[llvm] d4bfc14 - [KnownBits] Check for conflict-freedom in exhaustive tests

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-05-24T10:34:44+02:00
New Revision: d4bfc144eaa6e34eafaab1e8574421ebd2bb78ed

URL: https://github.com/llvm/llvm-project/commit/d4bfc144eaa6e34eafaab1e8574421ebd2bb78ed
DIFF: https://github.com/llvm/llvm-project/commit/d4bfc144eaa6e34eafaab1e8574421ebd2bb78ed.diff

LOG: [KnownBits] Check for conflict-freedom in exhaustive tests

And make sure udiv() Exact does not produce conflicts.

Added: 
    

Modified: 
    llvm/lib/Support/KnownBits.cpp
    llvm/unittests/Support/KnownBitsTest.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Support/KnownBits.cpp b/llvm/lib/Support/KnownBits.cpp
index 1a5f1ad4cf03e..13d79a389fd6a 100644
--- a/llvm/lib/Support/KnownBits.cpp
+++ b/llvm/lib/Support/KnownBits.cpp
@@ -839,6 +839,8 @@ KnownBits KnownBits::udiv(const KnownBits &LHS, const KnownBits &RHS,
       Known.Zero.setBit(0);
     // Odd / Even -> impossible
     // Even / Even -> unknown
+    if (Known.hasConflict())
+      Known.setAllZero();
   }
 
   return Known;

diff  --git a/llvm/unittests/Support/KnownBitsTest.cpp b/llvm/unittests/Support/KnownBitsTest.cpp
index 457b7c8a5af14..1607ddfdec502 100644
--- a/llvm/unittests/Support/KnownBitsTest.cpp
+++ b/llvm/unittests/Support/KnownBitsTest.cpp
@@ -79,6 +79,7 @@ static void testUnaryOpExhaustive(
       }
     });
 
+    EXPECT_TRUE(!Computed.hasConflict());
     EXPECT_TRUE(isCorrect(Exact, Computed, Known));
     // We generally don't want to return conflicting known bits, even if it is
     // legal for always poison results.
@@ -110,6 +111,7 @@ static void testBinaryOpExhaustive(
         });
       });
 
+      EXPECT_TRUE(!Computed.hasConflict());
       EXPECT_TRUE(isCorrect(Exact, Computed, {Known1, Known2}));
       // We generally don't want to return conflicting known bits, even if it is
       // legal for always poison results.