1 files changed, 21 insertions, 0 deletions
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index a6ad6bf8cae..6f0196069f2 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1506,6 +1506,27 @@ static void computeKnownBitsFromOperator(const Operator *I, KnownBits &Known,
         // of bits which might be set provided by popcnt KnownOne2.
         break;
       }
+      case Intrinsic::fshr:
+      case Intrinsic::fshl: {
+        const APInt *SA;
+        if (!match(I->getOperand(2), m_APInt(SA)))
+          break;
+
+        // Normalize to funnel shift left.
+        uint64_t ShiftAmt = SA->urem(BitWidth);
+        if (II->getIntrinsicID() == Intrinsic::fshr)
+          ShiftAmt = BitWidth - ShiftAmt;
+
+        KnownBits Known3(Known);
+        computeKnownBits(I->getOperand(0), Known2, Depth + 1, Q);
+        computeKnownBits(I->getOperand(1), Known3, Depth + 1, Q);
+
+        Known.Zero =
+            Known2.Zero.shl(ShiftAmt) | Known3.Zero.lshr(BitWidth - ShiftAmt);
+        Known.One =
+            Known2.One.shl(ShiftAmt) | Known3.One.lshr(BitWidth - ShiftAmt);
+        break;
+      }
       case Intrinsic::x86_sse42_crc32_64_64:
         Known.Zero.setBitsFrom(32);
         break;