commit 47923622c663ffad8b14aa93706183290d4f6791
Author: Andrew MacLeod <amacleod@redhat.com>
Date:   Thu Nov 12 11:53:52 2020 -0500

    Cleanup range of address calculations.
    
    Align EVRP and ranger for how ranges of ADDR_EXPR are calculated.
    
            gcc/
            * gimple-range.cc: (gimple_ranger::range_of_range_op): Check for
            ADDR_EXPR and call range_of_address.
            (gimple_ranger::range_of_address): Rename from
            range_of_non_trivial_assignment and match vrp_stmt_computes_nonzero.
            * gimple-range.h: (range_of_address): Renamed.
            * range-op.cc: (pointer_table): Add INTEGER_CST handler.
            gcc/testsuite/
            * gcc.dg/tree-ssa/pr78655.c: New.

diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 92a6335bec5..4f5d5024fa9 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -431,8 +431,9 @@ gimple_ranger::range_of_range_op (irange &r, gimple *s)
       m_cache.register_dependency (lhs, op2);
     }
 
-  if (range_of_non_trivial_assignment (r, s))
-    return true;
+  if (gimple_code (s) == GIMPLE_ASSIGN
+      && gimple_assign_rhs_code (s) == ADDR_EXPR)
+    return range_of_address (r, s);
 
   if (range_of_expr (range1, op1, s))
     {
@@ -446,48 +447,84 @@ gimple_ranger::range_of_range_op (irange &r, gimple *s)
   return true;
 }
 
-// Calculate the range of a non-trivial assignment.  That is, is one
-// inolving arithmetic on an SSA name (for example, an ADDR_EXPR).
+// Calculate the range of an assignment containing an ADDR_EXPR.
 // Return the range in R.
-//
-// If a range cannot be calculated, return false.
+// If a range cannot be calculated, set it to VARYING and return true.
 
 bool
-gimple_ranger::range_of_non_trivial_assignment (irange &r, gimple *stmt)
+gimple_ranger::range_of_address (irange &r, gimple *stmt)
 {
-  if (gimple_code (stmt) != GIMPLE_ASSIGN)
-    return false;
+  gcc_checking_assert (gimple_code (stmt) == GIMPLE_ASSIGN);
+  gcc_checking_assert (gimple_assign_rhs_code (stmt) == ADDR_EXPR);
 
-  tree base = gimple_range_base_of_assignment (stmt);
-  if (base)
+  bool strict_overflow_p;
+  tree expr = gimple_assign_rhs1 (stmt);
+  poly_int64 bitsize, bitpos;
+  tree offset;
+  machine_mode mode;
+  int unsignedp, reversep, volatilep;
+  tree base = get_inner_reference (TREE_OPERAND (expr, 0), &bitsize,
+				   &bitpos, &offset, &mode, &unsignedp,
+				   &reversep, &volatilep);
+
+
+  if (base != NULL_TREE
+      && TREE_CODE (base) == MEM_REF
+      && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
     {
-      if (TREE_CODE (base) == MEM_REF)
+      tree ssa = TREE_OPERAND (base, 0);
+      gcc_checking_assert (irange::supports_type_p (TREE_TYPE (ssa)));
+      range_of_expr (r, ssa, stmt);
+      range_cast (r, TREE_TYPE (gimple_assign_rhs1 (stmt)));
+
+      poly_offset_int off = 0;
+      bool off_cst = false;
+      if (offset == NULL_TREE || TREE_CODE (offset) == INTEGER_CST)
 	{
-	  if (TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
-	    {
-	      int_range_max range1;
-	      tree ssa = TREE_OPERAND (base, 0);
-	      if (range_of_expr (range1, ssa, stmt))
-		{
-		  tree type = TREE_TYPE (ssa);
-		  range_operator *op = range_op_handler (POINTER_PLUS_EXPR,
-							 type);
-		  int_range<2> offset (TREE_OPERAND (base, 1),
-				       TREE_OPERAND (base, 1));
-		  op->fold_range (r, type, range1, offset);
-		  return true;
-		}
-	    }
-	  return false;
+	  off = mem_ref_offset (base);
+	  if (offset)
+	    off += poly_offset_int::from (wi::to_poly_wide (offset),
+					  SIGNED);
+	  off <<= LOG2_BITS_PER_UNIT;
+	  off += bitpos;
+	  off_cst = true;
 	}
-      if (gimple_assign_rhs_code (stmt) == ADDR_EXPR)
+      /* If &X->a is equal to X, the range of X is the result.  */
+      if (off_cst && known_eq (off, 0))
+	  return true;
+      else if (flag_delete_null_pointer_checks
+	       && !TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr)))
+	{
+	 /* For -fdelete-null-pointer-checks -fno-wrapv-pointer we don't
+	 allow going from non-NULL pointer to NULL.  */
+	   if(!range_includes_zero_p (&r))
+	    return true;
+	}
+      /* If MEM_REF has a "positive" offset, consider it non-NULL
+	 always, for -fdelete-null-pointer-checks also "negative"
+	 ones.  Punt for unknown offsets (e.g. variable ones).  */
+      if (!TYPE_OVERFLOW_WRAPS (TREE_TYPE (expr))
+	  && off_cst
+	  && known_ne (off, 0)
+	  && (flag_delete_null_pointer_checks || known_gt (off, 0)))
 	{
-	  // Handle "= &a"  and return non-zero.
 	  r = range_nonzero (TREE_TYPE (gimple_assign_rhs1 (stmt)));
 	  return true;
 	}
+      r = int_range<2> (TREE_TYPE (gimple_assign_rhs1 (stmt)));
+      return true;
     }
-  return false;
+
+  // Handle "= &a".
+  if (tree_single_nonzero_warnv_p (expr, &strict_overflow_p))
+    {
+      r = range_nonzero (TREE_TYPE (gimple_assign_rhs1 (stmt)));
+      return true;
+    }
+
+  // Otherwise return varying.
+  r = int_range<2> (TREE_TYPE (gimple_assign_rhs1 (stmt)));
+  return true;
 }
 
 // Calculate a range for phi statement S and return it in R.
diff --git a/gcc/gimple-range.h b/gcc/gimple-range.h
index 88d2ada324b..dde41e9e743 100644
--- a/gcc/gimple-range.h
+++ b/gcc/gimple-range.h
@@ -62,7 +62,7 @@ protected:
   ranger_cache m_cache;
 private:
   bool range_of_phi (irange &r, gphi *phi);
-  bool range_of_non_trivial_assignment (irange &r, gimple *s);
+  bool range_of_address (irange &r, gimple *s);
   bool range_of_builtin_call (irange &r, gcall *call);
   bool range_with_loop_info (irange &r, tree name);
   void range_of_ssa_name_with_loop_info (irange &, tree, class loop *,
diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 86d1af7fe54..b746aadb603 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -3328,6 +3328,7 @@ pointer_table::pointer_table ()
   set (GT_EXPR, op_gt);
   set (GE_EXPR, op_ge);
   set (SSA_NAME, op_identity);
+  set (INTEGER_CST, op_integer_cst);
   set (ADDR_EXPR, op_addr);
   set (NOP_EXPR, op_convert);
   set (CONVERT_EXPR, op_convert);
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr78655.c b/gcc/testsuite/gcc.dg/tree-ssa/pr78655.c
new file mode 100644
index 00000000000..e9158e07268
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr78655.c
@@ -0,0 +1,37 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fno-tree-ccp -fno-tree-forwprop -fno-tree-fre -fdump-tree-evrp" } */
+
+struct A{int a,b;};
+inline int*f1(struct A*p){return&p->a;}   /* offset of 0.  */
+inline int*f2(struct A*p){return&p->b;}   /* Offset of non-zero.  */
+inline int*g(struct A*p){return(int*)p+1;} /* Always non-zero offet.  */
+
+/* Should be able to eliminate all calls to bad().  */
+ 
+void bad(void);
+
+int
+main() 
+{
+  struct A* ptr = 0;
+  struct A addr;
+
+  if (f1 (ptr) != 0)
+    bad();
+  if (f1 (&addr) == 0)
+    bad();
+
+  if (f2 (ptr) == 0)
+    bad();
+  if (f2 (&addr) == 0)
+    bad();
+    
+  if (g (ptr) == 0)
+    bad();
+  if (g (&addr) == 0)
+    bad();
+  
+}
+
+/* { dg-final { scan-tree-dump-not "bad" "evrp"} } */
+
