The opcode is not the handler
The same loop ran 23% faster with int parameters, and only with OPcache on. Operand classes pick a handler when the file compiles; proven types pick a different one.
Tags
benchmarking
7 posts
Appending to a string is free until someone else holds it
The same .= statement took 0.269 ms and 218.836 ms in two loops that differ by one assignment. What a zend_string costs, where literals live, and why implode is not the fix.
A property hook emits the same opcode as a plain property
Plain, backed and virtual property reads compile to one identical FETCH_OBJ_R. What separates them is a function call the opcode does not show, measured at nine times.
A declared property is cheaper than an array key
One hundred thousand four-field records cost 143.54 bytes each as objects and 397.14 as associative arrays. Where the crossover is, and what one undeclared property costs.
A by-reference foreach leaves a reference in every element
Walking an array with foreach ($rows as &$row) wraps every element in a zend_reference. On a million integers that is 32 MB the loop never gives back.
OPcache, the JIT, and where time actually goes
OPcache removes compilation, not execution. The JIT reaches arithmetic-heavy code and little else. Where the remaining time lives.
Benchmarking PHP without lying to yourself
Microbenchmarks measure exactly what you tell them to, which is rarely what you meant. Method, noise, and the numbers worth reporting.