cranelift: Round inline stack probes down, not up #8397
+27
−20
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When we have
enable_probestack
turned on and setprobestack_strategy
to "inline", we have to compute how many pages of the stack we'll probe.The current implementation rounds our stack frame size up to the nearest multiple of the page size, then probes each page once.
However, if our stack frame is not a multiple of the page size, that means there's a partial page at the end. It's not necessary to probe that partial page, just like it's unnecessary to probe at all if the frame is smaller than one page. Either way, any signal handler needs to be prepared for stack accesses on that last page to fault at any time during the function's execution.