add power function to APInt

llvm/include/llvm/ADT/APFloat.h

@@ -1531,6 +1531,26 @@ inline APFloat abs(APFloat X) {
   return X;
 }
 
+/// Returns X^N for N >= 0.
+inline APFloat pow(const APFloat &X, int64_t N) {
+  assert(N >= 0 && "negative exponents not supported.");
+  if (N == 0) {
+    return APFloat::getOne(X.getSemantics());
+  }
+  APFloat Acc = X;
+  int64_t RemainingExponent = N;
+  while (RemainingExponent > 1) {
+    if (RemainingExponent % 2 == 0) {
+      Acc = Acc * Acc;
+      RemainingExponent /= 2;
+    } else {
+      Acc = Acc * X;
+      RemainingExponent--;
+    }
+  }
+  return Acc;
+};
+
 /// Returns the negated value of the argument.
 inline APFloat neg(APFloat X) {
   X.changeSign();

llvm/include/llvm/ADT/APInt.h

@@ -2263,6 +2263,9 @@ APInt mulhs(const APInt &C1, const APInt &C2);
 /// Returns the high N bits of the multiplication result.
 APInt mulhu(const APInt &C1, const APInt &C2);
 
+/// Compute X^N for N>0.
+APInt pow(const APInt &X, int64_t N);
+
 /// Compute GCD of two unsigned APInt values.
 ///
 /// This function returns the greatest common divisor of the two APInt values

llvm/lib/Support/APInt.cpp

@@ -3108,3 +3108,22 @@ APInt APIntOps::mulhu(const APInt &C1, const APInt &C2) {
   APInt C2Ext = C2.zext(FullWidth);
   return (C1Ext * C2Ext).extractBits(C1.getBitWidth(), C1.getBitWidth());
 }
+
+APInt APIntOps::pow(const APInt &X, int64_t N) {
+  assert(N >= 0 && "negative exponents not supported.");
+  if (N == 0) {
+    return APInt(X.getBitWidth(), 1);
+  }
+  APInt Acc = X;
+  int64_t RemainingExponent = N;
+  while (RemainingExponent > 1) {
+    if (RemainingExponent % 2 == 0) {
+      Acc = Acc * Acc;
+      RemainingExponent /= 2;
+    } else {
+      Acc = Acc * X;
+      RemainingExponent--;
+    }
+  }
+  return Acc;
+};