From 61dd8dab1f0b349fb4124cfd8e2a11a161f13e4a Mon Sep 17 00:00:00 2001
From: Eric Botcazou <ebotcazou@adacore.com>
Date: Tue, 10 Nov 2020 10:26:35 +0100
Subject: [PATCH] Fix wrong code for boolean negation in condition at -O2

The problem is the bitwise/logical dichotomy for operators and the
transition from the former to the latter for boolean types: if they
are 1-bit, that's straightforward but, if they are larger, then you
need to be careful because you cannot, on the one hand, turn a bitwise
AND into a logical AND and, on the other hand, *not* turn e.g. a
bitwise NOT into a logical NOT if they occur in the same computation,
as the first change will drop the masking that may need to be applied
after the bitwise NOT if it is not also changed.

Given that the ranger turns bitwise AND/OR into logical AND/OR for
booleans,  the patch does the same for bitwise NOT.

gcc/ChangeLog:
	* range-op.cc (operator_logical_not::fold_range): Tidy up.
	(operator_logical_not::op1_range): Call above method.
	(operator_bitwise_not::fold_range): If the type is compatible
	with boolean, call op_logical_not.fold_range.
	(operator_bitwise_not::op1_range): If the type is compatible
	with boolean, call op_logical_not.op1_range.

gcc/testsuite/ChangeLog:
	* gnat.dg/opt88.adb: New test.
---
 gcc/range-op.cc                 | 28 +++++++++---------
 gcc/testsuite/gnat.dg/opt88.adb | 52 +++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+), 14 deletions(-)
 create mode 100644 gcc/testsuite/gnat.dg/opt88.adb

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index bbb2a61ae35..aff9383d936 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -2706,27 +2706,21 @@ operator_logical_not::fold_range (irange &r, tree type,
   if (empty_range_varying (r, type, lh, rh))
     return true;
 
-  if (lh.varying_p () || lh.undefined_p ())
-    r = lh;
-  else
-    {
-      r = lh;
-      r.invert ();
-    }
-  gcc_checking_assert (lh.type() == type);
+  r = lh;
+  if (!lh.varying_p () && !lh.undefined_p ())
+    r.invert ();
+
   return true;
 }
 
 bool
 operator_logical_not::op1_range (irange &r,
-				 tree type ATTRIBUTE_UNUSED,
+				 tree type,
 				 const irange &lhs,
-				 const irange &op2 ATTRIBUTE_UNUSED) const
+				 const irange &op2) const
 {
-  r = lhs;
-  if (!lhs.varying_p () && !lhs.undefined_p ())
-    r.invert ();
-  return true;
+  // Logical NOT is involutary...do it again.
+  return fold_range (r, type, lhs, op2);
 }
 
 
@@ -2749,6 +2743,9 @@ operator_bitwise_not::fold_range (irange &r, tree type,
   if (empty_range_varying (r, type, lh, rh))
     return true;
 
+  if (types_compatible_p (type, boolean_type_node))
+    return op_logical_not.fold_range (r, type, lh, rh);
+
   // ~X is simply -1 - X.
   int_range<1> minusone (type, wi::minus_one (TYPE_PRECISION (type)),
 			 wi::minus_one (TYPE_PRECISION (type)));
@@ -2761,6 +2758,9 @@ operator_bitwise_not::op1_range (irange &r, tree type,
 				 const irange &lhs,
 				 const irange &op2) const
 {
+  if (types_compatible_p (type, boolean_type_node))
+    return op_logical_not.op1_range (r, type, lhs, op2);
+
   // ~X is -1 - X and since bitwise NOT is involutary...do it again.
   return fold_range (r, type, lhs, op2);
 }
diff --git a/gcc/testsuite/gnat.dg/opt88.adb b/gcc/testsuite/gnat.dg/opt88.adb
new file mode 100644
index 00000000000..a6abd018611
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/opt88.adb
@@ -0,0 +1,52 @@
+-- { dg-do run }
+-- { dg-options "-O -ftree-vrp -fno-inline" }
+
+procedure Opt88 is
+
+  Val : Integer := 1;
+
+  procedure Dummy (B : out Boolean) is
+  begin
+    B := True;
+  end;
+
+  function Test return Boolean is
+  begin
+    return False;
+  end;
+
+  procedure Do_It (OK : out Boolean) is
+
+    Blue : Boolean := False;
+    Red  : Boolean := False;
+
+  begin
+    OK := True;
+    Blue := True;
+    Dummy (Red);
+
+    if Red then
+      Red := False;
+
+      if Test then
+        Dummy (Red);
+      end if;
+    end if;
+
+    if Blue and not Red then
+      Val := 0;
+    end if;
+
+    if Red then
+      OK := False;
+    end if;
+  end;
+
+  OK : Boolean;
+
+begin
+  Do_It (OK);
+  if not OK then
+    raise Program_Error;
+  end if;
+end;
-- 
2.30.2