[ValueTracking] Implement computeKnownBits for llvm.vector.reduce.{or,and}

Author: goldsteinn

llvm/lib/Analysis/ValueTracking.cpp

@@ -1624,8 +1624,10 @@ static void computeKnownBitsFromOperator(const Operator *I,
         computeKnownBits(I->getOperand(1), Known2, Depth + 1, Q);
         Known = KnownBits::ssub_sat(Known, Known2);
         break;
-        // for min/max reduce, any bit common to each element in the input vec
-        // is set in the output.
+        // for min/max/and/or reduce, any bit common to each element in the
+        // input vec is set in the output.
+      case Intrinsic::vector_reduce_and:
+      case Intrinsic::vector_reduce_or:
       case Intrinsic::vector_reduce_umax:
       case Intrinsic::vector_reduce_umin:
       case Intrinsic::vector_reduce_smax:

llvm/test/Transforms/InstCombine/known-bits.ll

@@ -1197,10 +1197,7 @@ define i1 @extract_value_smul_fail(i8 %xx, i8 %yy) {
 
 define i8 @known_reduce_or(<2 x i8> %xx) {
 ; CHECK-LABEL: @known_reduce_or(
-; CHECK-NEXT:    [[X:%.*]] = or <2 x i8> [[XX:%.*]], <i8 5, i8 3>
-; CHECK-NEXT:    [[V:%.*]] = call i8 @llvm.vector.reduce.or.v2i8(<2 x i8> [[X]])
-; CHECK-NEXT:    [[R:%.*]] = and i8 [[V]], 1
-; CHECK-NEXT:    ret i8 [[R]]
+; CHECK-NEXT:    ret i8 1
 ;
   %x = or <2 x i8> %xx, <i8 5, i8 3>
   %v = call i8 @llvm.vector.reduce.or(<2 x i8> %x)
@@ -1223,10 +1220,7 @@ define i8 @known_reduce_or_fail(<2 x i8> %xx) {
 
 define i8 @known_reduce_and(<2 x i8> %xx) {
 ; CHECK-LABEL: @known_reduce_and(
-; CHECK-NEXT:    [[X:%.*]] = or <2 x i8> [[XX:%.*]], <i8 5, i8 3>
-; CHECK-NEXT:    [[V:%.*]] = call i8 @llvm.vector.reduce.or.v2i8(<2 x i8> [[X]])
-; CHECK-NEXT:    [[R:%.*]] = and i8 [[V]], 1
-; CHECK-NEXT:    ret i8 [[R]]
+; CHECK-NEXT:    ret i8 1
 ;
   %x = or <2 x i8> %xx, <i8 5, i8 3>
   %v = call i8 @llvm.vector.reduce.or(<2 x i8> %x)