Three synthetic Tast functions calling C: eight integers so two go on the
stack, and a callee that does a 16-byte aligned spill and answers -1 if it
was entered with rsp misaligned. The third calls it from inside a binary
operator.
The third fails. Alignment at a call site is not a property of the prologue
-- it is a property of how much the expression evaluator has pushed, and
the evaluator spills the left operand across the right one's evaluation. A
call in that right operand runs 8 bytes off. Nothing in the arithmetic tests
could see it, because they call nothing that spills a vector register.
This is the raylib failure mode exactly, and it is left red for one commit
so the record shows the probe found it rather than agreeing with the code.
Joseph Ferano
faba8a49f8