search for: xrayinstrumentation

Hi Dean, I've noticed that XRay in llvm\lib\CodeGen\XRayInstrumentation.cpp compares its threshold against Function::size() . However, Function::size() returns the number of basic blocks (as I understand, such as cycle bodies, if/else bodies, switch-case bodies, etc.), rather than the number of instructions. Was your intent to count the instructions instead? The name...

...ffectively behaves as a return instruction (isReturn = true) and wraps whatever the return instruction is, along with all operands -- this is used to replace the return instructions, and when lowered will unpack into the appropriate nop-sled-padded return sequence. We rely on a MachineFunctionPass (XRayInstrumentation) to observe IR functions with xray-specific attributes (function-instrument=xray-{always,never}, or xray-instruction-threshold=N), that then insert the pseudo-instructions to the machine instructions that get lowered appropriately. While lowering, we keep track of the instrumentation points marked...