Wasmtime GitHub notifications bot (Jun 08 2022 at 06:50): Wasmtime GitHub notifications bot (Jun 08 2022 at 06:50):cfallin opened PR #4243 from fix-atomic-cas to main:
The current lowering helper for
cmpxchgreturns the literal RealReg
raxas its result. However, this breaks a number of invariants, and
eventually causes a regalloc panic if used as a blockparam arg (pinned
vregs cannot be used in this way).In general we have to return regular vregs, not a RealReg, as results of
instructions during lowering. However #4223 added a helper for
x64_cmpxchgthat returns a literalrax.Fortunately we can do the right thing here by just giving a fresh vreg
to the instruction; the regalloc constraints mean that this vreg is
constrained toraxat the instruction (at its def/late point), so the
generator of the instruction need not worry aboutraxhere.Fixes second issue reported by @bjorn3 in #4234.
cc/fyi @abrown, but I missed this in review (sorry!).
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Wasmtime GitHub notifications bot (Jun 08 2022 at 06:50):cfallin requested abrown for a review on PR #4243.
Wasmtime GitHub notifications bot (Jun 08 2022 at 06:50):cfallin requested fitzgen for a review on PR #4243.
Wasmtime GitHub notifications bot (Jun 08 2022 at 13:13):abrown submitted PR review.
Wasmtime GitHub notifications bot (Jun 08 2022 at 13:13):abrown merged PR #4243.
Last updated: Nov 22 2024 at 17:03 UTC