diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -4063,8 +4063,10 @@
   unsigned BitWidth = OpVT.getScalarSizeInBits();
 
   // Is the constant a known power of 2?
-  if (ConstantSDNode *Const = dyn_cast<ConstantSDNode>(Val))
-    return Const->getAPIntValue().zextOrTrunc(BitWidth).isPowerOf2();
+  if (ISD::matchUnaryPredicate(Val, [BitWidth](ConstantSDNode *C) {
+        return C->getAPIntValue().zextOrTrunc(BitWidth).isPowerOf2();
+      }))
+    return true;
 
   // A left-shift of a constant one will have exactly one bit set because
   // shifting the bit off the end is undefined.
@@ -4072,6 +4074,8 @@
     auto *C = isConstOrConstSplat(Val.getOperand(0));
     if (C && C->getAPIntValue() == 1)
       return true;
+    return isKnownToBeAPowerOfTwo(Val.getOperand(0), Depth + 1) &&
+           isKnownNeverZero(Val, Depth);
   }
 
   // Similarly, a logical right-shift of a constant sign-bit will have exactly
@@ -4080,8 +4084,13 @@
     auto *C = isConstOrConstSplat(Val.getOperand(0));
     if (C && C->getAPIntValue().isSignMask())
       return true;
+    return isKnownToBeAPowerOfTwo(Val.getOperand(0), Depth + 1) &&
+           isKnownNeverZero(Val, Depth);
   }
 
+  if (Val.getOpcode() == ISD::ROTL || Val.getOpcode() == ISD::ROTR)
+    return isKnownToBeAPowerOfTwo(Val.getOperand(0), Depth + 1);
+
   // Are all operands of a build vector constant powers of two?
   if (Val.getOpcode() == ISD::BUILD_VECTOR)
     if (llvm::all_of(Val->ops(), [BitWidth](SDValue E) {
@@ -4103,6 +4112,34 @@
       isKnownToBeAPowerOfTwo(Val.getOperand(0), Depth + 1))
     return true;
 
+  if (Val.getOpcode() == ISD::SMIN || Val.getOpcode() == ISD::SMAX ||
+      Val.getOpcode() == ISD::UMIN || Val.getOpcode() == ISD::UMAX)
+    return isKnownToBeAPowerOfTwo(Val.getOperand(1), Depth + 1) &&
+           isKnownToBeAPowerOfTwo(Val.getOperand(0), Depth + 1);
+
+  if (Val.getOpcode() == ISD::SELECT || Val.getOpcode() == ISD::VSELECT)
+    return isKnownToBeAPowerOfTwo(Val.getOperand(2), Depth + 1) &&
+           isKnownToBeAPowerOfTwo(Val.getOperand(1), Depth + 1);
+
+  if (Val.getOpcode() == ISD::AND) {
+    // Looking for `x & -x` pattern:
+    // If x == 0:
+    //    x & -x -> 0
+    // If x != 0:
+    //    x & -x -> non-zero pow2
+    // so if we find the pattern return whether we know `x` is non-zero.
+    for (unsigned OpIdx = 0; OpIdx < 2; ++OpIdx) {
+      SDValue NegOp = Val.getOperand(OpIdx);
+      if (NegOp.getOpcode() == ISD::SUB &&
+          NegOp.getOperand(1) == Val.getOperand(1 - OpIdx) &&
+          isNullOrNullSplat(NegOp.getOperand(0)))
+        return isKnownNeverZero(Val.getOperand(1 - OpIdx), Depth);
+    }
+  }
+
+  if (Val.getOpcode() == ISD::ZERO_EXTEND)
+    return isKnownToBeAPowerOfTwo(Val.getOperand(0), Depth + 1);
+
   // More could be done here, though the above checks are enough
   // to handle some common cases.
   return false;
diff --git a/llvm/test/CodeGen/X86/known-pow2.ll b/llvm/test/CodeGen/X86/known-pow2.ll
--- a/llvm/test/CodeGen/X86/known-pow2.ll
+++ b/llvm/test/CodeGen/X86/known-pow2.ll
@@ -50,11 +50,12 @@
 ; CHECK-LABEL: pow2_shl:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    movl %esi, %ecx
-; CHECK-NEXT:    notl %edi
+; CHECK-NEXT:    movl %edi, %eax
 ; CHECK-NEXT:    # kill: def $cl killed $cl killed $ecx
-; CHECK-NEXT:    shrl %cl, %edi
-; CHECK-NEXT:    testb $4, %dil
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    shrl %cl, %eax
+; CHECK-NEXT:    andl $4, %eax
+; CHECK-NEXT:    shrl $2, %eax
+; CHECK-NEXT:    # kill: def $al killed $al killed $eax
 ; CHECK-NEXT:    retq
   %d = shl nuw nsw i32 4, %y
   %and = and i32 %x, %d
@@ -98,12 +99,13 @@
 ; CHECK-LABEL: pow2_srl:
 ; CHECK:       # %bb.0:
 ; CHECK-NEXT:    movl %esi, %ecx
+; CHECK-NEXT:    movl %edi, %eax
 ; CHECK-NEXT:    andb $7, %cl
-; CHECK-NEXT:    notl %edi
 ; CHECK-NEXT:    # kill: def $cl killed $cl killed $ecx
-; CHECK-NEXT:    shll %cl, %edi
-; CHECK-NEXT:    testl $1048576, %edi # imm = 0x100000
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    shll %cl, %eax
+; CHECK-NEXT:    shrl $20, %eax
+; CHECK-NEXT:    andl $1, %eax
+; CHECK-NEXT:    # kill: def $al killed $al killed $eax
 ; CHECK-NEXT:    retq
   %yy = and i32 %y, 7
   %d = lshr i32 1048576, %yy
@@ -155,9 +157,8 @@
 ; CHECK-NEXT:    movl $1048576, %eax # imm = 0x100000
 ; CHECK-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; CHECK-NEXT:    roll %cl, %eax
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %edi, %eax
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %eax, %edi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %d = call i32 @llvm.fshl.i32(i32 1048576, i32 1048576, i32 %y)
   %and = and i32 %x, %d
@@ -207,9 +208,8 @@
 ; CHECK-NEXT:    movl $1048576, %eax # imm = 0x100000
 ; CHECK-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; CHECK-NEXT:    rorl %cl, %eax
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %edi, %eax
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %eax, %edi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %d = call i32 @llvm.fshr.i32(i32 1048576, i32 1048576, i32 %y)
   %and = and i32 %x, %d
@@ -262,9 +262,8 @@
 ; CHECK-NEXT:    cmpl $262144, %eax # imm = 0x40000
 ; CHECK-NEXT:    movl $262144, %ecx # imm = 0x40000
 ; CHECK-NEXT:    cmovbl %eax, %ecx
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %edi, %ecx
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %ecx, %edi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %yy = shl i32 1, %y
   %d = call i32 @llvm.umin.i32(i32 %yy, i32 262144)
@@ -327,9 +326,8 @@
 ; CHECK-NEXT:    shrl %cl, %esi
 ; CHECK-NEXT:    cmpl %esi, %eax
 ; CHECK-NEXT:    cmoval %eax, %esi
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %edi, %esi
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %esi, %edi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %yy = shl i32 1, %y
   %zz = lshr i32 2147483648, %z
@@ -397,9 +395,8 @@
 ; CHECK-NEXT:    cmpl $262144, %eax # imm = 0x40000
 ; CHECK-NEXT:    movl $262144, %ecx # imm = 0x40000
 ; CHECK-NEXT:    cmovll %eax, %ecx
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %edi, %ecx
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %ecx, %edi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %yy = shl i32 1, %y
   %d = call i32 @llvm.smin.i32(i32 %yy, i32 262144)
@@ -462,9 +459,8 @@
 ; CHECK-NEXT:    shrl %cl, %esi
 ; CHECK-NEXT:    cmpl %esi, %eax
 ; CHECK-NEXT:    cmovgl %eax, %esi
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %edi, %esi
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %esi, %edi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %yy = shl i32 1, %y
   %zz = lshr i32 2147483648, %z
@@ -535,9 +531,8 @@
 ; CHECK-NEXT:    shrl %cl, %r8d
 ; CHECK-NEXT:    testb $1, %dil
 ; CHECK-NEXT:    cmovnel %edx, %r8d
-; CHECK-NEXT:    notl %esi
-; CHECK-NEXT:    testl %esi, %r8d
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %r8d, %esi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %yy = shl i32 1, %y
   %zz = lshr i32 2147483648, %z
@@ -624,8 +619,11 @@
 ; CHECK-NEXT:    pand %xmm0, %xmm2
 ; CHECK-NEXT:    pandn %xmm7, %xmm0
 ; CHECK-NEXT:    por %xmm2, %xmm0
-; CHECK-NEXT:    pand %xmm0, %xmm1
+; CHECK-NEXT:    pcmpeqd %xmm2, %xmm2
+; CHECK-NEXT:    pand %xmm1, %xmm0
+; CHECK-NEXT:    pxor %xmm1, %xmm1
 ; CHECK-NEXT:    pcmpeqd %xmm1, %xmm0
+; CHECK-NEXT:    pxor %xmm2, %xmm0
 ; CHECK-NEXT:    retq
   %yy = shl <4 x i32> <i32 1, i32 1, i32 1, i32 1>, %y
   %zz = lshr <4 x i32> <i32 2147483648, i32 2147483648, i32 2147483648, i32 2147483648>, %z
@@ -662,10 +660,9 @@
 ; CHECK-NEXT:    pand %xmm0, %xmm2
 ; CHECK-NEXT:    pandn %xmm7, %xmm0
 ; CHECK-NEXT:    por %xmm2, %xmm0
-; CHECK-NEXT:    pcmpeqd %xmm2, %xmm2
-; CHECK-NEXT:    pand %xmm0, %xmm1
+; CHECK-NEXT:    pand %xmm1, %xmm0
+; CHECK-NEXT:    pxor %xmm1, %xmm1
 ; CHECK-NEXT:    pcmpeqd %xmm1, %xmm0
-; CHECK-NEXT:    pxor %xmm2, %xmm0
 ; CHECK-NEXT:    retq
   %yy = shl <4 x i32> <i32 1, i32 1, i32 1, i32 1>, %y
   %zz = lshr <4 x i32> <i32 2147483648, i32 2147483648, i32 2147483648, i32 2147483648>, %z
@@ -772,9 +769,8 @@
 ; CHECK-NEXT:    movl %eax, %ecx
 ; CHECK-NEXT:    negl %ecx
 ; CHECK-NEXT:    andl %eax, %ecx
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    testl %edi, %ecx
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    testl %ecx, %edi
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %yy = shl nuw nsw i32 4, %y
   %nyy = sub i32 0, %yy
@@ -854,10 +850,9 @@
 ; CHECK-NEXT:    movl $4, %eax
 ; CHECK-NEXT:    # kill: def $cl killed $cl killed $ecx
 ; CHECK-NEXT:    shll %cl, %eax
-; CHECK-NEXT:    notl %edi
-; CHECK-NEXT:    andl %eax, %edi
-; CHECK-NEXT:    testl $65535, %edi # imm = 0xFFFF
-; CHECK-NEXT:    sete %al
+; CHECK-NEXT:    andl %edi, %eax
+; CHECK-NEXT:    testl $65535, %eax # imm = 0xFFFF
+; CHECK-NEXT:    setne %al
 ; CHECK-NEXT:    retq
   %dd = shl nuw nsw i16 4, %y
   %d = zext i16 %dd to i32