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cranelift-wasm: Fix reachability tracking for if .. else .. end
#1143
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We weren't previously keeping track of quite the right information for whether an `if .. else .. end`'s following block was reachable or not. It should be reachable if the head is reachable and either the consequent or alternative end reachable (and therefore fall through to the following block) or do an early `br_if` to it. This commit rejiggers `ControlStackFrame::If` to keep track of reachability at the end of the consequent (we don't need to keep track of it at the end of the alternative, since that is simply `state.reachable`) and adds Wasm tests for every reachability situation we can encounter with `if .. else .. end`. Fixes bytecodealliance#1132
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Thanks, I confirm this fixes all the pending wasm tests to add, as well as all the Spidermonkey tests that were passing before. I can review it, but @sunfishcode probably has a better preexisting understanding of this code, since he's reviewed the first batch of changes. |
sunfishcode
approved these changes
Oct 15, 2019
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Thanks! |
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We weren't previously keeping track of quite the right information for whether an
if .. else .. end's following block was reachable or not. It should be reachable if the head is reachable and either the consequent or alternative end reachable (and therefore fall through to the following block) or do an earlybr_ifto it.This commit rejiggers
ControlStackFrame::Ifto keep track of reachability at the end of the consequent (we don't need to keep track of it at the end of the alternative, since that is simplystate.reachable) and adds Wasm tests for every reachability situation we can encounter withif .. else .. end.Fixes #1132