[Support] Add KnownBits::concat method

Add a method for the various cases where we need to concatenate 2 KnownBits together (BUILD_PAIR and SHIFT_PARTS in particular) - uses the existing APInt::concat 'HiBits.concat(LoBits)' convention

Differential Revision: https://reviews.llvm.org/D130557

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/unittests/Support/KnownBitsTest.cpp b/llvm/unittests/Support/KnownBitsTest.cpp
index 04c1d7c..1d609e9 100644
--- a/llvm/unittests/Support/KnownBitsTest.cpp
+++ b/llvm/unittests/Support/KnownBitsTest.cpp
@@ -508,4 +508,29 @@ TEST(KnownBitsTest, CommonBitsSet) {
   });
 }
 
+TEST(KnownBitsTest, ConcatBits) {
+  unsigned Bits = 4;
+  for (unsigned LoBits = 1; LoBits < Bits; ++LoBits) {
+    unsigned HiBits = Bits - LoBits;
+    ForeachKnownBits(LoBits, [&](const KnownBits &KnownLo) {
+      ForeachKnownBits(HiBits, [&](const KnownBits &KnownHi) {
+        KnownBits KnownAll = KnownHi.concat(KnownLo);
+
+        EXPECT_EQ(KnownLo.countMinPopulation() + KnownHi.countMinPopulation(),
+                  KnownAll.countMinPopulation());
+        EXPECT_EQ(KnownLo.countMaxPopulation() + KnownHi.countMaxPopulation(),
+                  KnownAll.countMaxPopulation());
+
+        KnownBits ExtractLo = KnownAll.extractBits(LoBits, 0);
+        KnownBits ExtractHi = KnownAll.extractBits(HiBits, LoBits);
+
+        EXPECT_EQ(KnownLo.One.getZExtValue(), ExtractLo.One.getZExtValue());
+        EXPECT_EQ(KnownHi.One.getZExtValue(), ExtractHi.One.getZExtValue());
+        EXPECT_EQ(KnownLo.Zero.getZExtValue(), ExtractLo.Zero.getZExtValue());
+        EXPECT_EQ(KnownHi.Zero.getZExtValue(), ExtractHi.Zero.getZExtValue());
+      });
+    });
+  }
+}
+
 } // end anonymous namespace