ADDITIONAL SYSTEM INFORMATION :
Windows 11 [Version 10.0.26100.2894]
JDK 21.0.6, 23.0.2, 24-ea+35, 25-ea+8

A DESCRIPTION OF THE PROBLEM :
Use numberOfLeadingZeros inside a short loop.
Use arrays for input, output, or both.
Access arrays sequentially.
Do not use branching statements such as if statements within the loop.
A certain number of loops (hundreds of thousands of times?).
Under these conditions, it may return a number that is 1 less at the boundary where the value changes.
Could the Intrinsic of Integer.numberOfLeadingZeros be causing the problem?

0x01FFFFFF: expected=7, actual=6
0x03FFFFFE-0x03FFFFFF: expected=6, actual=5
0x07FFFFFC-0x07FFFFFF: expected=5, actual=4
0x0FFFFFF8-0x0FFFFFFF: expected=4, actual=3
0x1FFFFFF0-0x1FFFFFFF: expected=3, actual=2
0x3FFFFFE0-0x3FFFFFFF: expected=2, actual=1

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
var out = new int[0x2000004];
for (int i = 0; i < out.length; i++)
out[i] = Integer.numberOfLeadingZeros(i);
System.out.println(out[0x1FFFFFF]);


---------- BEGIN SOURCE ----------
public class Main {
public static void main(String[] args) {
arrayOutput(0x01000000, 0x02000004);
arrayOutput(0x03000000, 0x04000004);
arrayOutput(0x07000000, 0x08000004);
arrayOutput(0x0F000000, 0x10000004);
arrayOutput(0x1F000000, 0x20000004);
arrayOutput(0x3F000000, 0x40000004);
System.out.println();

for (int loop = 0; loop < 5; loop++) {
arrayInput(0x200000);
}
}

static void arrayOutput(int from, int to) {
var output = new int[to - from];
for (int i = from; i < to; i++) {
output[i - from] = Integer.numberOfLeadingZeros(i);
}

for (int i = from; i < to; i++) {
int nlz = Integer.numberOfLeadingZeros(i);
if (nlz != output[i - from]) {
System.out.printf("0x%08X: expected=%d actual=%d%n", i, nlz, output[i - from]);
}
}
}

static void arrayInput(int size) {
int expected = 0;
for (int i = 0; i < size; i++)
expected += Integer.numberOfLeadingZeros(-1 >>> i);

var input = new int[size];
java.util.Arrays.setAll(input, i -> -1 >>> i);
int actual = 0;
for (int i = 0; i < size; i++)
actual += Integer.numberOfLeadingZeros(input[i]);

System.out.printf("expected=%d, actual=%d%n", expected, actual);
}
}
---------- END SOURCE ----------