree name, basic_block bb,
-			    bool search_dom)
-{
-  // Non-call exceptions mean we could throw in the middle of the
-  // block, so just punt on those for now.
-  if (cfun->can_throw_non_call_exceptions)
-    return false;
-
-  // We only care about the null / non-null property of pointers.
-  if (!POINTER_TYPE_P (TREE_TYPE (name)))
-    return false;
-  if (r.undefined_p () || r.lower_bound () != 0 || r.upper_bound () == 0)
-    return false;
-  // Check if pointers have any non-null dereferences.
-  if (non_null_deref_p (name, bb, search_dom))
-    {
-      // Remove zero from the range.
-      unsigned prec = TYPE_PRECISION (TREE_TYPE (name));
-      r.intersect (wi::one (prec), wi::max_value (prec, UNSIGNED));
-      return true;
-    }
-  return false;
-}
-
 // Allocate an populate the bitmap for NAME.  An ON bit for a block
 // index indicates there is a non-null reference in that block.  In
 // order to populate the bitmap, a quick run of all the immediate uses
@@ -1014,9 +1004,6 @@ ranger_cache::range_of_def (irange &r, tree name, basic_block bb)
       else
 	r = gimple_range_global (name);
     }
-
-  if (bb)
-    m_non_null.adjust_range (r, name, bb, false);
 }
 
 // Get the range of NAME as it occurs on entry to block BB.
@@ -1034,8 +1021,6 @@ ranger_cache::entry_range (irange &r, tree name, basic_block bb)
   // Otherwise pick up the best available global value.
   if (!m_on_entry.get_bb_range (r, name, bb))
     range_of_def (r, name);
-
-  m_non_null.adjust_range (r, name, bb, false);
 }
 
 // Get the range of NAME as it occurs on exit from block BB.
@@ -1089,6 +1074,9 @@ ranger_cache::range_of_expr (irange &r, tree name, gimple *stmt)
    if (gimple_range_ssa_p (expr))
     {
       exit_range (r, expr, e->src);
+      // If this is not an abnormal edge, check for a non-null exit.
+      if ((e->flags & (EDGE_EH | EDGE_ABNORMAL)) == 0)
+	m_non_null.adjust_range (r, expr, e->src, false);
       int_range_max edge_range;
       if (m_gori.outgoing_edge_range_p (edge_range, e, expr, *this))
 	r.intersect (edge_range);
@@ -1467,3 +1455,82 @@ ranger_cache::range_from_dom (irange &r, tree name, basic_block bb)
     }
   return true;
 }
+
+// This routine will update NAME in block BB to the nonnull state.
+// It will then update the on-entry cache for this block to be non-null
+// if it isn't already.
+
+void
+ranger_cache::update_to_nonnull (basic_block bb, tree name)
+{
+  tree type = TREE_TYPE (name);
+  if (gimple_range_ssa_p (name) && POINTER_TYPE_P (type))
+    {
+      m_non_null.set_nonnull (bb, name);
+      // Update the on-entry cache for BB to be non-zero.  Note this can set
+      // the on entry value in the DEF block, which can override the def.
+      int_range_max r;
+      exit_range (r, name, bb);
+      if (r.varying_p ())
+	{
+	  r.set_nonzero (type);
+	  m_on_entry.set_bb_range (name, bb, r);
+	}
+    }
+}
+
+// Adapted from infer_nonnull_range_by_dereference and check_loadstore
+// to process nonnull ssa_name OP in S.  DATA contains the ranger_cache.
+
+static bool
+non_null_loadstore (gimple *s, tree op, tree, void *data)
+{
+  if (TREE_CODE (op) == MEM_REF || TREE_CODE (op) == TARGET_MEM_REF)
+    {
+      /* Some address spaces may legitimately dereference zero.  */
+      addr_space_t as = TYPE_ADDR_SPACE (TREE_TYPE (op));
+      if (!targetm.addr_space.zero_address_valid (as))
+	{
+	  tree ssa = TREE_OPERAND (op, 0);
+	  basic_block bb = gimple_bb (s);
+	  ((ranger_cache *)data)->update_to_nonnull (bb, ssa);
+	}
+    }
+  return false;
+}
+
+// This routine is used during a block walk to move the state of non-null for
+// any operands on stmt S to nonnull.
+
+void
+ranger_cache::block_apply_nonnull (gimple *s)
+{
+  if (!flag_delete_null_pointer_checks)
+    return;
+  if (is_a<gphi *> (s))
+    return;
+  if (gimple_code (s) == GIMPLE_ASM || gimple_clobber_p (s))
+    return;
+  if (is_a<gcall *> (s))
+    {
+      tree fntype = gimple_call_fntype (s);
+      bitmap nonnullargs = get_nonnull_args (fntype);
+      // Process any non-null arguments
+      if (nonnullargs)
+	{
+	  basic_block bb = gimple_bb (s);
+	  for (unsigned i = 0; i < gimple_call_num_args (s); i++)
+	    {
+	      if (bitmap_empty_p (nonnullargs) || bitmap_bit_p (nonnullargs, i))
+		{
+		  tree op = gimple_call_arg (s, i);
+		  update_to_nonnull (bb, op);
+		}
+	    }
+	  BITMAP_FREE (nonnullargs);
+	}
+      // Fallthru and walk load/store ops now.
+    }
+  walk_stmt_load_store_ops (s, (void *)this, non_null_loadstore,
+			    non_null_loadstore);
+}
diff --git a/gcc/gimple-range-cache.h b/gcc/gimple-range-cache.h
index b54b6882aa8..589b649da26 100644
--- a/gcc/gimple-range-cache.h
+++ b/gcc/gimple-range-cache.h
@@ -36,12 +36,41 @@ public:
   bool non_null_deref_p (tree name, basic_block bb, bool search_dom = true);
   bool adjust_range (irange &r, tree name, basic_block bb,
 		     bool search_dom = true);
+  bool set_nonnull (basic_block bb, tree name);
 private:
   vec <bitmap> m_nn;
   void process_name (tree name);
   bitmap_obstack m_bitmaps;
 };
 
+// If NAME has a non-null dereference in block BB, adjust R with the
+// non-zero information from non_null_deref_p, and return TRUE.  If
+// SEARCH_DOM is true, non_null_deref_p should search the dominator tree.
+
+inline bool
+non_null_ref::adjust_range (irange &r, tree name, basic_block bb,
+			    bool search_dom)
+{
+  // Non-call exceptions mean we could throw in the middle of the
+  // block, so just punt on those for now.
+  if (cfun->can_throw_non_call_exceptions)
+    return false;
+  // We only care about the null / non-null property of pointers.
+  if (!POINTER_TYPE_P (TREE_TYPE (name)))
+    return false;
+  if (r.undefined_p () || r.lower_bound () != 0 || r.upper_bound () == 0)
+    return false;
+  // Check if pointers have any non-null dereferences.
+  if (non_null_deref_p (name, bb, search_dom))
+    {
+      // Remove zero from the range.
+      unsigned prec = TYPE_PRECISION (TREE_TYPE (name));
+      r.intersect (wi::one (prec), wi::max_value (prec, UNSIGNED));
+      return true;
+    }
+  return false;
+}
+
 // This class manages a vector of pointers to ssa_block ranges.  It
 // provides the basis for the "range on entry" cache for all
 // SSA names.
@@ -106,6 +135,8 @@ public:
 
   void propagate_updated_value (tree name, basic_block bb);
 
+  void block_apply_nonnull (gimple *s);
+  void update_to_nonnull (basic_block bb, tree name);
   non_null_ref m_non_null;
   gori_compute m_gori;
 
diff --git a/gcc/gimple-range-path.cc b/gcc/gimple-range-path.cc
index 3bf9bd1e981..483bcd2e582 100644
--- a/gcc/gimple-range-path.cc
+++ b/gcc/gimple-range-path.cc
@@ -358,7 +358,7 @@ path_range_query::range_defined_in_block (irange &r, tree name, basic_block bb)
     }
 
   if (bb)
-    m_non_null.adjust_range (r, name, bb);
+    m_non_null.adjust_range (r, name, bb, false);
 
   if (DEBUG_SOLVER && (bb || !r.varying_p ()))
     {
@@ -528,7 +528,7 @@ path_range_query::adjust_for_non_null_uses (basic_block bb)
       else
 	r.set_varying (TREE_TYPE (name));
 
-      if (m_non_null.adjust_range (r, name, bb))
+      if (m_non_null.adjust_range (r, name, bb, false))
 	set_cache (r, name);
     }
 }
diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 73398ddef99..04075a98a80 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -35,6 +35,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-scalar-evolution.h"
 #include "gimple-range.h"
 #include "gimple-fold.h"
+#include "gimple-walk.h"
 
 gimple_ranger::gimple_ranger () :
 	non_executable_edge_flag (cfun),
@@ -117,8 +118,10 @@ gimple_ranger::range_of_expr (irange &r, tree expr, gimple *stmt)
       // If name is defined in this block, try to get an range from S.
       if (def_stmt && gimple_bb (def_stmt) == bb)
 	{
-	  range_of_stmt (r, def_stmt, expr);
-	  m_cache.m_non_null.adjust_range (r, expr, bb, true);
+	  // Check for a definition override from a block walk.
+	  if (!POINTER_TYPE_P (TREE_TYPE (expr))
+	      || !m_cache.block_range (r, bb, expr, false))
+	    range_of_stmt (r, def_stmt, expr);
 	}
       // Otherwise OP comes from outside this block, use range on entry.
       else
@@ -151,7 +154,12 @@ gimple_ranger::range_on_entry (irange &r, basic_block bb, tree name)
   if (m_cache.block_range (entry_range, bb, name))
     r.intersect (entry_range);
 
-  m_cache.m_non_null.adjust_range (r, name, bb, true);
+  if (dom_info_available_p (CDI_DOMINATORS))
+    {
+      basic_block dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
+      if (dom_bb)
+	m_cache.m_non_null.adjust_range (r, name, dom_bb, true);
+    }
 
   if (idx)
     tracer.trailer (idx, "range_on_entry", true, name, r);
@@ -227,6 +235,9 @@ gimple_ranger::range_on_edge (irange &r, edge e, tree name)
   else
     {
       range_on_exit (r, e->src, name);
+      // If this is not an abnormal edge, check for a non-null exit .
+      if ((e->flags & (EDGE_EH | EDGE_ABNORMAL)) == 0)
+	m_cache.m_non_null.adjust_range (r, name, e->src, false);
       gcc_checking_assert  (r.undefined_p ()
 			    || range_compatible_p (r.type(), TREE_TYPE (name)));
 
@@ -436,6 +447,16 @@ gimple_ranger::fold_stmt (gimple_stmt_iterator *gsi, tree (*valueize) (tree))
   return ret;
 }
 
+// Called during dominator walks to register any side effects that take effect
+// from this point forward.  Current release is only for tracking non-null
+// within a block.
+
+void
+gimple_ranger::register_side_effects (gimple *s)
+{
+  m_cache.block_apply_nonnull (s);
+}
+
 // This routine will export whatever global ranges are known to GCC
 // SSA_RANGE_NAME_INFO and SSA_NAME_PTR_INFO fields.
 
diff --git a/gcc/gimple-range.h b/gcc/gimple-range.h
index ec568153a8d..0733a534853 100644
--- a/gcc/gimple-range.h
+++ b/gcc/gimple-range.h
@@ -60,6 +60,7 @@ public:
   void dump_bb (FILE *f, basic_block bb);
   auto_edge_flag non_executable_edge_flag;
   bool fold_stmt (gimple_stmt_iterator *gsi, tree (*) (tree));
+  void register_side_effects (gimple *s);
 protected:
   bool fold_range_internal (irange &r, gimple *s, tree name);
   void prefill_name (irange &r, tree name);
diff --git a/gcc/testsuite/gcc.dg/pr104288.c b/gcc/testsuite/gcc.dg/pr104288.c
new file mode 100644
index 00000000000..95eb196f9e4
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr104288.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-evrp -fdelete-null-pointer-checks" } */
+/* { dg-skip-if "" { keeps_null_pointer_checks } } */
+
+void keep(int result) __attribute__((noipa));
+void keep(int result)
+{
+    if (result)
+        __builtin_exit(0);
+}
+
+void foo (void *p) __attribute__((nonnull(1)));
+
+void bar (void *p)
+{
+  keep (p == 0);
+  foo (p);
+  if (!p)
+    __builtin_abort ();
+}
+
+/* { dg-final { scan-tree-dump-not "abort" "evrp" } } */
+/* { dg-final { scan-tree-dump-times  "== 0B;" 1 "evrp" } } */
diff --git a/gcc/tree-vrp.cc b/gcc/tree-vrp.cc
index 62946450b13..e9f19d0c8b9 100644
--- a/gcc/tree-vrp.cc
+++ b/gcc/tree-vrp.cc
@@ -4309,9 +4309,11 @@ public:
 
   bool fold_stmt (gimple_stmt_iterator *gsi) OVERRIDE
   {
-    if (m_simplifier.simplify (gsi))
-      return true;
-    return m_ranger->fold_stmt (gsi, follow_single_use_edges);
+    bool ret = m_simplifier.simplify (gsi);
+    if (!ret)
+      ret = m_ranger->fold_stmt (gsi, follow_single_use_edges);
+    m_ranger->register_side_effects (gsi_stmt (*gsi));
+    return ret;
   }
 
 private: