[llvm] ecb9d94 - [KnownBits] Speed up conflict handling in ForeachKnownBits in unit test. (#94943)

[via llvm-commits]

Author: Jay Foad
Date: 2024-06-10T11:03:18+01:00
New Revision: ecb9d94a8bfb07591fdfcf3418c5cfafcad5a13d

URL: https://github.com/llvm/llvm-project/commit/ecb9d94a8bfb07591fdfcf3418c5cfafcad5a13d
DIFF: https://github.com/llvm/llvm-project/commit/ecb9d94a8bfb07591fdfcf3418c5cfafcad5a13d.diff

LOG: [KnownBits] Speed up conflict handling in ForeachKnownBits in unit test. (#94943)

Exit early if known bits have a conflict. This gives me a ~15% speed up
when running this in my Release+Asserts build:

$ unittests/Support/SupportTests
--gtest_filter=KnownBitsTest.*Exhaustive

Added: 
    

Modified: 
    llvm/unittests/Support/KnownBitsTest.h

Removed: 
    


################################################################################
diff  --git a/llvm/unittests/Support/KnownBitsTest.h b/llvm/unittests/Support/KnownBitsTest.h
index 974051891d48e..807ce31381efb 100644
--- a/llvm/unittests/Support/KnownBitsTest.h
+++ b/llvm/unittests/Support/KnownBitsTest.h
@@ -38,6 +38,12 @@ void ForeachNumInKnownBits(const KnownBits &Known, FnTy Fn) {
   unsigned Max = 1u << Bits;
   unsigned Zero = Known.Zero.getZExtValue();
   unsigned One = Known.One.getZExtValue();
+
+  if (Zero & One) {
+    // Known has a conflict. No values will satisfy it.
+    return;
+  }
+
   for (unsigned N = 0; N < Max; ++N) {
     if ((N & Zero) == 0 && (~N & One) == 0)
       Fn(APInt(Bits, N));