[gcc r11-9543] Range on entry should only check dominators for non-null.

[gcc r11-9543] Range on entry should only check dominators for non-null.

[Andrew Macleod]

https://gcc.gnu.org/g:ed35d4205e8c139d27d3d47c528aaa9f82f0ac1b

commit r11-9543-ged35d4205e8c139d27d3d47c528aaa9f82f0ac1b
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Mon Jan 31 11:37:16 2022 -0500

    Range on entry should only check dominators for non-null.
    
    Range-on-entry checks should no check the state of non-null within the current
    block.   If dominators are present, use the dominator.
    
            PR tree-optimization/104288
            gcc/
            * gimple-range-cache.cc (ssa_range_in_bb): Only use non-null from the
            dominator entry ranges.
            * gimple-range.cc (gimple_ranger::range_of_expr): Ditto.
            gcc/testsuite/
            * gcc.dg/pr104288.c: New.

Diff:
---
 gcc/gimple-range-cache.cc       | 19 ++++++++++++-------
 gcc/gimple-range.cc             | 16 ++++++++++------
 gcc/testsuite/gcc.dg/pr104288.c | 23 +++++++++++++++++++++++
 3 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/gcc/gimple-range-cache.cc b/gcc/gimple-range-cache.cc
index 6ddeca3766d..b05b804d513 100644
--- a/gcc/gimple-range-cache.cc
+++ b/gcc/gimple-range-cache.cc
@@ -905,14 +905,19 @@ ranger_cache::ssa_range_in_bb (irange &r, tree name, basic_block bb)
       // Try to pick up any known global value as a best guess for now.
       if (!m_globals.get_global_range (r, name))
 	r = gimple_range_global (name);
+      // Check for non-null on entry if dominators are available by
+      // resetting def_bb to the block we want to search.
+      if (dom_info_available_p (CDI_DOMINATORS))
+	{
+	  basic_block dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
+	  // Check if pointers have any non-null dereferences.  Non-call
+	  // exceptions mean we could throw in the middle of the block, so just
+	  // punt for now on those.
+	  if (dom_bb && r.varying_p () && !cfun->can_throw_non_call_exceptions
+	      && m_non_null.non_null_deref_p (name, dom_bb))
+	    r = range_nonzero (TREE_TYPE (name));
+	}
     }
-
-  // Check if pointers have any non-null dereferences.  Non-call
-  // exceptions mean we could throw in the middle of the block, so just
-  // punt for now on those.
-  if (r.varying_p () && m_non_null.non_null_deref_p (name, bb) &&
-      !cfun->can_throw_non_call_exceptions)
-    r = range_nonzero (TREE_TYPE (name));
 }
 
 // Return a static range for NAME on entry to basic block BB in R.  If
diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index f861459ed96..42c637458ad 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -979,10 +979,14 @@ 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);
-  else
-    // Otherwise OP comes from outside this block, use range on entry.
-    range_on_entry (r, bb, expr);
+    return range_of_stmt (r, def_stmt, expr);
+
+  // Otherwise OP comes from outside this block, use range on entry.
+  range_on_entry (r, bb, expr);
+  // Check for non-null in the predecessor if dominators are available.
+  if (!dom_info_available_p (CDI_DOMINATORS))
+    return true;
+  basic_block dom_bb = get_immediate_dominator (CDI_DOMINATORS, bb);
 
   // No range yet, see if there is a dereference in the block.
   // We don't care if it's between the def and a use within a block
@@ -992,8 +996,8 @@ gimple_ranger::range_of_expr (irange &r, tree expr, gimple *stmt)
   // in which case we may need to walk from S back to the def/top of block
   // to make sure the deref happens between S and there before claiming
   // there is a deref.   Punt for now.
-  if (!cfun->can_throw_non_call_exceptions && r.varying_p () &&
-      m_cache.m_non_null.non_null_deref_p (expr, bb))
+  if (dom_bb && !cfun->can_throw_non_call_exceptions && r.varying_p ()
+      && m_cache.m_non_null.non_null_deref_p (expr, dom_bb))
     r = range_nonzero (TREE_TYPE (expr));
 
   return true;
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" } } */